The document discusses the physiology of high pressure experienced during deep sea diving. It explains that as depth increases, pressure increases linearly and gas volumes in the body decrease. Issues that can arise include nitrogen narcosis, oxygen toxicity, carbon dioxide buildup, and decompression sickness during ascent. Decompression sickness occurs when nitrogen dissolved in tissues comes out of solution rapidly, forming bubbles that block blood vessels. Treatment involves recompression in a hyperbaric chamber to resolve bubbles.

1. DrSanjeev Shrivastava
MBBS,MD
AssociateProfessor
DEPT.OFPHYSIOLOGY
PHYSIOLOGY OF
HIGH PRESSURE

2. Sea water is approximately 800 times more dense than air.
Therefore, it exerts much greater pressure on the body of a diver.
The weight exerted by the atmosphere on an area of 1m2, is
approximately 10,000 kg at sea level.
At 30m, a diver will experience a pressure of 4 ATM (1 ATM
exerted by the atmosphere, & 3 ATM exerted by the 30m of
water above him).

3. Physiology of Deep-Sea Diving
Effect of sea depth on
pressure (top table) and on
gas volume (bottom).

4. Volume of Nitrogen Dissolved in the Body
Fluids at Different Depths.
sea-level volume of nitrogen dissolved in the body
at different depths is as follows

5. PHYSIOLOGYOFHIGH
ATMOSPHERICPRESSURE.



Atmospheric pressure of
760 mmHgat sea level is –
1 atmospheric pressure.
For every 33ft descend it
increases by 1 atmospheric
pressure.
Highatm pressure seen in
 Deepsea diving
 Submarines
 Caisson’sworkers.
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7. PHYSIOLOGICALPROBLEMS
UNDERDEPTH.
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 Due to mechanical effects
 Due to effect of high pressure on respiratory
gases.

8. PHYSIOLOGICALPROBLEMSDUETO
MECHANICAL EFFECTS OF HIGH
ATMOSPHERICPRESSURE.
 At a depth of more than
30 meters (100 ft)
 Caving of the chest
 Damage to the face
 Squeezing of air inthe
Paranasal sinuses &
middle ear.
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9. PHYSIOLOGICALPROBLEMSDUETO
EFFECTOFHIGHPRESSUREON
RESPIRAATORYGASES.
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 Effect of increases PO2
 Effect of increased Pn2 (nitrogen narcosis)
 Effect of carbon dioxide build up.

10. EFFECTOFINCREASEDPO2
 Acute oxygen toxicity
–disorientation,
dizziness, convulsions
& coma
 Chronic oxygen
toxicity
 Irritation of airways
 Pulmonary oedema &
atelectasis
 Bronchopneumonia.
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11. Inhalation of mixture of 80% Nitrogen and 20% oxygen at
high pressure
At 120 feet feels joviality & careless (rapture of the deep)
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 membrane of neurons and
impairs the conduction like gas anesthetics

12. EFFECTOFINCREASEDPN2
(NITROGENNARCOSIS)
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13. EFFECTOFCARBONDIOXIDE
BUILDUP.
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14. PHYSIOLOGICALPROBLEMS
OFASCENT.
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 DecompressionSickness
 AirEmbolism

15. DECOMPRESSIONSICKNESS
 Caisson’s
disease/Dysbarism/co
mpressionofair
sickness/the
bends/diver’s palsy.
 Cause–under high
pressure nitrogen in the
breathed air dissolved
in the body fluids &fats.
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16. DECOMPRESSIONSICKNESS
 When individual
ascend rapidly to sea
level, nitrogen is
decompressed &
escapes from the
tissue in the form of
bubbles
 These bubbles block
the blood vessels –
ischemia & infarction.
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17. Divers breath 80% nitrogen under water
Nitrogen under such high pressure gets dissolved
in blood
Gets accumulated in tissues and fats
During slow ascends these dissolved gas gets
eliminated by lungs slowly
But rapid ascend causes formation of nitrogen
bubbles
Which produces symptoms

