MICHIGAN SEA GRANT COLLEGE PROGRAMARCHIVES jHicdQ-8-7Y-H/

by Lee H. Sorners8fld

Martin J. Nemiroffyp GRgp Michigan Sea Grant ~ ~ ~ ~ ~ MICHU-SG-79-603

HYPERBARIC CHAMBERATTENDANT'S HANDBOOK

revised j

TEE UNIVERSITY OF MICHIGAN

HYPERBARIC CHA%ERATTENDANT'S HANDBOOK

Revised 1978!

LEE 8 SOMERS g PH.D.

Department of Atmospheric and Oceanic ScienceDepartment of Physical Education

and

MARTIN J. NEMZROFF, M D.

Department of Internal Medicine, Pulmonary DivisionThe University of Michigan Medical School

December 1978

MZCHU-SG-79-603

Price: $8.00

Cover photograph by Jim Galbraith courtesy of Sligex Home Newspapers.

CONTENTS

General

Selected TerminologyUnits of Measure

1 2~ ~ ~ ~ ~

~ ~ ~ r ~

7

8

14

~ ~ ~ ~ 92 r

an Example~ r ~ r r ~

~ ~ ~ ~ r

15

1515

1616

17

27

28

2929

30

31

31

35

SECTION 1: INTRODUCTION

SECTION 2: THE HYPERBARIC CHAMBER FACILITIES

General

Description and Specifications ofHyperbaric Chamber

Pressure Vessels

Doors ~ ~ ~ ~ ~ ~ ~ ~ ~ rViewportsService/Medical LockPenetrations and FittingsU.S. Navy Pressure Test

Air and Gas Supply Systems

Low-Pressure Air Supply SystemHigh-Pressure Air Supply SystemChamber Air SupplyAir Supply RequirementsValve CalibrationAir Purity StandardOxygen Breathing SystemStop ValvesLine Pressure GaugesColor Coding and LabelingNoise Control

Equipment For Use in Hyperbaric Chamber

Electrical Equipment

Switches, Receptacles, and FittingsLighting SystemsService SystemsPower SystemEmergency Lighting/Power

Communication SystemsInstrumentation

Chamber Monitoring Equipme~tOxygen Monitoring EquipmentFire Extinguishing Equipment and AgentsChamber Heating and CoolingAutomatic Ventilation and Pressure

Control System

18

19202022

23

2425

2626

26

31

32

33

33

34

34

36

37

General

Personnel Requirements37

37

38

Tending the Patient 39

General

Oxygen Breathing39

40

Tending the Chamber 41

4l

4242

Pre-Dive Checklist

~ ~ r r

Systems

5152

53

53

54

GeneralHousekeepingPreventive Maintenance

Sanitation Equipment

SECTION 3: CHAMBER OPERATlON

Personnel Qualifications

Attendant ResponsibilitiesRegulator SettingsChamber VentilationEntering and Leaving the Chamber

During Treatment

Chamber s ~ ~ ~ ~ ~ ~ ~ ~ ~ ~Air Supply SystemExhaust SystemOxygen Supply SystemElectrical SystemCommunications SystemsFire PreventionMiscellaneous � Inside ChamberMiscellaneous � Outside ChamberPersonnel Assignments

Post-Dive Maintenance Checklist

Chambe r' ~ ~ ~ ~ i ~ ~ ~ ~ ~ ~Air Supply SystemOxygen Supply SystemElectrical and CommunicationsFire Prevention SystemMiscellaneous

Safety Precautions for Chamber OperationChecklist

Documentation and Records

SECTION 4: MAINTENANCE OF HYPERBARIC CHAMBERFACILITIES

45

46

46

47

47

47

47

47

48

48

4949

4950

50

50

PaintingFilters andViewportsDoors

54

54

54

55

~ ~ ~ ~ ~

Absorbers~ ~ ~

~ ~ ~

~ ~ ~

~ 0 ~

Pressurization and Pressure-Control Equipment 55

55

55

~ ~

~ ~

55

56~ 0

0

56

57

58

0 0

~ 0

~ 0

59

69

69

70

70

70

70

7l

During7l

72

72

Emergency Medical Kit 72

74

CompressorsCompressed-Air CylindersPressure Indicating and Regulating

DeviceS 0 ~ 0 ~ ~ ~ 0 ~ ~ ~ ~ ~Manual Valves

Fire PreventionAtmospheric Hazards and ConsiderationsChamber Cleaning and Sterilization

SECTION 5: THERAPEUTIC COMPRESSION.

General ~ ~ ~ ~ ~ 0 0 0 ~ ~ ~ ~ ~ ~ ~Patient ExaminationDecompression Sickness Pain Only!Decompression Sickness Serious SymptomsGas Embolism 0 ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ComplicationsGeneral Notes on Treatment of Gas Emboli

and Decompression Sickness.Carbon Monoxide PoisoningSmoke InhalationCyanide PoisoningGas GangreneDiscussion of Treatment TablesDrug. Therapy or Medical Adjuncts to

Therapeutic Compression

Low Molar Dextran

PlasmaHeparin 0 0 ~Steroids

DigitalisAminophyllinUse of Blood Pressure CuffPrecautions to be Observed

Chamber Treatment

Handling the Doubtful CaseTest of Pressure

Use of Emergency Medical Supplies

~ 0

~ ~

~ ~

!~ ~

~ ~

sm

~ ~

~ 0

~ ~

~ ~

~ ~

~ ~

595960

60

6l

6l

64

656666

66

67

Surface DecompressionOmitted DecompressionDiver Candidate Pressure and Oxygen

T es't o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~Pressurizing Personnel for Training

Demonstration

~ ~ ~ ~ 7 5

76~ ~ ~ ~ ~

Tolerance77~ 4 ~

and

~ o ~ e 78

~ ~ e ~ ~ ~ 8 1APPENDICES

Appendix A: Standard Air DecompressionTables and Repetitive DiveTables from U.S. Navy DivingOperations Handbook 81

Appendix B: Surface Decompression TablesFrom U.S. Navy Diving Manual . . 99

U.S. Navy Therapeutic CompressionTables for Decompression Sicknessand Gas Embolism . . . . . . . . 111

Appendix C:

U.S. Air Force Therapeutic Com-pression Depth/Time Profiles . . 121

Appendix D:

Ventilation Air Requirements forTherapeutic CompressionSchedules . . . . . . . . . . . 131

Appendix E:

Appendix F: Examination of a Diving Casualty 137

Forms e ~ ~ ~ ~ ~ a ~ ~ ~ ~ ~ 1 4 3Appendix G:

SECTION 6: ADDITIONAL USES OF HYPERBARIC CHAMBERS 75

SECTlON L

INTRODUCTION

GENERAL

Hyperbaric chamber facilities for human occupancy varyin size and complexity from simple two-compartment portablediving support units to multi-chamber hospital or saturationdiving complexes. Generally, Large facilities are individualin design and require specific manuals, procedures, andpersonnel training programs unique to that given facility.Although the smaller portable chambers commonly used to supportnon-saturation diving operations have some design variations,they are somewhat similar from a standpoint of sub-systemsconfiguration, operation, maintenance, safety precautions,and, consequently, personnel training. This handbook has beenprepared as a training and operational guide for small/portable hyperbaric chambers. Some topics are addressedin generalized terms. Naturally, this handbook must besupplemented with appropriate information unique to thedesign and operation of each facility.

Portable size chambers may be used on ships and bargesto support diving operations or, more or less, permanentlyinstalled at hospitals, research, or diver training facilities.The primary functions of these facilities are to provideemergency recompression treatment for diving accidents;provide surface decompression capability; support diverengineering and hyperbaric research; and/or to serve as aneducational aid in engineering, oceanography, diving andmedical courses. In addition, the hyperbaric chamber willbe used to treat casualties from pressurized construction/cassion work, aviation related decompression and suchmedical problems as gangrene, carbon monoxide poisoning, andsmoke inhalation.

Training programs for hyperbaric chamber attendants/operators has generally only been available at commercialdiving, military, and specific medical hyperbaric facilities.Recent developments in occupational safety and healthregulations necessitates the availability of approvedhyperbaric chambers and qualified operators in universityand research agency diving programs. Consequently, hyperbaricchamber personnel training materials and operational guidelinesare no required for an increasing number of non-military andnon-commercial diving programs.

This handbook has been prepared. to meet these requirements.In addition, when properly supplemented for specific chambersand operations, it may serve as a "safe practices" manual inpartial fulfillment of specified occupational safety and

health requirements.

U.S. Navy Diving Manual, Volume I: Air Diving NAVSHIPS0994-LP-001-9010!

U.S. Navy Recompression Chamber Operator's Handbook NAVSHIPS 0090014-5010!

Fundamentals of Hyperbaric Medicine Publication No. 1298,National Academy of Sciences/National Research Councill966; currently out-of-print!

Portions of this handbook are quoted directly from thesepublications to insure accuracy and proper procedures.

SELECTED TERMINOLOGY

Terminology and abbreviations used in this handbook arebased on those commonly used by divers and chamber attendants.

Actual cubic feet measured at a specific pressure ordepth.

acf:

acfm: Actual cubic feet per minute.

ASMZ: Refers to the American Society of Mechanical Engineers.

A measure of pressure expressed in terms of atmosphericabsolute includes barometric pressure!.

ata:

A measure of pressure equivalent to standard atmosphericpressure at sea level, 14.7 psi, 760 mm Hg, 33 fsw orl0 msw.

atm:

Bottom Time: The time interval between leaving the surfaceand beginning ascent back to the surface.

cf: Cubic feet.

cfm: Cubic feet per minute.

Chamber Supervisor: The person responsible for planning thepressurization, instructing the crew, making certainall necessary equipment is available and functioningproperly, taking all necessary precautions againstforeseeable contingencies, and is responsible forthe safety of the operation.

This handbook is a revised and expanded version of theoriginal Universit of Michi an. H erbaric Chamber Attendant'sHandbook. Et rs intended to serve as a convenient goads forcse rn operating a portable hyperbaric chamber and in thetreatment of diving casualties as well as an educational text.The primary sources of information for this handbook are:

Decompression: The reduction of environmental or ambientpressure to atmospheric pressure.

Decompression Chamber: A pressure vessel designed forcompression and decompression of personnel,experimental animals, or equipment.

Decompression Schedule: A time-depth profile with a specificbottom time and depth, for which a specific pressurereduction or decompression time sequence has beencalculated.

Decompression Sickness: A physiological condition with avariety of symptoms which may result from the formation ofgas or gas bubbles in the blood or body tissues of diversduring or subsequent to ascent or other pressure reduction.

Demand System: A gas-supply system that supplies gas onlywhen the user inhales.

DOT: Refers to the Department of Transportation formerlydesignated on cylinders as ICC!.

Filter: A device used in gas supply systems to removemoisture, oil, and particulate matter from thebreathing gas.

fpm: Feet per minute.

Free-Flow System: A gas supply system that supplies gas tothe chamber by continuous flow.

Hard Piping: Rigid permanent or semi-permanent piping, asdistinguished from temporary, flexible hoses.

High Pressure Air: Air supplied at a pressure in excess of500 psi.

Hyperbaric Chamber: A pressure vessel designed for compressionof personnel, experimental animals, or equipment topressures in excess of surface atmospheric pressure.

Hyperbaric Conditions: Pressure conditions in excess ofsurface atmospheric pressure.

low Pressure Air: Air supplied at a pressure of less than500 psi.

Maximum Working Pressure: The maximum pressure to which apressure containment device can be exposed underoperating conditions.

Neurological Decompression Sickness: Decompressio~ sicknessinvolving the brain, spinal cord, or nerves.

OSHA: The Occupational Safety and Health Administration.

Oxygen Cleaning: A special cleaning procedure to removecontamination in apparatus used in supplying oxygenunder pressure. This is a precaution used to preventoxygen related ignition or explosion.

Oxygen Compatibility: The ability of a substance to comeinto contact with high-pressure oxygen withoutignition.

Oxygen Service Equipment: Equipment or components whichstore or convey a gas having an oxygen concentrationaf 40% or greater.

Oxygen Toxicity: The adverse physiological response to anexcessive partial pressure of oxygen.

Partial Pressure: That portion of the total gas pressureexerted by a pazticular constituent of the gasmixture.

Personnel Lock: A chamber compartment through which person-nel pass from one air pressure environment to another.

Pressure: Defined as force per unit area. In diving,pressure denotes an exposure to greater than surfacepressure � ATA!.

psi: Pounds per square inch.

psia: Pounds per square inch absolute.

psig: Pounds per square inch gauge.

PVHO: Pressure vessel for human occupancy.

Receiver: A pressure vessel designed for the storage of gas.ln conventional operations this is generally a low-pressure reserve gas tank located between the breathinggas source and the chamber connection.

scf: Standard cubic feet or number of cubic feet of gasmeasured at a pressure of one atmosphere andtemperature of Oo F.

scfm: Standard cubic feet per minute.

Timekeeper/Recordkeeper: A person responsible for keepingpersonnel pressurization time and compiling theinformation required for the compression record.

Treatment Table: A time-pressure-gas profile which is calcu-lated to eliminate the symptoms of decompressionsickness'

UNITS OF MEASURE

Metric Unit,U.S. Unit

28.3l7 liters �!0.28317 cubic meters m !

1 cubic foot

0.0703 kg/gm270.3 gm/cm

1 psi

l atmosphere atm! 1.0133 bars

1.0332 Kg/cm760 mm Hg

Units of measure used in this handbook are generallyexpressed in the U.S. Customary System. The conversion ofcommonly used U.S. units to international metric! unitsis as follows:

SECTION 2

THE HYPERBARIC CHAMBER FACILITY

GENERAL

The hyperbaric chamber facility is a complex of pressurevessels and support systems designed to accommodate humansubjects/patients, experimental animals, and/or equipmentunder selected pressures greater than one atmosphere. Faci-lites can range in size and complexity from a compact, benchtype unit capable of accommodating a small experimental animalto a larger unit capable of maintaining several human occu-pants under pressure for several weeks. Some hospital unitswill accommodate a patient and a team of doctors, nurses, andattendants along with sufficient apparatus to perform complexsurgical operations. However, relatively simple moderatesized units are used for supporting routine non-saturation!diving operations.

The hyperbaric chamber facility for human occupancy willgenerally consist of the following units or systems:

l. One or more pressure vessels suitably connected;

2. Pressurization system primary and emergency!;

3. Piping system;

4. Air-flow controls;

5. Electrical system;

6. Communication system primary and secondary!;

7. Oxygen supply system;

8. Noise-suppression system;

9. Fire-control system;

10. Occupant/patient, comfort supplies bedding, etc.!;

ll. Gas analysis equipment; and

12. Temperature-humidity regulation system on larger units!.

Because of the wide diversity in physical size, systemdesign, and application, each of the above mentioned systemswill bear different emphasis in the different designs. Mosthyperbaric complexes are of individual design. Only thesmaller portable two-compartment chambers commonly used in

routine offshore diving bear similarity or some degree ofstandardization in design. It will be the purpose of thisdiscussion to provide a general description of the variousparts of the portable hyperbaric complex used in routine or non-saturation! diving operations. Such chambers areroutinely used for diver training, surface decompression,and hyperbaric treatment of decompression sickness/air embolism.For discussion purposes a description and specifications fora 54-inch double lock hyperbaric chamber will be given below.This chamber is representative of those used in the commercialdiving industry to meet the need for portability, corrosionresistance, operational simplicity, and economy. Academic/scientific divers will probably most often use this type ofchamber for field operations.

A phantom view of a two-lock hyperbaric chamber andgeneralized gas supply system are shown in Figures 1 and2.

GENERAL DESCRIPTION AND SPECIFICATIONS OF AN EXPd2'LEHYPERBARIC CHAMBER*

The chamber is a horizontal cylinder consisting ofan inner and outer lack, mounted on a substantial skid.

Dimensions

The chamber is 54" I.D. �371 mm! by 148" �759 mm!in length overall. The length of the inner lock is 98"�489 mm! and the length of the outer lock is 50" �270 mm!.The overall height is 68" �721 mm! and the weight of thechamber is approximately 5000 lbs. �272 kg!.

Certification

The chamber is inspected and approved by the AmericanSociety of Mechanical Engineers A.S.M.E.! and the U.SCoast Guard. Other certificatians are available as anoption.

The maximum operating depth of this chamber is 337 feetof sea water �00 m!, 150 psig �0 bar!.

*General specifications for the Model 72240 Double LockDecompression Chamber supplied by Saturation Systems, Inc.,4887-A Ronson Court, San Diego, California 9211.

4 4 ~

FIGURE l Phantom view of tow-3.oct recompression chamber From U.S. Navy Diving Manual!.

loner tock2. Outer Lock

Air Supply Theo Valve4. Air SuppfyOne ValvefL Main Lock Preaaure

Kquafizfng ValveL Exhauet-Vwo Valve7e ExtleuatOne ValveL Oxygen ftlanftoldL HeffuntOxfrgen

Menffokl1L Relief Valve4M peig11. flffedfcaf 4ek-f S

'1l ineft cffe.

1 2 Vfewportdnner lock �}12. Vfewporbouter lock �!14. Ug~ner loch 80

wa» �!1L Ugf~er lock M

«tatt �!1L TtenatnitteMeceiver {2!fr. Ie~2e-xeS"1 L Sencft1L Pteeaure Qage-

outahte �!2fL Preaatue Gage-

Inaftfe �!

FIGURE 2 Recompression chamber gas supply schematic From U.S. Navy Diving Manual!.

OuterLock

Oxg9en Cylfwith Ve,'res He-Ib Qylind~

«tie Velwe

ec ee

11

Two doors having a 30" �60 mm! diameter opening are pro-vided for series access from the deck to the outer lock tothe inner lock. Both doors utilize a half-inch 0-ring forsealing and are double hinged.

Handles

Handles are provided above each door on both sides tofacilitate entering and exiting the hatch.

View Ports

Four 8" �00 mm! o-ring sealed, pressure seating,conical acrylic view ports are provided, three in the innerlock, one in the outer lock. Internal retaining rings arestainless steel. Four tapped holes are provided externallyfor mounting shipping covers.

Surface Finish

The decompression chamber is sandblasted inside and outprior to painting and installation of fittings. Interior andexterior surfaces are painted with an appropriate epoxy coating.

Deck Plates

Corrosion resistant non-skid aluminum deck plates arei~stalled in each lock.

LiftincCnLu s

Two lifting lugs are attached to the top of the chamberfor the attachment of slings.

Penetrations

Twenty-one, 3000 psi {206 bar!, stainless steel, fullcouplings up to one inch NPT are installed. Spare penetra-tors are plugged on both sides with NPT plugs.

All piping is hydrostatically tested to 1.5 times themaximum working pressure. All valves and fittings are ofbrass and tubing is of copper except for an external PVCexhaust duct. All piping is cleaned for oxygen service andleak tested 110% on air after assembly.

Air Su 1 S stem

Outside controls are provided for both locks. Two3/4" supply connections with check and selector valves

12

are installed. with a 2-1/2" �4mm!, 0-400 PSI�-30 bar! pressure gauge indicating on-line pressure.

All piping is color coded with black epoxy paint. Airsilencers are provided internally and all valves are ballvalves.

Outside controls are provided for both locks.Air silencers are fitted inside and out. One inchpiping and ball valves are utilized in the exhaustsystem.

De th Monitorin

A six inch diameter Roylyn 1/4% accurate depth guageis provided for each lock externally. Calibration in feetof sea water or meters of sea water is to be specified bythe customer. External needle valve hull stops andcross connections are provided so that gauges can be reachedagainst each other for accuracy. Piping is color codedyellow.

