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 [O 2 ] deficiency in the blood cells and tissues sufficient to cause impairment of function.

Types of Hypoxia l Hypemic l Stagnant l Histotoxic l Hypoxic

Hypemic Hypoxia Inability of the blood to accept oxygen in adequate amounts

Stagnant Hypoxia Reduced blood bloodflow Blood moving slowly adequateoxygen Red blood cells not replenishing tissue needs fast enough

Red blood cells Red blood cells retain oxygen retain oxygen Inability of the cell to accept or use oxygen Histotoxic Hypoxia Poisoned tissue adequateoxygen

Hypoxic Hypoxia Reduced pO 2 in the lungs (high altitude) Body tissue Red blood cells

Hypoxia Symptoms Subjective: Feel Air hunger Hot and Cold Flashes Apprehension Euphoria Fatigue Belligerence Nausea Blurred vision Headache Numbness Dizziness Tingling Denial Air hunger Hot and Cold Flashes Apprehension Euphoria Fatigue Belligerence Nausea Blurred vision Headache Numbness Dizziness Tingling Denial

Hypoxia Signs Objective: See HyperventilationCyanosis Mental confusion Poor Judgment Lack of muscle coordination

Stages of Hypoxia l Indifferent Stage l Compensatory Stage l Disturbance Stage l Critical Stage

Indifferent Stage l Altitudes Air: ,000 FEET l Symptoms: decrease in night 4000 feet

Compensatory Stage l Altitudes Air :10, ,000 FEET l Symptoms: impaired efficiency drowsiness poor judgment decreased coordination

CAUTION! Failure to recognize symptoms and take corrective action may result in an aircraft mishap Failure to recognize symptoms and take corrective action may result in an aircraft mishap

Disturbance Stage l Altitudes Air:15, ,000 FEET

Disturbance Stage symptoms W Sensory l Vision l Touch & pain l Hearing

Disturbance Stage Disturbance Stage symptoms W Mental l Memory l Judgment l Reliability l Understanding

Disturbance Stage symptoms W Personality l Happy Drunk versus the l Mean Drunk

Disturbance Stage symptoms W Performance l Coordination l Flight Control l Speech l Handwriting

put back on oxygen Time off Oxygen 1 minute 2 minutes 3 minutes 4 minutes 5 minutes 6 minutes

CAUTION!CAUTION! Failure to recognize symptoms and take corrective action may result in an aircraft mishap Failure to recognize symptoms and take corrective action may result in an aircraft mishap

Disturbance Stage W Signs l Hyperventilation l Cyanosis

Critical Stage l Altitudes Air:20,000 FEET and above l Symptoms: loss of consciousness convulsions death

WARNING! When hemoglobin saturation falls to serious cellular dysfunction occurs; and if prolonged, can cause death WARNING! 65%

Factors modifying hypoxia symptoms l Pressure altitude l Rate of ascent l Time at altitude l Temperature l Physical activity l Individual factors l Physical fitness l Self-imposed stresses

Alcohol it’s a no brainer! Tobacco keep self imposed stresses out of the aircraft Drugs Exhaustion Hypoglycemia

2000 feet B U Z Z 1 ounce = alcohol

Expected Performance Times FL 430 & above9-12 seconds FL seconds FL seconds FL minutes FL /2 - 3 minutes FL minutes FL minutes FL 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

Hypoxia u Prevention limit time at altitude breathing oxygen l pressurized cabin

Hypoxia u Treatment oxygen descend to a safe altitude

AR 95-1 Altitude Restrictions and Oxygen Requirements 14,000 10,000 12,000 1 Hour Total 30 Min Total Unpressurized Pressurized 10,000 14,000 25,000 Maintain Cabin PA at or below 10, Min Supply of O2 for all occupants Crew O2 masks readily available Supplemental Oxygen Required

AR 95-1 Altitude 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 40-8 Flight 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?