Abg’s, cpap, & vents

Respiratory Care for Paramedics

ABG, CPAP, Ventilation

1-13 Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P 1

Ventilation vs. Respiration

1-13 Voitek A. Novakovski RRT, CCEMT-P 2



Respiratory Cycle, Capacities, and Volume

Physiology of Respiration


Normal ABG Values

Abnormalities of Respiration Ventilation / perfusion (V/Q) defect

– Ratio of pulmonary alveolar ventilation to pulmonary capillary perfusion is disrupted

– Normal V/Q ratio is 1:0.8 = VA/CO – Area of lung receives ventilation little or no blood

flow = dead space ventilation u Increased FIO2 results in increased SpO2

u PCO2 may be normal or increased

– Area of lung receives blood flow but no ventilation = shunt unit

u Increased FIO2 does not result in increased SpO2

u PCO2 may be normal or decreased

© 2011 UMBC Breathing Management CCEMT-P SM 1-13 8

Pathophysiology of Respiratory Disorders


Shunt Normal Dead Space


Types of Failure u Hypoxemic

– Room air PaO2 ≤ 50 or SpO2 ≤ 85% u Hypercarbic

– PaCO2 ≥ 50 – pH ≤ 7.32

u Caution with patients that have acute on chronic failure – Their normal SpO2 may be ≈ 88% – Their normal PCO2 may be ≥ 50


Manifestations of Respiratory Distress

u  Altered Mental Status u  Increased Work of Breathing

– Tachypnea -the single most important indicator of critical illness

– Accessory muscle use, retractions, paradoxical breathing pattern

u  Catecholamine release – Tachycardia, diaphoresis, hypertension

u  Abnormal blood gas values –  Oxyhemaglobin Saturation



Pulse Oximetry u  IR spectroscopy u  Arterial oxygen saturation u  False readings

– CO poisoning – Temperature extremes – Medications causing vasoconstriction – Nitrates – Movement – Extraneous light sources

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Oxygen Saturation Curve


Pathophysiology of Hypoxemia u Ventilation/Perfusion Mismatch

– Shunt effect – Increased Dead Space

u Alveolar Hypoventilation

u Decreased Diffusion – Pulmonary Contusion – High Altitude – Pulmonary Edema


A nasty mosis

9/11/2011 Voitek A. Novakovski BSRC, RRT, NREMT-P,

CCEMT-P, 17

Pathophysiology of Hypercapnia

u Bradypnia – decreased f (resp rate) u Hypopnia – decreased Vt (tidal vol)

a.  VT=VA+VD Average VD=150 ml or≈30% b.  Minute Volume = the total amount of

air going in and out of the lungs per minute

c.  Minute Alveolar Ventilation = the total amount of air going into and out of the alveoli per minute = f X (VT-VD)





A.  f=12, VT=400ml A.  ? VA=

B.  f=24, VT=250ml A.  ? VA=

1. Which patient will have a higher CO2?



u Hypovolemia u Low cardiac output u Pulmonary embolus u High mean airway pressures u Short-term compensation by

increasing tidal volume and/or respiratory rate


Capnography u  IR spectroscopy u  CO2 levels at airway entrance u  Alveolar CO2 levels may be

estimated u  Excellent detector of cardiac output

– CPR – Keep ETCO2 ≥ 10 – ROSC – Sudden increase to ≥ 35-40

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Arterial Blood Gas (ABG) Acid-base balance / respiratory involvement

– pH, PO2, & PCO2 are measured (HCO3 is calculated)

– Assess pH: acidosis / alkalosis e.g. ± pH 7.40 – Assess pCO2: hyper / hypocapnea ± 40 – Changes in pH from changes in PCO2

u Acute: 10 mmHg change in PCO2 = 0.08 change in pH

u Chronic: 10 mmHg change in PCO2 = 0.03 change in pH

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Arterial Blood Gas (ABG)

– There is no such thing as complete compensation u If change in pH not from PCO2 than there is a metabolic component


ABG Sampling

u  Radial artery puncture – Modified Allen Test – needs to

be done u  Indwelling access

– Procedure varies by device

u  I-STAT, IRMA etc. portable blood gas analyzers known as POC devices. Know the law, CLIA determines who can analyze.

