Basic Aeromedical

Transport

Presented at: ACEM Workshop

By: Sutuspun Kay Kajornboon,

M.D., Dip. Av. Med. (UK)

Director, Civil Aeromedical Center, BMC

Date: 2011

TROPOSPHERE

From sea level to FL 300-600 Depending

on temperature

Temperature Lapse Rate 1.98 oC / 1,000 ft.

Water Vapor : Seasons & Weather,

Turbulance

Most Flying occurs

Dr. Sutuspun Kajornboon

Physiological Division

PHYSIOLOGICAL ZONE:

MSL to 10,000 ft.

PHYSIOLOGICAL DEFICIENT ZONE

10,000 ft. to 50,000 ft.

SPACE - EQUIVALENT ZONE

> 50,000 ft.

Dr. Sutuspun Kajornboon

Physiological impact of decreased atmospheric

pressure

Decrease of Total Pressure

Evolved Gas Problem

*Decompression

sickness

Decrease of Atmospheric Pressure

Decrease of Partial

Pressure

Trapped Gas Problem

*Ear Barotrauma

*Sinus Barotrauma

*Gastrointestinal gas

expansion

*Barodentalgia

*Etc.: pneumothorax,

peumomediastinum

Hypoxia

Dr. Sutuspun Kajornboon

mm Hg0200 400 600 760

80k

70k

60k

40k

30k

20k

10k

50k

Feet

Change of Pressure with Altitude

1/2

1/4

1/10

Partial Pressure

Air at Sea Level

O2 = 21% pO2 = 160 mm Hg

N2 = 78% pN2 = 593 mm Hg

Other = 1% = 7 mm Hg

Total = 100% = 760 mm Hg

Partial Pressure

Air at 10,000 ft.

O2 = 21% pO2 = 110 mm Hg

N2 = 78% pN2 = 408 mm Hg

Other=1% = 5 mm Hg

Total=100% =523 mm Hg

Partial pressures in mm Hg at sea level

103

570

40

47

Alveolar air

Carbon dioxide

Water vapour

Oxygen

Nitrogen

160

593

Atmospheric air

Oxygen

Nitrogen

0

760

Other 7

Alveolar Gases

10,000 ft

523 mm Hg

55O2

381N2

40

47

CO2

H2O

Sea level

760 mm Hg

103O2

570N2

40

47

CO2

H2O

Relationship between alveolar p02, altitude and Hb saturation

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100 110

sea level5k10k15k20kAltitude (ft)

Alveolar pO2 (mm Hg)

% Hb

saturation

Alveolar Gases

10,000 ft

523 mm Hg

55O2

381N2

40

47

CO2

H2O

Sea level

760 mm Hg

103O2

570N2

40

47

CO2

H2O

18,000 ft

380 mm Hg

Air

39O2

264N2

30

47

CO2

H2O

Symptoms and Signs

Performance Effects

personality change

loss of judgement

loss of self-criticism

euphoria

loss of short term memory

mental incoordination

Symptoms and Signs

Physical Effects

muscular incoordination

sensory loss - vision

- touch

hot flushes

cyanosis

hyperventilation

Symptoms and Signs

Late Effects

semi-consciousness

unconsciousness

death

Times of Useful Consciousness

Altitude TUC

FL 180 20 - 30 min

FL 220 10 min

FL 250 3 - 5 min

FL 300 1 - 2 min

FL 350 30 - 60 sec

FL 400 15 - 30 sec

FL 430 9 - 12 sec

Factors Affecting Tolerance to

Hypoxia - I

• altitude

• time

• rate of ascent

• exercise

• cold

• illness

Factors Affecting Tolerance to

Hypoxia - II

• fatigue

• drugs and alcohol

• smoking

• stress and workload

• physical fitness

• hangover

TRAPPED GAS

DISORDERS

80k

34k

18k

0

53k

4 x

1 x

10 x

Gas Expansion at Altitude

The Middle Ear

Eardrum

Eustachian tube

Inner earOuter ear

Gas Expansion in

the Ear - Climb

Pressure in the

middle ear is

greater than the

outside’s pressure.

Gas Contraction in

the Ear - Descent

Pressure in the middle

ear is less than the

outside’s pressure.

