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 Oxygen Miscellaneous gases
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. Effects of Partial Pressure
The increased partial pressure of the component gases in the air you breathe at depth explains why divers must be concerned with:
Decompression Sickness (DCS)
Nitrogen Narcosis (Narc’d)
Oxygen Toxicity (OxTox)
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 02, CO2, CO and other contaminants can be toxic.
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. Henry’s Law
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.

14. DCS cont Bubble Formation: Decompression:
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: Cause of Decompression Sickness
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

17. Residual Nitrogen Time
Residual Nitrogen Time (RNT)
N2 remains in the body for up to 24 hours after a dive
RNT must be accounted for on all repetitive dives
Rep dive = any dive made within 24 hours of a previous dive

18. 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

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

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

21. Entry bay to Catalina Hyperbaric Chamber

22. Inside of hyperbaric chamber

23. 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

24. There is never a guarantee you will not get DCS!

25. Nitrogen Narcosis
Other Names
Narced
Rapture of the deep

26. Narcosis cont. Cause Depth at which Narcosis occurs
Narcotic effect of N2 at depth
Depth at which Narcosis occurs
Varies with the individual
For the same individual can vary from dive to dive.

27. What’s Your Limit?

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

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

30. Narcosis cont. Onset Prevention First Aid 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

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

32. 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.

33. 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

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

35. Embolism cont Contributing Factors First Aid 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 chamber as appropriate/necessary

36. DAN is the clearinghouse for diving medicine.
Diving medicine FAQ
Membership
Insurance supplement
Student insurance

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

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

39. Overexertion cont Prevention First Aid
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.

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

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

42. Divers Dieresis Cause Symptoms 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

43. 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 feet and slowly to allow time to equalize.

44. 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.

45. 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.