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Quiz Time 2. pH 7.28, PCO2 55, PO2 58 3. pH 7.52, PCO2 25, PO2 48 4. pH 7.25, PCO2 50, PO2 70 5. pH 7.50, PCO2 30, PO2 75 6. pH 7.22, PCO2 34, PO2 94 7. pH 7.37, PCO2 52, PO2 50


Ventilator Management

9/11/2011 Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P 27

Insufflation of Tobacco Smoke per Rectum

Copyright Intensive Care On-line Network 2002

Ventilator Procedures

In case of instability or mechanical difficulty, disconnect the ventilator and use manual ventilation.

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u  To calculate how long an oxygen tank will last (safety factor ≠ 200 psig)

–  Know the tank factors: u  H or K = 3.14 u  M = 1.65 u  E = 0.28 u  D = 0.16

u  Tank Life in Minutes = (tank pressure in psi x factor) liters per minute

8. You have a Pt on a non-rebreather @ 15 Lpm. You are using an E cylinder with 1800 psig. How long will it last before you should change it?

1-13 30

On-Board O2 Calculation

Terminology u  Fraction of Inspired

Oxygen (FiO2) u  Tidal Volume (VT) u  Deadspace (VD) u  Frequency (f) u  Minute Ventilation (VE) u  Minute Alveolar

Ventilation (VA) u  Flow Rate u  Inspiratory Time

u  I:E Ratio u  Airway Pressure

–  Actual –  Mean –  Peak

u  Compliance u  PEEP

(Positive End Expiratory Pressure)/CPAP

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Fraction of Inspired Oxygen u Oxygen concentration, expressed as

fraction in decimal form – e.g. 50% O2 = FiO2 0.5 – FiO2 of 0.65 = 65% O2

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Airway Pressure u Actual (Paw)

– Real-time airway pressure u Mean (MAP)

– Mean pressure over one complete ventilatory cycle or over a specific period of time

u Peak (PIP) – Highest pressure over a single

ventilatory cycle CCEMT-P SM 6/98

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Inspiratory (I) Time u Amount of time to deliver a single

breath, measured in seconds u In Time Cycled Ventilation:

I time x flow rate = VT 9. If frequency is 12, and I time is 1.5

seconds, what is the Expiratory (E) time?

10. How long is each breath cycle

© 2001 UMBC Breathing Management CCEMT-P SM 6/98

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Flow Rate u Inspiratory (I) flow measured in lpm u Maintain desired I : E ratio u Flow may affect pressures u In Time Cycled Ventilation:

flow rate x I time = VT 30 Lpm x 1.5 seconds = 750 ml 60 Lpm x 0.5 seconds = 500 ml

11. 40 Lpm x 0.75 second = ? VT

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I:E Ratio u Ratio of time for I:E for normal

breathing is 1:2 u Clinical situations may require ratio

to change (ET tubes cause resistance to exhalation and may require longer expiratory times and I:E of 1:3 or longer.

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Compliance u Measure of the willingness of the

lungs to expand with a positive pressure breath – Increased compliance

u Lungs are more receptive to a mechanical breath

u Reflected in lower airway pressures

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Spontaneous vs. Mechanical breathing - supine

u  increases ventilation to non-perfused areas u  increases V/Q mismatch u  increases posterior consolidation/atelectasis u  increased diaphragmatic tone decreases

atelectasis u  decreases venous return and cardiac output

9/11/2011 Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P, AE-C

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– Decreased compliance u Lungs are less receptive to a mechanical

breath, and airway pressures increase – Patient may be developing a pneumo or

hemothorax, – Restrictive lung disease or process such as

pneumonia, or atelecasis – Developing ARDS or pulmonary edema

u Patients with COPD usually have high compliance with increased expiratory resistance.


