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ALTITUDE. PHYSIOLOGY. OUTLINE. Classifications of Hypoxia Signs and symptoms of Hypoxia Stages of Hypoxia Prevention of Hypoxia Provisions of AR 95-1 Provisions of AR 40-8. REFERENCES. FM 1-301, Aeromedical Training for Flight Personnel, May 1987
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ALTITUDE PHYSIOLOGY
OUTLINE Classifications of Hypoxia Signs and symptoms of Hypoxia Stages of Hypoxia Prevention of Hypoxia Provisions of AR 95-1 Provisions of AR 40-8
REFERENCES 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
Hypoxia State of oxygen [O2] deficiency in the blood cells and tissues sufficient to cause impairment of function.
Types of Hypoxia • Hypemic • Stagnant • Histotoxic • Hypoxic
HypemicHypoxia Inability of the blood to accept oxygen in adequate amounts + + + + + + + + + + + + + + +
Stagnant Hypoxia adequate oxygen Reduced blood flow Blood moving slowly Red blood cells not replenishing tissue needs fast enough
Histotoxic Hypoxia Inability of the cell to accept or use oxygen adequate oxygen Red blood cells retain oxygen Poisoned tissue
Hypoxic Hypoxia Reduced pO2 in the lungs (high altitude) Red blood cells Body tissue
HypoxiaSymptoms Subjective: Feel Air hunger Hot and Cold Flashes Apprehension Euphoria Fatigue Belligerence Nausea Blurred vision Headache Numbness Dizziness Tingling Denial
HypoxiaSigns Objective: See Hyperventilation Cyanosis Mental confusion Poor Judgment Lack of muscle coordination
Stages of Hypoxia • Indifferent Stage • Compensatory Stage • Disturbance Stage • Critical Stage
Indifferent Stage • Altitudes Air: 0 - 10,000 FEET • Symptoms: decrease in night vision @ 4000 feet
Compensatory Stage • Altitudes Air : 10,000 - 15,000 FEET • Symptoms: impaired efficiency drowsiness poor judgment decreased coordination
CAUTION! Failure to recognize symptoms and take corrective action may result in an aircraft mishap
Disturbance Stage • Altitudes Air: 15,000 - 20,000 FEET
Sensory Vision Touch & pain Hearing Disturbance Stagesymptoms
Mental Memory Judgment Reliability Understanding Disturbance Stagesymptoms
Personality Happy Drunk versus the Mean Drunk Disturbance Stagesymptoms
Performance Coordination Flight Control Speech Handwriting Disturbance Stagesymptoms
Time off Oxygen 1 minute 2 minutes 3 minutes 4 minutes 5 minutes 6 minutes put back on oxygen
CAUTION! Failure to recognize symptoms and take corrective action may result in an aircraft mishap
Signs Hyperventilation Cyanosis Disturbance Stage
Critical Stage • Altitudes Air: 20,000 FEET and above • Symptoms: loss of conscious ness convulsions death
WARNING! 65% When hemoglobin saturation falls to serious cellular dysfunction occurs; and if prolonged, can cause death WARNING!
Pressure altitude Rate of ascent Time at altitude Temperature Physical activity Individual factors Physical fitness Self-imposed stresses Factors modifying hypoxia symptoms
it’s a no brainer! Drugs Alcohol Tobacco Exhaustion Hypoglycemia keep self imposed stresses out of the aircraft
B U Z Z alcohol 2000 feet 1 ounce =
Expected 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 flying in a pressurized cabin is reduced approximately one-half following loss of pressurization such as in a: RD rapid decompression
Prevention limit time at altitude breathing oxygen pressurized cabin Hypoxia
Treatment oxygen descend to a safe altitude Hypoxia
AR 95-1Altitude Restrictions and Oxygen Requirements Supplemental Oxygen Required Unpressurized 14,000 30 Min Total 1 Hour Total 12,000 10,000 Pressurized Crew O2 masks readily available 25,000 10 Min Supply of O2 for all occupants 14,000 10,000 Maintain Cabin PA at or below 10,000
AR 95-1Altitude 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 40-8Flight 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