Inside Control S stem o tional!

Air supply consists of 3/4" ball valves and pipinginside and out for both locks with air silencers installedinside. Exhaust utilizes a bilge exhaust tube in eachlock, 1" ball valves inside and out, and a 1" JICconnection externally. Depth monitoring is provided bya 6" c aisson g auge in each lock optional! . Pipingcolor coded as above.

BIBS Su 1 S stem

Double needle valve hulL stops with soft seats areprovided in each lock. Internally a manifold is providedwhich allows connections of up to four masks. A checkvalve is provided on the supply connection and all BIBSsupply piping is color coded green. BIBS masks areavailable as an option!.

BIBS Exhaust

Double ball valve hull stops are provided in eachlock. Internally a four station manifold is providedfor the connection to the mask. All piping is colorcoded with silver epoxy paint.

Fine Decom ression/Sam le S stem � tional!

Single needle valve hull stops are provided externallyin each lock. Piping is color coded w'th silver epoxypaint.

13

Relief Valve S stem

A ball valve hull stop and relief valve are providedin the inner lock. The ball valve provides the abilityto override a relief valve in the event of failure. Allpiping is color coded with silver epoxy paint.

E ualizin S stem

On the internal head separating the inner and outerlock a ball valve is provided in the outer lock whichallows equalizing of the two locks. A silencer isprovided in each lock.

Electrical S stem

All electrical components mounted externally of the cham-ber are of a weatherproof type. Fuse overload protection isprovided for all power circuits.

Intercom S stem

A weatherproof battery powered communication systemwith a frequency response from 300 Hz to 12,000 Hz isprovided. input is provided from an open speaker andthe BIBS masks in each lock. The operator may utilizean open speaker or a boom-mic headset in the push-to-talk mode.

Sound Powered Communication S stem

Sound powered communication handsets are providedin each lock and at the operator's station.

Electrical Penetrators

Electrical penetrators are four-conductor bulk-head penetrators with a design working pressure of1000 PSI �9 bar!, not a stuffing tube.

Chamber Li htin

Chamber lighting is provided by low voltage externalbulbs placed in front of a port. Power inputs are avail-able for 220 or 110 volts AC, 50 or 60 Hz.

Documentation

Saturation Systems, Inc. shall supply two copies ofeach of the following:

A Recommended Spares List designed to cope with typicalcomponent failures due to wear and damage.

Certi icates of approval.

Drawings pertinent to installation and maintenance.

Some of the above such as chamber lighting, the intercomand BIBS exhaust may be listed as optional by the manufacturer;however, they should be included for safe chamber operations.Zn addition, many manufacturers will supply the followingoptional equipment:

l. Special oxygen mask,

2. Fold-up bunk,

3. Fire retardant mattress/bedding,

4. Medical lock,

5. Special lighting systems,

6. Oxygen monitor,

7. C02 scrubber,

8. Temperature control system,

9. Timers, and

10. Door dogs.

PRESSURE VESSELS

The central component of a hyperbaric chamber facilityis the pressure vessel. For most efficient structural design,pressure vessels are normally made either cylindrical, orspherical in shape. Cylindrical vessels usually have dishedheads at the ends. Vessels for this general research servicemay be either of the single or multiple compartment varieties,depending upon their application. In accord with safety andhealth standards, pressure vessels for human occupancy mustbe at least two-compartment or lock models. Large hyperbaricchamber complexes may have three or more compartments.

Any pressure vessel designed for human occupancy usinggas other than pure oxygen under pressure must have at leastone compartment designed for a minimum working pressure of6 ata. This is mandatory to permit, the treatment of casesof decompression sickness and air embolism in accordancewith standard practices developed and established by theU.S. Navy.

Design of the chamber should conform throughout toSection VIII of the American Society of Mechanical Engineers ASME! Boiler and Pressure Vessel Code � Unfired PressureVessels' Hyperbaric chambers used on diving operations

covered by Subchapter V, Marine Occupational Safety and HealthStandards, Part 197-General Provisions, Subpart B, CommercialDiving proposed Rule, Federal Register 0 42 FR 58716!Department of Transportation, U.S. Coast Guard must complywith Section VIII Division I or Division 2, and PVHO-1 ofthe ASIA Code. In addition, specific requirements aredesignated in Part 197. Rules/standards established by thestate and municipality in which the hyperbaric chamberfacility is located concerning pressure vessels and supportequipment must also be complied with. In addition, theU.S. Navy has specific specifications for hyperbaric chambersused in military service.

The ASME Codes clearly specify both the method of designand the method for testing pressure vessels for structuralintegrity. The standard hydrostatic pressure prescribedfor this test is 1.5 times the design working pressure. Inaddition, the qualification of service inspectors and periodsand methods of inspection are also specified, based uponthe type of service and method of installation.

Doors

All chamber doors or hatches! should preferably sealwith pressure to prevent accidental opening when the chamberis pressurized. The doors seal against a rubber 0-ring orgasket. This o-ring must be periodically lubricated with asilicone compound to reduce deterioration drying! and retainsealing effectiveness. The o-ring should be inspected priorto each use to insure it is properly in place.

The doors should be fitted with a locking or retainingdevice to stabilize the door and prevent potentially damagingmovement during transport. On some chambers the doors may alsobe "dogged" or locked closed at the start of pressurization;however, the locking device should be released as soon as apressure seal is achieved. All installed man-way door lockingdevices must be designed so they can be operated from bothsides of a closed hatch.

Each chamber compartment must have at least one viewportthat allows observation of any occupant from the outside.Generally, pressure setting, o-ring sealed acrylic viewportsare provided. Acrylic ports must meet the requirements ofPVHO - 1 of the ASME Code. Portable chamber viewports shouldbe fitted with removable external covers for protection duringtransport.

Service/Medical Lock

Some chambers are equipped with a small service or pass-throughlock so that food, body waste, medical supplies, equipment andinstruments may be passed into or out of the chamber without

16

using the main access locks. It should be recognized thatthe service lock must be equalized so that the pressure insidethe lock is equal to the pressure on the opening side beforethe door is opened. Vents must be provided on both sidesof the lock for this purpose, and some units are designedwith an interlock between the venting mechanism and the door-opening mechanism. Unlocking a door with pressure behind itcan cause a serious accident.

Penetrations and Fittin s

During the design of the chamber, a certain number ofpenetrations for piping and electrical services will berequired. Additional capped-off penetrations should beprovided. During the life of the chamber additional serviceinstallations may be required, and the difficulty of providingadditional penetrations should be avoided if possible. Interiormounting pads and clips should be provided. in the designof the vessel to eliminate the need for later welding. Sinceno general recommendation as to the number needed can be made,it is suggested that the designer and operator determinethese needs on a basis of intended use for each facility.

U.S. Na Pressure Test

In accordance with recommendations made by the U.S. Navya periodic pressure test must be conducted on recompressionchambers when they are initially installed, moved and rein-stalled, and at five-year intervals at a given location. Thetest is to be conducted as follows:

1. Pressurize inner compartment to 100 fsw. Usingsoapy water or an equivalent solution, leak-test all shellpenetration fittings, viewports, hatch seals, hatch dogs, valveconnections, pipe joints, and shell weldments.

2. Nark leaks. Depressurize compartment and adjust,repair, or replace components as necessary to eliminate leaks.

a. Viewport leaks: Remove viewport gasket replace ifnecessary!, wipe clean and. lubricate with appropriatelubricant. When reinstalling viewport, tighten retain-ing ring bolts until the gasket just compresses e~venlabout. the viewport. Do not compress the gasket.

b. Weldment leaks: Repair in accordance with applicablerequirements for unfired pressure vessels. Consultthe chamber manufacturer or a local representative forspecific instructions. Following weldment repairs,the chamber must be hydrostatically tested permanufacturer's specifications for recertification.Special instructions for hydrostatic testing arealso available from the U.S. Navy Experimental DivingUnit.

17

3. Repeat steps 1 and 2 until all leaks have been eliminated.

4. Pressurize compartment to chamber's maximum designpressure not hydrostatic pressure! and hold for five minutes The pressure should be stabilized at the specified depthrelative to ambient temperature prior to starting test time.! .

5. Depressurize compartment to 165 fsw. Hold for onehour. Xf pressure drops below 145 fsw, locate and mark leaks.Depressurize chamber and repair leaks in accordance with step2 above and repeat this process until final pressure is at least145 fsw The pressure should be stabilized at the specifieddepth relative to ambient temperature prior to starting testtime.! .

6. Repeat steps 1 through 5 leaving the inner door openand outer door closed. Leak test those portions of the chambernot previously tested.

AIR AND GAS SUPPLY SYSTEMS

The safety and comfort of the occupants of a hyperbaricchamber depend upon adequate and reliable air/gas supplysystems. The air supply system should be designed to accomplishthe following objectives:

l. Have a ready source of supply to bring the chamber fromatmospheric pressure to the operation pressure in areasonable period of time. The U.S. Coast Guardspecifies a minimum pressurization rate of 2 ATA �6 ft!per minute to 60 fsw �8 msw! and at least 1 ATA perminute thereafter. Some authorities state that achamber facility should have gas capacity and flowcapacity sufficient to pressurize the treatment inner!compartment, from 1 ATA to 6 ATA in a period not toexceed 2 minutes.

2. Have an adequate capacity to ventilate the chambercontinuously at a satisfactory rate at the appropriateworking pressures. For the analysis of "satisfactoryrate," the following criteria apply:

a. The total percentage of oxygen in the chamber atmos-phere should not exceed 25 percent under anycircumstances.

b. The total partial pressure of carbon dioxide shouldnot exceed 10 mm Hg under any circumstances.

c. The concentration of other atmospheric contaminantsshould be maintained within acceptable values forsafety, health, and general occupant comfort.

18

3. Have a sufficient high-pressure reserve supply to beable to bring the chamber from atmospheric pressureto the operating pressure a minimum of two timeswithout additional charging of the high-pressuresystem supply. The U.S. Navy specifies that thesecondary emergency! air system be of sufficientcapacity to pressurize the chamber once to 165 fsw� ATA! and ventilate for one hour. At the Universityof Michigan an effort is made to maintain 5500 to6000 scf of air in high-pressure reserve. This issufficient for a complete treatment of a singlepatient on a Table 6A with one attendant using theinner lock only and. overboard oxygen discharge.

4. Have a minimum pressurization rate of 2 ATA per minuteto 60 fsw and at least 1 ATA thereafter and have adecompression rate of 1 ATA per minute to 33 fsw U.S.C.G. requirement!.

Low-Pressure Air Su 1 S stem

A low-pressure air supply system for a chamber facilitymay consist of one or more continuously running low-pressurecompressors. The system should consist of the compressorfitted with inlet air filters, mufflers as required, pressurerelief valves, pressure-regulating valves as required, anaftercooler and appropriate water/oil separators, traps, andfilters.

Low-pressure compressozs are available in either oil-lubricated or non-oil-lubricated types. Since oil in theatmosphere of a hyperbaric chamber is undesirable, non-oil-lubricated compressors are highly preferable. If oil-lubricatedcompressors are used, they must be equipped with adequate oilseparators to remove oil from the air before it is suppliedto the chamber. The use of an in-line total hydrocarbondetector is a desirable feature for detection of oil vaporin the air line. However, this device is seldom used withsmall hyperbaric chamber systems. Attendants must be alertfor oil odor and periodic inspection of air siliencerswill reveal residue oil.

The discharge of the compressor should lead to an airreceiver or volume tank. A large volume tank will facilitaterapid, initial pressurization rate and serve as additionalmechanism for condensing removing! moisture/oil dropletsfrom the air. The volume tank must be routinely drained.From the volume tank, the air will go to the chamber viasuitable flow- and pressuze-control systems.

Since compressed air can not be stored efficientlyat low pressure, no storage other than the very smallamount in the receiver is provided, and the compressorwill generally run continuously during periods of chamber

19

ventilation. A check valve should be provided between thecompressor system and the chamber complex to prevent backflowin the event of compressor failure or line breakage.

Hi h-Pressure Air Suvpl System

When a low-pressure system is used, a backup high-pressure system should be provided. High pressure in thisinsta~ce would generally be from 2000 to 3500 psi. Sufficientair should be stored in cylinders to supply at least twofillings of the chamber to maximum operating pressure.However, more realistically enough air should be held inhigh-pressure reserve to successfully complete a Table 6Atreatment one patient/one attendant; overboard oxygendischarge!. This calls for a storage capacity of 5500 to6000 scf ~ The U.S. Navy requires sufficient secondary airsupply to pressurize the chamber once to 165 fsw � ata!and ventilate for one hour. This requirement may becalculated as follows:

C = 6V + 2160s

where, C = total capacity of secondary system in standardcubic feet, V = chamber volume in cubic feet, 6 = atmosphereequivalent of 165 fsw absolute!, and 2160 = standard cubicfeet of air required for maximum ventilation rate givenhere as 36 scfm for 1 hour assuming one sedate patientand one active attendant with an overboard oxygen dischargesystem!. Naturally, this figure will be dependent on thenumber of personnel and type of oxygen system. The U.S.Navy bases their calculations on two patients, one attendant,and no overboard discharge system. Therefore, the ventilatio~reauirement at the 60 fsw oxygen breathing rate is 140.7scfm or a one hour requirement of 8442 scf of air.

The air for the high-pressure system may be purchasedin cylinders and piped to the system, or a compressorcapable of delivering a suitable volume of air at themaximum storage pressure of the system may be used tocharge a system of storage cylinders. In the event thata compressor is installed, it should be fitted with anintake filter and muffler, an aftercooler, and a dischargeseparator and filter to remove vapors and water from thecompressor discharge. The compressor will discharge airto t: he storage cylinders. As in the case of low-pressurecompressors, the presence of oil in the compressor dischargemust: be avoided.

Air from the high-pressure system shall be carried tothe mains supplying the chamber complex through a reducingstation regulators! that reduces the pressure to a suitablevalue above maximum chamber operating pressure. Two reducingregulators in parallel, each capable of full system flow,are desirable. The air supply regulator s! should be set

20

to maintain a minimum supply pressure of 50 psig over themaximum chamber pressure. A setting of 350 psig is consideredideal for air supplied from high-pressure air banks. However,all piping/hoses, fittings, and valves carrying this airmust have a working pressure equal to or in excess of theregulator pressure.

Chamber Air Su 1

All air should be supplied to the chamber service valvesat a pressure suitably above the maximum chamber operatingpressure. Each lock of the chamber must have a manuallyoperable supply valve, operated from the outside forpressurizing and ventilating lock. In addition, controlscan be provided to permit the personnel in the chamber tocontrol the rate of pressurization and the ventilation rate.In this instance, the controls inside the chamber must becapable of being overridden by controls on the outside.

Zf automatic pressure and ventilation control is to beprovided, provision should be made for manual override ofthe automatic system. Manual override in this instanceshould not depend upon an outside power source for itsoperation. Automatic controls are seldom used on portablechambers.

Chamber exhaust should be constructed for operation ina manner similar to the inlet system, permitting exhaustcontrol by either attendants on the outside, by personnelon the inside, or by automatic means. Final manual controlmust he outside. The exhaust. from all of the locks of thechamber complex should be run to a vent stack. Insideexhaust lines must be fitted with a suction guard. Eachlock of the chamber must be supplied with a relief valvein conformance with the ASME code requirements. In addition,drain valves in the bottom of each chamber are suggestedas an aid in wash down. Drains should be run to a suitablesump. Metal damage-control plugs should be installed inthe drain outlets, and be in place at all times exceptwhen washing down.

Air Su 1 Re uirements

The U.S. Navy recommends hyperbaric chamber treatmentfacility have a primary and a secondary air supply systemwhich satisfy the following requirements:

Primary � sufficient air to pressurize the chamberto 165 fsw and ventilate through a completetreatment.

Secondary � sufficent air to pressurize the chamberonce to 165 fsw and ventilate for one hour.

Either system may consist of air banks or a suitable compressoror both. Chamber operators using high-pressure primary air

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Primary System Capacity for chamber not equippedwith an overboard oxygen discharge system; assumingtwo patients and one tender in the chamber!.

C = 12V + 58,757P

= total capacity of primary system standard cubic feet!

where, CP

V = chamber volume cubic feet!

12 = atmospheres equivalent for 165 fttimes 2 pressurizations absolute!

58,757 total air required to ventilate duringa Table 4 treatment scf!

Table 7, reproduced from the U.S. Navy RecompressionChamber Operator's Handbook, gives data concerningthe ventilation rates and total air requirementsfor two patients and one attendant undergoing recom-pression treatment. As indicated, the maximum airflow rate that. the system need deliver is 140.7 scfm�2 stop at 60 ft!.

2. Primary System Capacity for chamber equipped withan overboard oxygen discharge system; assuming onepatient breathing oxygen and one attendant breathingair in the chamber! .

C ~ 12V + 33,825p

where, 33,825 total air required to ventilateduring a Table 4 treatment scf!

Table 8 gives data concerning the ventilation ratesand total air requirements for one patient and oneattendant undergoing recompression treatment in achamber equipped with an overboard oxygen dischargesystem. As indicated, the maximum air flow rate thatthe system need deliver is 3S.9 scfm �6S ft stop!.Table 9 gives data for air requirement in a chamberwithout the overboard discharge system.

3. Secondary System Capacity for chamber not equippedwith an overboard oxygen discharge system; assumingtwo patients and one attendant in the chamber! .

C = 6V + 8,442

supply systems must be able to calculate air requirementsfor use with various tables to insure that sufficient airis maintained for treatments The required total capacityis calculated as follows:

22

where, C = total capacity of secondary system scf!p

V = chamber volume cf!

6 = atmospheres equivalent of 165 ft a!

8,442 = maximum ventilation rate of 140.7scfm for l hr.

4. Secondary Supply System for chamber equipped withan overboard oxygen discharge system; assuming onepatient breathing oxygen and one attendant breathingair in the chamber!.

C = 6V + 2,160

where, 2,160 ~ maximum rate of 36 scfm for l hr.

internal volume for most cylindrical chambers:

V = chamber volume, cf ~ 0.00046 D2Lc

V = inner compartment volume, cf = 0.70Vi c

V ~ outer compartment volume, cf = 0.30 V0 c

wher e, D = inside diameter o f shell, inches

L = overall length of chamber, inches

Valve Calibration

The standard procedure for determining volume ventilationis to open the chamber exhaust valve a given number of turns or fraction of a turn!, which provides a given number of cubicfeet of ventilation per minute at a specific chamber pressure.Constant chamber pressure during the ventilation period is thenmaintained with the air supply or control valve. To calibratethe exhaust valve, use the following procedure:

l. Mark the valve ha~die to facilitate relativelyaccurate determination of the number of turns andfraction of turns.

2. Compute the rates of ventilation at various depthsthat are commonly needed in treatment. Zf the airsupply is ample, determination of ventilation ratesfor 30, 60, l00 and l65 ft may be sufficient, becausethe valve opening specified for a given flow at onedepth will provide at least that much at a greaterdepth. It will be convenient to know the valvesettings for rates like 30, 60, or 120 cfm becausethese give a simple relationship between volume and

23

time. Be certain to use settings for ventilationrates required at 30 and 60 foot stops that arecompatible with the chamber and normal number ofoccupants.

