Physiological response to high barometric pressure

1. Physiological response to high
barometric pressure

2. Hyperbarism:
• When human beings descend beneath the sea, the
pressure around them increases tremendously and
exposes the blood in the lungs to extremely high alveolar
gas pressure.

3. Relationship of pressure to sea depth
Boyle’s law:
Volume 1/α Pressure

4. Effect of High Partial Pressures of Individual
Gases on the Body
• Nitrogen Narcosis
• Oxygen Toxicity

5. Nitrogen Narcosis
• At 120 feet feels joviality & careless
• At 150 to 200 feet, the diver becomes drowsy.
• At 200 to 250 feet, loss of strength.
• Beyond 250 feet, becomes unconsciousness
Nitrogen narcosis similar like alcohol intoxication
Nitrogen reacts with fatty acids in cell memb of neurons and
impairs the conduction like gas anesthetics

6. Oxygen Toxicity
Acute oxygen poisoning:
•Nausea
•muscle twitchings
•dizziness
•disturbances of vision
•Irritability
•Disorientation
•seizures followed by coma
Generation of oxygen free radicals swamp the
enzyme system to remove it
Reacts with polyunsaturated fattyacids of cell
memb causes brain dysfunction
Chronic Oxygen Poisoning: Causes Pulmonary edema

7. Decompression of the diver after excess
exposure to high pressure

8. Decompression Sickness (Synonyms: Bends, Compressed Air
Sickness, Caisson Disease, Diver’s Paralysis, Dysbarism)
Symptoms:
• Pain in the joints
• Pain in the muscles of arms & neck
• Nervous system symptoms: dizziness, paralysis &
unconsciousness
• Shortness of breathing (chokes)
• Death

9. Physiological principles of prevention and
management of decompression sickness
Decompression table:
60 minutes at a depth of 190 feet
• 10 minutes at 50 feet depth
• 17 minutes at 40 feet depth
• 19 minutes at 30 feet depth
• 50 minutes at 20 feet depth
• 84 minutes at 10 feet depth
Decompression chamber

10. Scuba (Self-Contained Underwater Breathing Apparatus)
Diving
Contains oxygen & helium

11. Helium
• Has only about one fifth the narcotic effect of nitrogen
• Only about one half as much volume of helium dissolves
in the body tissues as nitrogen
• Low density of helium (one seventh the density of
nitrogen) keeps the airway resistance for breathing at a
minimum work of breathing

12. The deepest SCUBA dive record-Ahmed garb,
1090 ft in Red sea

13. Thank you