Decompression sickness

Decompression sickness(DCS) is caused by inadequate decompression. Occasionally, DCS occurs even if normal decompression procedures are followed, as certain factors increase the likelihood of this condition. This must be taken into account by increasing decompression time when necessary, or by avoiding the predisposing factor altogether, whenever possible. These factors must be monitored closely, as they increase the likelihood of DCS:

• a.injuries;
• b.obesity;
• c.hangover;
• d.age;
• e.strenuous physical exercice;
• f.dehydration no matter the cause;
• g.poor physical fitness;
• h.cold;
• i.mental stress;
• j.fatigue;and
• k.infection.

Whenever possible, the complete history of the dive and any predisposing factors should be considered when diagnosing DCS.

Decompression sickness symptoms usually appear shortly after a dive or exposure to high pressure. If the required decompression period has been significantly reduced or completely omitted, the diver could be affected by decompression sickness before even reaching the surface. In general, the first symptoms manifest themselves as follows:

• 40% occur within 1 hour of surfacing;
• 60% occur within 3 hours;
• 95% occur within 6 hours and
• 99% occur within 24 hours.

When the first symptoms occur more than 24 hours after a dive, other causes should be investigated before diagnosing decompression sickness, while keeping in mind that divers may experience symptoms and fail to report them right away.

Factors to be considered while evaluating symptoms include the depth and duration of the dive, the decompression table used, the stress level (eg. cold, hard work), and the likelihood of other conditions, such as AGE. The Centre de médecine de plongée du Québec should be contacted if there are any doubts on the condition of the diver.

A wide range of symptoms may signal the onset of decompression sickness, and while some will be so obvious that there will be no doubt about the diagnosis,  more elusive symptoms may not be detected unless a thorough examination of the patient is performed.

Symptoms of decompression sickness among professional divers have been found to occur with the following frequency:

• a. Pain only: 22%
• b. Neurologic:40%
• c.  Vestibular: less than 12%
• d. Pulmonary (chokes): lessthan 3%
• e. General symptoms: 15%
• f. Fatigue: a common symptom in all cases of DCS

Eighty percent of all recreational divers suffering from decompression sickness   treated at a hyperbaric chamber experience neurological symptoms. The reason that pain as the only symptom is seldom reported among recreational divers is probably because many of them do not have easy access to hyperbaric treatment, and tend not to report their symptoms. If you have any doubts on your condition, contact the Centre de médecine de plongée du Québec.