Deep sea diving physiology

2. Learning Objectives
• After attending this lecture the student will be
able to understand
• 1-The physiological changes in body in deep
sea workers.
• 2-Disturbances in human body during rapid
ascent from deep sea and its management.

3. Deep-Sea Diving and Other
Hyperbaric Conditions
• When human beings descend beneath the sea,
the pressure around them increases
tremendously.
• To keep the lungs from collapsing, air must be
supplied at very high pressure to keep them
inflated.
• This exposes the blood in the lungs to
extremely high alveolar gas pressure, a
condition called hyperbarism.

4. Relationship of Pressure to Sea
Depth.
• At sea level, atmospheric pressure = 1
atmosphere
• At 33 ft depth, atmospheric pr = 2 atm.
• with every 33 ft depth, pressure increases by 1
atmosphere .

6. EFFECT OF SEA DEPTH ON GAS VOLUME
BOYLE’S LAW
8 atmosphere
2 atmosphere

7. Effect of High Partial Pressures of Individual
Gases on the Body
Nitrogen Narcosis at High Nitrogen Pressures
SYMPTOMS:
• Like alcohol intoxicity: (Euphoria, drowsiness,
impaired memory, impaired thought making
.becomes too clumsy to perform the
work,anesthetised

8. • In deep sea divers, when they inhale gas
mixture having Nitrogen,
nitrogen being lipid soluble is dissolved in
body tissues.

9. • At sea level, where pressure is 1 atmosphere,
1 liter of nitrogen is dissolved in body tissues.
At depth of 100 feet, pressure is 4 atmosphere & 4
liters of nitrogen will be dissolved in body tissues.
• Out of this gas dissolved, ½ is dissolved in body
fluids & ½ in body fats. dissolves in the fatty
substances in neuronal membranes--
• altering ionic conductance through the membranes,
reduces neuronal excitabilitybrain dysfunction

11. Oxygen Toxicity at High Pressures

12. Effect of High Alveolar PO2 on Tissue PO2.
• Po2 in the lungs is about 3000 mm Hg
• total oxygen content in each 100 milliliters of blood of
about 29 volumes per cent,
• 20 volumes per cent bound with hemoglobin and 9
volumes per cent dissolved in the blood water
• Tissues use their normal amount of oxygen, about 5
milliliters from each 100 milliliters of blood,

13. • Po2 is approximately 1200 mm Hg, which
• means that oxygen is delivered to the tissues at this
extremely high pressure (normal 40 mm Hg).
• once the alveolar Po2 rises above a critical level,
the hemoglobin-oxygen buffer mechanism is no
longer capable of keeping the tissue Po2 in the
normal, safe range between 20 and 60 mm Hg.

14. Excessive Intracellular Oxidation as a Cause of
Nervous System Oxygen Toxicity—“Oxidizing Free
Radicals.”
• oxygen free radicalssuperoxide free radical
O2- and peroxide OH-radical in the form of
hydrogen peroxide.
• peroxidases, catalases, and superoxide
dismutases.tissue enzymes to neutralize.

15. • Above a critical alveolar PO2 (i.e., above about 2
atmospheres PO2), the hemoglobin-O2 buffering
mechanism fails, and the tissue PO2 can then rise
to hundreds or thousands of millimeters of
mercury.
• At these high levels, the amounts of oxidizing free
radicals literally swamp the enzyme systems
designed to remove them, and now they can have
serious destructive and even lethal effects on the
cells

16. Oxygen Toxicity at High Pressures
• 1- oxidize the polyunsaturated fatty
• Acids of many of the cell membranes.
• 2-oxidize some of cellular enzymes, thus
damaging severely the cellular metabolic
systems-Nervous System Oxygen Toxicity

17. Acute Oxygen Poisoning
• breathing O2 at 4 atmospheres pressure of O2
(PO2 = 3040 mm Hg) will cause brain
seizures followed by coma in most people
within 30 to 60 minutes.
• The seizures often occur without warning and,
are likely to be lethal to divers submerged
beneath the sea. within 30 to 60 minutes.

18. Other symptoms of acute oxygen
poisoning
• nausea, muscle twitchings, dizziness,
disturbances of vision, irritability, and
disorientation.
• Exercise greatly increases the diver’s
susceptibility to O2 toxicity, causing
symptoms to appear much earlier and with far
greater severity than in the resting person.

