AVIATION PHYSIOLOGY AVIATION PHYSIOLOGY The Scientific The Scientific Foundation of Foundation of Air Medical Transport Air Medical Transport Blair Munford, FANZCA Blair Munford, FANZCA NRMA CareFlight/New South NRMA CareFlight/New South Wales Medical Retrieval Wales Medical Retrieval Service Service
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AVIATION PHYSIOLOGYAVIATION PHYSIOLOGYThe Scientific Foundation The Scientific Foundation
ofofAir Medical TransportAir Medical Transport
Blair Munford, FANZCABlair Munford, FANZCA
NRMA CareFlight/New South NRMA CareFlight/New South Wales Medical Retrieval Wales Medical Retrieval
Service Service
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Aviation Physiology and Aviation Physiology and Critical Care TransportCritical Care Transport
RELEVANT TO:RELEVANT TO: Mode of TransportMode of Transport
– Road vs rotorwing vs fixed wingRoad vs rotorwing vs fixed wing Patient SelectionPatient Selection Patient TreatmentPatient Treatment Aircrew IssuesAircrew Issues
– Risks, precautions, fitness to fly.Risks, precautions, fitness to fly.
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Aviation Medicine vs Aviation Medicine vs AeromedicineAeromedicine
Partial Space Equivalent ZonePartial Space Equivalent Zone– 45-600,000’. Pressurisation mandatory45-600,000’. Pressurisation mandatory
Total Space Equivalent ZoneTotal Space Equivalent Zone– >600,000’ (200km). Weightlessness>600,000’ (200km). Weightlessness
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HYPOXIAHYPOXIA“The Hidden Enemy of Air Medical “The Hidden Enemy of Air Medical
Transport”Transport”
PATIENTSPATIENTS AIRCREWAIRCREW
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CLASSIFICATION OF HYPOXIACLASSIFICATION OF HYPOXIA
Hypoxic HypoxiaHypoxic Hypoxia
Anaemic HypoxiaAnaemic Hypoxia
Stagnant HypoxiaStagnant Hypoxia
Histotoxic HypoxiaHistotoxic Hypoxia
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EFFECTS OF HYPOXIAEFFECTS OF HYPOXIA
CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM– Progressive dysfunction starting with Progressive dysfunction starting with
retina & higher centres.retina & higher centres. RESPIRATORY SYSTEMRESPIRATORY SYSTEM
– Increased MV with decreased PaCO2.Increased MV with decreased PaCO2. CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM
– HR increases followed by peripheral HR increases followed by peripheral vasoconstriction & cerebral vasoconstriction & cerebral vasodilatationvasodilatation
Example I - Lear 35Example I - Lear 35Maximum cabin pressure differential 430mm Maximum cabin pressure differential 430mm
Hg So @ 40,000’ (=141 mm Hg) can maintain Hg So @ 40,000’ (=141 mm Hg) can maintain cabin altitude of 570 mmHg = 8000’cabin altitude of 570 mmHg = 8000’
Example II - King Air 200.Example II - King Air 200.Sea level cabin altitude requested. Max cabin Sea level cabin altitude requested. Max cabin
pressure differential = 350 mm Hg. So can pressure differential = 350 mm Hg. So can fly at 410 mm Hg = 16,000’fly at 410 mm Hg = 16,000’
Remember mechanisms of heat loss:Remember mechanisms of heat loss:
CONVECTIONCONVECTION
CONDUCTIONCONDUCTION
EVAPORATIONEVAPORATION
RADIATIONRADIATION Outside air temperatureOutside air temperature
– drops 2 degrees C per 1000’ risedrops 2 degrees C per 1000’ rise Helo patients also at risk of temp riseHelo patients also at risk of temp rise
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THERMAL STRESS I: THERMAL STRESS I: Special Risk Patients Special Risk Patients Paralysed/SedatedParalysed/Sedated IntoxicatedIntoxicated Polyinfused/transfusedPolyinfused/transfused Immersion or other wetImmersion or other wet Pre existing Pre existing
Precipitating factors include:Precipitating factors include: TurbulenceTurbulence Spatial disorientationSpatial disorientation Hot/stuffy environmentHot/stuffy environment Hunger or oversatiationHunger or oversatiation Fear or unpleasant stimuliFear or unpleasant stimuli MedicationsMedications
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““THIRD SPACING”THIRD SPACING” Fluid leakage into interstitiumFluid leakage into interstitium Increased during transportIncreased during transport MultifactorialMultifactorial
– VIBRATIONVIBRATION– G forcesG forces– TemperatureTemperature
Effects include:Effects include:– Oedema/swelling under castsOedema/swelling under casts– Effective dehydration/hypovolaemiaEffective dehydration/hypovolaemia
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DYSTEMPORISMDYSTEMPORISM Common name: “jet lag”Common name: “jet lag” Occurs with transmeridian travelOccurs with transmeridian travel Disturbance of circadian rhythmDisturbance of circadian rhythm Sun following (westward) versus sun Sun following (westward) versus sun
shortening (eastward) travel.shortening (eastward) travel. Influenced by: activity/food/alcoholInfluenced by: activity/food/alcohol Hypnotics for sleep restoration:Hypnotics for sleep restoration:
– Temazepam vs oxazepamTemazepam vs oxazepam
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FATIGUE I: THE PROBLEMFATIGUE I: THE PROBLEM
Fatigue itself is a stressorFatigue itself is a stressor Fatigue is also the common point of Fatigue is also the common point of