Acute Barotitis Media

Eardrum

Eustachian tube

BAROTITIS MEDIA

• An acute/chronic traumatic inflammation

caused by pressure difference between

the air in the middle ear and that of the

surrounding atmosphere.

• Symptoms: pain, deafness, tinnitus and

occasionally, vertigo.

Prevention

• Equalized pressure by:

• Chewing action or moving jaw side to

side

• Yawning or swallowing

• Valsalva

• Do not fly with a cold.

Valsalva Maneuver

• Take a deep breath.

• Hold the nostrils shut tight.

• Tense the cheek & neck muscles.

• Force pressure similar to blowing your

nose. ( Strong short burst )

The Sinuses

Frontal sinus

Maxillary sinus

Ethmoidal sinuses

Sphenoidal sinus

Barosinusitis Media

• Signs: fullness around the eyes area to

sharp stabbing pain

• : trace of blood with nasal discharge

Treatment & Prevention

• Seek treatment for URI/Sinusitis

• Do a valsalva maneuver for relief

• Use antihistamine nasal spray

Intestinal Gas Expansion

• Sea Level = 1.0 Liter

• 10,000 ft. = 1.5 Liter

• 30.000 ft. = 4.0 Liter

• 40,000 ft. = 7.0 Liter

• 50,000 ft. = 17.0 Liter

Gas Expansion in

the Stomach

Gas Expansion in

the Large Bowel

Gas Expansion in

the Small Bowel

?

Prevention

• Avoid gas producing food.

• Chew your food completely.

• Avoid drinking large amount of liquid

before flight.

• Start the day with good bowel habits

• Avoid chewing gum during ascent

RELIEF OF SYMPTOMS

• Belching (upper GI)

• Passing wind (lower GI)

• Maintain level flight (for cockpit crew)

• Descent to lower altitude if pain is severe

(for cockpit crew)

Gas Expansion in the Lungs

- pneumothorax

- air embolism

- pneumomediastinum

Prevention of Trapped Gas

Problems

• Fly only when healthy

• See a doctor if ill

• Equalize pressures frequently on

descent

• Avoid gas producing foods, maintain

a healthy diet

Flight Environment• GLARE

• Strong bright light from the sun above and

reflected from the clouds below

• Health effect from UVa & UVb causing

eyes irritation pterygium & cataract

(long term)

• Effect pilot more than cabin crew

Noise & Vibration

Library

Heavy truck

Jet take-off

Pneumatic road drill

Business office

Quiet woods

140 dB

0

Pa 200,000,000

100

80

60

120

40

20

20,000,000

200,000

2,000,000

20,000

2000

200

20

Acceptable Noise Levels.

• No NIHL with 75 - 80 dB(A)

exposures.

• OH&S limit of 85 dB(A) for 8 hour

working day (Daily Noise Dose).

• Aircrew exposures regularly exceed this.

Flight Environment

Noise

• Communication

• Stress

• Fatigue

• Distraction

• Deafness (hearing loss)

• Vibro-acoustic Syndrome

Vibration

• Pain threshold

• Stress

• Fatigue

• Motion Sickness

• Speech problem

• Hyperventilation

• Soft tissue injury (backpain)

Personal Protective Equipment:

Aircrew helmets.

Aircrew headsets.

Earmuffs.

Insert earplugs.

Active Noise Reduction.

Flight Environment• HUMIDITY

• Human are comfortable with humidity around 60-70%; Cabin humidity could be as low as less than 30%

• Can cause throat & upper airway irritation prone to viral infection & make jet lag worse

• Dryness exacerbate chronic skin problems such as allergy, eczema, dandruff

HUMIDITY

• Drinks more water or fluids

• Avoid alcohol, too much

coffee or tea

Flight Environment• UNUSUAL MOTION

• Unexpected movements in all three axis which is not normally encounter on the ground confusion, stress and motion sickness.

• Long term worsen the effect of jet lag and fatigue easily

• Turbulence are health hazard for aircrew

Med-crew Environment

• CONFINED WORKING AREA

• Psychologically stressful: constantly

avoiding obstacles; worse in claustrophobia

• Physically a safety hazard: can get injured

easily especially during turbulence

Thank you for your attention