Compliance

Resistance u This is reflected when there is a high

PIP but low plateau pressures and a long exhalation time. – Common with Asthma or Acute COPD

exacerbation


Mechanical Ventilation u  Complications

–  Bio-mechanical Trauma/Pneumothorax u  Reduced by PEEP u  Avoid overdistention

–  Airway trauma u  Keep head aligned with torso

–  Atelectasis u  Humidify the air (HME) u  Avoid excessive suction u  Vary Pt’s position

–  Oxygen toxicity u  Use the lowest FIO2 that results in adequate PaO2

–  Device dependence

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Portable Ventilators u  Complications

– Machine failure – Hypotension – Pulmonary infection – GI malfunction – Renal malfunction – CNS malfunction – Psychological trauma

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Potential Complications of MV u Ventilator malfunction

– Manually ventilate patient u Cardiovascular compromise

– Especially initial hypotension which responds well to fluid bolus

– Careful to avoid fluid overload u Check BS for crackles

u Dysrhythmias – Monitor vital signs

u Monitor PIP for changes – Breath sound equality

Potential Complications of MV u Pulmonary oxygen toxicity

– goal: FIO2 as low as possible while maintaining a PaO2 > 70, SpO2 ≥ 94%

u Positive fluid balance – monitor BP, I/O, and breath sounds

u Gastric distention – monitor bowel sounds, NG tube


Principles of Ventilatory Support u Oxygenation

– PO2 u Affected by controlling FiO2, FRC, and/or

Mean Paw

u Ventilation – pH – PCO2

u Affected by controlling VA (Minute Alveolar Ventilation)

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Common Mechanical Ventilator Characteristics (1 of 2)

u Power source: pneumatic or electric – External – Internal

u Cycling – Which variable terminates inspiratory

phase of breath: vol, time, flow, or pressure

u Breath delivery – Either positive or negative pressure

Common Mechanical Ventilator Characteristics (2 of 2)

u Parameters – Mode, tidal volume, respiratory rate,

flow, FiO2, PEEP selected by clinician u Ventilator circuit

– Reusable or disposable u Alarms

– Vary in type – Set for individual patient, never disabled

Ventilator Setup Procedures – FiO2: Always start at 1.0 and adjust by SpO2 – Select mode (if Pt transport try to mimic

settings of ventilator patient is on) – Set respiratory rate – Set tidal volume, Insp time, or Pressure – Set flow rate; if adjustable – Set PEEP – Connect ventilator and observe for stability – Check PIP, Plateau Pressure, and return Vol, – Set alarms – Patency of circuitry and all connections – Check vital signs, SpO2, and ETCO2

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Modes of Ventilation u Overview

– Control – Assist/Control – Synchronized Intermittent Mandatory

Ventilation (SIMV) – Pressure Control – Pressure Support – Continuous Positive Airway Pressure

(CPAP)

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Control All parameters of the ventilator cycle

(frequency, VT, flow rate) are controlled by the ventilator – Patient is “locked out” from triggering a

breath – Patient has no active role in ventilatory

cycle – Rarely used

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Assist/Control u  Usually Volume cycled ventilation

– Most popular and easily applied – Essential parameter to control is volume

delivery, inspiratory flow (time), f (rate), FiO2, and sensitivity (-2cmH2O)

u Tidal volume (VT) and minute volume (VE) are predictable, PIP variable

u Anxious patients may create stacking u Ventilator may be triggered by road

vibrations. 53

9/11/2011 CCEMT-P Voitek A. Novakovski BSRC, RRT, NREMT-P,

CCEMT-P, AE-C 54

SIMV or SIMV with PS u Ventilator delivers set number of machine

breaths at set FiO2 – Respiratory rate, Insp Flow, and VT are set – Synchronized with patient’s spontaneous efforts

u Additional spontaneous breaths possible through circuit – Spontaneous breaths may Pressure assisted – Flow rate and VT are patient controlled – Keeps respiratory muscles active and

coordinated u Decreases stacking and need for sedation

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CCEMT-P, AE-C 56


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Pressure Control u Pressure limited-time cycled ventilation

