ALTITUDE PHYSIOLOGY OUTLINE Classifications of Hypoxia Signs and symptoms of Hypoxia Stages of Hypoxia Prevention of Hypoxia Provisions of AR 95-1 Provisions.

ALTITUDEALTITUDE

PHYSIOLOGYPHYSIOLOGY

OUTLINEOUTLINE

Classifications of HypoxiaSigns and symptoms of HypoxiaStages of HypoxiaPrevention of HypoxiaProvisions of AR 95-1Provisions of AR 40-8

REFERENCESREFERENCES

FM 1-301, Aeromedical Training for Flight

Personnel, May 1987

AR 95-1, Flight Regulations, september 1997

AR 40-8, Temporary Flying Restrictions Due to

Exogenous Factors

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

Disturbance StageDisturbance Stagesymptomssymptoms

Personality Happy Drunk

versus the

Mean Drunk

Disturbance StageDisturbance Stagesymptomssymptoms

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

FL 250 3 - 5 minutes

FL 220 8 - 10 minutes

FL 180 20 - 30 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

AR 95-1AR 95-1Altitude Restrictions and Oxygen RequirementsAltitude Restrictions and Oxygen Requirements

14,000

10,000

12,0001 Hour Total

30 Min Total

Unpressurized

Pressurized

10,000

14,000

25,000

Maintain Cabin PA at or below 10,000

10 Min Supply of O2 for all occupants

Crew O2 masks readily available

Supplemental Oxygen Required

AR 95-1AR 95-1Altitude Restrictions and Oxygen RequirementsAltitude Restrictions and Oxygen Requirements

If pressurization is lost above 14,000’, an immediate descent will be made to a cabin pressure altitude of 10,000’ or below.

Then unpressurized restrictions apply

AR 40-8AR 40-8Flight Restrictions Due to Exogenous FactorsFlight Restrictions Due to Exogenous Factors

• Flying duty is prohibited for 24 hours after SCUBA diving

• Aircrew members will not be regular blood donors. • After blood donation, aircrew members will be restricted from flying for 72 hours

• Performance of flying duty is prohibited for 12 hours after any altitude chamber flight

Questions?