19. Chronic Oxygen Poisoning Causes Pulmonary Disability.
• after only about 12 hours of
• 1 atmosphere oxygen exposure, lung
passageway congestion, pulmonary edema,
and atelectasis caused by
• damage to the linings of the bronchi and
alveoli begin to develop.

20. Carbon Dioxide Toxicity at Great
Depths in the Sea
• Up to an alveolar Pco2 of 80 mm Hg, the diver
tolerates by increasing the minute respiratory
volume a maximum of 8- to 11-fold.
• Beyond 80-mm Hg alveolar Pco2, the respiratory
center begins to be depressed,
• because of the negative tissue metabolic effects of
highPco2. The diver’s respiration then begins to
fail and develops severe respiratory acidosis, and
lethargy, narcosis, and finally anesthesia, coma,
death.

21. • Decompression Sickness (Also Known As
Bends, Compressed Air Sickness, Caisson
Disease, Diver’s Paralysis, Dysbarism).

22. What is Caisson
• Caisson’s worker, works in chambers having air at high
pressure. a caisson is a retaining, watertight structure sealed at
the top and filled with compressed air to keep water and mud
out at depth
• These workers dig tunnels under rivers or to work on the
foundations of a bridge.
• In hyperbaric conditions, as body is exposed to high pressure,
they must breathe air with increased pressure (so that lung
should not collapse).

24. • When caisson’s workers breathe air with increased
pressure (nitrogen & oxygen with increased pressure)
 NITROGEN NARCOSIS (effect of Nitrogen with
increased pressure).
• When the diver remains beneath the sea for an hour
or more and is breathing compressed air, the depth at
which the first symptoms of mild narcosis appear is
about 120 feet

25. • Under hyperbaric conditions, in deep sea diving,
body tissues become saturated with nitrogen
• The nitrogen dissolved in the water of the body
comes to almost complete equilibrium in less than 1
hour, but
• the fat tissue, requiring five times as much transport
of nitrogen and having a relatively poor blood
supply, reaches equilibrium only after several hours.
• if the person remains at a deep level for several
hours, both the body water and body fat become
saturated with nitrogen

26. Nitrogen cannot be metabolized in the body, so
amount of gas dissolved, remain as such.
• Under hyperbaric conditions, in deep sea
diving, body tissues become saturated with
nitrogen.

27. De-Compression Sickness / Dysbarism / Bends
/ Diver’s paralysis / Bends:
• Normally deep sea divers ascend to sea-level
gradually so that Nitrogen from the body fluids
and tissues is removed gradually.
• So no harmful effect on the body is produced.
• If deep sea divers ascend to sea level rapidly
Decompression sickness.

29. • Under hyperbaric conditions, in deep sea
diving, body tissues become saturated with
nitrogen
• On rapid ascent to sea level this bubble
formation occurs because Nitrogen tries to
come out.
• Bubble formation in blood vessels of brain 
Paralysis.
• Around nerves  Paresthesia, itching and
severe pain.
• There may be severe pain around joints
(bends) when bubbles form around joints.

30. Symptoms of Decompression
Sickness (“Bends”).
• gas bubbles blocking many blood vessels indifferent
tissues. There may be severe pain around joints
(bends) when bubbles form around joints.
• At first, only the smallest vessels are blocked by
minute bubbles, but as the bubbles coalesce,
progressively larger vessels are affected. Tissue
ischemia and sometimes tissue death are the result

31. 1-bends
• In the 85 to 90 per cent of those persons
• symptoms are pain in the joints and muscles of
the legs and arms, The joint painaccounts for
the term “bends”

32. 2-paralysis
• In 5 to 10 per cent nervous system symptoms
occur, ranging from dizziness in about 5 per
cent to paralysis or collapse
• and unconsciousness in as many as 3 per
cent.The paralysis may be temporary, or
damage may be permanent.

33. 3-chokes
• 2 per cent develop “the chokes,” caused by
massive numbers of microbubbles plugging
the capillaries of the lungs; this is
characterized by serious shortness of
• breath, often followed by severe pulmonary
edema and, death.

34. • In coronary arteries, bubbles air embolism 
Cardiac damage

35. Tank Decompression and Treatment of Decompression
Sickness. Treatment and Prevention
• 1-Recompression of diver in pressurized
chambers. Then pressure is decreased
gradually.
• 2-Similarly caisson’s operators when they are
moved out of chamber, pressure is gradually
reduced.