–  Inspiration ends at a pre-set time and airway pressure

– Volume per breath may be variable – Often used with ARDS to limit applied pressure – Exhaled volume must be monitored closely – Not well tolerated by awake patients and

usually requires deep sedation



CCEMT-P, AE-C 59

Pressure Support u  Pressure limited-flow cycled ventilation

–  Inspiration limited by applied pressure, and ends at a pre-set terminal flow

–  Volume per breath may be variable –  Lungs should be relatively free of resistance and

compliant –  Patient sedated or cooperative –  Usually support needed for less than 24 hours or

weaning from long term ventilation –  May be used for long-term chronic support

u  Often used with SIMV to enchance spontaneous breaths and overcome ET tube resistance.

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CCEMT-P, AE-C 61

Dual Modes u Starts as a Pressure Limited mode which

adjusts the pressure limit on a breath by breath basis in order to achieve a desired Tidal Vol (VT) and/or Minute Vol (VE)

u Utilize the advantages of pressure limited modes which allow flow to more accurately meet patient demand. – PRVC: Pressure Regulated Volume Control – Volume Control Plus – Volume Support – Automode

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General Clinical Guidelines Tidal volume (VT) Respiratory rate (f) FiO2 Flowrate PIP Minute volume (VE) Sensitivity High Pressure Limit Low Pressure Limit

6-8 ml/Kg 10-14 bpm (ETCO2 35-40) ABG (PO2) or SpO2≥94% 40-60 lpm (I:E ratio) ≤ 40 cmH2O ABG(PCO2/pH)ETCO2 -2 cm, adjust as needed 10 cm above PIP 10 cm below PIP

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Monitors u Airway Pressure (Paw or PIP)

– Real time manometer or graph – Range: 0-120 cm H2O (depends on vent)

u Monitor Display – Breath rate – Flow – High pressure alarm – Low pressure alarm – PEEP – I time or I:E – VT – VE

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Ventilator Alarms u High airway pressure (PIP) u Low airway pressure u High respiratory rate u Low respiratory rate u High minute volume u Low minute volume u Low exhaled tidal volume u Apnea

Ventilator Alarms (con’t) u High pressure limit

– Usually set 10 cm H2O above patient’s average PIP

– When activated, ventilator terminates breath u Causes of high pressure alarm violation

– Resistance to gas flow: kinks or water in tubing, secretions, bronchospasm, patient coughing, gagging, “fighting the ventilator”

– Decrease in lung compliance, lungs become “stiffer”: atelectasis, pneumothorax, pulmonary edema

Ventilator Alarms (con’t) u  Low pressure limit

– Primary cause: patient disconnect, or leak in system

–  Inspiratory flow too low and patient gasping for air (increase flow to meet demand)

u  Low exhaled volume or minute ventilation – Usually set ~10% below set VT and average VE – Ensures adequate alveolar ventilation is

maintained – Causes: air leaks, decrease in compliance with

PSV and PCV, high pressure alarm triggered and breath delivery terminated

– Check for bubbling in chest tubes

u High Rate: usually set ≈ 10 over average rate – Alarm indicates agitation, hypoxia, or

insufficient VT – Check vital signs, SpO2, ETCO2, exhaled

VT, or provide sedation – May be due to “auto-cycling”, check

sensitivity, or check for leaks in circuit


Ventilator Alarms (con’t)

Ventilator Alarms (cont) u High exhaled tidal volume or minute

ventilation – Increased metabolic demand – Neurologic abnormality – May indicate hypoxemia – Anxiety – Pain – Fever – Acidosis

Ventilator Alarms (con’t) u Low Rate: usually set ≈ 10 below

average rate – For spontaneous breathing modes like

PS or CPAP this alarm is critical and indicates either patient is fatigued or over sedated.

u Low tidal volume: usually ≈ 10% below average or set VT – Alarm usually due to leak in the system – In PS or CPAP pt fatigued or over

sedated 1-13 Voitek A. Novakovski RRT, CCEMT-P 70

Ventilator Alarms (cont)

u Apnea Alarm: this alarm is mostly used with PS or CPAP: – Patient has stopped breathing – May initiate apnea backup ventilation on

some ventilators u Disconnect: some ventilators have

this alarm in addition to a low pressure alarm.

