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A word of warning this month along the lines of general dive safety and fitness. The past year has seen a spate of diving accidents, the cause of which may be attributed to a combination of both bad luck and poor fitness.
The recent deaths of a number of South Australian recreational divers is a sad reminder that a diving medical at the time of your course does not guarantee good diving health 30 years later. I have discussed this in an earlier newsletter but again would urge any club members whose health/weight/age have changed significantly since their last visit to the doctor, to have another diving medical. A list of appropriately qualified medical practitioners is available on the SPUMS website (www.spums.org.au).
In terms of bad luck, we have seen two divers recently who have suffered decompression sickness (DCS) following very "safe" and conservative dives. One to 9m for 41 mins, and one to 18m for 36 mins. The risk of developing DCS on these dives based on probablistic (mathematical) modelling is very low (around 0.5%). Why do people get bent on dives like these and is it as uncommon as one might imagine?
A review at the Adelaide Hyperbaric Unit by Steve Goble looked at the incidence of "shallow water" DCS around Australia (defined as dives to 10m or less). A total of 50 divers fitted the criteria of shallow water DCS (not arterial gas embolus), and of these 15 divers dived a square profile i.e. one depth, one ascent. These 50 divers represent about 10% of all divers treated for DCS.
The shallowest dive was 3m, but for such extremely shallow exposures repetitive dives, prolonged bottom times and multiple ascents were usually factors. For the 15 divers with a single square dive profile, one can only postulate what caused them to get sick on that particular day, when some had dived without incident on many separate occasions. Factors such as dehydration, viral illness, timing in the menstrual cycle and cardiac abnormalities such as PFO (patent foramen ovale), may have played a role.
The take home message? No matter what kind of dive you have performed, if you think you might be bent, get medical advice and don’t assume you must have done something wrong. Delays in treatment may decrease the chances of a full resolution of symptoms and will not improve the chances of getting you back in the water!
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