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?