ALTITUDE PHYSIOLOGY OUTLINE The Atmosphere Hypoxia Types Stages Hyperventilation Trapped Gas Disorders Evolved Gas Disorders.

ALTITUDEALTITUDE

PHYSIOLOGYPHYSIOLOGY

OUTLINEOUTLINE

• The Atmosphere• Hypoxia

• Types• Stages

• Hyperventilation• Trapped Gas Disorders• Evolved Gas Disorders

REFERENCESREFERENCES

FM 1-301, Aeromedical Training for Flight

Personnel, May 1987

FM 1-204, Night Flight Techniques and

Procedures, October 1983

TROPOSPHERE

Sea level to flight level 300 - 600 depending on temperature, latitude and season.

Physical DivisionsPhysical Divisions of the Atmosphere

STRATOSPHERE

IONOSPHERE

EXOSPHERE

MOUNT EVEREST 29,028 FEET

1200 miles

600 miles

50 miles

Tropopause

Physiological ZonesPhysiological Zones of the Atmosphere of the Atmosphere

EFFICIENT ZONE: SEA LEVEL TO 10,000 FEETEFFICIENT ZONE: SEA LEVEL TO 10,000 FEET

SPACE EQUIVALENT ZONE: 50,000 FEET AND ABOVESPACE EQUIVALENT ZONE: 50,000 FEET AND ABOVE

DEFICIENT ZONE: 10,000 TO 50,000 FEETDEFICIENT ZONE: 10,000 TO 50,000 FEET

10,000

50,000

78 % Nitrogen (N2)

21 % Oxygen (O2)

1 % Other

(.03 % CO2)

Composition of AirComposition of Air

14.7 PSI

Sea Level PressureSea Level Pressure

Scale

lbs

760 mm Hg

OR

29.92 in. Hg

Barometer / Altimeter

PERCENT COMPOSITION OF THE ATMOSPHERE REMAINS

CONSTANT

BUT PRESSURE

DECREASES

WITH ALTITUDE

SIGNIFICANT PRESSURE ALTITUDESSIGNIFICANT PRESSURE ALTITUDES

ALTITUDE PRESSURE

FEET mm/HG ATMOSPHERES

0 760 1

18,000 380 1/2

34,000 190 1/4

48,000 95 1/8

63,000 47 1/16

Partial PressurePartial Pressure

(Dalton’s Law)(Dalton’s Law)760 mm Hg760 mm Hg

47 --- mm/Hg 95 ---190 ---380 ---523 ---760 ---

21%O2

78% N2

1% O

ther

The pressure exerted by a mixture of gases is equal to the sum of the partial pressures of

each gas in the mixture.

Pt = P1 + P2 + ...+ Pn

(Dalton’s Law)(Dalton’s Law)

HypoxiaHypoxia

State of oxygen [O2] deficiency in the blood cells

and tissues sufficient to cause impairment of

function.

Types of HypoxiaTypes of Hypoxia

Hypemic

Stagnant

Histotoxic

Hypoxic

HypemicHypemic HypoxiaHypoxia

Inability of the Inability of the blood to blood to

accept oxygen accept oxygen inin

adequate adequate amountsamounts

++

++++

++

++++

++

++++

++

++

++

++ ++++

Stagnant HypoxiaStagnant HypoxiaStagnant HypoxiaStagnant Hypoxia

ReducedReduced bloodbloodflowflow

Blood Blood movingmovingslowlyslowly

adequateadequateoxygenoxygen

Red blood cells Red blood cells not replenishing not replenishing

tissue needs tissue needs fast enoughfast enough

Red blood cellsRed blood cells retain oxygenretain oxygen

Inability of Inability of the the

cell to accept cell to accept or use or use oxygenoxygen

Histotoxic HypoxiaHistotoxic Hypoxia

Poisoned tissuePoisoned tissue

adequateadequateoxygenoxygen

Hypoxic HypoxiaHypoxic HypoxiaReduced Reduced

pOpO22

in the in the lungslungs(high (high

altitude)altitude)

