Remember that the term decompression illness (DCI) includes both decompression sickness (DCS), resulting from dissolved nitrogen (or another inert gas) being eliminated from a diver’s body tissues, and arterial gas embolism (AGE), which is caused by air entering the arterial blood as a result of a burst lung.
1. Getting DCI while diving within the limits
Divers who get DCI have often been diving within the limits of their dive computer or tables. The risk of DCI increases upon exceeding these limits, which indicates that the limits cannot accurately account for individual differences between divers and the various factors that can influence nitrogen uptake and elimination during a dive. All divers shouldadd conservatism to their decompression calculations, especially if the diving is purely recreational and dive time doesn’t need to be maximised.
2. Insufficient oxygen
Many dive operators in remote areas do not have access to a sufficient supply of oxygen. It can sometimes take over 24 hours for an evacuation team to reach some remotelocations, so a large supply of oxygen is required to last until an injured diver receives appropriate medical care. Check this out before going on a trip to an area without good access to suitable medical facilities.
3. A mottled rash is a common sign of DCI
This is often associated with the presence of a patent foramen ovale (PFO). Skin-related DCI used to be relatively uncommon in recreational divers, but in more recent years, it has become far more common. Part of the reason for this could be the result of the more frequent and longer dives and shorter surface intervals enabled by dive computers.
4. DCS after ascending from shallow depths
It used to be thought that one had to dive deeper than 10 metres before DCS was a risk, but this is now known to be untrue – some divers have suffered from DCS after ascending from six or seven metres.
5. Bubbles forming in diver's bodies
Caused by repetitive and deep dives, these bubbles can be detected using ultrasound, and usually do not cause symptoms. Some divers “bubble” more than others. A slow ascent rate and doing a safety stop reduces the amount of bubbling and therefore the risk of DCI.
6. Some more susceptible to DCI than others
Divers with a patent foramen ovale (PFO), which is a common heart defect that can enable blood to flow across the heart, have a significantly higher risk of DCI (sometimes quoted as two to eight times, depending on the size of the hole). Other factors such as being overweight, age, lack of fitness, and dehydration may also play a role, although there is little hard evidence to support some of these beliefs.
7. Oxygen first aid is often poorly done
Oxygen first aid is very important in the management of DCI, but it is often delayed and given using unsuitable equipment for a short period. To maximise the benefit, near- 100 percent oxygen should be given from the time symptoms first occur, and should be continued until a diving doctor advises that it be stopped.
8. DCI was first reported in 1667 in a snake
Boyle (see Boyle’s Law) placed a viper in a vacuum and noticed a bubble forming in its eye.
9. You could burst a lung and get DCI at 1.2 metres
If a diver fills their lungs with compressed air and surfaces without exhaling, there is enough pressure change in the first 1.2 metres from the surface to over-expand the lungs to the point of causing a tear.
Taken from Asian Diver’s DIVERAHOLIC, volume 145