High Altitude & Deep Sea Diving

1. High Altitude & Deep Sea Diving

2. Acclimatization to High altitude Kilimanjaro High Altitudes & Deep sea Diving

3. High altitudes • Over 40 million people in the world • Live and work at terrestrial elevations between 10,000 ft and 18,000 ft • Theses ranges are considered • High altitudes Kilimanjaro High Altitudes & Deep sea Diving

4. High altitudes • In the Andes and Himalayas • Natives inhabit permanent settlements • At elevations 18,000 ft above sea level • Prolonged exposure of un-acclimatized individual • Can cause death from hypoxia Kilimanjaro High Altitudes & Deep sea Diving

5. Hypoxia of High Altitude • As one ascends to high altitudes • One encounters problems associated with • Hypoxia • ↑ Radiation • Exposure to cold Kilimanjaro High Altitudes & Deep sea Diving

6. Hypoxia of High Altitude • Basic causes of hypoxia • As altitude increases • Barometric pressure falls • % composition of air does not change appreciably • Partial pressure of respiratory gases fall Kilimanjaro High Altitudes & Deep sea Diving

7. Hypoxia of High Altitude • At an altitude of 18,000 ft (5,500m) • Barometric pressure is ½ normal • 380 mm Hg • PO2 of moist inspired air • (380 – 47)*0.2093 = 70 mm Hg • Note summit of Kilimanjaro • 19,536 ft (5963 m) Kilimanjaro High Altitudes & Deep sea Diving

8. Hypoxia of High Altitude • At summit of Everest 29,028 ft • Barometric pressure = 250 mm Hg • PO2 of moist inspired gas = 43 mm Hg • At altitude of 63,000 ft • Barometric pressure = 47 mm Hg • PO2 of moist inspired gas = 0 mm Hg High Altitudes & Deep sea Diving

9. Effects of High Altitude on Bar Pressure & PO2 Kilimanjaro High Altitudes & Deep sea Diving

10. Effects of High Altitude on Bar Pressure & PO2 High Altitudes & Deep sea Diving

11. High Altitude Vs PAO2, PACO2, O2sat% High Altitudes & Deep sea Diving

12. High Altitude Vs PAO2, PACO2, O2sat% High Altitudes & Deep sea Diving

13. Hypoxia of High Altitude • Effects of CO2 and water vapour • Even at high altitude • CO2 production is still there • Water vaporizes in alveoli • Leading to dilution of alveolar O2 concentration • PAO2 = (PB – PCO2 – 47) Kilimanjaro High Altitudes & Deep sea Diving

14. Effect Of Breathing Pure O2 • Space that was occupied by Nitrogen • Is now occupied by oxygen • This improves the % saturation of Hb with oxygen High Altitudes & Deep sea Diving

15. Effect Of Breathing Pure O2 High Altitudes & Deep sea Diving

16. Effects Of Breathing Pure O2 • An aviator breathing oxygen in an un-pressurized air craft • Can ascend to far higher altitudes than one not breathing pure O2 • Limit for an un-acclimatized individual • Arterial O2 saturation of 50% • Only for a short time exposure of hypoxia High Altitudes & Deep sea Diving

17. Effects Of Breathing Pure O2 • This occurs at an altitude of • 23,000 ft • In an un-pressurized plane % when • Individual not breathing pure oxygen • When individual is breathing pure oxygen • PAO2 remain 90% • Up to altitude of 39,000 ft • Falls to 50% at 47,000 ft High Altitudes & Deep sea Diving

18. Effects of Acute Hypoxia • Begin at about 12,000 ft • Drowsiness, lastitude • Mental & muscle fatigue • Headaches, nausea • Euphoria • Above 18,000 ft • Muscular twitches & convulsions • Above 23,000 ft • Coma, death High Altitudes & Deep sea Diving

19. Acclimatization: Respiration • ↑ pulmonary ventilation • Hyperventilation • Exposure to low PO2 stimulate chemoreceptors • Stimulate respiration • Leads to 65% increase in alveolar ventilation High Altitudes & Deep sea Diving

20. Acclimatization: Respiration • This is an immediate compensation for high altitude • Makes it possible for a person to ascend thousands feet • The ↑ in alveolar ventilation decreases CO2 • ↓ PCO2 and ↑ pH • Both leads to inhibition of respiration • Tend to oppose stimulatory effect of hypoxia High Altitudes & Deep sea Diving

21. Acclimatization: Respiration • After 2 to 5 days • Inhibition fades away • Ventilation ↑ 3 to 7 times the normal level • Active pumping of HCO3- from CSF • Cause ↓ pH in CSF • Chemoreceptors are once more stimulated High Altitudes & Deep sea Diving

22. Acclimatization: O2 Transport • Haemoglobin • Hypoxia causes release of erythropoeitin • ↑ production of RBCs • Polycythemia • Haematocrit increases • From 40 – 45% to 60 – 65% • Hbg increase from 15gm% to 22 gm% High Altitudes & Deep sea Diving

23. Acclimatization: O2 Transport • Total result is • ↑ in circulating Hbg • 50% to 90% more than normal • Polycythemia • Increase viscosity • However, these adaptive changes • Slow to develop • Take about 2 – 3 weeks • Become fully developed after many moths High Altitudes & Deep sea Diving

24. Acclimatization: O2 Transport • ↓ affinity of Hbg for O2 • Effect of ↑ 2:3 DPG • Shift O2 –Hb dissociation curve to the right • Diffusion capacity of lung for O2 • 21 ml/mmHg/min • Increases up to 3 times more High Altitudes & Deep sea Diving

25. Acclimatization • Increased capillary density • ↑ the number of capillaries • ↓ the distance between capillary & cells High Altitudes & Deep sea Diving