Body tissueBody tissue

Red Red blood cellsblood cells

HypoxiaHypoxiaSymptomsSymptoms

Subjective: FeelSubjective: Feel

Air hunger Air hunger Hot and Cold FlashesHot and Cold Flashes

Apprehension Apprehension EuphoriaEuphoria

Fatigue Fatigue BelligerenceBelligerence

Nausea Nausea Blurred visionBlurred vision

Headache Headache NumbnessNumbness

Dizziness Dizziness Tingling Tingling

Denial Denial

Air hunger Air hunger Hot and Cold FlashesHot and Cold Flashes

Apprehension Apprehension EuphoriaEuphoria

Fatigue Fatigue BelligerenceBelligerence

Nausea Nausea Blurred visionBlurred vision

Headache Headache NumbnessNumbness

Dizziness Dizziness Tingling Tingling

Denial Denial

HypoxiaHypoxiaSignsSigns

Objective: SeeObjective: See

HyperventilationHyperventilation

CyanosisCyanosis

Mental confusionMental confusion

Poor JudgmentPoor Judgment

Lack of muscle coordinationLack of muscle coordination

Stages of HypoxiaStages of Hypoxia

Indifferent Stage

Compensatory Stage

Disturbance Stage

Critical Stage

Indifferent StageIndifferent Stage

Altitudes

Air: 0 - 10,000 FEET

Symptoms: decrease

in night vision @ 4000 feet

Compensatory StageCompensatory Stage

Altitudes

Air : 10,000 - 15,000 FEET

Symptoms: impaired efficiencydrowsinesspoor judgmentdecreased coordination

CAUTION!CAUTION!

Failure to recognize symptoms and Failure to recognize symptoms and take corrective action may result in take corrective action may result in

an aircraft mishapan aircraft mishap

Disturbance StageDisturbance Stage

Altitudes

Air: 15,000 - 20,000 FEET

Disturbance StageDisturbance Stagesymptomssymptoms

Sensory Vision

Touch & pain

Hearing

Disturbance StageDisturbance Stagesymptoms

Mental Memory Judgment Reliability Understanding


Personality Happy Drunk

versus the

Mean Drunk


Performance Coordination Flight Control Speech Handwriting

put back on oxygen

Time off Oxygen

1 minute1 minute

2 minutes2 minutes

3 minutes3 minutes

4 minutes4 minutes

5 minutes5 minutes

6 minutes6 minutes

CAUTION!CAUTION!CAUTION!CAUTION!

Failure to recognize symptoms Failure to recognize symptoms and take corrective action may and take corrective action may

result in an aircraft mishapresult in an aircraft mishap

Disturbance StageDisturbance Stage

Signs Hyperventilation

Cyanosis

Critical StageCritical Stage

Altitudes

Air: 20,000 FEET and above

Symptoms: loss of consciousnessconvulsions

death

WARNING!WARNING!

When hemoglobin saturation falls toWhen hemoglobin saturation falls to

serious cellular dysfunction occurs; serious cellular dysfunction occurs;

and if prolonged, can cause deathand if prolonged, can cause death

WARNING!

65%65%

Factors modifying hypoxia Factors modifying hypoxia symptomssymptoms

Pressure altitude Rate of ascent

Time at altitude

Temperature

Physical activity Individual factors Physical fitness Self-imposed stresses

Alcohol

it’s a no brainer!it’s a no brainer!

Tobacco

keep keep self imposed stressesself imposed stresses out of the aircraft out of the aircraft

Drugs

ExhaustionHypoglycemia

2000 feet

2000 feet

BBUUZZZZ

1 ounce =

1 ounce =

alcoholalcohol

Expected Performance TimesExpected Performance TimesExpected Performance TimesExpected Performance Times

FL 430 & above 9-12 seconds

FL 400 15 - 20 seconds

FL 350 30 - 60 seconds

FL 300 1 - 2 minutes

FL 280 2 1/2 - 3 minutes




Expected performance time for a crew member Expected performance time for a crew member flying in a pressurized cabin is reduced flying in a pressurized cabin is reduced

approximately one-half following approximately one-half following loss of pressurization such loss of pressurization such

as in a:as in a:

RDRDrapid decompression rapid decompression

HypoxiaHypoxia

Prevention

limit time at altitude

breathing oxygen

pressurized cabin

HypoxiaHypoxia

Treatment

oxygen

descend to a safe altitude

HyperventilationHyperventilationdefinitiondefinition

an excessive rate and depth of respiration leading to the abnormal

loss of CO2 from the blood.