3. Determine the necessary valve settings for theselected flows and depths by using the chamber itselfas a measuring vessel and a stopwatch for timing.

a. Calculate the time required to change thechamber pressure by 10 ft if the exhaust valvesetting were allowing air to escape at thedesired rate close to the given depth. Usethe formula:

T = Vx 20

where, T = time in seconds for chamberpressure to change 10 ft.

V ~ internal volume of compartmentbeing used for test cf!.

R = rate of ventilation desired incfpm as measured at chamber pressure.

P = chamber pressure gauge! in feetof sea water.

b. Pressurize the empty compartment to 5 ft. beyondthe given depth. Open the exhaust valve a certainamount and determine the time required for achange of 10 ft. For example, if checking fora depth of 165 ft, pressurize to 170 ft and clockthe time required for decompression to 160 ft.Repeat the procedure while varying the valveopening until you determine what setting willprovide a rate closest to the calculated time.Calculate times for other rates and depths anddetermine settings in the same way. Make achart or table of valve settings.

This procedure is difficult with L/4-turn ballvalves used on many civilian chambers. Areference template may be required on the valve.

Air Purit Standard

The quality of air supplied to the chamber shall conformto reasonable and acceptable safety standards. The followingU.S. Coast Guard specifications are recommended as a minimumstandard for field operations:

Oxygen: 20 to 22% by volume or normal atmospheric!

Carbon Dioxide: maximum l000 parts per million

Carbon Monoxide: maximum 20 parts per million

Solid/liquid particulates including oil!. 5 milligramsper cubic meter

Hydrocarbons includes methane and all other hydrocarbonsexpressed as methane: 25 parts per million

A routine air testing program should be established andequipment should be available at the chamber for carbonmonoxide analysis.

Ox en Breathin S stem

Chambers for human occupancy should be provided withauxiliary sources of gas supply. Piping systems insideeach chamber compartment should be supplied for pure oxygenfor therapeutic and decompression use. The systems shouldbe sized to permit a flow at least equal to the maximumdemand of all persons occupying the chamber inspiringsimultaneously. A sufficient oxygen supply must be avail-able; at least l500 scf is recommended. In addition, pipingsystems for compressed air must be provided with multipleoutlets in each chamber. Properly fitting masks with demandregulators should be supplied in each compartment in quantitiessufficient for the total number of occupants, and sparesshould be provided in reasonable quantity. In some largechamber complexes a special breathing-air piping system isprovided for use in the event of fire-contaminated. atmosphereand for general purposes. In addition some chambers arepiped for the use of helium-oxygen and/or nitrogen-oxygenbreathing mixtures by mask. Adequate flow rate throughreducing valves to insure adequate supply to the compartmentsshould be assured in the design phase. Placing reducingvalves inside the chamber provides automatic regulation ofover-ambient pressure.

A hyperbaric chamber may be equipped with both standardand overboard discharge type oxygen breathing masks. Thestandard type oxygen mask consists of an oral-nasal mask,demand regulator for oxygen supply, and appropriate hosesand fittings. Exhaust gas is discharged directly into thechamber. Oxygen breathing mask with an overboard dischargesystem consists of the same basic components as the standardmask with the addition of a mask mounted vacuum regulatorand appropriate hoses and fittings to exhaust the exhaledbreath.

The cylinder pressure oxygen is reduced to approximately75 psig by a pressure regulator. This low pressure oxygenflows through a lightweight, flexible hose to a demandregulator located on the mask. A control knob on the demand

25

regulator allows adjustment of flow in order to minimizebreathing resistance or permit constant flow if desired.Oxygen delivery pressure may also be adjusted by the outsideattendants to enhance flow characteristics.

In the overboard discharge units, the diver's exhalationis removed through a regulator mounted on the left side ofthe mask. The regulator exhaust is connected by hose to theoutside of the chamber. ' For a pressure differential inexcess of 60 fsw, a second vacuum regulator must be connectedbetween the hose and the chamber wall to limit the differentialpressure at the outlet of the mask mounted regulator. Aninterlock valve is an integral part of the system. Thissafety device shuts off the vacuum should a supply pressureloss occur. Do not ressurize the unit to a depth greaterthan 60 ft unless it is fitted with an auxiliary vacuumregulator or the discharge hose has been disconnected forthe external exhaust port.

These units should be inspected for unrestricted opera-tion by the attendant prior to each use. The hose fittingsare inserted into properly labeled connectors on the wall ofthe chamber. After testing, the internal and external valvesare closed until oxygen is required.

The mask must be cleaned with an antiseptic solution antibacterial soap and warm water, alcohol, sterilizingagent, etc.! after each use and stored in a sealed plasticbag. Routine inspection and preventive maintenance arerequired annually or when malfunction is evident. Generallyinspection and repa' r service are provided hy the manufactureror his local representative. Manufacturer's instructionmanuals included with each mask should be consulted forfurther information. Such manuals are to be retained at thechamber facility for immediate access.

All oxygen system components must be designed and appro-priately cleaned for oxygen service. Oils and lubricants canignite in the presence of higher pressure/percentage oxygenwith disastrous consequences. Xn addition, NO SMOKING signsare to be displayed in oxygen storage areas and at thechamber location. Smoking shall be strictly prohibited.

Stop valves should be installed on the exterior of thechamber hull for all gas lines when chamber controls arelocated at a remote console. These valves must be appro-priately labeled and accessible to operations personnel.Over-pressure relief devices should be fitted with a ball-type stop valve between the hull and the relief device tofacilitate manual control in the event of relief devicemalfunction.

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Line Pressure Gau es

On-line and stand-by gas bank pressure gauges shouldbe installed in the immediate vicinity of the chamber controlstation. lf not, provisions should be made in operatingprocedures for routine periodic checks on available bankpressure. The primary gas supply line-pressure gauges shouldbe installed at the control station within the chamberoperator's field of vision while operating supply controlvalves.

Color Codin and Labelin

All lines should be identified and labeled to indicatefunction, content, maximum pressure, and direction of flow.The following U.S. Navy color coding system is frequentlyused.

Color

AI.P/AHP

02

He-02

BuffHe

In addition a schematic of the chamber piping/gas supplysystem should be posted for operator reference purposes.

Noise Control

When air is moving at high velocity, the turbulence inthe air results in high noise levels. Suitable mufflersinstalled at points of large air-pressure drops may berequired to reduce the noise. These mufflers must beperiodically inspected and cleaned to insure that hazardousoil deposits do not accummulate. For inlets that areintermittent or used for pressurization only, higher noiselevels may be permitted. For continuous operation, a noiselevel below 80 decibels should be attained.

Ear protectors should also be provided for all occupants,especially those exposed to chamber noise levels on a routinebasis. Small vent holes must. be drilled in each ear pieceto insure prevention of external ear squeeze.

Air low/high pressure!

Oxygen

Exhaust

Nitrogen

Helium-Oxygen Mix

Helium

Black

Green

Silver

Light Gray

Orange

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EQU IPMENT FOR USE IN HYPERBARIC CHAMBERS

Safety is the prime consideration in the design andselection of equipment for use in hyperbaric chambers. Seriousfires have taken place in both hyperbaric and altitude chambersfor a variety of reasons, and. each may be traced to a priorhazardous condition. With increased size, number, and com-plexity of instruments involved in medical hyperbaric chambers,hazardous conditions may be introduced unless meticulous careis paid to the nature of every material and the design ofeach piece of ecuipment used. Broadly speaking, equipmentwith excessive heat output, with exposed leads and connectionsthat might spark or short-circuit, or that may burn andrelease toxic products or dense smoke should be consideredas potential hazards. The use of lubricants, equipmentrequiring oil or grease lubrication, or oil-filled hydraulicequipment requires careful consideration. Oil and greaseare known to ignite spontaneously in the presence of highoxygen concentrations.

Another source of hazard is the introduction of volatilesubstances in a hyperbaric chamber. Volatile anesthetics,hydrocarbons, alcohols, and many other chemicals can produceconditions that lead to either flash fires or toxic hazards.

Equipment that is not vented or that is affected byvariations in chamber pressure should be viewed with concern.Light bulbs, vacuum tubes, ampules, closed cans and bottlesall have the capability of imploding or exploding with pres-sure variations where slow leaks cannot relieve the pressuredifference in slowly venting devices.

Equipment reliability must be evaluated because therepair and replacement of equipment or parts will beextremely difficult, if not impossible, under operatingconditions. Where necessary, standby systems should beprovided for all vital equipment. In the repair of devices,no temporary make-shift repairs should be allowed. Repairpersonnel should be fully aware of the use of such equip-ment and the types of hazards to be guarded against.

A small test chamber, able to withstand several timesthe pressure of the main hyperbaric facility and to containcomponents to be used in the main facility, is a usefuladjunct to the hyperbaric facility in checking, underoperating conditions, the suitability of equipment to gointo the main chamber.

Floor area should be conserved to a maximum degreeto allow free access to all parts of the chamber, and equip-ment should be designed to use the vertical dimension tothe fullest possible extent to minimize the use of thelimited floor space. Permanently installed equipment shouldbe accessible at. all times, so that fire or other potential

28

hazards may be instantly coped with. Electrical leads andpiping runs should be kept close to the walls or ceilingand out of the way of passages and. walking spaces.

Underwater technologists have been developing equipmentto withstand submergence in the ocean for long periods oftime at great depth. Television and other types of cameras,as well as detecting and recording equipment for otherpurposes, have been developed, tested, and have provenacceptable under pressure. When selecting equipment foruse in hyperbaric facilities, some equipment suitable foruse in the ocean depths may prove applicable to the problemand should be considered for use in hyperbaric chambers.

This section discusses the various equipment necessaryin hyperbaric facilities and their safety and operatingfeatures under hyperbaric conditions.

Electrical E ui ment

The use of electrical equipment and electrical systemdesign will vary considerably with the size, type, location,and application of the chamber. With the exception of lowvoltage communications wires � to 12 volt systems!, smallor portable chambers are generally equipped with externalelectrical systems. On the other hand, large chambercomplexes, especially those used for medical purposesor saturation diving operations, may have considerableinside electrical wiring requirements. A wiring/electricalsystem diagram should be available to operations personnelat the chamber location.

The electrical supply available to these chambercomplexes should be an ungrounded system, with allenclosures and conduits grounded to the chamber as specifiedin Sections 517-1 to 517-9 of the National ElectricalCode or other appropriate codes.

An approved type of ground detector including visualindication and an audible alarm should be installed to monitorcontinually the circuits in the chamber. The reason for anungrounded system is that if one wire of the circuitbecomes grounded for any reason, no short-circuit sparkswill result. The circuitry on the outside of the chambercan be a grounded system.

All external electrical installations shall conform to theapplicable sections of the Standard of the National Board ofPire Underwriters for Electrical Wiring and Apparatus asrecommended by the National Fire Protection Association. Allequipment supplied shall be in accordance with NET standards.Other codes shall apply where applicable.

Switches, Rece tacles, and Fittin s. Electrical codesmay be quite specific far certain chamber complex applications.This is especially true for large medical application chambercomplexes. The National Electrical Code specifies thatequipment in atmospheres containing combustible anestheticsfalls in group C of Section 500-2 of the code, and it, isnecessary that equipment be approved not only for the classof location but also for the specific gas, vapor, or dustthat will be present.

Li htin S stems. The large chambers should have ageneral lighting system capable of supplying 60-l00 footcandlesof general illumination. All internal lighting fixtures shouldbe permanently installed and of the enclosed type. All generallighting shall be controlled from outside the chamber.

In addition, lights permanently installed in the chamber,should be pressure tested to a minimum of two times theintended maximum working pressure.

Portable and small chambers are often equipped withexternal lights which illuminate the chamber through view-ports. The U.S. Coast Guard requires a general interiorillumination level of at least 2S foot candles with 50 footcandles over bunks and in work areas. External lighting isconsidered the safest method of chamber illumination.However, care must be taken to avoid application of excessiveheat to acrylic viewports. High intensity reflector-typebulbs can produce sufficient heat to melt acrylic plasticif they are placed too close to the viewport. Properpositioning and a periodic "touch test" are necessary.The lighted viewports should not be significantly warmerthan non-illuminated viewports.

Internally located light sources are the traditionaltype and are still the most frequently encountered in U.S.Navy and large civilian chambers. They can be the leastcostly since for low-pressure chambers using normal aircomposition, small, relatively inexpensive, pipe-sizedstuffing tubes can serve to pass the electrical conductorsthrough the hull. In many cases commerically available-components, originally intended for other purposes, are usedfor asembling in-board systems. Some highly refined systemsof this basic type are successfully used at high pressureswith mixed gases. These systems use custom-fabricatedfixtures, special high pressure lamp enclosures, mi~eral-filled electrical conduits vented outboard, and otherwell-engineered, built-in safety precautions.

Light sources external to the chamber range from assimple a device as a spotlight directed through a largeviewport to one as sophisticated as an acrylic light pipeor fiberoptic system utilizing small pipe-sized penetrations.

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The standard Navy aluminum, double-lock recompressionchamber, was designed for 100-psi maximum operating pressureand for utilizing an internally located incandescent lampsystem. This system uses a standard Navy, clear marinenavigational light enclosure inside of which a 115-volt ACdouhle-filament lamp is located. A specially designedbase is provided so that a pressure-tight seal is obtainedwith the hull.

Commercial proprietary acrylic light pipe ALP!systems are available, for example, the Perry cold lightsystem and the Canty HYL-250 pressure vessel light.

The Perry cold light system is marketed by PerryOceanographics, Riviera Beach, F1orida, for use in therecompression chambers they manufacture. This systemconsists of a low voltage power supply to drive an externallylocated high intensity bayonet base lamp and an acryliclight pipe assembly. The acrylic light pipe is mushroom-shaped on the inboard side for efficient light distributionand has a 1-inch NPT male thread machined on the smallend. When screwed into a 1-inch NPT female hull opening a l-inch NPT stainless steel pipe coupling provided withthe system!, it makes a pressure tight transparent lightpenetration.

The Canty HYL-250 Pressure Vesse1. Light is manufacturedby J.M. Canty Associates, of Tonawanda, New York. Thesystem consists of three basic assemblies �! a power andcontrol unit, �! a light source, and �! an acrylic rod.The power and control unit contains a 115-volt inputvariable transformer with an output of 0 to 120 voltsfed into a 24-volt high-current step-down transformer. Theunit also contains a pilot light, fuse, and off-on switch.A five-conductor cable connects the power unit to the lightsource which contains a 250-watt EKS 24-volt tungstenhalogen projection lamp with an integral dichroic reflector.An infrared absorbing glass filter is located in front ofthe lamp. A thermal switch wired in series with the lampprovides overheating protection. Cooling is providedby a small 110-volt fan. A compression fitting is locatedin the light source housing along the light axis of theprojection bulb. This fitting couples the light sourceassembly to the acrylic light pipe ALP! .

Service Systems. Zn the installation of servicesystems, one should consider providing additional penetrationsin the chamber walls in excess of those to be used immediately,since both additional instrument and power leads, includingshielded instrument leads, may be required with time and theexperience of use. All switches and circuit breakers shouldbe mounted outside the chamber, and each circuit should havea pilot light to indicate whether it is on or off.

in which air is continuously circulated for ventilationpurposes will require substantial amounts of electricalpower. This power will be required to run compressors,cooling water pumps, and for the operation of all otherrunning equipment. An adequate amount of standby powershould be available to maintain minimum necessary servicesin the event of failure of the primary supply. It isfrequently unwise to rely upon the hospital's or vessel'semergency power system for this purpose.

Portable chamber power requirements are relativelylimited. Generally, the external viewport lights requirestandard 110 or 220 volt AC supply. In some cases, powerconverters are used to facilitate use of 12 volt bulbs.Emergency lighting is provided by standard diver's lightsinside the chamber and/or hand lights placed. in theviewports outside the chamber. Self-contained handlights should be also provided for outside controls'illumination, the timekeeper/recordkeeper, the supervisorand other personnel as required. A routine chargingor battery servicing procedure will be required for allportable lights. Extra bulbs must be available for alllights.

Emer enc Lightin /Power. As previously stated, anappropriate number of hand-held lights should be availableat the chamber location for use by both inside and outsidepersonnel. In addition, self-contained emergency chamberroom lights that automatically activate in the event ofpower failure are highly recommended. Operations relyingon electrically operated air compressors for primary andsecondary air supplies must have an auxiliary power generator! system that automatically activates if primarypower fails. A non-power system associated high-pressureair storage is recommended. All emergency lighting andpower systems should be subjected to rigid periodicinspection, test, and maintenance schedules.

Communication S stems

At least two separate means of communication should beprovided for each lock of the chmaber to permit communicationbetween locks, and from any lock to the outside of the chamber.The first method should consist of a wall-mounted sound-powered telephone. One such telephone should be installedin each lock of the chamber complex.

In addition, for more general and more effective use,a nonsparking, non-flammable amplified system of voicecommunication should be provided with speaker microphonesin a convenient location to provide voice conznunication amongvarious stations as required. Communication from inside to

32

outside should not require the speaker to go to a microphoneor operate any controls. Standard surface-supplied diverwire-type communicators are commonly used for portablechambers. Extra batteries must be available at the chambercomplex.

In large medical facility chambers it is also desirableto install a telephone connected to the local telephoneexchange in the chamber for outside communication, but thedialing and switching must be done outside of the chamber,with only the handset installed in the compartment.Explosion-proof handsets are available and should be used.

Instrumentation

Each lock of the chamber complex shall be fittedwith a caisson gauge or equivalent! covering the full rangeof pressure for which the chamber has been designed. Eachoperating station should be supplied with a pressure gaugeto read the pressure in the chamber.

Internal and external indications of temperature andhumidity in the chambers should he provided in large complexes.

For those chamber complexes using oil-lubricated com-pressors, a total hydrocarbons indicator to monitor the airsupply is desirable.

Depending upon the uses to which the chamber is to beput, a wide variety of other instruments may be used withinit from time to time. Reliable information if needed aboutthe behavior of many standard instruments under pressurehigher than atmospheric, and it will be necessary to obtaininformation as to their performance, reliability, and safetyof use under hyperbaric conditions. In general, this in-formation should be obtained from other researchers workingin the field or from the manufacturer, having ascertainedthat the problems of hyperbaric use are appreciated by him.

An approved type of ground detector including visualindication and an audible alarm should be provided. todetect any grounding of the ungrounded portion of theelectrical system.

Pressure gauges for monitoring the pressure in airbanks, air receiver, and supply lines should. be supplied.Monitoring of the discharge temperature of compressorsis also recommended. All such permanent system monitorsshould be outside the chamber, convenient to the chamberoperator.

33

Chamber Monitorin E ui ment

The basic instrumentation needed for monitoring theoperation of a pressure chamber has been outlined. Znaddition, it would be useful to obtain and record certainother data during operation or experiments. For example:

l. Chamber-ventilation rate

2. Rate of rise and fall of pressure

3. Chamber pressure

4. Atmospheric temperature

5. Relative humidity

6. Oxygen partial pressure

7. Carbon dioxide concentration or pressure

8. Flammable-gas concentration and identification

Pressure, temperature, relative humidity, and air flowcan be measured very accurately with standard, commezciallyavailable gauges and transducers. Oxygen partial pressureof effluent air can be measured with commercially availableinstruments. Carbon dioxide can be continuously analyzedby an infrared C02 analyzer sampling the effluent air.Detectors capable of measuring concentrations of explosivegases are commercially available for use in mines, andshould give satisfactory service in the area of a hyperbaricfacility.

A detailed permanent record of information should bekept for each opezation or experiment, and recorded.Standard single or multi-channel recording devices capableof making continuous recordings from the types of sensorsmentioned are available commercially.