36. Nitrogen Elimination from the Body; Decompression Tables.
• If a diver is brought to the surface slowly,
enough of the dissolved nitrogen can usually
be eliminated by expiration through the lungs
to prevent decompressionsickness.
• About two thirds of the total nitrogen is
liberated in 1 hour and about 90 per cent in 6
hours.

37. Slow ascent of the diver
• Decompression tables have been prepared by
theU.S. Navy that detail procedures for safe
decompression.
• To give the student an idea of the
decompression process, a diver who has been
breathing air and has been on the sea bottom
for 60 minutes at a depth of
• 190 feet is decompressed according to the
following schedule:

38. • 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
• Thus, for a work period on the bottom of only 1
hour, the total time for decompression is about 3
hours.

39. Tank Decompression and Treatment of Decompression Sickness.
• the total time for decompression is kept about 3
hours.so that the dissolved nitrogen can usually be
eliminated by expiration through the lungs .

40. 4-“Saturation Diving” and Use of Helium-Oxygen Mixtures in
Deep Dives.
• When divers must work at very deep levels—between 250
feet and nearly 1000 feet—they frequently live in a large
compression tank for days or weeks at a time, remaining
compressed at a pressure level near that at which they will be
working.
• This keeps the tissues and fluids of the body saturated with
the gases to which they will be exposed while diving.
• Then, when they return to the same tank after
• working, there are no significant changes in pressure, so that
decompression bubbles do not occur

41. -Use of Helium-Oxygen Mixtures in Deep
Dives.
• In very deep dives, especially during saturation diving, helium is
usually used in the gas mixture instead of nitrogen
(1) it has only about one fifth the narcotic effect of nitrogen;
• (2) only about one half as much volume of helium dissolves in the
body tissues as nitrogen
• (3) the low density of helium (one seventh the density of nitrogen)
keeps the airway resistance for breathing at a minimum which is very
important because highly compressed nitrogen is so dense that airway
resistance can become extreme, making the work of breathing beyond
endurance.

42. 5-Reduce oxygen conc in gas mixture
• in very deep dives it is important to reduce
• the oxygen concentration in the gaseous
mixture to aviod oxygen toxicity would result.
• For instance, at a depth of 700 feet (22
atmospheres of pressure), a 1 per cent oxygen
mixture will provide all the oxygen required
by the diver,

43. Scuba (Self-Contained
Underwater Breathing
Apparatus) Diving
• 1943, Jacques Cousteau
• (1) tanks compressed air or breathing mixture,
• (2) a “reducing”valve for reducing the very high
pressure from the tanks to a low pressure level,
• (3) a “demand” valve and exhalation valve that
allows air to be pulled into the lungs with slight
negative pressure and then to be exhaled into the
sea
• (4) a mask and tube system

46. • The most important problem with SCUBA is the
limited amount of time one can remain beneath
the water surface; only a few minutes are
possible at a 200-foot depth.
• The reason for this limitation is that tremendous
airflow from the tanks is required to wash CO2
out of the lungs—the greater the depth, the
greater the airflow in terms of quantity of air per
minute that is required, because the volumes
have been compressed to small sizes.

47. Escape from Submarines
• escape from a submerged submarine same
problems as in deep sea diver.
• Escape is possible from as deep as 300 feet
without use of any apparatus.
• However, proper use of rebreathing devices,
especially when using helium, theoretically
can allow escape from as deep as 600 feet or
perhaps more.

48. Health Problems in the Submarine
Internal Environment
• Radiation
• Carbon monoxide poisioning

49. Hyperbaric Oxygen Therapy
• The intense oxidizing properties of high-
pressure voxygen (hyperbaric oxygen) can
have valuable therapeutic effects in several
important clinical conditions. Therefore, large
pressure tanks are now available in many
medical centers into which patients can be
placed and treated with hyperbaric oxygen.

50. Hyperbaric Oxygen Therapy
• The oxygen is usually administered at Po2s of
2 to 3 atmospheres of pressure through a
mask or intratracheal tube, whereas the gas
around the body is normal air compressed to
the same high-pressure level.

51. • 1-treatment of gas gangrene by infection of
clostridial bacteria grow best under anaerobic
conditions
• 2-decompression sickness,
• 3-arterial gas embolism
• 4- carbon monoxide poisoning,
• 5-osteomyelitis,
• 6-myocardial infarction