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Ventilator Alarms (cont) u Apnea Alarm: this alarm is mostly

used with PS or CPAP: – Patient has stopped breathing – May initiate apnea backup ventilation on

some ventilators u Disconnect: some ventilators have

this alarm in addition to a low pressure alarm.

Ventilator Alarms (continued) u Ventilator Inoperative (some vents)

– normal operation ceases u Breathe room air if spontaneous breathing is present

–  recoverable u Loss of external power or voltage out of range u Mode switch temporarily set to Off

– non-recoverable u Software or CPU problem

u External Power Low/Fail – Ventilators with this alarm switch to internal

battery

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Ventilator Alarms (cont) u Battery Low/Fail

– Switch to external power u Low PEEP

– Monitored PEEP value deviates from manually set value: check for leaks in system

u Transducer Calibration – Self test shows baseline pressure +/- 2 cm

H2O from zero – Calibrate ventilator

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Flow-Restricted, Oxygen-Powered Ventilation Device (1 of 4)

u Third potential source for artificial ventilation – Manually triggered ventilator or demand

valve – Used to ventilate apneic patients or to

administer supplemental oxygen to spontaneously breathing patients


Demand valve triggered by the negative pressure generated during inhalation

Valve automatically delivers 100% oxygen and stops the flow of gas at the end of inhalation.

Patients find it most comfortable if they hold the mask to their face themselves.


u Apneic patients – Pushbutton on top of the FROPVD can control

the flow of oxygen. – When depressed, 100% oxygen flows at a rate

of 40 L/min. u Requires an oxygen source

– Operator cannot feel whether the patient is being adequately ventilated with this device.


u Use – Has been used for several years – Recent findings suggest that it should not be

used routinely because of the high incidence of gastric distention and damage to intrathoracic structures caused by barotraumas.

– Should not be used when ventilating infants or children or for patients with possible cervical spine or chest injury

– Cricoid pressure may need to be maintained to ventilate nonintubated patients.

Skill Drill 11-21: Flow-Restricted, Oxygen-Powered Ventilation for Apneic Patients (1 of 2)

Step 1

Step 2

Step 3

Skill Drill 11-21: Flow-Restricted, Oxygen-Powered Ventilation for Apneic Patients (2 of 2)

Step 4 Step 5

Skill Drill 11-22: Flow-Restricted, Oxygen-Powered Ventilation Device for Conscious, Spontaneously Breathing Patients

Step 1 Step 2 Step 3

PEEP vs. CPAP

? ? ?

?

?


CCEMT-P, AE-C 83


CCEMT-P, AE-C 84

Lung Volume

Inspiratory Capacity

F.R.C. Functional Residual Capacity

TOTA

L LU

NG

CA

PAC

ITY

(600

0 cc

)

500 cc

3100 cc

1200 cc

1200 cc

Inspiratory Reserve

Tidal volume

Expiratory Reserve

Residual Volume

PEEP u Positive end expiratory pressure u Increases functional residual

capacity (FRC)

9/11/2011 CCEMT-P Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P,

AE-C 85


CCEMT-P, AE-C 86

Collateral channels of ventilation: Pendeluft


PEEP u  Definition

– Positive End Expiratory Pressure: The Application of positive pressure to the airway at end exhalation.