Ox en Monitorin E ui ment

An oxygen analyzer is useful for monitoring oxygenconcentrations in chambers where oxygen is used for therapy,research, or surface decompression. Based on current U.S.Navy recommendations, the oxygen Level in hyperbaric chambersshould not exceed 25 percent. Higher concentrations constitutea specific fire hazard.

Several oxygen analyzers are available. Some unitsare placed outisde the chamber with a remote sensor locatedinside the chamber; an appropriate chamber penetration isrequired. Small, portable galvanic cell type units may beplaced directly in the chamber. Tn choosing portable units

34

for hyperbaric use, be certain to consult with the manufacturerto be certain that the unit is compatible with hyperbaricenvironments. Since many units readout in response to partialpressure of oxygen relative to one atmosphere pressure,mathematical conversions must be made to denote the truereading at depth. Manufacturer's instruction manuals shouldbe consulted for detailed information on specific oxygenanalyzers.

Fire Extin uishin E ui ment and A ents

The U.S. Navy's Desi n Manual: H erbaric Facilities NAVFAC DM-39! states that "although research has beenperformed on nonaqueous extinguishing agents, studies havenot yet reached the point where any extinguishing agentcan be recommended with confidence as being superior toa water spray with adequate drainage." The manual furtherstates that tests have shown that a hand-aimed stream ofwater is one of the most effective ways to put out a smallfire in its initial stages" and that sand and water bucketsare "in a class of items which can do no harm and may dosome good."

Therefore, containers of water and/or a small hand-held water spray fire extinguisher are most frequently usedin small/portable chambers. Each type of extinguisher shouldbe tested in the chamber under pressure equivalent to 60 fswprior to initial installation and periodically inspectedthereafter.

A fire extinguisher using water as the extinguishingmedium, if pressurized, must be propelled by compressedair, nitrogen, helium, or other substances that are non-toxic to the occupants of the chamber.

Xn large chambers an overhead fixed-drench or fogdelivery system is used. The system must be periodicallytested. Both automatic and manual discharge systems areused,

Chamber Heatin and Coolin

Chamber air should be cooled either by precoolingincoming air or by recirculation through cooling coils tomaintain both a comfortable temperature and reasonable�0 to 60 per cent! humidity.

Air flow in surgical chambers should enter at thetop and exhaust at the bottom to facilitate the removalof dust and toxic agents that are usually heavier than theair itself.

Standard principles of heat transfer and air conditioningapply to the heating, cooling, and humidity problems associ-ated with this type of chamber.

35

It is recommended that only chilled water, hot water,or low-pressure steam be used in coils entering the compart-ments. The use of other refrigerants or fluids couldintroduce toxic contaminants in the event of a leak.

Although compact equipment is avaiable, very fewportable or small chambers are equipped for heating andcooling. Special precautions should be observed to preventexcessive heat buildup when chambers are exposed to thesun, especially in the tropics. Placing divers in asun-heated chamber and applying rapid pressurizationcan lead to nearly intolerable temperatures and heatstroke, a potentially fatal condition. Provide shadeover the chamber and, if necessary, cool the chamber.by flushing the exterior with water. In cold climateswhere the chamber must he operated outside, provide ampledry, warm clothing and blankets for occupants.

Automatic Ventilation- and Pressure-Control S stem

In addition to manual controls, which must in anyevent be installed, it is possible to control both thepressure and the flow through these chambers automatically.Zither solenoid-operated, motor-operated, or pneumaticallyoperated valves may be installed in the inlet and exhaustlines to the chamber.

As one example, potentiometers suitably connected canserve as valve controls. The potentiometer on the inletvalve can be used to preset. a valve opening or rate offlow for ventilation. A potentiometer in conjunction witha slide-wire pressure transducer and control amplifier canbe used to provide pressure control at the exhaust valve.

In this system, a constant. rate of flow through theinlet valve is maintained, and the exhaust valve opening iscontrolled so as to maintain constant pressure in the chamber.

A chart recorder suitable for working with a conductivecurve and curve follower may be provided as a substitute forthe potentiometer manual pressure control. In this mannera pressure-versus-time control of the chamber pressure may beestablished, and a preprogrammed decompression schedule maybe run.

Generally, these automatic systems are of individualdesign with respect to specific chamber complexes. Computercontrolled systems will probably be incorporated into moderncomplexes.

Electrical, electronic, or pneumatic failure in anypart of the control system should cause all valves to failsafe in the closed position so as to maintain whateverpressure is in the chamber at the time.

At present automatic systems are not generally used withportable or small chamber facilities.

36

Sanitation E ui ment

In small portable chambers toilet facilities generallyconsist of a hospital-type bed. pan and hand-held urinal.Some large facilities include an old fashioned covered"pot." A container of water and soap should be availablefor personal body care during long treatments. Generally,sanitation equipment and supplies including toilet paper,towels and wash cloths! are locked in as required andimmediately removed after use. In larger chamber complexesspecially designed hyperbaric chamber toilets, sinks, andwater systems are often available.

37

SECTION 3

CHAMBER OPERATION

The hyperbaric chamber must be maintained ready forimmediate use. After each use, it must be closely checked,cleaned, and reconditioned as necessary. Pre-dive and post-dive maintenance procedures are discussed in this handbook.

In conducting a recompression treatment, all attendingpersonnel must work as a team for the benefit of the patient.Outside attendants normally control descent, operate thechamber, monitor the time and depth, and maintain communicationswith inside personnel. The physician may accompany thepatient or he may designate a medical technician or chamberattendant. to monitor the patient inside the chamber. Theoverall treatment is coordinated by the senior member of theteam who is designated as the chamber supervisor.

Effective recompression treatment requires that everymember of the team be thoroughly trained and proficient inthe performance of his duties. It is desirable that allmembers of the non-medical team be able to carry out allduties associated with the operatio~ of the chamber.

PERSONNEL REQUIREMENTS

The number of people required to run the chambervaries slightly according to its use. However, the minimumteam necessary to conduct any hyperbaric chamber operationinvolving placement of personnel under pressure consistsof the following members.

Chamber Attendant No. 1 � responsible for operationof the gas supplies, pressurization, ventilation,and decompz'ession; stationed outside;

Chamber Attendant No. 2 � responsible for keepingindividual and overall times on the operation,maintaining a complete recozd, and communicatingwith personnel inside the chamber; and

Chamber Supervisor � completely in charge at thescene of operation.

When the number of qualified personnel available islimited, the Chamber Supervisor may assume the responsibilitiesof one of the attendants. In some cases, the physician may

38

also assume the role of Chamber Supervisor. It is necessary,however, to emphasize that. at least two qualified individualsmust in attendance outside the chamber, and that one individualmust assume the responsxbzlity of Chamber Supervisor wheneverpersonnel are under pressure in the chamber.

During treatment of diving accident victims and othertherapeutic applications, a physician familiar with hyperbaricmedicine must be in attendance either inside or outside ofthe chamber. A physician stationed outside the chambershould make decisions regarding treatment, medication, etc.The physician stationed outside the chamber may assume theresponsibilities of one of the designated chamber attendantsor the Chamber Supervisor, if he is so qualified and no otherpersonnel are available. In addition, patients must beaccompanied inside the chamber by a physician, medical tech-nician, or other individual designated by the on-site phy-sician.

When pressurizing personnel for research, training, ordemonstration purposes, it is desirable to use an InsideAttendant, who is familiar with the diagnosis of diving-relatedsicknesses and monitors the chamber occupants. At Navyfacilities the Inside Tender usually pressurizes and depressurizesthe chamber by using inside valving. However, a number ofcivilian chambers are not equipped with inside valving, andthe outside attendant assumes this responsibility.

When pressurizing personnel for non-medical purposes,a qualified physician must be "on-call" to provide medicalassistance or consultation if required. The Chamber Supervisor,a Diving Coordinator, or a Diving Safety Committee may requestthe physic;ian's presence at the chamber for specific activities.

Personnel Qualifications

The operator of a hyperbaric chamber must be thoroughlytrained in the mechanical operation of the chamber, and beable to recognize the symptoms of decompression sickness,air embolism, and oxygen toxicity. A chamber operator mustbe capable of:

l. Operating all mechanical systems including airsupply compressors/banks, oxygen supply bank,and chamber controls;

2. Recognizing and eliminating all sources of combustiblematerials in the chamber;

3. Determining appropriate gas supply and ventilationrequirements;

4. Completing pre-and post-dive inspections, preparation,and maintenance procedures;

39

Thoroughly understanding and using U.S. Navytreament and decompression tables.

5.

6. Ensuring accuracy of all gauges and timing devices;

Keeping complete records of chamber and supportsystems operations;

7.

8. Recognizing and managing pressure related injuries;

9. Tending personnel inside the chamber;

10. Assisting medical personnel; and

ll. Administering standard first aid and CPR.

Training courses are generally designed for each specificfacility.

TENDING THE PATIENT

General

When conducting a recompression treatment, the insideattendant will generally be a physician, medical technician,or other person familiar with advanced first aid and divingaccidents. The inside attendant must be familiar with alltreatment procedures and signs, symptoms, and treatment ofall diving-related sicknesses.

The inside attendant insures that the patient is lyingdown in a position which permits free blood circulation toall his extremities. He will close the chamber door andsignal the outside attendant to begin pressurization at thenormal rate:

� pain only Type l! or serious25 fpm.

Gas Embolism � as fast as possible.

The inside attendant will monitor the patient's conditionduring descent. It may be necessary for him to request thatthe rate be decreased to allow the patient to equalize. Ifthe patient is not a trained diver, it will be necessary toinstruct him in equalization methods prior to pressurization.If the patient is unconscious or unable to equalize, thephysician may elect to perform a myringotomy perforate theeardrums! prior to or during pressurization. In order tosimplify communication procedures, the inside and outsideattendants generally agree on basic hand signals. Normally,if the inside attendant holds up a clinched fist, he isrequesting the outside attendant to stop pressurization in

40

order to allow the occupant's ears to equalize. The standard"OK" hand signal means resume pressurization. The outsideattendant will adjust, the rate of pressurization in accordancewith the degree of difficulty experienced by the occupants.

During the phases of treatment, the inside attendantmust constantly watch for signs of relief of the patient' ssymptoms. Drugs which will mask the signs of the patient' ssickness should be avoided. Observation of these signsis the principal method of diagnosing the patient's sicknessand the depth and time of their relief designates thetreatment table to be used. All observations should bereported to and recorded by the outside attendant. Thefinal recommendation as to which treatment table shouldbe used must be made b the attendin h sician. Oncethe treatment has been rescrxbed, zt ma be alteredonl b the attendin h sicxan.

During decompression of the patient, the insideattendant may breathe oxygen beginning at the 40 ftstop. If Table 5, 6 or 6A is used, the attendantnormally breathes air throughout the treatment. Ifthe treatment involves a repetitive dive for theattendant or if Table 6 or 6A are lengthened duringtreatment, the attendant must breathe oxygen duringthe last 30 min. of treatment.

Other responsibilities of the inside attendantinclude:

l. Communication with outside personnel;

2. Observing the patient for signs of oxygen toxicity;

3. Providing first aid as required by the patient;

4. Providing normal assistance to the chamber asrequired.

5. Administering oxygen;

6. Maintaining a clean chamber; and

7. Transferring body waste as required.

Ox en Breathin

l. Use oxygen whenever permitted to do so by the tablesunless the user is known to be intolerant of oxyqen.

2. Adjust the breathing mask so that it seals tightlyaround the face.

3. Nake sure that. the tender knows the varioussymptoms of oxygen poisoning and how to react.to each symptom. Remember the symptoms byV-E-N-T-I-D Vision-Ears-Nausea-Twitching-Irritability-Dizziness!.

Ventilate the chamber in accordance with thenumber of occupants breathing oxygen.

4.

Be aware of increased fire hazard due to oxygenenriched environments and take a11 precautionsto prevent a fire.

TENDING THE CHAMBER

Res onsibilitiesAttendant

The outside attendants are responsible for:

Preparing the chamber; maintaining and controllingthe air supply to the chamber;

2. Maintaining the oxygen supply to the chamber;

3. Keeping times on all phases of treatment andpersonnel pressurization descent, stops, ascent,overall treatment!;

4. Keeping a complete record of the treatment;

5. Communicating with inside personnel;

Pressurizing and decompressing personnelentering and leaving the chamber during treatment;

6.

7. Pressurizing and depressurizing the chamber;

8. Ventilating the chamber;

9. Monitoring the oxygen level in the chamber;

10. Monitoring the amount of remaining oxygen;

Monitoring continually the chamber gauges anddecompression stops;

12. Operating the medical lock if available!;

13. Assisting physicians as needed;

14. Providing refreshments as required water, juice, food!;

42

15. Handling body waste and other debris locked outby inside attendant;

16. Keeping the Chamber Supervisor and the physician s!informed of treatment and operation status at alltime s.

Re ulator Settin s

When the primary air supply is high-pressure air fromstorage cylinders, a high-flow capacity regulator is usedto reduce the air from cylinder pressure to chamber pressure.The air supply regulator should be set to maintain a minimumsupply pressure of 50 psig over the maximum chamber pressure.A setting of 350 psig is considered ideal for air suppliedfrom high pressure air cylinders. Regulator settings forthe oxygen supplies are dependent on the inhalators installedin the chamber. Most inhalators should be supplied with gasbetween 75 and 100 psig over the chamber pressure. If thepatient is experiencing difficulty breathing, the pressuremay be adjusted upon the request of the inside attendant.

Chamber Ventilation

Ventilation of the chamber with fresh air is necessaryto maintain safe levels of carbon dioxide and oxygen insidethe chamber. The rates at which air must be circulated throughthe chamber depend on the number of personnel inside thechamber, their level of activity, and the gas which theyare breathing. The size of the chamber does not influencethe amount of air required for ventilation. Note thatincreasing depth increases the actual mass of air requiredfor chamber ventilation; however, when the amount of airis expressed in volumes as measured at chamber pressure,increasing pressure does not change the number of cubicfeet required. The following rules apply all volumesare expressed in cfm as measured at chamber pressure!:

l. When breathing air or helium-oxygen in the chamber

a. 2 cfm for each person. at restb. 4 cfm for each person not at rest

2. When breathing oxygen by mask in the chamber no overboard discharge system!

a. 12.5 cfm for each person at restb. 25.0 cfm for each person not at restc. No additional ventilation for each man not

breathing oxygen

3. When breathing oxygen by mask in a chamber withan overboard discharge system installed useventilation rate for air breathing.

43

4 ~ When breathing oxygen by mask in a chamber withoxygen monitoring equipment available, ventilateas required to maintain oxygen concentrations inthe chamber below 25 percent

5. When ventilation is interrupted

a. Not to exceed 5 minutes during any 30 minuteperiod

b. When resumed, twice the required cfm fortwice the period of interruption, then resumenormal rate.

The ventilation requirements for normal chamberoperations are as follows assuming one sedate patientand one active attendant!:

CHAMBER DEPTH FSW}

VZNTILATION RATE ACFM! SCFM!

When decompressing from 60 to 30 FSW and 30 to 0 FSW on Table5,6, or 6A, use the appropriate rate for the nearest depthgiven on the above table.

Constant ventilation is by far the most effectivemethod of ventilation in terms of the amount of air requiredfor ventilation. However, it has the disadvantage of exposingthe chamber occupants to a constant source of noise. At thehigh ventilation rates required for oxygen breathing, thisnoise can reach the ranges where hearing damage may becomea real hazard for the chamber occupants. Most chambers areequipped with baffle systems or mufflers to reduce the noiseto a minimum. If high noise levels do occur, especiallyduring exceptionally high ventilation rates, the occupantsof the chamber should be required to wear ear protectors.In some model ear protectors it may be necessary to drill

165140

120100

80

60 air!60 �2!50 air!50 �2!40 air!40 �2!30 air!30 �2}20 air}20 �2!10 air!10 �2!

6 366 316 296 246 216 17

12.5 356 15

12. 5 316 13

12. 5 286 12

12.5 246 10

12.5 206 9

12.5 16

a small hole in the central cavity to prevent sealing aroundthe ear which could cause an ear squeezers

As an alternate to constant ventilation proceduresrecommended by the U.S. Navy, civilian and commercialdivers or chamber attendants frequently use a very highventilation rate for one or two minutes out of every fiveminutes. The length of ventilation time per five minuteperiod will depend on the capacity of the air supplysystem, the gas being breathed in the chamber, and theactivity level of the occupants. Nost individuals findthe periodic ventilation scheme desirable over constantventilation from a standpoint of comfort. It should,however, be used with discretion and an oxygen monitoringdevice is highly recommended to insure that the oxygenconcentrations do not exceed 25 percent.

The above rules for chamber ventilation are notintended to limit ventilation. Zf air is reasonablyplentiful, more air than specified should generally beused to insure lower concentrations of carbon dioxideand oxygen. There is seldom any danger of having toolittle oxygen in the chamber. Even with no ventilationand a high carbon dioxide level, the oxygen presentwill be adequate for a long time. The rules given alsoassume that air circulation in the chamber is reasonablygood during ventilation. Having the inlet near one endand the outlet near the other end helps promote goodventilation.

The quantity of air ventilated through the chamberis controlled by regulating the precalibrated exhaustvalve outside the chamber or by a flow meter. Once theair supply rate is established, the air supply valveis regulated to maintain a constant chamber pressure.

Znterin and Leavin 0he Chamber Durinz Treatment

During extensive treatments, medical personnel mayprefer to periodically lock into the chamber to examinethe patient or administer medication and then come backout, rather than remain inside throughout the treatment.Also, inside attendants may fatigue and need relief. Thisprocedure is only possible with two compartment chambers.

In operation the outer compartment of a two-compartmentchamber is kept at atmospheric pressure while the patientand attendant are inside the inner compartment. Personnelentering the chamber go into the outer lock and securelyclose the door. The outer compartment is then pressurizedat a rate controlled by the occupant's ability to equalize,but not to exceed 75 fpm. The outside attendant must recordthe time that pressurization begins in order to determinethe decompression schedule for these personnel when they are

ready to leave the chamber. When the pressure in the outerand inner compartments is equal, the inside door will open.

To leave the chamber, the personnel again enter theouter lock and the inside attendant closes and secures thedoor. When they are ready to start the ascent, one outsideattendant records the time and consults the U.S. Navy StandardAir Decompression Tables. The other outside attendant thenbegins to slowly depressurize the outer compartment. Constantobservation or communication is maintained with the insideattendant to insure that a seal has been made on the innerdoor. The outside attendant may also determine if the innerdoor is sealing properly by simultaneously monitoring thedepth gauges of both compartments. If the inner compartmentgauge starts to drop, then the door isn't sealed and depres-surization must be stopped. Outer lock pressure is controlledthrough decompression by the outside attendant.

Some chambers are also equipped with a small medicallock or compartment for the purpose of transferring medicalsupplies, food, liquids, and waste into and out of the pres-surized chamber. Zn small chambers the outer compartmentmay be used for this purpose.

The medical compartment generally consists of a cylindri-cal pressure shell with doors hinged on either end. Two valvespenetrate the lock which permits it to be equalized witheither chamber pressure or atmospheric pressure.

To load the medical compartment the outside attendantrequests that the inside attendant close the inside valveand open the outside valve to insure that the compartmentis depressurized. Then he opens the outside door, placesthe material in the compartment and closes and bolts thedoor. The inner door, at this time, is sealed shut bythe interal pressure of the chamber. The outside attendantthen closes the outside valve and informs the inside attendantthat the compartment is ready for pressurization. The insideattendant releases the inner door latch and opens the insidevalve which allows pressurization of the compartment withchamber air. Under normal conditions the compartment shouldbe pressurized slowly approximately 25 fpm to minimize thelatent heat buildup and loss due to the heat of compressionand expansion.

