Diving Medicine for SCUBA Divers

359 Pages·10.355 MB·English

Diving Medicine for Scuba Divers 4th edition 2012
Published by Carl Edmonds
Ocean Royale, 11/69-74 North Steyne
Manly, NSW, 2095 Australia
[email protected]

First edition, October 1992
Second edition, April 1997
Third edition January 2010
Forth edition January 2012

National Library of Australia Catalogue
1. Submarine Medicine
2. Scuba Diving Injuries
3. Diving – physiological aspects

Copyright: Carl Edmonds
Title 1 of 1 - Diving Medicine for Scuba Divers
ISBN: [978-0-646-52726-0]

To download a free copy of this text, go to
www.divingmedicine.info

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ACKNOWLEDGMENTS

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For the 1st and 2nd editions of this text
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John Pennefather, who assisted Carl Edmonds in reviewing and updating
the text

Clarrie Lawler, who supplied many excellent diagrams

Richard Chesher, for spectacular photographs

John Lippmann CEO, DAN Asia-Pacific, for advice, corrections and
,
preparation of both earlier and this edition

Richard Pyle for technical diving diagrams Cis-Lunar Development
Laboratorie
DIVING MEDICINE FOR SCUBA
DIVERS
GENERAL DIVING RELATED
BACKGROUND MEDICAL PROBLEMS
1. History of Diving 30. Hearing Loss
2. Physics 31. Disorientation
3. Physiology 32. Miscellaneous Disorders –
4. Breath-hold Diving Contact Lenses
5. Equipment Muscular Cramps
6. Diving Environments Other Ear Problems
7. Stress Disorders — Panic and Fatigue Headache
8. Female Divers Pulmonary Oedema (SDPE)
Sunburn
SPECIFIC DIVING DISEASES Seasickness
(PRESSURE RELATED DISEASES) Jaw Joint Arthritis
9. Ear Barotrauma Explosions
10. Sinus Barotrauma 33. Unconsciousness in Divers
11. Pulmonary Barotrauma 34. Why Divers Die
12. Other Barotraumas 35. Sudden Death Syndrome
13.Decompression Theory & Physiology 36. Psychological Disorders
14. Decompression Procedures Tables 37. Drugs and Diving
15. Decompression Sickness Clinical
16. Decompression Sickness Treatment TREATMENT and PREVENTION
17. Dysbaric Osteonecrosis 38. Medical Examinations for Divers
18. Nitrogen Narcosis 39. First Aid Kit
19. HPNS 40. Oxygen Therapy Techniques
20. Hypoxia 41. Training and Safety Checklist
21. Oxygen Toxicity 42. Resuscitation Review
22. Carbon Dioxide Problems
23. Carbon Monoxide Toxicity RECENT DEVELOPMENTS
24. Breathing Gas Contamination 43. Technical Diving

AQUATIC DISEASES APPENDICES
25. Drowning A. Diving Medical Library
26. Salt Water Aspiration Syndrome B. Emergency Contact Numbers
27. Cold and Hypothermia C. In-water O2 Recompression Therapy
28. Infections D. Divers Alert Network
29. Dangerous Marine Animals

GEM of WISDOM, learnt the hard way.
If a diver suffers an illness/accident that you
cannot understand or prevent, then it will happen
again – but often with more serious consequences.
Chapter 1
All chapters, full text, free download, available at http://www.divingmedicine.info

HISTORY of DIVING

Historians are unable to identify the first divers. Probably the techniques they used were similar
to those of the native pearl and sponge divers. They may have used a stone weight to ensure
rapid descent, but it is unlikely that they could dive deeper than 30 metres, or spend longer than
2 minutes underwater. Later, diving was employed for military purposes (such as destroying
ships anchoring cables, boom defences, etc.) and for salvage work. Divers took part in great
naval battles between 1800 BC and 400 BC. Alexander the Great was said to have descended in
a diving bell (circa 330 BC) but the details are scarce and some of the stories of the descent are
fanciful.

Commercial diving evolved through the 19th and 20th centuries and encompassed salvage and
shell diving, extending into exploration, deep diving, off shore oil rigs, aquaculture, ecology
and most importantly for you – recreational diving.

The history of diving evolved in two directions. The first is the development of diving
equipment – described in this chapter. The second is the understanding of diving physiology
and medicine – described in the rest of this text.

Fig. 1.1

A Roman historian, Pliny, recorded the earliest use of surface supplied breathing air by divers
in AD77, when a breathing tube connected the diver to the surface. This possibly represents an
Chapter 1 — 1
early "schnorkel". Its use was limited to very shallow dives, since man's respiratory muscles
cannot draw air very far down from the surface – maximum half a metre. It was also depth
limited due to the excessive volume of the breathing tube.

Leonardo da Vinci sketched several designs for diving equipment and submarines. Many
diagrams of divers' hoods can be found in other historical texts from 1500 AD onwards, but
much of this equipment would not have worked at
depths greater than a few feet. They did, however,
attest to man's desire to remain below the surface
for extended periods. In 1680 Borelli, an Italian,
designed a diving set which purported to be a self-
contained diving apparatus. Although it was
impracticable, the idea was revolutionary at that
time. Despite the fact that much diving equipment
was primitive and rarely functioned adequately,
diving bells were used with success from the 17th
century onwards.