– Used to increase FRC to normal levels. u  Used with other mechanical ventilation modes

such as A/C, SIMV, PS, or PCV

5 cm H2O PEEP

CPAP u Definition: PEEP applied to a spontaneously

breathing patient: without mechanical assist. – Continuous Positive Airway Pressure: Constant

positive pressure throughout the ventilatory cycle

– Requires spontaneous respiratory drive – Rate and VT determined entirely by the patient

10 cm H2O PEEP

Time

Spontaneous Breathing


CCEMT-P, AE-C 90


CCEMT-P, AE-C 91

CPAP u Must set back-up ventilation

parameters if available u Benefits by normalizing FRC:

– Increases compliance – Decreases atelectasis – Reduces pulmonary edema – Increases PaO2 – Decreases work of breathing (WOB) – Splints airways in Asthma and COPD

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CPAP The National Association of EMS Physicians (NAEMSP) believes that noninvasive positive pressure ventilation

(NIPPV) is an important treatment modality for the prehospital management of acute dyspnea. This document is the official position of the NAEMSP.

Read More: http://informahealthcare.com/doi/abs/

10.3109/10903127.2011.561418


CCEMT-P, AE-C 93

10 Commandments of Transport Ventilation

1)  Maintain set PEEP (bagging) 2)  Hold ETT when switching 3)  Your vent = their vent 4)  Transition to vent early and observe 5)  Security of airway. Re-tape if necessary 6)  Adequate portable oxygen supply 7)  Judicious use of paralytics or sedatives 8)  Track plateau versus PIP 9)  Maintain EtCO2 and SpO2 10) Minimal to no changes


CCEMT-P, AE-C 94

Critical Care Ventilator Transport u  It is important that you set your ventilator to

settings as close as possible to what kept the patient stable in the hospital. Adjust as needed

u  If you are unable to stabilize the patient on your ventilator, then a respiratory therapist may be required to accompany you using the hospital ventilator, or you may have to refuse transport.

u  If you take their ventilator, make sure it is compatible with your power source.

u  Do not attempt to transport a patient that is beyond your capability to maintain.


CCEMT-P, AE-C 95

Pharmacologic Adjuncts u Bronchodilators

– β2-agonists – Anticholinergics (ipratropium)

u Corticosteroids u Sedatives u Paralytics u Pressors u Inotropic agents



CCEMT-P, AE-C 97

Paul Andrate

Quiz u Pt 32 y/o intubated on vent, VT

450ml, f 14, FiO2 1.0 – ABG pH 7.37, PCO2 42, PO2 64 – What would you change or add?

u Pt 17 y/o Asthmatic on 4L/NC with bilat insp and exp wheezes. – ABG pH 7.43, PCO2 36, PO2 92 – What 2 classes of drugs plus other

options might help this young man?

1-13 Voitek A. Novakovski BSRC, RRT, NREMT-P,

CCEMT-P 98

Noninvasive Positive-Pressure Ventilation (NPPV)


Relative Contraindications for NPPV

u Decreased level of consciousness u Poor airway protective reflexes u Copious secretions u Cardiovascular instability u Progressive pulmonary

decompensation u Upper gastrointestinal hemorrhage


Initiation of NPPV u Set FIO2 at 1.00 u Hypoxemic failure

– Inspiratory pressure (IPAP) 10 cm H2O – Expiratory pressure (EPAP) 5 cm H2O – Titrate EPAP in 2 cm H2O increments

u Ventilatory failure – IPAP 10 and EPAP 2 cm H2O – Titrate IPAP in 2 cm H2O increments

Initiation of NPPV u Make changes every 15-30 minutes u Monitor vital signs, appearance,

pulse oximetry and blood gases u Head of bed at 45° angle u Consider gastric decompression u Intubation if patient deteriorates

Airway pressure release ventilation


APRV


APRV u  Advantages

–  Lower peak/plateau –  Spontaneous

breathing permitted –  Decreased sedation –  Elimination of NMB

u  (Frawley & Habashi 2001)

u  Potential disadvantages –  Change in compliance

= change in volume –  New technology –  Limited access –  More research –  Transports



Health & Medicine

Abg’s, cpap, & vents