When the compartment pressure equals the chamber pressure,the inside door will unseal and can be opened. To passmaterials out. of the chamber, the procedure is reversed.

PRE-DIVE CHECKLIST

Chamber

46

1. CLean

2. Free of all extraneous equipment

3. Free of noxious odors

4. Doors and seals undamaged, seals lubricated

Pressure gauges inspected or calibrated within12 months check inspection tag or label!

6. Power on

Air Su l S stem

Primary air supply operational test, operatefor at least 2 minutes!

Secondary air supply operational and regulatorset at 200 � 350 psi

2.

Secondary air supply adequate for one pressurizationand one hour of ventilation at maximum requiredrate minimum!

3.

Equalization valve � closed if so equipped!8.

Inside emergency chamber exhaust valve - closed if so equipped!

9.

Outside emergency chamber exhaust valve � open if so equipped!

10.

ll. Fittings clean

12. Filter clean check chamber log!

Exhaust S stem

l. Terminates clear of chamber

2. Nufflers attached

3. Exhaust valves � closed

4. Primary air system supply valve-open

5. Bleed moisture separator s! on filter system

6.' Primary chamber supply valve-open

7. Inner and outer compartment supply valves � closed

Ox en Su l S stem

l. Cylinder full; marked as breathing or medical oxygen USP!; cylinder valve � open

2. Replacement cylinder on hand

3. Oxygen masks or inhalators! installed and functioning4. Regulator set at 7S psig

S. Fittings tight

6. Oxygen manifold valves closed until required!

7. Overboard discharge valves closed until required!Electrical S stem

l. Power to chamber � on

2. Lights operational extra bulbs available!

3. Emergency hand-held lights inside and outside

Communications S stems

l. All phones operational

2. Extra battery available

Fire Prevention

1. Proper extinguisher or sand and water container inchamber

2. Fire-resistant mattress and blankets in chamber

3. Minimum amount of combustible material in chamber;preferably enclosed in metal container

4. Fire-resistant clothing worn by all chamber occupants if possible!

5. No visible signs of oil in chamber

Miscellaneous � Inside Chamber

l. Primary medical kit

2. Additional medical equipment and supplies as requiredby physician

3. Ear protectors for noise

Oxygen analyzer when oxygen is to be used; ifinitial depth exceeds 66 fsw, the anlyzer should belocked in at depth oxygen is to be used!

S. Emergency light check batteries!

Miscellaneous - Outside Chamber

l. Stopwatches wind and check operation!

Cumulative timeTreatment. timeDecompression time - personnel leaving chamberSpare

'a ~

b.

C.

d.

2. Treatment tables

3. Decompression tables

4. Record book or sheets

5. Additional medical supplies

6.

7. Paper and pencils

8. Emergency room lighting

Display "NO SMOKING � OXYGEN IN USE" sign on chamberroom door and on the chamber.

9.

1G. Emergency telephone numbers displayed

Chamber room clean and extra equipment properlystowed

Chairs and desks available for medical staff andtimekeeper/recordkeeper

Coffee, tea, cream, sugar, fruit juice, and/orother refreshments available

13.

Medical locker accessible to physician and treatmentpersonnel only

14 ~

1S. Non-essential personnel restricted

Personnel Assi nments

l. Supervisor

2. Operator

Appropriate containers for body waste - may be lockedin as needed

3. Timekeeper/Recordkeeper

4. Physician s!

S. Backup Personnel

POST-DIVE h&INTENANCE CHECKLIST

Chamber

l. Clean inside with vegetable base soap and warmfresh water and wipe dry

2. Remove all but necessary support items from chamber

3. Clean and lubricate door seals and seats

4. Check viewports for damage; replace as necessary

5. Open exhaust valves and secure exhaust systems

6. Air out chamber

7. Close outer door

Air Su l S stem

1. Close all air supply line to chamber

2. Shut down primary air compressors and refuel if required!

3. Inspect primary air system and report repair ormaintenance requirements to proper authorities

4. Deactivate regulators and bleed air from line ofhigh-pressure systems as required!

5. Record filter time in appropriate book

6. Change filter materials, if necessary

7. Recharge high-pressure cylinders and recordpressure of air in bank

Ox en Su l S stem

l. Close cylinder valves

2. Bleed lines and deactivate regulator

3. Replace empty oxygen cylinders, as required, with'BREATHING OXYGEN"

4. Insure that spare full oxygen cylinders are available

5. Remove oxygen inhalators from the chamber

6. Wash and disinfect oxygen masks

7. Close oxygen supply and overboard discharge valves

Electrical and Communications S stems

l. Power to chamber � off

2. Secure phones

3. Check for damage to wiring, pressure-proof lighthousing, etc.

4. Replace light bulbs as necessary

5. Replace batteries as necessary

Fire Prevention S stem

l. Secure fire extinguishings equipment

2. Clean and dry blankets, mattresses and clothing

3. Encase all flammable materials in chamber in fireresistant container

Niscellaneous

l. Initiate repairs or replacement as required

2. Stow ear protectors

3. Replenish consumahles

4. Restock and stow medical kit.

5. Stow oxygen analyzer

6. Allow stop watches to run down and stow

7. Enter records in appropriate books or files; stowrecord books

8. Stow decompression and treatment tables

9. Clean and stow containers for body waste

lO. Replace batteries in portable emergency light

ll. Replenish paper and pencil supply at control desk.

51

SAFETY PRECAUTIONS FOR CHAMBER OPERATION CHECKLIST

l. Take all precautions against fire.

Provide fire extinguishing equipment or materialsinside the chamber.

2.

Use fire retardant and nonstatic materials in thechamber when possible.

3.

Ventilate the chamber according to specifiedrates and gas mixtures.

4.

Remain alert for the symptoms and signs ofoxygen toxicity:

5.

a. Vision abnormality such as 'tunnel vision"!b. Hearing abnormalityc. Nausea

d. Twitching usually in lips or other facialmuscles, but may affect any muscle; the mostfrequent and clearest sign of oxygen toxicity!

e. Irritability or behavior changes!Dizziness

g. Convulsions

Assure proper decompression of all personnelleaving the chamber before treatment is completed.

6.

Insure that the chamber and its auxiliary equipmentare in operational condition at all times.

7.

Insure that all personnel are trained in the opera-tion of the equipment and are available to do anyjob required in treatment.

8.

Prepare the chamber for immediate reuse followinga treatment.

9

Do not use oil on any oxygen fitting or piece ofchamber equipment.

10.

11. Maintain all gas supply cylinders full.

12. Avoid, damage to the doors and seals.

l3.

Prohibit the use of electrical appliances in thechamber unless the unit is specially designed foruse in hyperbaric oxygen environments.

14.

Never allow open flame, matches, cigarette lighters,or pipes to be carried into the chamber.

52

DOCUMENTATION AND RECORDS

The following documents/records should be maintainedand retained in the vicinity of the chamber:

1 ~ Operating, maintenance and repair logs for allmachinery;

2. Life support system log;

3. Chamber operations log;

4. Chamber personnel roster with telephone numbersand recall procedures;

5. Chamber operating procedures;

6. Chamber emergency procedures;

7. Operator quali.fication records;

8. Gas purity sampling records/results;

9. Valve and gauge calibration data;

10. Chamber test documentation;

ll. Decompression Tables;

12. Treatment Tables;

13. Pre- and Post-dive check lists;

14. Emergency and consultation telephone number index;

15. Appropriate safety precautions displayed whereappropriate;

16. Appropriate medical forms;

17. Appropriate legal/release forms;

18. Chamber information sheet/booklet for visitors;

19. Pressurization cards for personnel to carryafter pressurization;

20. Reference books/manuals and equipment operation/maintenance manuals.

21. Copies of federal/state/local codes and regulationsrelevant to chamber installations and operation.

53

SECTION 4

MAINTENANCE OF HYPERBARIC CHAMBER FACILITIZS

GENERAL

The maintenance program for any hyperbaric facilitymust emphasize three important areas: personal safety tothe occupants of the hyperbaric chamber, cleaning techniquesthat are compatible both with chamber materials and withthe accepted standards of cleanliness, and reliable performanceof pressurization components and controls.

Safety in a hyperbaric facility involves factors notnormally encountered wheze high environmental aiz pressuresare not present. Some materials normally considered thatare only slightly combustible will exhibit increased flam-mability when exposed to the greater oxygen partial pressurein pressuzized aiz, and moderately flammable materials mayburn violently under the same conditions. Fire becomesincreasingly hazardous and is complicated by the inabilityof persons vithin the hyperbaric chamber to Leave quicklyin case of fire. It is therefore imperative that highlycombustible matezials be prohibited for use in hyperbaricchambers, and moderately combustible materials be kept toan absolute minimum. All fire-fighting and emergencybreathing apparatus must be maintained in good repair andready for immediate use at all times.

HOUSEKEEPING

1. High cleanliness and sanitary standards shall bemaintained in the hyperbaric chamber.

2. Cleaning techniques and materials shall be approvedby the manufacturer of the chamber to ensure compati-bility with materials of construction and to preventaccidental damage to devices requiring specialhandling.

3. The hyperbaric chamber must not be used for storageof diving equipment and supplies.

4. Materials that are flammable or can produce toxicvapors must not be used within the hyperbaric chamber.

5. Sealable glass containers should not, as a zule,be approved for use or stozage within the chamber.If such a container is approved it must becapable of withstanding safely the maximum chamber

54

pressure when applied both externally with theinside depressurized, and internally with theoutside at ambient pressure.

PRZVENT IVZ MAINTENANCE

Surfaces of steel chambers must be protected fromrusting. All paints used within the chamber must be selectedfor minimum flammability and for non-toxic properties. Paintshould not be applied too heavily nor allowed to build up,as a heavy buildup increases the hazard of flammability.Painted surfaces shall be well sanded down before additionalpaint is applied. Painting shall be kept to an absoluteminimum.

Corrosion products are best removed by hand or by usinga slender pointed tool, being careful not to gouge orotherwise damage the base metal. The corroded area and asmall area around it should then be cleaned to remove anyremaining paint and/or corrosion products.

Steel chambers should be painted with only fire-retardingpaint. lf there is any doubt as to the type of paint that haspreviously been used, the chamber should be cleaned down tobare metal and repainted. Use one coat of primer and one coatof exterior paint for inside surfaces. Exterior surfacesshould be given one coat of primer and two coats of exteriorpaint. After painting, do not use the chamber until thepaint is thoroughly dry and all volatile vapors have beenremoved from the chamber.

Fil.ters and Absorbers

Air filters and. moisture absorbers shall be cleaned orreplaced on a regular schedule to maintain suitable atmos-phere control within the chamber. Schedules should be basedon conservative intervals as determined from initial systemperformance and as recommended by the manufacturer.

Where transparent plastic is used for viewports orenclosures, care must be exerted at all times to preventscratching the surface. Keep all abrasive substances awayfrom the plastic and avoid wiping it when dry. Use onlynon-abrasive, mild soap solutions for washing and flushthoroughly with clean, warm water if possible. If theviewing surface receives a scratch, it should be polishedout or replaced. Yellowing or crazing of plastic viewportsindicates weakening that is justification for replacement.Inspections every six months are recommended. Glassviewports must be replaced at the first sign of any hairline

55

crack or other sign of failure.

An acrylic viewport should not be lubricated or comeinto contact, with any Lubricant. When reinstalling viewport,take up retaining ring boots until the gasket just compressesevenly about the viewport. Do not over compress the gasket.Doors

Door seals should. be replaced when they no longer sealwell.

PRESSURI ZATION AND PRESSURE-CONTROL EQUIPMENT

Where air compressors are used to pressurize or ventilatea hyperbaric chamber, they must be maintained in prime conditionby following all servicing recommendations of the manufacturer,and periodic inspections must be carried out. Air filters andmoisture traps shall be inspected and cleaned or replacedfrequently. The discharge piping shall be inspected occasion-ally for signs of oil contamination, and the compressorserviced if the contamination rate is above the manufacturer'sspecifications. Reliability is of great. importance, and wornor weak components must be replaced as soon as detected.

Com ressed-Air C linders

The Department of Transporation requires that allhigh-pressure cylinders be hydrotested every five orseven years and that accurate records of test resultsbe kept. If the cylinders are removed and filled by avendor, adequate inspections shall be performed by thevendor at the time of filling. If cylinders are filledby system air-pumping equipment, a regular program ofmaintenance must be followed, based on approved industrialpractice. This will include frequent inspections for oilcontamination and water accumulation in cylinders and forserviceability of the cylinders and all associated regulators,valves, connections, and pipes. When the inspectionperiod arrives, the cylinders shall be removed from serviceand hydrostatically tested by a competent, authorizedcylinder-inspection facility.

Pressure Indicatin and Re ulatin Devices

Regulators, gauges, relief valves, and similarapparatus used to measure or control pressure shall bechecked frequently for accuracy by comparison with standardreference gauges. They shall be recalibrated, readjusted,repaired, or replaced when inaccuracies or erratic actionsare noted.

56

Manual Valves

Manual valves shall be repaired in accordance withvalve manufacturer's recommendations. Valve packing, disk,and seat materials shall be as prescribed by the systemmanufacturer. All parts shall be kept clean and free fromany traces of oil.

FlRE PREVENTION

The greatest single hazard in the use of a recompressionchamber is from explosive fire. Fire may propagate two tosix times faster than at atmospheric conditions because ofthe high partial pressure of oxygen in the chamber atmosphere.The following precautions must be taken to minimize firehazard:

l. Remove any fittings or equipment which do notconform with the standard requirements for thehyperbaric chamber's electrical system or whichare made of any flammable materials. Permit nowooden deck gratings, benches or shelving in thechamber � replace them with metal or otherfireproof material.

2. Equip the chamber with flameproof bedding material;if a mattress is used, ensure that it is completelyenclosed in a flameproof cover or sheeting. Do notput any more bedding in a chamber than is necessaryfor the comfort of the patient, and never useblankets of wool or synthetic fibers because of thepossibility of sparks from static electricity.

3. Only fire-retarding paint may be used in a chamber.If there is any doubt as to the type of paint thathas previously been used, the chamber should becleaned down to bare metal and repainted. Use onecoat of primer and one coat of white for chamberinterior surfaces. Exterior surfaces are to begiven one coat of primer and two coats of whiteor colored paint. After painting, do not usethe chamber until the paint is thoroughly dry andall volatile vapors have been removed from thechamber. Repainting requires removal of the existingpaint down to bare metal.

4. Keep oil and volatile materials out of the chamber.If any have been used, ensure that the chamber isthoroughly ventilated before pressurization. Do notput oil on or in any fittings or high-pressure line;and if for any reason oil is spilled in the chamberor soaked into any chamber surface or equipment, itmust be completely removed. If lubricants arerequired, use only those approved. Regularly inspect

57

and clean air filters and accumulators in the airsupply lines to protect against the introductionof oil or other vapors into the chamber. Permitno one to wear oily clothing into the chamber.

5. Never permit anyone to carry smoking materials,matches or lighters into a chamber, even if hedoes not intend to use them. A warning signshould be posted inside and outside the chamber.

6. The chamber must be equipped with appropriatefire-fighting materials such as buckets ofwater and sand. Fire extinguishers containingcarbon tetrachloride, C02, or dry powder mustnever be used. These chemicals are toxic inconfined, pressurized atmospheres.

ATMOSPHERIC HAZARDS CONS EDERATZONS

To some degree, all volatile substances are toxic,narcotic, or both, in direct proportion to the partial pres-sures of the evolved gases. Within a closed vessel, such asa hyperbaric chamber, much of the incarcerated materialmay be assumed to be volatile, hence toxic. For example,oil-base paints continue to emit potentially toxic hydro-carbon vapors many months after application; spilledmercury, which is nearly impossible to recover completely,will vaporize for years; and accidental release of the toxicfluids of the commonly used aromatic compounds might quicklyresult in disastrous atmospheric contamination.

Even during intermittent exposures anticipated in thehyperbaric chamber, the physiological hazard of low-leveltoxic substances in the chamber should not be minimized.All captive atmospheres are subject to toxic contamination,and the operational requirements of the hyperbaric chamberwill surely offer a large and ever-changing spectrum ofthese contaminants. Over the course of several years ofclinical work, inside operators will accumulate hundredsof exposure hours, increased considerably in effect bymultiplication of partial pressures. Therefore, it isconceivable that repeated exposures under conditions ofincreased ambient pressure might be equivalent to long-term continous exposure. Future research will undoubtedlyshed light on the problem, but it is important, pendingthe acquisition of definitive data, to eliminate, reduce,or at least control all potentially toxic substances withinthe hyperbaric chamber.

Of the many potentially toxic contaminants, the hydrocarbonsdeserve primary consideration. Depending on chemical structure,some volatility or oxidation can be predicted of any hydro-carbon. Many of these compounds cannot be removed from the

58

atmosphere by known techniques. Thus, methanol, acetone,toluene, and a host of similarly volatile materials mustbe excluded, or at least rigidly controlled, for use in thehyperbaric chamber. Mercury is difficult to remove aftera significant spill and can produce mercury poisoning inindividuals subject to daily exposure. Any electronicdevice with a spark gap will eventually produce a signifi-cant quantity of ozone and reaction by-products of nitrogenand oxygen; all must be detected and eliminated.

Hyperbaric chambers with closed atmospheric systemswill require examination of all sources of potential atmos-pheric contamination because human exposures will be con-tinuous and long. Even if the known toxic contaminantscould be eliminated or accounted for in such a captiveatmosphere, the normally innocuous atmospheric componentswould have to be considered. For long term exposure in ahigh-pressure synthetic gas, the safe proportions of inertgases and oxygen will have to be defined. The inert gaschosen should probably be helium which offers relativeimmunity from narcosis and poses only a small densityproblem at the pressures contemplated. Oxygen, however, willrequire rigid control because high partial pressures at aprolonged exposure to oxygen will probably result in pulmonarydamage.

Thus, a careful control of the atmosphere of the hyper-baric chamber is desirable today; in the future it will bemandatory. The problem cannot be ignored.

CKVIBER CLEANING AND STERILIZATEOIJ

Proper chamber construction includes drain plugsand removable floors to facilitate cleaning. Soap andwater scrubbing is desirable for cleaning.

Beta-propiolactone vapor makes an excellen chamber-sterilizing agent. The vapor should be left in the chamberfor a period of 12 hours or more, and then flushed out with air.

59

SECTION 5

THERAPEUTIC COMPRESSION

GENERAL

PATIENT EXAMINATION

Normally the patient will be examined in the hospitalor outside the chamber by the attending physician prior topressurization. When the sickness is in question, or whenserious symptoms or signs of gas embolism are present,treatment may be started immediately. The patient, in thissituation, is examined inside the chamber. The minimumexamination includes:

l. A discussion with the patient to determine thecause of the accident, how he feels, and hisgeneral psychological responses.

2. Testing the patient' s

EyesightHearingReflexesMuscular coordinationStrengthBalancePulse rateBlood pressureRespiration rate

a.

b.

c

d.e.

f.