Emotional (fear, apprehension, excitement)

Pressure breathing

Physical stress

Hypoxia

HyperventilationHyperventilationCausesCauses

HyperventilationHyperventilation SymptomsSymptoms

tingling sensations muscle spasms hot and cold sensations visual impairment dizziness unconsciousness

HyperventilationHyperventilation reason for symptomsreason for symptoms::

loss of carbon dioxide [CO2]

shift in pH balance

HyperventilationHyperventilationsignificancesignificance

incapacitation of an otherwise outstanding, healthy aviator.

confusion with hypoxia

Don’t Panic

Control your breathing

HyperventilationHyperventilationpreventionprevention

Check your oxygen equipment - it may be hypoxia

above 10,000 feet

possible hypoxia

below 10,000 feetprobable hyperventilation

HyperventilationHyperventilationcorrective actioncorrective action

DysbarismDysbarism

syndrome resulting from the effects, syndrome resulting from the effects, excluding hypoxia, of a pressure excluding hypoxia, of a pressure differential between the ambient differential between the ambient

barometric pressure and the barometric pressure and the pressure of gases within the bodypressure of gases within the body

Boyle’s LawBoyle’s Law

The volume of a gas is inversely proportional to its

pressure; temperature remaining constant.

DRY GAS EXPANSIONWET GAS EXPANSION1.8X 2.0X16,000

2.5X 25,000 3.0X

34,,000 5.0X

43,000

4.0X

9.5X6.0X

Gas Expansion

Watch your diet, don’t eat too fast Avoid soda and large amounts of water just

prior to going to altitude

Don’t chew gum during ascent

Keep regular bowel habits; eat your fiber

Gas ExpansionGas Expansionprevention of abdominal gas painsprevention of abdominal gas pains

Middle Ear

Opening to throatOpening to throatEustachian tubeEustachian tube

External earMiddle ear

Ear drum

Semicircular canal Cochlea Auditory nerve

Middle Ear Cavity

Eustachian Tube

Atmospheric Pressure

Tympanic Membrane

External Ear

Middle Ear Cavity

Eustachian TubeBlocked / Infected

Tympanic Membrane

External EarAtmospheric Pressure

Pressure EffectPressure Effect

Ear Block

Clear

Normal tympanic membrane (ear drum)Normal tympanic membrane (ear drum) Inflamed ear drumInflamed ear drum

Infected ear drumInfected ear drum

Frontals

Ethmoids

MaxillarySphenoids

The SinusesThe Sinuses

Treatment of an Sinus/Ear Block Treatment of an Sinus/Ear Block

1.1. Stop the descent of the aircraft and attempt Stop the descent of the aircraft and attempt to clear by valsalva. to clear by valsalva.

22. If unable to clear, climb back to altitude until . If unable to clear, climb back to altitude until clear by pressure or valsalva.clear by pressure or valsalva.

33. Descend slowly and clear ear frequently . Descend slowly and clear ear frequently during descent.during descent.

BarodontalgiaBarodontalgia

Tooth pain due to:

Gum abscess: dull pain on ascent Inflamed pulp: sharp pain on ascent

Inflamed maxillary sinus: pain primarily on descent

Decompression Decompression SicknessSickness

Henry’s LawHenry’s Law

The amount of gas dissolved in solution is directly proportional to the pressure of the gas over the solution

WARNIN

G

WARNIN

G

Evolved gas disorders are considered serious

and medical treatment and advice

must be sought immediately.

Evolved Gas DisordersEvolved Gas Disorders

The BendsThe Bends

ParesthesiaParesthesia

The ChokesThe Chokes

Central Nervous System-CNSCentral Nervous System-CNS


N2 bubbles become trapped in the joints. Onset is mild, but eventually painful!

The BendsThe Bends


ParesthesiaParesthesia N2 bubbles form along nerve tracts. Tingling and itchy sensation and possibly a mottled red rash.


The ChokesThe Chokes N2 bubbles block smaller pulmonary vessels. Burning sensation in sternum. Uncontrollable desire to cough. Sense of suffocation ensues.


CNSCNS N2 bubbles affect spinal cord. Visual disturbances, paralysis, one sided tingling.

Evolved gas factorsEvolved gas factors

Rate of ascent

Altitude

Body fat content Age

Exercise

Duration of exposure

Repeated exposure

Descend

100% Oxygen

Decompression SicknessDecompression Sicknesstreatmenttreatment

Land at nearest location where qualified medical assistance is available.

Compression greater than 1 atmosphere (absolute).

Scuba Divers Beware!Scuba Divers Beware!

24 Hour restriction

24 Hour restriction

between diving and flying!!!!!

between diving and flying!!!!!

or be bent!or be bent!

?QUESTIONS?

QUESTIONS?

ALTITUDE PHYSIOLOGY OUTLINE The Atmosphere Hypoxia Types Stages Hyperventilation Trapped Gas Disorders Evolved Gas Disorders.

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