2. ALTITUDE PHYSIOLOGY

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

4. REFERENCES FM 1-301, Aeromedical Training for Flight Personnel, May 1987 FM 1-204, Night Flight Techniques and Procedures, October 1983

5. TROPOSPHERE Sea level to flight level 300 - 600 depending on temperature, latitude and season. Physical Divisions Physical Divisions of the Atmosphere STRATOSPHERE IONOSPHERE EXOSPHERE MOUNT EVEREST 29,028 FEET 1200 miles 600 miles 50 miles Tropopause

6. Physiological Zones of the Atmosphere EFFICIENT ZONE: SEA LEVEL TO 10,000 FEET SPACE EQUIVALENT ZONE: 50,000 FEET AND ABOVE DEFICIENT ZONE: 10,000 TO 50,000 FEET 10,000 50,000

7. 78 % Nitrogen (N 2 ) 21 % Oxygen (O 2 ) 1 % Other (.03 % CO 2 ) Composition of Air

8. 14.7 PSI Sea Level Pressure Scale lbs 760 mm Hg OR 29.92 in. Hg Barometer / Altimeter

9. PERCENT COMPOSITION OF THE ATMOSPHERE REMAINS CONSTANT BUT PRESSURE DECREASES WITH ALTITUDE

10. SIGNIFICANT PRESSURE ALTITUDES ALTITUDE PRESSURE FEET mm/HG ATMOSPHERES 07601 18,000 3801/2 34,0001901/4 48,000951/8 63,000471/16

11. Partial Pressure (Dalton’s Law) 760 mm Hg 47 --- mm/Hg 95 --- 190 --- 380 --- 523 --- 760 --- 21% O2O2 78% N 2 1% Other

12. The pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each gas in the mixture. Pt = P 1 + P 2 +...+ Pn (Dalton’s Law)

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

14. Types of Hypoxia l Hypemic l Stagnant l Histotoxic l Hypoxic

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

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

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

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

19. 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

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

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

22. Indifferent Stage l Altitudes Air: 0 - 10,000 FEET l Symptoms: decrease in night vision @ 4000 feet

23. Compensatory Stage l Altitudes Air :10,000 - 15,000 FEET l Symptoms: impaired efficiency drowsiness poor judgment decreased coordination

24. 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

25. Disturbance Stage l Altitudes Air:15,000 - 20,000 FEET

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

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

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

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

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

31. 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

32. Disturbance Stage W Signs l Hyperventilation l Cyanosis

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

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

35. 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

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

37. 2000 feet B U Z Z 1 ounce = alcohol

38. Expected Performance Times FL 430 & above9-12 seconds FL 40015 - 20seconds FL 35030 - 60 seconds FL 3001 - 2 minutes FL 2802 1/2 - 3 minutes FL 2503 - 5 minutes FL 2208 - 10 minutes FL 18020 - 30 minutes

39. 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

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

41. Hypoxia u Treatment oxygen descend to a safe altitude

42. Hyperventilation definition an excessive rate and depth of respiration leading to the abnormal loss of CO 2 from the blood.

43. n Emotional (fear, apprehension, excitement) n Pressure breathing n Physical stress n Hypoxia HyperventilationCauses

44. Hyperventilation Symptoms l tingling sensations l muscle spasms l hot and cold sensations l visual impairment l dizziness l unconsciousness

45. Hyperventilation reason for symptoms:  loss of carbon dioxide [CO 2 ] ê shift in pH balance

46. Hyperventilation significance * incapacitation of an otherwise outstanding, healthy aviator. * confusion with hypoxia

47. n Don’t Panic n Control your breathing Hyperventilationprevention Check your oxygen equipment - it may be hypoxia

48. n above 10,000 feet possible hypoxia n below 10,000 feet probable hyperventilation Hyperventilation corrective action

49. Dysbarism syndrome resulting from the effects, excluding hypoxia, of a pressure differential between the ambient barometric pressure and the pressure of gases within the body syndrome resulting from the effects, excluding hypoxia, of a pressure differential between the ambient barometric pressure and the pressure of gases within the body

50. Boyle’s Law The volume of a gas is inversely proportional to its pressure; temperature remaining constant.

51. DRY GAS EXPANSION WET GAS EXPANSION 1.8X 2.0X 16,000 2.5X 25,000 3.0X, 34,000 5.0X 43,000 4.0X 9.5X 6.0X Gas Expansion

52. l Watch your diet, don’t eat too fast l Avoid soda and large amounts of water just prior to going to altitude l Don’t chew gum during ascent l Keep regular bowel habits; eat your fiber Gas Expansion prevention of abdominal gas pains

53. Middle Ear Opening to throat Eustachian tube External ear Middle ear Ear drum Semicircular canal Cochlea Auditory nerve

54. Middle Ear Cavity Eustachian Tube Atmospheric Pressure Tympanic Membrane External Ear Middle Ear Cavity Eustachian Tube Blocked / Infected Tympanic Membrane External Ear Atmospheric Pressure Pressure Effect Ear Block Clear

55. Normal tympanic membrane (ear drum) Inflamed ear drum Infected ear drum

56. Frontals Ethmoids Maxillary Sphenoids The Sinuses

57. Treatment of an Sinus/Ear Block 1. Stop the descent of the aircraft and attempt to clear by valsalva. 2. If unable to clear, climb back to altitude until clear by pressure or valsalva. 3. Descend slowly and clear ear frequently during descent.

58. Barodontalgia l Tooth pain due to: l Gum abscess: dull pain on ascent l Inflamed pulp: sharp pain on ascent l Inflamed maxillary sinus: pain primarily on descent

59. Decompression Sickness

60. Henry’s Law l The amount of gas dissolved in solution is directly proportional to the pressure of the gas over the solution

61. WARNING Evolved gas disorders are considered serious and medical treatment and advice must be sought immediately.

62. Evolved Gas Disorders l The Bends l Paresthesia l The Chokes l Central Nervous System-CNS

63. Evolved Gas Disorders l N2 bubbles become trapped in the joints. Onset is mild, but eventually painful! l The Bends

64. Evolved Gas Disorders l Paresthesia l N2 bubbles form along nerve tracts. Tingling and itchy sensation and possibly a mottled red rash.

65. Evolved Gas Disorders l The Chokes l N2 bubbles block smaller pulmonary vessels. Burning sensation in sternum. Uncontrollable desire to cough. Sense of suffocation ensues.

66. Evolved Gas Disorders l CNS l N2 bubbles affect spinal cord. Visual disturbances, paralysis, one sided tingling.

67. Evolved gas factors l Rate of ascent l Altitude l Body fat content l Age l Exercise l Duration of exposure l Repeated exposure

68. l Descend l 100% Oxygen Decompression Sickness treatment l Land at nearest location where qualified medical assistance is available. l Compression greater than 1 atmosphere (absolute).

69. Scuba Divers Beware! 2 4 H o u r r e s t r i c t i o n b e t w e e n d i v i n g a n d f l y i n g ! ! ! ! ! or be bent!

70. ? QUESTIONS?