This section provides information useful in diagnosingand treating decompression sickness, gas embolism, and otheremergency medical problems. The first step of any treatmentinvolves diagnosing the sickness. Signs and symptoms rela-tive to each sickness are listed, followed by the actionwhich must be immediately taken once the sickness is confirmed.A flow chart is given to provide a systematic method oftreating each sickness. Once the treatment table Tables1-6! has been established, treatment is normally concludedby carrying out the decompression procedures specified inthat table. If complications develop during or after treat-ment, the procedures given at the end of this section willapply. Dig nosis and rescri tion of treatment are theres onsibzlxt of the attendxn h sxcian s!. Experiencedchamber attendants are generally very familiar with thediving sicknesses and may be called on to offer commentor advice. The attendant should not, however, assume theres onsibilit of rescrxbin treatment without a royaland direction of a uglified h sician.

60

An examination protocol is included in Appendix F.

DECOMPRESSION SICKNESS PAIN ONLY!

b * * ' h'

Symptoms: Local pain, usually in joints of arms orlegs; itching.

Signs: Diver complaining of joint pain. Pain notpromoted by touch or vigorous rubbing.Blotchy skin rash.

Immediate Action:

l. Stop massive bleeding if present.

2. Examine patient.

3. Enter chamber; begin pressurization at 25 fpm.

Treatment: See Figure 3.

DECOMPRESSION SICKNESS SERIOUS SYMPTOMS!

' ~

Symptoms: Dizziness; defective visio~; paralysis;shortness of breath; extreme fatigue;extreme pain; abdominal pain; rining in ears.

Diver staggering; paralyzed extremities;rapid breathing; choking; diver complaining ofextreme pain; doubled over with pain; collapseor unconsciousness.

Signs:

Immediate Action:

l. Restore breathing using mouth-to-mouth resuscitation,bag, or mechanical resuscitator.

Complete records of physical examinations must bemaintained. In addition to the initial examination outsideof the chamber, the physician will generally examine thepatient extensively during early stage of treatment andperiodically thereafter. The recordkeeper will record allinformation upon request of the physician. Each recordentry must include the exact time, either actual clock timeor time into treatment using beginning of pressurizationas "zero" time, in accord with the physician's instructions.

61

2. Stop massive bleeding, if present ~

3. Begin pressurization at 25 fpm.

4. Examine patient.

Treatment: See Figure 3

GAS EMBOLZ SM

Symptoms: Fatigue, dizziness, blurred vision; paralysisor weakness of extremities; chest discomfortor pain; progressively worsening.

Signs: Diver confused, staggering, having difficultyseeing; paralyzed or weakened extremities;blueness; chest pain, rapid shallow breathing,unequal expansion of chest wall pneumothorax!.Blueness of skin, lips or fingernails; difficultybreathing; shock mediastinal emphysema!;Swelling of neck; crackling sensation when skinmoved, change in voice, difficulty breathing subcutaneous emphysema!;

Collapse or unconsciousness.

Immediate Action:

L. Restore breathing using mouth-to-mouth resuscitation,bag, or mechanical resuscitator.

2. Stop massive bleeding, if present.

3. Treatment of pneumothorax by physician if diagnosisindicates!.

4. Pressurize patient to 16S ft as fast as possible.

5. Examine patient.

Treatment: See Figure 3.

COMPLICATIONS

1 ~ Worsening of the patient's condition during treatment see below!.

2. Recurrence of the patient's original symptoms ordevelopment of new symptoms during treatment seeFigure 4!.

There are three major complications which may affect therecompression treatment of a patient.

62

OECOMPRESSION SICKNESS TREATMENT GAS EM8OUSII TREATMENT

FIGURE 3 Decompression Sickness Treatment and Gas EmbolismCharts From U.S. Navy Diving Manual!.

63

RECURRENCE FOLLOWtNG TREATMENTRECURRENCE DURlNG TREATMENT

FXGURE 4 Recurrence During Treatment and Recurrence FollowingTreatment Charts From U.S. Navy Diving Manual!.

64

Recurrence of the patient's original symptoms ordevelopment of new symptoms following treatment see Figure 4!.

3.

Patient's Condition Worsenin

l. Stop the ascent.

Consider the use of 80% helium � 20% oxygen ifpatient is experiencing difficulty breathing.

2.

3. Examine for pneumothorax or tension pneumothorax.

4. Treat as a recurrence during treatment.

GENERAL NOTES ON TREATMENT OF GAS EMBOLISM AND DECOMPRESSIONSICKNESS*

If a patient's condition is not considered fullysatisfactory at the conclusion of the normal periodat 60 ft Table 6!, or if an additional safeguardis desired for any reason, given an additionalcycle of treatment �0 mins. oxygen,' 5 mins. air!at 60 ft. Observe for evidence of oxygen toxicity.

The period at 30 ft may also be extended by onecycle l5 min. air, 60 min oxygen!.

2.

The use of Table 4 has long been regarded as the"treatment of last resort." In general, oxygentreatment tables have a far better success ratethan air treatment tables. Some authorities avoidTable 4 entirely when oxygen can be given and,in any case, limit periods on air at 165 ft to30 min. or less. As stated above, Table 6 oxygentreatment can be extended. It can also be repeated.Adjunctive medical treatment should be consideredwhen the response to recompression and oxygen isnot prompt and adequate.

A fundamental rule is not to continue ascent ifa patient's condition has worsened. This situationis handled as a recurrence durin treatment. Detailsfor dealing with recurrence are given in thishandbook and the U.S. Navy Diving Manual.

4.

*These notes are based on comments given by E.H. Lanphier,M.D., in The New Science of Skin and Scuba Divin , AssociationPress, 1974 and the 13th edition of The Merck Manual.

65

5. The possibility of late recurrence dictates thatthe patient be retained at or near the chamber foxat least 6 hours and in the vicinity for at least24 hours.

6. Patients who require recompression treatment mayalso require first aid or other medical or surgicalprocedures. In most instances, both may be accom-plished or the priorities are clear. Adequate fluidintake is important.

Decom ression shock is an obvious medical problem.Maintenance of normal blood volume by usual methods isclearly indicated. Low molecular weight dextran Dextran40, Rheomacrodex! is useful to combat hemtologic changesespecially in patients with severe or persistent symptoms. The usual maximum is one liter/day for 5 days.!

Steroids are considred a useful adjunct by some,emphattrca ty so in suspected spinal cord edema. A suggesteddose is Decadron, 10 mg Z.V., followed by 4 mg Z.M. every6 hours. Tapering is not required for use not longer than72 hours. The possibility of lowering 02 tolerance suggestswithholding steroids until the 30 ft stage of Table 6.

Sedatives and narcotics may obscure the symptomatologyand entail risk of respiratory insufficiency. They shouldbe avoided or given in minimal effective dosage. A~s irincan be given in usual amounts and. is administered routinelyby some authorities.

Routine precautions in handling medication at pressureinclude opening ampules and needling the stopper of vialsand, Z.V. bottles before compression. An inadequately ventedZ.V. bottle may, for example, implode on descent or explodeduring ascent. Zf the medications are not used, they mustbe discarded.

CARBON MONOXIDE POISONING

Hyperbaric oxygen is used to eliminate carbon monoxidefrom the blood. Zn addition, sufficient oxygen is physicallydissolved in the plasma during hyperbaric treatment to supplythe body's metabolic needs until elimination is complete.

Headache, nausea, vomiting, dizziness,rapid heart beat, irregular heartbeat, cherry-red color, visual changes,drowsiness, confusion, lack of coor-dination, coma, death.

Signs and Symptoms:

The use of h~e erin is considered controversial. Zthas been advocated in shock and to combat hematologic changes.

66

Treatment: Pressurize patient to 3 ata �6 fsw! until carbonmonoxide in the blood is reduced to a safe level,usually one hour. Oxygen is administered in 20min. intervals with 5 min of air breathing betweenoxygen breathing periods.

SMOKE INHALATION

The vast majority of smoke inhalation patients sufferfrom carbon monoxide poisoning and should be treated forcarbon monoxide poisoning until proven otherwise.

CYANIDE POISONING

Certain cyanide intoxications are not immediatelyand dramatically fatal. Cyanide poisons the blood andcauses tissue hypoxia. Chemical treatment will eventuallyrid the blood of cyanide, however, hyperbaric oxygen isnecessary to sustain the patient through the criticalperiod.

Treatment: Pressurization must be initiated immeidately.The chamber is pressurized to 3 ata �6 fsw! .The appropriate medications are administered.The patient is placed on oxygen; the pressureis slowly reduced to 33 fsw, and subsequentdecompression is determined by the patient' sclinical condition and the chamber attendant'sstandard air decompression requirement.

GAS GANGRZNE

Human tissues that have compromised blood circulationare prone to develop a gas forming infection called gasgangrene. Formerly, surgical removal of the tissue was thedefinitive form of therapy. While this is still true, itis now generally recognized that in cases of severe gasgangrene, the presurgery use of hyperbaric oxygen substantiallyimproves the patient's chance for survival.

Treatment: The patient is treated at 3 ata �6 fsw! for90 min., three times during the first 24 hours.Two 90 min. treatments are given the second 24hours and on the third and fourth days, onetreatment. Generally the patient will breatheoxygen for 20 min intervals with 5 min periodsof air breathing between the oxygen intervals.When the patient is clinically stable, surgicaltherapy is carried out even if the full courseof hyperbaric treatment has not been completed.

67

DISCUSSION OF TREATMENT TABLES*

Today, oxygen recompression is the treatment of choicefor most cases of decompression sickness with the maximumtreatment depth being 60 feet. Zn air embolism, a briefexcursion to 165 feet is indicated before returning to 60feet for oxygen treatment.

Historically, air compression has been used for thetreatment of both decompression sickness and air embolismusing standard U.S. Navy Air Treatment Tables 1 through 4,promulgated in 1945. These tables represented a nine foldimprovement in procedures used prior to that time. Formany years- they were considered quite acceptable despitetheir very lengthy durations of 6 to 38 hours. The overallfailure rate on the initial compression using the tables period 1946 to 1964! was only 14.3%. However, for thesingle year l963, the failure rate was 21.9%. By 1964 ithad climbed to 26.7%. Even more disconcerting was the factthat the failure rate on initial compressions for serioussymptoms on Tables 3 and 4 had jumped from 29.7% in theperiod from 1946 to 1964 to 46.4% in 1963 and 47.1% in 1964.The reason for the increasing failure rate was that morecivilian scuba divers who had failed to observe any sortof standard decompression schedule were being treated atU.S. Navy facilities and the cases being treated were muchmore serious.

To address these increasing problems in treatment,the U.S. Navy reinvestigated some earlier work in theuse of oxygen breathing at relatively low pressures fortreatment of decompression sickness. Between 1964 and1966 U.S. Navy researchers developed two new treatmentschedules and tested them in the field on over 50 cases.The failure rate for all initial compressions in theexperimental group was only 2% as compared with 26.7% forTables 1 through 4 in the year 1961. The failure ratein the "serious symptom" cases was only 3.6% in the oxygentreated group. Comparing data, the experimental case loadwas composed of older divers who had been exposed for longerbottom time durations at deeper depths. Analysis of theresults showed them to be statistically valid.

As a result of this work oxygen recampression is nowthe treatment of choice. Oxygen treatment Tables 5 and6! were approved by the U.S. Navy in 1967.

~ Modified from the paper "Hyperbaric and Anciliary Treatmentof Decompression Sickness, Air Embolism and RelatedDisorders" by Eric Kindwall, M.D.

68

Air embolism treatment also changed at the time of theintroduction of the oxygen treatment tables, as the U.S. Navypromulgated Tables 5A and 6A, the "embolism tables" !, atthe time that the oxygen tables were approved. Previouslyair embolism had always been treated on Tables 3 or 4.Experimental animal research demonstrated that only abrief com ression with air to 6 ATA was necessary to restorecrrculation an unction, even i f followed by immediatedecompression to the surface. In humans, however, oxygenis used from 60 feet to the surface as a safety factor andto reduce cerebral edema.

Table 5, only 135 minutes in length, is used formild or "pain only" cases of decompression sickness.This form of decompression sickness, which does not presentneurologic or pulmonary symptoms but only pain, is termed"Type 1". Table 5 may be used for Type 1 decompressionsickness if the patient gets ~com lets relief of all hissymptoms within l0 minutes breathing oxygen at 60 feet.Should his pain not. disappear within 10 minutes time,he is automatically committed to Table 6.

Table 6 is for "serious symptoms" Type ZZ cases!referable to the central nervous or pulmonary systems andrecurrences of previously treated decompression sicknessof any kind. It is also used for "pain only" cases whichdo not respond with complete relief within 10 minutes at60 feet and for cases of decompression sickness which begintheir onset while the diver is still decompressing fromhis original dive. This latter situation is termed,"decompression sickness occurring under pressure." Thetable is 285 minutes in length, but may be lengthened anadditional 100 minutes if necessary.

Table 6A is for cases of air embolism which showcomplete resolution of all symptoms within 30 minutesbreathing air at l65 feet � ATA! . Please note that useof former Table 5A has been discontinued.

Previously it was mandatory that if the patient hadnot recovered completely or was not, rapidly recovering after30 minutes at 165 feet, he was then committed to Table 4�8 hours in length!. Experience has shown that this isnot necessary and maximum benefit of compression to 6 ATAwill have been realized within a few minutes of reaching165 feet. It is more important. at this point to decompressto 60 feet and start the patient on oxygen.

If after adequate treatment on the appropriate tablethe patient still has neurological symptoms remaining,it may be useful to retreat him once or twice a day for90 minutes at 2.5 ATA with 100%, oxyge~ for several daysfollowing the initial treatment.

Treatment Tables 1-6 are included in Appendix C ofthis handbook.

69

DRUG THERAPY QR MEDICAL ADJUNCTS TO THERAPEUTIC COMPRESSION*

Making the assumption that one has compressed the patientor is about to, and that the nitrogen bubbles present in hisbody have been or will be quickly obliterated, the damage tothe body caused by their having been present must bereckoned with.

Damage from bubbles which we have been able to discernis increased sludging of the blood, increased plateletaggregation and micro-thrombi, hemo-concentration, with lossof volume from the vascular compartment and spinal cordand brain edema. Drug therapy would be directed at correct-ing any of the above.

Below are listed some drugs which have been used inthe treatment of decompression sickness and/or air embolism!as adjuncts to compression. As every case of decompressionsickness is different, careful choice is necessary on thepart of the physician.

Low Noh.ar Dextran Dextran 40, Rheomacrodex!

Low molar Dextran has been a useful plasma expanderbut in non-diving diseases there is now some question asto whether is is superior or even as good as its heavieranalog Dextran 80.

In decompression sickness, however, it is extremelyuseful as it appears to alter the charge on the surfaceof the red cells and tends to prevent rouleaux formation.Even though it is rapidly excreted by the healthy kidney,it is useful in immediately expanding blood volume, theloss of which is the usual problem in a severe case ofdecompression sickness. In a normal individual, 500 mlgiven twice a day for a maximum of five days is usually safe.If a patient has had symptoms for more than two hours priorto treatment, Kindwall gives 500 ml intra-venously asa matter of routine. The agent should not be continued ifthe patient is asymptomatic after chamber treatment. Incases of severe shock, Dextran 40 alone should not be reliedupon.

Plasma Reconstituted Plasma, Plasmanate!

This is a useful volume expander which can be givenin cases of shock due to decompression sickness. Thisagent should be reserved only for shock due to decompressionsickness'

«Taken from the paper, "Hyperbaric and Anciliary Treatmentof Decompression Sickness, Air Embolism and RelatedDisorders" by Eric Kindwall, M.D.

70

Despite its common use as an anti-coagulent in hospitals,heparin appears to exert its beneficial effect in decompressionsickness because of its lipemia clearing ability and not itsanti-coagulant effect. Kindwall's feeling is usually to reserveit for cases of decompression sickness shock. A suggesteddosage is 7,500 units intravenously followed by 5,000 unit doseat intervals later if necessary.

Steroids

Steroids are chiefly useful in those cases where onesuspects central nervous system involvement or edema ofthe spinal cord or brain. Theoretically. steroids will tendto exascerbate oxygen toxicity, although information oncases of oxygen convulsions occurring on Tables 5 or 6 whenthe patient has been pre-treated with steroids is limited.However, Kindwall's practice is to sometimes withholdsteroids until the 30 foot stop has been reached, especiallyif the patient is showing signs of incipient oxygen toxicity.

Hyperbaric oxygen itself has very strong vaso-constrictiveproperties and for this reason tends to reduce intra-cranialpressure on the order of 50% within five minutes of commencement.of oxygen breathing at three atmospheres absolute. However, oneshould use steroids to continue control of edema after thepatient has left the chamber, especially with spinal cord orcerebral damage. The dose which has been customary isDexamethazone phosphate 10 mg I.V. followed by fourevery six hours up to 72 hours. If given for no longerthan 72 hours, the steroid can be discontinued abruptly andneed not be tapered. If continued for longer than 72 hours,tapering of the dose is necessary. Even during the short72 hour regimen recommended here, however, steroid ulceris a very real possibility and should the patient have anytype of ulcer history at all, he ought to be placed onprophylactic antacids.

Digitalis can be quite useful in decompression sicknessif the heart rate is high. In one case treated by Kindwall,it appeared to be the drug which saved the patient's life wheneverything else had been used. The digitalizing drug can beone of the quick-acting intravenous cardiac glycosides suchas Cedilanid-D. 0.8 mg. Z.V.

If a patient suffers from "chokes" due to decompressionsickness and does not experience relief upon immediate recom-pression, it may be tempting to give this drug. However, theKindwall experience has not been encouraging in treating chokeswith Aminophyllin.

71

Use of Blood Pressure Cuff

If one is treating a diver for a mild case of "pain only,Type I" decompression sickness, and only one sore spotpersists in a knee or elbow, one may become committed toTable 6 as the stopwatch approaches ten minutes. In sucha situation it may be worthwhile to try applying a bloodpressure cuff over the sore spot and rapidly pump it upto 300 mm. of Mercury. The cuff then is immediatelyreleased. In about half the cases, the pain will vanisheven after the blood pressure cuff has been removed.If it does not, nothing is lost.

Precautions to be Observed Durin Chamber Treatment

It is important to bear in mind that the laws of physicsare immutable and if one does not observe them continuously,the patient may suffer dire consequences. Be sure that allglass I.V. bottles are vented while used in the chamber.If a vent tube does not extend from the air vent needle openingin the bottle, all the way up to the air filled space at thebottom of the bottle when hanging, the air above the fluidwill expand during decompression, driving the entire contentsof the I.V. container into the patient to be followed by abolus of air depending upon how empty the bottle is at thetime decompression is started. It is preferable to useflexible plastic bags as containers for I.V. fluids in thechamber and then one never has to be concerned about thisproblem. Discard any opened or vented medication not used.

The most common error in treating decompression sicknesis failure to recognize the seriousness of the patient' scondition. Even if the patient complains only of subjectivepain, do as thorough a neurologic exam as possible. If anyneurologic signs are present, even if the patient is notaware of them, it will automatically mean he must be treatedon a longer table. Be sure to check for subcutaneous emphysemain the neck, and of course, listen and percuss for pneumothorax.A diver presenting with mild symptoms may sometimes get worse especially if it is a spinal cord case! while undergoingoxygen treatment. This could be due to the development ofspinal cord edema and/or thrombosis of the spinal arteries.Don't panic if this occurs but simply administer steroids,low molar Dextran and perhaps in such cases, heparin.