18. Inflammation
The gas: tissue interface can activate
complement, other inflammatory pathways &
inflammatory cells, leading to an acute
inflammatory response
Ischaemia
Blood flow obstruction can lead to ischaemia &
infarction of tissue/organs
Coagulation
The gas:blood interface can activate clotting
factors, leading to intravascular coagulation

19. Emboli
Bubbles forming in the blood can
disrupt blood flow
Cell Disruption
Bubbles forming within cells can damage their
internal structure & lead to loss of function
Tissue Rupture
Large bubbles forming in the vasculature may
cause vessels to rupture. Similarly, bubbles
forming in other spaces (e.g. The lungs) may
cause them to rupture

20. Mechanical Compression
Large bubbles may compress surrounding
structures, causing damage & leading to loss
of function

21. SYMPTOMS.
 Pain in joints & muscles
–Bends
 Sensation of numbness
 The chokes
 Paralysis of muscles
 Coronary ischemia & MI
 Neurological symptoms
–dizziness, collapse,
unconsciousness
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22. TREATMENT
 Tank Decompression.
 Diver in pressurised
tank & recompression
is done to dissolve
bubbles.
 Pressure lowered back
to normal.
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23. Severe decompression sickness can be a medical
emergency. Prompt resuscitation measures can
therefore save lives.
Administration Of O2
100% oxygen should be administered via a
mask. This will improve O2 saturations and
thus supply to any ischaemic tissues.

24. Warming
Wetsuits should be removed .
• Passive re- warming of patients should be
commenced to prevent hypothermia.
Lie Patient Horizontally
Lying patient horizontally limits air emboli
rising.
• Reduce the chances of emboli reaching the brain.

25. Slow decompression
Decompression chamber
Hyperbaric oxygen
Recompression followed by slow decompression in
Compression chamber--
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
Total 3 hours

26. Hyperbaric chamber:
A sealed compartment used to treat Air Embolism and
decompression sickness, in which pressure is first
increased and then gradually decreased.

27. AIREMBOLISM
 Due to entry of air into
blood circulation following
rupture of pulmonary
capillaries, arteries & veins
due to sudden expansion
of gases in lungs due to
sudden fall in atmospheric
pressure.
 Occurs in Caisson’s
workers & inRockets.
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28. AIREMBOLISM
 SYMPTOMS
 Chest pain, tachypnoea,
systemic hypotension,
hypoxemia
 Sometimes air emboli to
systemic circulation –
death.
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29. PREVENTION OF PHYSIOLOGICAL
PROBLEMS OCCURING AT DEPTH
& ASCENT.
 Measuresforshort
durationdive upto20
meters.
 Take rapid&deep
breaths before diving
–CO2washes out –N2
does not get enough
time to dissolve –O2
toxicity not occur.
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30. Self contained
underwater breathing
apparatus
Tank and valve system
used by deep sea divers
Contains oxygen &
helium (Heliox)

31. PREVENTION OF PHYSIOLOGICAL
PROBLEMS OCCURING AT DEPTH&
ASCENT.
 Measures for deeper &
longer dives.
 Useofbreathing
apparatus–gives gas to
breath & either dissolves
CO2( close circuits) or
bubbles out in water
(open circuits)
 SCUBA DIVING(Self-
Contained-Underwater-
Breathing-Apparatus)
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32. Has only about one fifth the narcotic effect of
nitrogen
Only about one half 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

33. High pressure nervous syndrome due to helium
HPNS is due to anesthetic effect of helium in
high pressure
Lipid soluble
Symptoms-
Drowsiness , tremors , in coordination
EEG changes

34. The deepest SCUBA dive
record-Ahmed Garb, 1090 ft in
Red sea.

35. PREVENTION OF PHYSIOLOGICAL
PROBLEMS OCCURING AT DEPTH&
ASCENT.
 Use of breathing
mixtures containing
helium & low oxygen
concentration –
prevent O2toxicity.
 Slow ascent or use of
Decompression Tank.
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36. THANK YOU.
Thursday, February 18, 2016