Decompression Sickness – The Bends – Caisson Disease

‘In the worst cases the diver began to feel faint a few minutes after return to the surface; soon he became unconscious and his pulse disappeared; and in a few minutes he was dead.’ J.S.Haldane Respiration

What is Decompression Sickness? To fully comprehend what happens to the body under pressure we need to know about Henry’s Law. Henry’s Law states that ‘the mass of a dissolved gas in a given volume of solvent at equilibrium is proportional to the partial pressure of gas.’

In simpler words as the depth increases the nitrogen in compressed air leaves through the alveoli of the lungs into the blood and to the tissues of the diver’s body. Over a certain period of time the amount of nitrogen in the tissues with large blood flow, then progressively into the fatty tissues, accumulates. On longer dives tissues will become ‘saturated’ and will not take up any more nitrogen. As the diver ascends there is usually a gap in time before tissues start releasing the nitrogen.

It is this lag that creates so many problems for divers.

When a large amount of nitrogen is dissolved in the tissues, reduction of the pressure when ascending causes the nitrogen to ‘outgas’ and form bubbles in the tissue cells. Ascending too quickly can cause the number and size of the bubbles to increase whilst they’re still in the tissue spaces and the blood. The damage the nitrogen bubbles cause may be felt as symptoms of decompression sickness (DCS).

Further ascent to altitude my also contribute to bubble formation. The average airline cabin is pressurised to 0.8 atm if a person flies too soon after diving, this additional decrease in pressure may be enough to allow bubbling or allow bubbles already in existence to enlarge.

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What may cause decompression sickness?

  • Obesity
  • Fatigue
  • Age
  • Poor physical condition
  • Dehydration
  • Illness affecting lung or circulatory efficiency
  • Prior musculoskeletal injury
  • Cold water
  • Heavy work
  • Rough sea conditions
  • Heated dry suits which leads to dehydration
  • Smoking

Symptoms

Most DCS comes on and shows symptoms in the first few hours after the end of a dive. Some even starts even before leaving the water. Most cases have developed symptoms within 24 hours of the dive. Yet it may take a diver 6-8 days or more to recognise the symptoms and seek medical advice.

Symptoms of DCS listed by frequency;

  • local joint pain – 89%
  • arm symptoms – 70%
  • leg symptoms – 30%
  • dizziness – 5.3%
  • paralysis – 2.3%
  • shortness of breath – 1.6%
  • extreme fatigue – 1.3%
  • collapse/unconsciousness – 0.5%

If a diver feels unwell or has any symptoms of DCS after a dive it is essential to remember that all signs and symptoms are pressure related until proven otherwise, usually by a diagnostic or therapeutic recompression, therefore most doctors will ask patients about pressure exposure as an aid to diagnosis. During the diagnosis patients will undergo a neurology test and be thoroughly questioned about their dive history, it is important when heading to your dive doctor to take your log books and dive computer in order to give your doctor the most amount of information for them to complete an accurate diagnosis.

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If a diver feels unwell or has any symptoms of DCS after a dive it is essential to remember that all signs and symptoms are pressure related until proven otherwise, usually by a diagnostic or therapeutic recompression, therefore most doctors will ask patients about pressure exposure as an aid to diagnosis.

During the diagnosis patients will undergo a neurology test and be thoroughly questioned about their dive, it is important when heading to your dive doctor to take your log book and dive computer in order to give your doctor the most amount of information for them to complete an accurate diagnosis.

If you suspect you have decompression sickness you must get in touch with your local dive chamber as soon as possible. DSC is very serious and if you do have it your symptoms will only worsen and left untreated it can lead to long term and permanent injury.

The website below has a list of the worldwide hyperbaric chambers;

http://www.londondivingchamber.co.uk/index.php?id=contact&page=11

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One response to “Decompression Sickness – The Bends – Caisson Disease

  1. Pingback: My Very First Dry Dive!! | Divers Who Want To Learn More·

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