During the course of compressrion, after the diver isinitially placed in the chamber, he occasionally will complainof increasing pain as the pressure is raised. This is oftenreferred to as a "bone bubble" which has no scientific meaningother than it identifies a sometimes-seen clinical occurrencesIt has been postulated that a tiny bubble of nitrogen underthe periostium is compressed, returning the periostium backto normal position, and that this causes intense pain. Regard-less of the cause, the only solution is to slow down thecompression rate until it is tolerable for the diver, but

72

persist until treatment depth is reached. Then, the painwill eventually diappear.

Handlin the Doubtful Case

Occasionally the diving doctor may be faced with adilemma when a patient who has just surfaced from a divecomplains of pain, perhaps in a knee or shoulder. This isespecially perplexing if the patient acknowledges a recentsprain in the area or if an obvious bruise is present. Ifthe pain continues to get worse one might suspect decompressionsickness. Mild symptoms of decompression sickness are oftenreferred to as "air pains" or "niggles" British!. "Airpains" or "niggles" persisting longer than 30 minutes shouldbe considered decom ression sickness and treated. Peopleoften refer to 'niggles and air pains" saying they "canfeel the bubbles running."

Test of Pressure

When faced with the problem of deciding to treat apatient for possible decompression sickness a test of pressureis the method of choice. Take the patient in the dry chamberto pressure of 60 feet for 20 minutes breathing oxygen. lf

Pit is usually safe to assume it is not decompression sickness.Should the pain later intensify or turn out to be true decom-pression sickness, nothing has been lost. Never recompressthe symptomatic diver in the water, even as a "test ofpressure."

EMERGENCY MEDICAL KIT

Each hyperbaric chamber facility must maintain anemergency medical kit which is available for use in or outof the chamber. The primary kit, small enough to carryinto the chamber, should contain routine diagnostic equip-ment and. other equipment needed immediately in an emergency.Because many sterile items must be considered contaminatedafter exposure to increased atmospheric pressure, it isdesirable to maintain a secondary supply of equipment andmedicines that will be sent into the chamber only ifspecifically required. The primary kit should include:

FlashlightStethoscopeOtoscope � OphthalmoscopeSphgmomanometer aneroid type, never mercury!Reflex hammerTuning forkPin and brush for sensory testTongue depressors

73

Emergency equipment and medications:

Tongue depressors taped and padded as a bitepad for use in case of convulsions or equivalent!

Oropharyngeal airwayResuscitation bag respiratorLaryngoscopeSterile scalpel and blade assortmentSterile hemostats two each!Syringe, 5 cc two each! with needles disposable!Bandage scissorsEpinephrine 1:1,000 aqueous for injectionSterile gauze padsCotton ballsBenzalkonium chloride

Miscellaneous

Adhesive tapeTourniquet

The secondary medical kit should contain:

Emergency equipment:

Suture material, sterileSuture needles, assorted, sterileSterile syringes disposable, plastic!

5 cc, 2 each10 cc, 2 each30 cc, 2 each

Sterile needles, 16,L8,20 and 22 gauge preferablydisposable!

Three-way stopcocks, sterile, 2 eachSterile thoracentesis needle, 16 gauge, 4 in. longSelection of endotracheaL tubes plastic! with low

pressure inflatable cuffs

Emergency medication:

Intravenous fluids:5% dextrose in saline5% dextrose in waterRinger's injection, lactatedLow molecular weight dextran Rheomacrodex Dextran-40!

Lidocaine �% and 4%!Corticosteroid: dexamethasone for intravenous or

intramuscular injectionAmobarbital sodium, injectablePhenobarbitaL, injectableDiazepam, injectableDiphenylythydantain sodium, injectable

74

Chloropromazine, injectableCodeine tabletsAspirinAn injectable antihistamineSterile water for injectionSurgical soap

Miscellanous

Nasogastric tubeAsepto syringeSterile bladder catheterization tray preferably

disposable!Zntravenous infusion kits, sterile, disposable two each!Gauze roller bandage, 1 in and 2 in, sterileBand-aids

Sterile gloves, surgicalSterile towelsSplintsAMBU-type resuscitatorEye patch

Use of Emer enc Medical Su lies

The sterile supplies, if not adequately sealed againstthe increased ambient pressure, should be inspected and re-sterilized after each pressure exposure, or, if not exposed,at six month intervals.

Not all drug ampules will withstand pressure, and bottlestoppers may be pushed in or the bottle implode!. Bottleswith stoppers may be vented with a needle during pressurizationand then discarded if not used.

The emergency kit should be sealed in such a way thatit can be readily opened when needed but will not be openedand plundered for no good cause. A broken seal will indicatethat it has been opened. The kit should contain a list ofcontents, and each time it is opened or at monthly intervalsin any case!, it should be checked for presence and conditionof items. Sterile supplies should be provided in duplicateso that one set can be autoclaved in the meantime.

Normally, use of the emergency medical kit will berestricted to the medical staff. Concise instructions foradministration of each drug should be provided in the kit.Remember that many items in this kit can be dangerous whenimproperly-used.

75

SECTION 6

ADDITIONAL USES OF HYPERBARIC C~%3ERS

In addition to being used for recompression treatment ofdiver's suffering from decompression sickness or gas embolismand other clinical applications, hyperbaric chambers arealso routinely used for:

l. Surface Decompression

2. Omitted Decompression

3. Diver Candidate Pressure and Oxygen Tolerance Test

4. Pressurizing Personnel for Training and Demonstration

SURFACE DECOMPRESSION

Surface decompression is a techniques for fulfilling all,or a portion, of the diver's decompression obligation in arecompression chamber. By using this technique, the timewhich the diver must spend in the water is significantlyreduced; and when oxygen is breathed in the recompressionchamber, the diver's total decompression is reduced.

Surface decompression offers many advantages which enhancethe diver's safety. Shorter exposure time in the water keepshim from chilling to a dangerous level. Inside the recompres-sion chamber, the diver can be maintained at a constantpressure, unaffected by surface conditions of the sea.Observed constantly by the chamber operator, and monitoredintermittently by medical personnel, any signs of decom-pression sickness can be readily detected and immediatelytreated.

If an oxygen breathing system is installed in therecompression chamber, surface decompression should beconducted in accordance with the Surface DecomprsssionTable Using Oxygen. If air is the only breathing mediumavailable, the SurfaCe Decompression Table Using Air mustbe used. Both tables, and the specific instruction fortheir use, are in Change l �994-001-9011! to the U.STNa Divin Manual, NAVSHIPS 0994-001-9010.

There is no surface decompression table for usefollowing an exceptional exposure dive. Additionally,repetitive diving tables for dives following surfacedecompression have not been calculated.

Prior to making a dive that will employ surfacedecompression procedures, the chamber must undergo a

76

predive checkout. Upon surfacing the diver, his tenders haveonly 3.5 min to remove his breathing gear, assist him intothe chamber, and begin recompression.

OMITTED DECOMPRESSION

Certain emergencies may interrupt or prevent specifieddecompression. Blow-up, exhausted air supply, bodily injury,and similar situations constitute such emergencies. If thediver shows any symptoms of decompression sickness or gasembolism, immediate treatment using the appropriate oxygenor air recompression treatment table is essential. Even ifthe diver shows no symptoms of decompression sickness, omitteddecompression must be made up in some manner to avert laterdifficulty.

l. Use of Surface Decom ression Tables. The SurfaceTable Using Oxygen or t e Sur ace Table Using Airmay be used to make up omitted decompression onlyif the emergency surface interval occurs at sucha time that water stops are not required or havealready been completed.

2. Surface Decom ression Tables Not A licable. Whenthe conditions which permit the use o t e surfacedecompression tables are not fulfilled, the diver' sdecompression has been compromised. Special caremust be taken to detect signs of decompressionsickness, regardless of what action is initiated.The diver must be returned to pressure as soonas possible.

a. If the chamber is equipped for oxygen breathing,take the patient to 60 ft at 25 fpm, having himbreathe oxygen from the surface. If no symptomsof decompression sickness appear after 10 min.decompress on Table 5. If symptoms appear andare not relieved after 10 min., decompress onTable 6.

b. If the chamber is not equipped for oxygen breathing,take the patient to 100 ft at 25 fpm and keep himat that depth for 30 min. If no symptoms ofdecompression sickness appear during that period,decompress on Table lA.

Consider any decompression sickness developed during or afterthese procedures as a recurrence.

77

DIVER CANDIDATE PRESSURE AND OXYGEN TOLERANCE TESTS

U.S. Navy and some government agency diving candidatesare required to pass a pressure and/or oxygen tolerance testbefore they are eligible for diver training or annual diverrecertification. The following test procedures were developedspecifically for diver candidate pressure and oxygen tolerancetests. Although the specific decompression is not in accor-dance with the Standard Air Decompression Table, it hasproven to be safe and effective over years of experience inU.S. Navy facilities.

l. The candidate must undergo an appropriate divingmedical examination and be cleared for diving.

2. Chamber procedures and equalization methods areexplained to the candidate s! as previously discussed.

3. The candidate s! and attendant enter the chamberand are pressurized to 112 ft at a rate which canbe tolerated by the candidate.

4. The chamber is ventilated for one minute at 112 ftto cool the interior.

5. Ascend to 60 ft at 60 fpm.

6. The attendant places an oxygen mask on the candidatesface, and the candidate breathes 100% oxygen for 30min. During this time the candidate remains atrest and the chamber is ventilated at 12.5 acfm or 5 acfm if chamber is equipped with an overboarddischarge!. The attendant must constantly monitorthe candidate for signs of oxygen toxicity.

7. After 30 min. the mask is removed and the chamberis depressurized to the surface at a rate of 60 fpm.

During pressurization the candidate must demonstratethe ability to equalize pressure in his ears, effectivelyand otherwise withstand the effects of pressure. Due con-sideration must be given to the presence of an upperrespiratory infection which may temporarily impair theability to equalize pressure.

During the oxygen tolerance test, if the candidateconvulses or exhibits definite preconvulsive signs i.e.,twitching of facial muscles or limbs!, he fails the test;remove the mask. The test is not to be repeated. If duringthe test the candidate complains of symptoms such as nausea,tingling sensation, dizziness, etc. the mask should beremoved and the test may be terminated. The test may berepeated at, a later date at the discretion of the attendingphysician.

78

PRESSURIZING PERSONNEL FOR TRAINING AND DEMONSTRATION

All university employees and students to be pressurizedin the hyperbaric chamber must have satisfactorily completeda medical examination given by an approved physician andpronounced physically qualified for such activity. A recordof the medical examination, signed by the physician, shallbe filed with the university diving coordinator and at thechamber facility.

Since many trainees will not be affiliated with theuniversity, a person who holds an approved skin and scubadiver certificate of training and is active in underwaterdiving or is an approved diver trainee from non-universityprograms may be exempted from the medical examination require-ment. at the discretion of the Chamber Supervisor and/or theattending physician. Exemptees must, however, sign a state-ment. attesting to the fact that they are not aware of anypersonal physical abnormalities that are contraindicationsto diving. All persons, regardless of affiliation, shall berequired to execute a Waiver, Release and Indemnity Agreementand Acknowledgement of Risk statement Appendix G! priorto entering the chamber.

The chamber attendants must interview each individualundergoing a pressure test, chamber orientation, or anoxygen tolerance test to insure that they conform to therequirements previously stated. The chamber attendantsshould ask the following questions of each person enteringthe chamber:

l. Have you had a good night's sleep?

2. Have you done anv heavy drinking in the last 12 hours?

3. Do you have a cold or have you recently had a cold?

4. Have you been hospitalized or suffered a seriousillness in the past year?

5. Do you have any physical problems which have orwould possibly have disqualified you from diving?

If the chamber attendant detects any unsatisfactory answersor observes any physical abnormality, he should reject theindividual from pressurization until the person is designatedas qualified by a physician. All personnel must sign appropriatemedical information and release forms prior to entering thechamber. Inform everyone that smoking is prohibited in thelaboratory area.

Trainees shall be instructed to stay clear of thechamber door and control area while the chamber is in operation.

79

Unauthorized personnel are not allowed to handle control valvesor watches.

Prior to admitting personnel to the chamher, the chamberattendant must ensure that shoes have been removed and thatno individual has materials such as cigarettes, pipes, lighters,pens, etc. in his pockets. All watches except for divingwatches should be removed. Although all normal clothing iscombvstible, cotton appears to be desirable over syntheticand wool materials because of its nonstatic property. Zfthe attendant detects high static electricity levels onclothing, he may request that the individual change intomore suitable garments. Ideally, fire-resistant clothingshould be issued to all chamber occupants.

As the personnel enter the chamber, instruct them tobe seated in a noncramped position. Ideally, no more thanfour persons should be pressurized in the university chamberat a time. Xf possible, a trained attendant should accompanythem in the chamber. Describe the pressurization sequenceemphasizing the equalization procedure and signal for stoppingpressurization in the event they are unable to equalize raise clenched fist!. Inform them to expect a high noiselevel issue ear protectors, if necessary! and significanttemperature increase due to the adiabatic heat of compressionduring descent. Some may wish to remove a sweater or outershirt to avoid excessive perspiring. When the chamber hasreached maximum depth, observe the occupants for signs ofanxiety, claustrophobia and nitrogen narcosis. Have themnote the changes in voice slight "Donald Duck"-likequality!, difficulty whistling, and increased resistanceto forceful inhalation through the nose due to the increaseddensity of the air. If the chamber is ventilated on aperiodic basis, the occupants should be forewarned of airbursts. Prior to depressurization of the chamber, informthe occupants to breathe normally and not to hold theirbreath during depressurization. Warn them that the airtemperature will decrease significantly and that a watervapor fog may form in the chamber. This is normal andthe occupants should not be alarmed. Request that occupantsnot handle the chamber door assembly or fire extinguishingequipment while under pressure.

Following decompression, the personnel who have beensubjected to pressure are requested to remain in thebuilding for one hour and in the vicinity for 12 hours.They should not fly for at least 12 hours, or more if soinstructed by the chamber supervisor or attending physician.If they experience any unusual symptoms or illness duringthe next 24 hours, they are requested to consult with thefacility's hyperbaric physician. An information cardshould be issued to all participants and they should carrythe card for 24 hours.

80

81

APPEND IX A

STANDARD AIR DECOMPRESSION TABLES

AND

REPETITIVE DIVE TABLES

U.S. NAVY DIVING OPERATIONS HANDBOOK

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99

APPEND1X B

SURFACE DKCOMPRESSZON TABLES

FROM U.S. NAVY DIVING MANUAL

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APPENDIX C

U.S. NAVY THERAPEUTIC COMPRESSION TABLES

FOR

DECOMPRESSION SICKNESS AND GAS EI1BOLISN

112

NOTES:

TABLE 1A. AIR TREATMENT

li4

TABLE 2A AIR TREATMENT

TABLE 3. AlR TREATMENT

TABLE 4. AIR TREATMENT

TABLE 5. OXYGEN TREATMENT

60 Oxygen 20

Air

20

60 to 30 30 75

30

30 Oxygen

30 Air 105

30to 0 30 Oxygen

1. Use � treatment of painwnly decompression sickness when oxygen can beused and symptoms are relieved within 10 min at 60 ft.

2. Descent rate � 25 fpm.

3. Ascent rate � 1 fmp. Do not compensate for slower ascent rates. Compensatefor faster rates by halting the ascent.

4. Time at 60 ft � begins on arrival at 60 ft

5. If oxygen breathing must be interrupted, allow 15 min after the reaction hasentirely subsided and resume schedule at point of interruption.

6. If oxygen breathing must be interrupted at 60 ft, switch to TABLE 6 uponarrival at 30 ft stop.

7. Tender breathes air throughout. If treatment is a repetitive dive for ilie tenderor the table is lengthened, the tender should breathe oxygen during thelast 30 min of ascent to the surface.

Does not include descent time.

Depth feet!

Time

minutes jBreathing

Media

Oxygen

Oxygen

Total

Elapsed Time minutes!

13.8

TABLE 6. OXYGEN TREATMENT

60 Ox n 20

Air

Oxygen 45

5060 Oxygen 7060

7560 to 30 30 Oxygen 105

30 15120

30 Oxygen30 15 Air 19530

30to 0 30

Use � treatment of decompression sickness when oxygen can be used andsymptoms are not relieved within 10 min at 60 ft. Patient breathesoxygen from the surface.

2. Descent rate � 25 fpm

3. Ascent rate � 1 fpm. Do not compensate for slower ascent rates. Compensatefor faster rates by halting the ascent.

4. Time at 60 ft � begins on arrival at 60 ft.

5. If oxygen breathing must be interrupted, allow 15 min after the reaction hasentirely subsided and resume schedule at point of interruption.

6. Tender breathes air throughout. lf treatment is a repetitive dive for the tenderor the table is lengthened, the tender should breathe oxygen during thelast 30 min of ascent to the surface.

Does not include descent time.

Depth feet!

Tl ITle minutes!

BreathingMedia

Oxygen

Oxygen

TotalElapsed Time

minutes!

119

TABLE 6A. OXYGEN TREATMENT

30165 Air 30165 to 60 Air 34

60 20 Oxygen

5960

60 Oxygen2079

6084

Oxygen60 Air 109

60 to 30 30 Oxygen 139

Air30 15 15430 60 Oxygen 21430

229Air

6030

3030to 0319

1. Use � treatment of gas embolism when oxygen can be used and symptomsmoderate to a major extent within 30 min at 165 ft,

2. Descent rate � as fast as possible.

3. Ascent rate � 1 fpm. Do not compensate for slower ascent rates. Compensatefor faster ascent rates by halting the ascent.

4. Time at '165 ft � includes time from the surface.

5. If oxygen breathing must be interrupted, allow 15 min after the reaction hasentirely subsided and resume schedule at point of interruption.

6. Tender breathes air throughout. If treatment is a repetitive dive for the tenderor the table is lengthened, the tender should breathe oxygen during thelast 30 min of ascent to the surface.

includes descent time.

Depth

feet!Time

minutes!Breathing

Media

Oxygen

Oxygen

TotalEia psed Time

minutes!

120

121

APPENDIX D

U. S. AZR FORCE THERAPEUTIC COMPRESSION

DEPTH/TIME PROFZLES

122

NOTES:

l23

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APPENDIX E

VENTILATION AIR REQUIREMENTS

FOR

THERAPEUTIC COMPRESSION SCHEDULES

132

NOTES:

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l37

APPENDIX F

EMNINATION OF A DIVING CASUALTY*

I. Preliminary Examination

Note: In cases where chamber treatment is required thisexam should take no more than l5 seconds and should onlydetermine that the patient's life is in no immediatedanger regarding the life sustaining fucntions.

A. Life sustaining functions

1. Breathing

Is the chest moving?Count number of breaths per minute.

c. Place ear on patient's back just below shoulderblades. Have him breathe normally and deeplywhile checking for sounds in the chest area suchas gargling, wheezing or sounds such as airrushing through a pipe. Compare the soundswith a normal person.

d. If patient is coughing, what type of couch isit, how often, and is there pain, blood, orphlegm. Did he have a cold or cough beforethe accident?

2. Heart

a. Listen for a pulse at the neck or groin!b. Take pulse rate per minute do not use thumb!

3. Hemorrhage

a. Stop any bleeding with direct pressure.

4. Shock

Signs and symptoms are low blood pressure, pallor,cold clammy skin, cyanosis bluish skin due tooxygen deficiency of blood!, weakness, lighthead-edness, thirst, sweating, tachycardia rapidheart action!.Check lips and fingernails for color.Check pupils in eyes for dilation.Is there dizziness, pain, or ringing in the ears?How does the patient look generally?

a.

b.

c ~

d.

e.

Examination protocol published by the Sante Fe Engineering& Construction Co.