Fig. 1.2

Diving with a helmet (the equivalent of an upturned bucket which enclosed the diver's head)
gradually became an accepted method. It contained air that was pumped down from the surface
following the development of efficient air pumps around 1800 AD. Bellows were used to force
air down to the divers. This allowed longer and deeper dives and brought to light the many
physiological problems caused by the undersea environment.

In 1837 Augustus Siebe marketed the first effective standard
diving dress. This incorporated an air-supply line connecting
a pump or compressor on the surface to a diving helmet. The
helmet was attached by an airtight seal to a flexible suit that
enclosed the diver and was filled with air.

Fig. 1.3
Siebe's helmet.

Chapter 1 — 2
The development of self-contained air supplies was
impeded by the lack of sufficiently powerful
compressors and reservoirs. In 1863 the Frenchmen,
Rouquayrol and Denayrouze, invented the first
satisfactory demand regulator for self-contained
underwater breathing apparatus (SCUBA), but due to
lack of suitable high pressure air compressors and
cylinders, it was limited to surface air supply lines.

In 1878 H. A. Fleuss made a workable self-
contained (closed-circuit) oxygen breathing
apparatus utilising caustic potash to remove exhaled
carbon dioxide. "Closed" refers to the absence of an
outlet for gas (i.e. no bubbles) and means that the
exhaled gas is rebreathed. This was the forerunner of
modern closed-circuit diving units.
Fig 1.4
Rouquayrol and Denayrouze, Diving suit 1863

Divers in the late 1800's were capable of reaching depths in excess of 50 metres, but the effects
of decompression sickness (or bends) caused much concern and many injuries to divers. Paul
Bert, a French scientist, was the first to explain that the disease was caused by the formation of
nitrogen bubbles in the body and proposed the idea of a slow ascent to the surface. It was not
until the early 20th century that Dr J. S. Haldane derived satisfactory mathematical
decompression tables to overcome this physiological problem of deep diving. The first
successful tables were based on the assumption that decompression sickness could be avoided
by not exceeding a 2:1 pressure reduction between stops. It reflected a mathematical model of
inert gas behaviour in a body and was to be the forerunner of current decompression tables.
Later observations showed this principle to be incorrect in many cases, but these early tables
and the later modified versions, prevented many divers from developing the bends.

Diving research this century has lead to a great improvement in all forms of diving equipment
and since 1940 the use of such equipment has increased greatly. The design by Cousteau and
Gagnan in 1943, of a proper demand-regulated air supply from compressed air cylinders worn
on the back has developed into modern day scuba.

The scuba equipment used today, with the high-pressure regulator on the cylinder and a single
hose to a demand valve in the mouth, was invented in Australia and marketed by an engineer
named Ted Eldred in the early 1950s, under the Porpoise trademark.

Closed-circuit rebreathing apparatus using, oxygen or oxygen/nitrogen mixtures, has also
been improved considerably since the early units used by Italian Naval divers in their attacks on
shipping in Gibraltar in 1941. With the advent of deeper diving, gas economy has become a
major problem and for this reason closed-circuit systems have achieved even greater
importance.

Diving to depths in excess of 100 metres required not only the development of specialised
closed or semi-closed circuit rebreathing apparatus, but also the use of other inert gas mixtures
mixed with oxygen. Nitrogen, because of its narcotic effect at depth, has been replaced largely
by other gases such as helium and hydrogen. These are not used without complications – as all
gases cause specific physiological problems and no ideal mixture yet exists.

Chapter 1 — 3
The advent of saturation diving has completely
revolutionised the ability to dive and work at great
depth, and for lengthy durations, and this is
economically rewarding. The system is based on
saturation at any depth of all the diver's tissues by
the inert breathing gas. Once this is achieved the
body is incapable of absorbing further amounts of
gas, no matter what the duration of exposure at this
depth. Hence, further exposure does not lengthen
decompression times. This practice is now adopted
for most diving with extended bottom times at
depths in excess of 100 metres.

In an attempt to reduce the risks in deep diving,
one-atmosphere diving suits (ADS) have been
developed out of strong lightweight alloys. These
suits are fitted with articulated joints and use
mechanical levers or claws for "hands". Some even
have mobility and propulsion, but all require backup
'rescue' facilities. They are equipped with a self
contained rebreathing apparatus and are often used
at depths of 200–300 metres. Although somewhat
bulky and requiring hoisting gear at the surface,
divers can achieve a reasonable degree of movement
at depth with the latest models. These suits are also
useful for inspection-type work, although much of
this is now done by non-manned Remote Operated
Vehicles (ROV's) with video surveillance.

Fig 1.6 The Royal Australian Navy
Clearance Diving Team, 1955, with
oxygen breathing equipmenrt and
wearing the famous “Clammy Death” suit.

Chapter 1 — 4
Chapter 2
All chapters, full text, free download, available at http://www.divingmedicine.info

PHYSICS

To understand the physical and physiological problems which can confront a diver, it is
helpful to recall a few basic physical laws of nature. Only a brief and simplified review of the
physics of diving is given in this text. For more detailed explanations, refer to the diving
manuals.

PRESSURE

Some of the major physical hazards are related to the effects of pressure. Pressure is defined
as force per unit area. i.e.
PRESSURE = FORCE
AREA

If a force is spread over twice the area, the pressure is halved.

This explains why, for example, wide tyres are preferable for driving on beaches. The weight
of the vehicle (force) when spread over a large area causes less pressure on the sand. This
vehicle is less likely to sink into the sand than one with narrow tyres.

The effect of stilleto heels on soft wooden boat decks
Chapter 2 — 1