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Dr. Jitendra Patel (MBBS, MD, ACME, Ph.D…)
Medical Educator, Researcher & Academic Administrator
Associate Professor, Department of Physiology
Email: dr.jrpatel84@gmail.com Web: www.esphys.weebly.com
Competency
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No. PY6.4 & 6.5 (Respiratory Physiology)
CompetencyDescribe and discuss the physiology of deep sea diving. Describe and discuss the decompression sickness.
D/L/Core K/KH/Y
AM Written/Viva voce
Integration No
Imp. Concept Problem and its solution in DSP
Phy. Trivia H/O Brooklyn Bridge
OUTLINE
Introduction
Physiological problem
Decompression sickness
Preventive measures
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Barometric Pressure Changes
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For every 10 m below the water surface(sea water) you go, the barometricpressure increases by 1 atm.
Total barometric pressure;
= (Pressure due to water) + (Pressure due to air)
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Gas Volume changes
Boyle’s law: P α 1/V
As the pressure increases volume of gas decreases.
1 lit
½ lit
¼ lit
1/8 lit
Sea level
33 ft
100 ft
233 ft
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Conditions of High Barometric pressure is met.......
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• Deep sea diving
• Submarines
• Caisson’s workers;
Those who dig underwater tunnels,
work in chamber (caisson’s chamber).
Physiological Problems
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Can be categorized…….
1. At depth - Due to compression
2. During ascent - Due to decompression
Compression and decompression of gas over liquid
Physiological Problems At Depth
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Partial pressure of O2, CO2 & N2 is increased
↑ pO2 (3000 mm Hg @ 4 Atm P)
[More free radicals = O2- ]
• Acute O2 toxicity
CNS complications : Disorientation, convulsions, coma
• Chronic O2 toxicity (8-24 hr @ 1-1.5 Atm P)
Lung congestion & edema
Physiological Problems At Depth
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• ↑ pN2
– Nitrogen dissolves in body fluids & fats specially
neurons of brain.
– Decreases excitability of neurons – Nitrogen narcosis.
• Euphoria,↓ mental functions, drowsiness, poor muscle
co-ordination.
Physiological Problems During Rapid Ascent
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1. Decompression sickness/
Caisson’s disease/
Dysbarism/
Bends/
Diver’s palsy.
2. Air embolism
Decompression sickness
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• Nitrogen forms bubbles & escapes from the
tissues;
• Bubbles block blood vessels;
• Tissue ischemia & tissue death.
Decompression sickness….cont
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• Symptoms
– Pain in joints & muscles of legs or arms – Bends
– Chokes – Shortness of breath
– Paralysis of muscles – Diver’s palsy
– Coronary ischemia or MI
– Neurological symptoms: Dizziness, Collapse, Unconsciousness
– Death
• Treatment – Tank decompression
Air embolism
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• Chest pain
• Tachycardia
• Hypotension
• Block the blood flow
• Death
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Preventive measures
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1. Use of breathing
apparatus:
open/closed circuit
• SCUBA diving; self-
contained underwater
breathing apparatus.
Preventive measures....cont
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2. Use of breathing mixture containing
helium & low O2
– Prevents O2 toxicity
– Helium;
• Easy to breath
• Fast diffusion
• Easy elimination of bubbles
• Less toxic than nitrogen
Preventive measures.....cont
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3. Slow ascent or decompression tank
• Principle: slow ascent
• Person is put into a pressurized tank.
• Decompression ;
30 m depth × 30 min dive…………NA
60 m depth × 60 min dive…………3 hours
100 m depth × 20 min dive……….3 hours
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Physiology Trivia
History
• In 1873: Dr. Andrew Smith first utilized the term
"caisson disease" describing 110 cases of decompression
sickness as the physician in charge during construction of
the Brooklyn Bridge.
• In1916: The decompression chamber was invented by
the Italian engineer Alberto Gianni.
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Address: Brooklyn Bridge, New York, NY 10038, USA
HIGH-YIELD TOPICS IN RS PHYSIOLOGY
1. Non-respiratory function of RS
2. Pressure and Volume changes during Rs
3. Pulmonary compliance
4. Surfactant
5. PFTs
6. Ventilator-perfusion ratio
7. Respiratory membrane
8. Transport of gases
9. Regulation of respiration
10. Hypoxia
11. Acclimatization
12. Dysbarism
13. Periodic breathing
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