138

II. Neuro-Muscular Examination

The 7 parts aid in determining the extent of illness.

Note: When interpreting the results of this examina-tion, be sure that abnormalities are a result of thediving disorder and not the result of a previousdisorder, i.e., many divers will exhibit a hearingimpairment as the result of time spent workingaround loud equipment.

A. Mental condition or status

Since less interference is required to impair thefunction of higher mental levels, test first for anorganic brain syndrome by observing:

1. Orientation

a. Time the first function to go>h. Place the next to go!c. Person severe impairment!

2. Memory

a. Immediate test with a number series!b. Recent happenings within last 24 hours!c. Remote background!

3. Mentation smarts!

a. Test by using serial 7's. Subtract 7 from100, then 7 from the answer and so on. If anerror is repeated like "93, 90, 33, 80, 73,70" this is called perseveration and usuallyindicates impairment!.

4. Xevel of consciousness

a. Watch for any fluctuation

5. Seizures

a. These are readily apparent

B. Cranial nerves

What to check and how to test all 12 pairs if possible.Test one side vs. the other side.

l. Sense of smell Olfactory nerves!

a. Test with coffee, one nostril at a time.

139

2. Sight Optic nerves!

a. Hold up fingers for him to count, testing oneeye at a time.

3. Eye movement Oculomotor, Trochlear, Abducens nerves!

a. Have the patient follow with his eyes as youmove your finger up and down, left and right.

4. Chewing Trigeminal nerves!

a. Can he clench his teeth.

5. Mouth Facial nerves!

a. Can the patient smile?b. Does he lift both corners of his mouth?

6. Hearing Acoustic nerve!

a. Test one ear at a time.

7. Talking Glossopharyngeal, Vegas nerves!

a. Check for gagging and proper enunciation.

8. Shoulder muscles Spinal Accessory nerves!

a. Have patient shrug his shoulders while youpress down on them.

9. Tongue Hypoglossal nerves!

a. Can he stick his tongue straight out not toone side!?

C. Sensory nerves

l. Sharp vs dull check one hand vs other!

a. Using sharp and dull objects, see if patientcan distinguish between them by testing

l! Back of the hand�! Base of thumb�! Base of the little finger

D. Motor nerves

1. Muscle strength

a. Have patient grip two of your fingers witheach hand. ls the strength the same in each hand?

140

b. With patient sitting or lying down, place yourhands on his legs just above the ankle and pressdown lightly. Have him try to lift his legs.Is the strength equal in each?

2. Range of motion

a. Check normal movement of both arms and legs

3. Muscle tone

a. Check if muscles are spastic in state ofcontraction! or flacid totally relaxed!.

E. Coordination Cerebellar function!

1. Point in space

a. Can patient touch your finger held in frontof him?

2. Finger to nose

a. Can he move his fingers from touching yoursto tip of his nose, repeating the motion?

3. Gait

a. Walking gait -check for rubber legs, staggeringand unsteadiness.

b. Tandem gait � walking heel to toe

4. Rhomberg test for balance vertigo!

a. Have patient stand straight, feet together,arms extended in. front with palms down,thumbs touching and eyes closed.

F. Reflexes

Note: Working in a chamber will usually precludeexacting examination of most reflexes. The knee willoften be the only observable reflex.

BicepsTricepsForearm

Knee

Ankle

a ~

b.

c ~

d.

e.

2. Babinski reflex

a. Run a blunt object up the side of the foot. Ifthe toes curl forward, a normal Babinski isindicated. If nothing happens, no conclusion

1. Basic reflexes check both sides with blunt instrument!

141

can be drawn. But if the toes flex backwardand spread, this is a reliable sign of impair-ment, a spinal hit or long nerve involvement.

G. Language problem

l. Aphasia condition

a. Check for language foul-ups like misplacedwords and wrong- word order.

142

EXAMINATION CHECK LIST

Patient Date

3. Hemorrhage

2. Heart 4. Shock

MENTAL CONDITION OR STATUS

L

L3. Mentation

CRANIAL NERVES COORDINATION

l. Sense of smell R L Olfactory!

2. Sight R L Optic!

3. Eye movement R L Oculomotor, Trochlear, Abducen

4. Chewing R L Trigeminal!

5. Mouth, smile R L Facial!

6. Hearing R L Acoustic!

7. Talking R L Glossopharyngeal, Vegas~

8. Shoulders R L Hypoglossal!

L I

L L IL L L

Examiner

LIFE SUSTAINING FORCES

l. Breathing

l. Orientation: TimePlace

Person

2. Memory: ImmediateRecent

Remote

Comments or conclusions

SENSORY NERVES

l. Sharp vs Dull R

MOTOR NERVES

l. Muscle strength R2. Range of motion R3. Muscle tone R

l. Point in space R2. Finger to nose R3. Gait: Walking

Tandem

4. Rhomberg Test

FLEXES

1. Basic: Biceps RTriceps RForearm R

Knee R

Ankle R

2. Babinski reflex R

LANGUAGE

l. Aphasia condition

143

APPENDIX G

FORMS

l44

NOTES:

145

HYPERBARIC CHANBER DIVE TRAINING RECORD

DATED I VE NO r TABLE USED SUPERVISOR

CHAMBER OPERATOR TIMEKEEPER INSIDE ATTENDANT PHYSICIAN

PRESSURIZATION START TOTAL BT TOTAL DEC TOTAL DI EXIT

DIVE PROFILE

MAX DEPTH BOTTOM TI

FSW MINS

DECOMPRESSIONFSWLEAVE DEPTH REQUIRED

30 ssw

20 Fsw

10 Fsw

TOTALREACH SURFACE

DIVERS IN CHAMBER

7.

8,2.

9,

10,

5.

COURSEr GROUP r OR D I VE DESIGNATION l

CHAMBER OPERATOR signg~eJ CHAMBER SUPERVISOR sign ture!

LEAVE SURFACE

REACH FS'W

R ACH 40 FSW

AV 40 FSW

REACH 30 Fsw

LEAvE 30 Fsw

REACH 20 FSW

LEAvE 20 Fsw

REACH 10 FSW

LEAVE 10 FSW

HRS MI NS SECS

0 00 00

FROM RZMRXS OÃ BACZ OF ~ZZS SHE ~r'

l46

147

THERAP EUT XC COMP RESS EON RZCORD

148

149

NON-D IVING ACCIDENT TREATNENT RECORD

D!VE NOa DATENAME OF PATIENT

CHAMBER OPERATOR TIMEKEEPER

PRESSURIZATION START TOTAL TIME UNDER PRESSURE EXIT CHA

TREATNENT PROFILE

LEAVE SURFACE

REACH FSW TREATMENT SCHEDULE

N OXYGEN

OFF OXYGEN

OXYGEN

NOTES

YGEN

EAVE FSW

REACH SURFACE

OF OXYGEN

EXIT CHAMBER

COMMENTS ON SYMPTOMS i MED I CAT ION r AND TREATMENT

PHYS I C I AN ai @nature!CHAMBER OP E RATO R t' e dogma fur e!

0 G N

ON OXYGEN

OFF OXYGEN

INSIDE ATTENDANT PHYSICIAN S

HRS MIN SECS

0 00 00

150

151

D IVING ACCIDENT TREATflENT RECORD

NAME OF PATIENT DIVE NOi DATE

INSIDE ATTENDANT PHYSIC!AN S!CHAMBER OPERATOR TIMEKEEPER

HRS MINS SECS

INITIAL DIAGNOSISL AV

F W

FSWREACH FSW TREATMENT SCHEDULE

F XYON OXYGEN NOTES

FF YGON OXYGENOFF OXYG NON OXYGENOFF OXY N

V F WFSW

X G N

OFF OXYGENON OXYGEN

0 YGON OXYGENOFF XYGENON OXYGEN

FF OXYGENON OXYGEN

N OXYGENOFF OXYGEN

XY N

LEAVE FSWREACH SURFACE

XIT CHAMBER

CHAMBER OPERATOR/SUPERVI SOR signature! PHYS I C I AN signature!

PRESSURIZATION START TOTAL TIME UNDER PRESSURE EXIT CHAMBER

TREATMENT PROFII E

152

TIMES FOR OTHER PERSONNEL PRESSURIZED

DEPTH DECOMPRESSION

DESCR I PT I ON OF ACC I DENTS SYMPTOMS i MED I CAT I ONr R REMARKS l

CYLINDER PRESSURES

START FINISHOXYGEN IOXYGEN IIAIR I

AIR III

ENTERCHAMBER

BOTTOMT I ME

LEAVECHAMBER

DATE

153

NAINTENANCE RECORD

DESCRIPT' ON PERFORNED BY

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l55

VOLUNTEER PERMISSION FOR HYPERBARICOXYGENATION PROCEDURE

Date

I understand that this research is for experimentalpurposes, and results cannot be fully foreseen Preliminarytests have been made and indicated precautions to protectvolunteers have been taken. The University of Michigandoes not represent that any injury will necessarily beavoided in every instance even when these precautionsare followed. Nevertheless, I voluntarily assume therisk involved, in order to advance medical knowledge. Iwill carefully follow instructions given for the conductof the experiment. I will not make any claim or demandupon the University of Michigan or its personnel forinjury, if any arises from the experiment. This doesnot relieve the University of negligence in the per-formance of the experiment.

I agree that data obatined from this experimentmay be used for medical or other scientific purposes,including publication, but my identity will not, be revealedunless I expressly consent, thereto'

I also authorize my admission to the University ofMichigan Hospital if deemed advisable by my physician.

Signature

l56

PATIZNT

PERMISSION FOR HYPERBARIC

OXYGENATION PROCZDURZ

Date

Time

I authorize Or. and such assis-tants as he may designate to administer hyper aric oxygenationtreatment to The nature ofthis treatment and the risks involve espite precautionshave been thoroughly explained to me. I voluntarily acceptthe risks involved and agree that the above-named physician,his assistants, University of Michigan Medical Center, andits personnel shall assume no responsibility for the resultsof this treatment or its interpretation.

Patient or Person Authorizedto Consent for Patient

Witness:

l57

THE UNIVERSITY OF MICHZGAN

UNDERWATER TECHNOLOGY LABORATORY

HYPERBARIC CHAMBER

PARENTAL OR GUARDIAÃ'S RESEASE AND INDEMNITY AGREEMENT

The Undersigned, being the parent, guardian, or personhaving the care and custody of

7 /may participate in the hyperbaric chamber pressurization andinstruction and in consideration of the University of Michiganof Ann Arbor, Michigan, permitting our son/daughter/ward to soparticipate, does hereby covenant and agree not to sue TheUniversity of Michigan of Ann Arbor, Michigan, for any claimwhich may arise out of the aforementioned activity, and doesfurther agree to indemnify and hold harmless the saidUniversity of Michigan of Ann Arbor, Michigan from any claimwhich our son/daughter/ward may claim from the aforementionedactivity.

Signature of Parent or GuardianDate

Signature o ParticipantDate

158

THE UNIVERSITY OF MICHIGAN

UNDERWATER TECHNOLOGY LABORATORY

PRESSURIZATION INSTRUCTIONS FOR HYPERBARIC CHAMBER VISITORS/TRAINKES

Welcome to the Underwater Technology Laboratory. Those individualswho will be undergoing orientation and pressurization must read and signthe medical information form and release forms prior to entering the chamber.Smoking in the laboratory is prohibited. The chamber attendant will askthe following:

Have you had: a. A good night's sleep?b. Any heavy drinking past 12 hours!?c. A recent cold?

d. Hospitalization or serious illness past year!?

When you have been approved for entering the chamber, pleaSe Stay clear Ofthe chamber door and control area while the chamber is in operation.Unauthorized persons are not allowed to handle control valves or watches.However, remain in the area so as to be available when your name is calledfor your pressurization.

Prior to entering the chamber. it is mandatory that you reaeve yourshoes and all objects such as cigarettes, lighters, matches, pens, paper,etc. from your pockets as a safety precaution. It is also necessary toremove your watch except diving watches! . Loosen belts and restrictiveclothing.

When entering the chamber, please be seated so as not to be in acramped position. There will be a qualified attendant operating thechamber and controlling pressure. When the air is turned on by theattendant, it will be noisy and the pressure increase will be felt.Start equalizing pressure in your ears immediately by yawning, swallowing,or holding your nose and trying to force air out. Should you experiencetrouble equalizing or pain in your ears, raise your hand and the atten-dant will stop pressurization. When pressure equalizes in your ears andpain is no longer felt, infoxm the attendant OK sign or telephone! andhe/she will continue pressurization. During pressurization there willalso be a noticeable increase in chamber temperature; remve outershirt if necessary to avoid excessive perspiring. During your stayat depth periodic bursts of air will be used to ventilate the chamber.The attendant will inform you when he/she is ready to depressurizethe chamber. Breathe normally during depressurization; do not hold~our breath. The chamber air temperature will cool significantly anda water vapor fog will form in the chamber- Do not be alarmed; theattendant will clear the fog when you reach decompression depth. Donot handle the chamber dooz assembly when under pressure, especiallyduring decompression.

Post Dive Procedures: After completion of the pressurization, you areto remain in the building for one hour and should remain in the Ann Arborarea for 12 hours. Do not fly for at least 24 hours. If you feel anyunusual symptoms such as pain in joints, respiratory distress, mentalconfusion, etc. contact Univer ity Medical Center Emergency Room and thephysician designated on the "MEDICAL VKRGENCY IDENTIFICATION CARD".Thank you for observing our safety procedures end regulations. Please carrythe "MEDICAL EMERGENCY IDENTIFICATION CARD" on your person for 24 hoursafter pressurization. We hope that this has been a pleasant and educationalexperience and wish you the best in the field of diving.

159

CONSENT FOR PRESSURIZATION IN HYPERBARIC CHAMBER

ACKNOWLEDGEMENT OF RISK

Pressure changes on the body can cause serious injury if any of theseconditions are present or were present in the past:

~ Upper respiratory infection presently or in the last week!~ Bronchospasm wheezing or asthma!

~ Repeated pneumonias, pleurisy or pneumothorax collapsed lung!Calcium scars in the lung~ Emphysema or severe fibrosis of the lung

~ Cavities, air pockets, or bullae in the lung~ Previous chest surgery or radiation

~ Diabetes or epilepsy

If any of the above are present before pressurization, consultation with theUniversity's hyperbaric medicine specialist will be necessary. As in diviag,any inability to equalize pressure in the ears, or severe sinus difficultywill cause severe pain and possible future hearing impairment. On depres-surization one must breathe normally as breathholding can cause air embolizationand possible pneumothorax ruptured lung!.

I, the Undersigned, do hereby certify that I have successfully completeda nationally recognized training course in skin aad scuba diving or that Ihave received a special orientation to pressurization in a hyperbaric chamber.I do acknowledge that I am fully aware of the nature of skin and scuba divingand/or pressurization ia a hyperbaric chamber with specific rererence to thefact that the activities involve a high level of physical exertion and thatpressure changes on the body can cause serious injury if various respiratoryabnormalities, cardiac abnormalities, or conditions which result in uncon-sciousness are present or were present in the past. I hereby certify that,to my knowledge, I have no medical problems that are incoasistent with highlevel physical exertion and the specific requirements related to skin andscuba diving or chamber activity. I further acknowledge that I am aware ofthe potential risk involved with diving and/or pressurization ia a hyperbaricchamber and that I openly accept these risks.

WITNESS '

SIGNATURE OF DIVER:

SIGNATURE OF PARENT OR GUARDIAN:

where applicable!DATE:

over!

160

WAIVER» RELEASE AND INDEMNITY AGREEMENT

The Uadersigned, for him/herself, his/her heirs, executors, adminis-trators or assigns agrees that in the event any claim for persoaal injury,property damage or wrongful death shall be prosecuted against the Universityof Michigaa he/she shall indemnify and save harmless the same University ofMichigan from any and all claims or causes of action by whomever or wherevermade or presented for personal injuries, property damage or wrongful death.

The Undersigned acknowledges that he/she has read the foregoing twoparagraphs, has been fully and completely advised of the potential dangersincidental to engaging ia the diving and. instruction activity and is fullyaware of the legal consequences of signiag the within instrument.

WITNESS:

SIGNATURE OF DIVER:

SIGNATURE OF PARENT OR GUARDIAN:

DATE: where applicable!

over !

For and. in consideratioa of permission to participate in hyperbaricchamber and Underwater Technology Laboratory activities class instructiongiven by Sea Grant Program, University of Michigan, City of Ann Arbor,County of Washtenaw, and State of Michigan, the Undersigned hereby volun-tarily releases, discharges, waives and relinquishes any and all actions orcauses of action for personal injury, property damage or wrongful deathoccurriag to him/herself arising as a result of engagiag or receivinginstructions in said activity or any activities incideatal thereto whereveror however the same may occur aad for whatever period said activities orinstructions may continue, and the Undersigned does for him/herself, his/her heirs, executors, administrators aad assigns hereby release, waive,discharge, aad relinquish any action or causes of action, aforesaid, whichmay hereafter arise for him/herself and for his/her estate, aad agrees thatunder ao circumstances will he/she or his/her heirs, executors, administratorsand assigns prosecute, present any claim for personal injury, propertydamage or wrongful death against the Uaiversity of Michigan or aay of itsofficers, agents, servants, or employees for aay of said causes of action,whether the same shall arise by the negligence of any of said persons, orotherwise. IT IS THE INTENTION OF THE UNDERSIGNED BY THIS INSTRUMENT, TOEXEMPT AND RELIEVE THE UNIVERSITY OF MICHIGAN FRQN LIABILITY FOR PERSONALINJVRY» PROPERTY DAMAGE OR WRONGFUL DEATH CAUSED BY NEGLIGENCE OR OTHERWISE.

161

UNDERWATER TECHNOLOGY LABORATORYHYPE RBARI C CHAME R

PRE-DIVE CHECKLIST

CHAMBER

AIR SUPPLY SYSTEM

Clean

Free of extraneous equipmentFree of noxious odorsDoor seals undamaged and in

place, seals lubricatedPressure gauges inspected and

adjusted if necessary!

Primary aiz supply compressorsoperational Emergency re-pair service or assistance:Work day, 4-2136 or 4-3410;Night, weekend, or holiday3-1131, Security Office!

Auxiliary Air Compressor offEmergency air supply availableEmezgency air supply regulator

and air line ready for useBleed filter moisture separatorClose inner and outer compart-

ment supply valvesOpen primary chamber supply

vaLves at chamber andon wall!; pressure100 + 10 psig.

Close inner and outercompartment exhaust valves

Operate primary supply forat least 2 minutes priorto pressurizing personnel chamber doors open!

OXYGKl SUPPLY SYSTEM

Cylinder $1 full, regulatorattached

Replacement cylinder availableClose oxygen manifold valvesOpen cylinder 41 valveSet regulator at 75 psig

Open oxygen manifold valves inside and outside! for

mask check

Install overboard dischargetype oxygen breathingmask oxygen inlet anddischarge!

Install standard oxygenbreathing mask in outerand inner lock � each!

Open outside oxygen dischargevalve

Test mask

Disconnect. mask overboard

inside discharge valve the inside attendant

will connect mask andopen valve when oxygenbreathing begins at60 FSW!

Oxygen manifold valve closed inside and outside!until required

ELECTRICAL AND COMMUNICATIONS SYSTEMS

Power to chamber lights onLights operationalSound-powered phones operationalDiver communications unit

operationalExtra battery for communications

unit available

Extra light bulb available forchamber light

Two emergency battery-poweredlights available outsidechamber!

Extra flashlight batteriesavailable