1. Diving Physiology

2. Objectives Identify the primary components of air. Discuss the processes of respiration and circulation. Identify the breathing stimulus. Describe the proper breathing pattern for a scuba diver and explain why. Describe three improper breathing patterns for a scuba diver. Identify the breathing gas you will be trained to use for scuba and explain why. State the cause, prevention, signs/symptoms, and first aid for: Decompression sickness (Bends), Nitrogen Narcosis, Air Embolism, and Over-Exertion.

3. Components of Air Nitrogen –Metabolically inert –Makes up approximately 79% of the air we breathe Oxygen –Metabolically active –Makes up approximately 20% of the air we breathe Miscellaneous gases –less than 1%

4. Partial Pressures Each component gas of air exerts its own pressure. The pressure of each individual gas is referred to as the partial pressure of the gas. The sum of the individual gas pressures represents the total pressure of the gas. The effect of the gas on the diver is determined by the partial pressure of the gas. Your regulator delivers the gas you breathe at ambient pressure and volume. At depth the mixture of the gas you breathe remains unchanged, the partial pressure of each of the component gases in the mix increases.

5. The increased partial pressure of the component gases in the air you breathe at depth explains why divers must be concerned with: –Decompression Sickness –Nitrogen Narcosis –Oxygen Toxicity –Carbon Monoxide

6. Respiration/Circulation Air taken into lungs –02 absorbed into blood by Hemoglobin –02 carried to body –Used and converted to CO2 CO2 carried to lungs where it is eliminated by respiration.

7. Breathing Stimulus Excess CO2

8. Breathing Patterns Proper Breathing Pattern Deeper and slower than normal. –Overcome resistance of dense air and regulator or snorkel –Provides a calming effect

9. Breathing Patterns Hyperventilation Panting Skip Breathing

10. Breathing Gas Air –80% N2 –21% 02 02, CO2, CO and other contaminants can be toxic. Fill your cylinder only with air from a reputable air fill station. Breathe only gases you have been trained to use.

11. Contaminated air Indications –Any smell –Any taste –Any texture Do not dive until the problem has been identified and corrected.

12. Decompression Sickness Other Names –DCS –Bends –Taking a hit Niggles –Throwing a bubble

13. DCS cont. Gas solubility: The amount of gas that dissolves in a fluid increases as the pressure of the gas in contact with the fluid increases. This process continues until equilibrium is reached. The reverse is also true; as the pressure of a gas in contact with a fluid decreases, the amount of gas dissolved in the fluid decreases to the point of equilibrium. This is known as Henry’s Law. (Just think of Henry Weinhard’s beer.)

14. DCS cont Bubble Formation: –If the pressure of a gas dissolved in a fluid is released too quickly, bubbles form within the fluid. Decompression: –If the pressure on a gas dissolved in a fluid is released gradually, excess gas can exit the liquid without bubbles forming.

15. DCS cont Application to scuba: –Scuba divers absorb N2 at increased pressure –N2 pressure within the diver increases. – If the scuba diver ascends too quickly, N2 bubbles can form within the blood. –This can lead to Decompression Sickness (DCS or Bends). Cause of Decompression Sickness –Ascending too quickly –Too deep for too Long

16. DCS cont Prevention: –Observe time and depth limits –Adhere to proper ascent rates –30 feet per minute –Include safety stops at the end of your dives There is never a guarantee you will not get DCS!

17. DCS cont Skin rash Weakness Paralysis Staggering Slurred speech Coughing Shortness of breath Unconscious Skin itch Joint or limb pain Unusual fatigue Numbness/tingling Chest/abdominal pain Incontinence Headache/dizziness Nausea

18. DCS cont Onset –Typically within 20 minutes-2 hours post dive –May not show up for several hours

19. DCS cont First Aid –Treat for Shock –First aid as necessary –Provide 100% 02 –Contact Emergency Medical System –Arrange transport to a recompression as appropriate/necessary

20. DCS cont Contributing Factors –Poor physical condition –Reverse Profiles –Strenuous exercise during or post dive –Dehydration/Alcohol –Fatigue –Repetitive/multi day diving –Cold –Hot tubs post dive –Altitude

21. Nitrogen Narcosis Other Names –Narced –Rapture of the deep

22. Narcosis cont. Cause –Narcotic effect of N2 at depth Depth at which Narcosis occurs –Varies with the individual.

23. Narcosis cont. Symptoms/Signs –Feeling of well being or euphoria (may be similar to alcoholic intoxication) –Idea fixation –Anxiety

24. Narcosis cont. Consequences –Impaired performance –Lack of awareness –Depth –Time –Air –Buddy –Direction

25. Narcosis cont. Onset –Sudden or rapid –may worsen with time. Prevention –Dive within your limits. –Expand your limits in controlled settings –Minimize task loading. First Aid –Ascend to a shallower depth –End dive if necessary

26. Air Embolism Other Names –Embolism –Arterial Gas Embolism (AGE) –Pulmonary overpressure –Lung Overpressure

27. Embolism cont. Cause –Holding breath on ascent –Air in lungs expands and escapes from the lungs into the bloodstream –Air bubble in the bloodstream blocks blood flow to the heart or brain.

28. Embolism cont Unconsciousness (immediately or soon after surfacing) Paralysis or weakness Convulsions Respiratory Arrest Bloody Froth (rare) Personality change Dizziness Visual Disturbance Chest Pain Disorientation Paralysis or Weakness Death

29. Embolism cont Onset –Typically immediately after the dive Prevention –Breath normally at all times –Never hold your breath especially during ascent This is most critical between 10 feet and the surface

30. Embolism cont Contributing Factors –Rapid ascent –Breath-holding –Lung congestion –Asthma –Lung damage or history of lung collapse –Other air trapping conditions First Aid –Treat for Shock –First aid as necessary –Provide 100% 02 –Contact Emergency Medical System –Arrange transport to a recompression as appropriate/necessary

31. Overexertion Causes –Poor buoyancy control –Diving overweighted –Exceeding you limits –Environmental conditions (surf, surge, current, surf)

32. Overexertion cont Indications –Unable to keep up with buddy –Fatigue –Cold –Gasping for breathe –Muscle cramps

33. Overexertion cont Prevention –Know your limits and dive within your limits –Practice good buoyancy control –Wear the proper amount of weight –Stop and rest before you are exhausted First Aid –Stop and rest until recovered. –End the dive.

34. Dehydration Cause –Breathing dehumidified air from cylinder Symptoms –Dry mouth –Thirst

35. Dehydration cont. Prevention –Drink plenty of water 2 liters a day plus 1 glass for each 20 minutes of exercise or each dive First Aid –Drink plenty of water

36. Divers Dieresis Cause –Increased pressure on body while diving –Body withdrawing blood to core to preserve core temperature Symptoms –You will feel the need to urinate more frequently than normal while diving

37. Ear Injuries While decompression sickness and lung overpressure are the most serious scuba maladies, ear injuries are the most common. Descents should be performed feet first through the first 10-15 feet and slowly to allow time to equalize.

38. Summary Air is a mixed gas Each component of air exerts it’s own partial pressure Because your regulator delivers air at ambient pressure and volume the, at depth the pressure of the gas is increased. DCS, Narcosis, and 02 toxicity can result from increased partial pressures.

39. Summary cont. Breathe only gases you are trained to breath. Air embolism can result from air expansion while holding your breath on ascent. Breathe normally at all times. Ear injuries are the most common injuries in scuba. Descents should be feet first and slow.