26. Acclimatization • Cardiac output • Increased by 20 – 30% immediately • But after few days • Return back to normal • May fall slightly below normal after few months • There is increase in blood flow to • Muscles, heart, brain High Altitudes & Deep sea Diving

27. Acclimatization: Cellular level • Enzymes adaptation to hypoxia • Increase number of mitochondria • Increase in cellular oxidative enzymes High Altitudes & Deep sea Diving

28. Failure to acclimatize • Chronic mountain sickness • After remaining at high altitudes for a long time • One develops mountain sickness • Red cell mass and haematocrit • Become exceptionally high High Altitudes & Deep sea Diving

29. Failure to acclimatize • Pulmonary arterial pressure • Become elevated more than during acclimatization • Right heart becomes greatly enlarged • Peripheral arterial pressure falls • Congestive heart failure develop High Altitudes & Deep sea Diving

30. Deep Sea diving

31. Physiologic effects • Relation of sea depth to pressure • A column of fresh water 34 ft (33 ft sea water) high • Exert the same pressure • As the atmosphere above earth High Altitudes & Deep sea Diving

32. Physiologic effects • A person 33 ft beneath the ocean • Exposed to pressure of 2 atmospheres High Altitudes & Deep sea Diving

33. Effects of Depth on pressure High Altitudes & Deep sea Diving

34. Effects of Depth on volume of Gases • Can be derived from gas laws • P1V1 = P2V2 • Example if • At sea level • P1 = 1 atmosphere, V1 = 1liter • At 33 ft below sea level • P2 = 2 atmosphere • V2 = (P1V1)/P2 = ½ liter • The air chambers of the diver • Will be compressed High Altitudes & Deep sea Diving

35. Nitrogen Narcosis • About 4/5th of air is nitrogen • At sea level pressure • Nitrogen has no bad effects to tissues • However, at high pressures • Nitrogen can cause varying degree of narcosis High Altitudes & Deep sea Diving

36. Nitrogen Narcosis • When a diver remains beneath the sea • For about 1 hr breathing compressed air • At 120 ft • Begins to have symptoms of mild narcosis • Exhibits joviality • Becomes careless High Altitudes & Deep sea Diving

37. Nitrogen Narcosis • At 150 – 200 ft • Becomes drowsy • At 200 – 250 ft • Diver usually becomes useless High Altitudes & Deep sea Diving

38. Nitrogen Narcosis • The narcosis is due to effects of dissolved N2 • N2 diffuses freely through fat • Into nervous tissue • Alters conduction of nerve impulse • Decreases excitability • Brain function becomes impaired High Altitudes & Deep sea Diving

39. Oxygen Toxicity • Effect of extremely high PO2 • When the PO2 increase above 100 mm Hg • Amount of dissolved O2 in water increases • The normal safe range of tissue PO2 • Is between 20 – 60 mm Hg • At higher tissue PO2 • Oxygen poisoning occurs High Altitudes & Deep sea Diving

40. Acute Oxygen Poisoning • Due to extremely high tissue PO2 • Exposure to 4 atmospheres pressure of O2 • Partial pressure of about 3040 mm Hg will cause • Seizures (convulsion) within 30 to 60 min • They occur without warning • Likely to be lethal to the diver • Other symptoms include • Nausea, muscle twitches, dizziness, disturbances of vision, irritability High Altitudes & Deep sea Diving

41. Oxygen Poisoning • Excessive intra cellular oxidation • Oxidizing free radicals • Molecular O2 • Active form of O2 • Oxygen free radicals • Super- oxide free radical (O2-) • Peroxide radicals (hydrogen peroxide) High Altitudes & Deep sea Diving

42. Oxygen Poisoning • At normal tissue PO2 • Small amount of free radicals are formed • Body contain enzymes that remove them • Peroxidases, catalases, superoxide dismutase High Altitudes & Deep sea Diving

43. Oxygen Poisoning • Above a critical level of alveolar PO2 (>2 atmospheres) • Hb – O2 buffering mechanism fail • Tissue PO2 rise tremendously • The amount of oxidizing free radicals  High Altitudes & Deep sea Diving

44. Oxygen Poisoning • Effects of oxidizing free radicals • Oxidize polyunsaturated fatty acids • Essential components of cell membranes • Oxidize cellular enzymes • Damage cellular metabolism • Nervous tissue • Very susceptible • Lethal effect caused due to brain damage High Altitudes & Deep sea Diving

45. Decompression of Diver • When a diver breathes compressed air for a long time • Amount of nitrogen dissolve in body fluid increase • The nitrogen dissolved in tissue • Not metabolized • Remains dissolve in tissue fluids High Altitudes & Deep sea Diving

46. Nitrogen Dissolved in Body Fluid High Altitudes & Deep sea Diving

47. Decompression Sickness • Also known as • Bends • Compressed air sickness • Caisson’s disease • Diver’s paralysis • Dysbarism High Altitudes & Deep sea Diving

48. Decompression Sickness • When a diver has been beneath the sea for a long time • Large amount of nitrogen • Become dissolved in body fluids • If the diver suddenly comes to the surface • Significant amount of nitrogen bubbles • Can develop in the body fluid • These can cause some damages • This is known as decompression sickness High Altitudes & Deep sea Diving

49. Decompression Sickness • Symptoms • Most of the symptoms are caused by • Bubbles blocking blood vessels • Air embolism • The symptoms include • Pain in joints and limb muscles • Nervous symptoms • Dizziness, paralysis, collapse High Altitudes & Deep sea Diving

50. Decompression Sickness • The chokes caused by • Massive numbers of bubbles plugging pulmonary capillaries • Shortness of breath • Severe pulmonary edema High Altitudes & Deep sea Diving