Did you know? The majority of divers DAN AP has managed with Decompression Illness (DCI) have been using dive computers and diving within the limits advised by their computers.

Most divers these days use dive computers and appear to be reasonably confident that they will avoid DCI as long as they dive within the limits of these devices. Interestingly, the majority of divers DAN AP has managed with DCI have been using dive computers and diving within the limits advised by their computers.

The issue is that dive computer algorithms are based on decompression models, which are generalisations of what might be occurring within a diver’s body. These models have inherent inaccuracies and cannot cater for the broad individual variation between divers and the type of dives undertaken.

Deeper dives, longer dives, short surface intervals and repetitive diving can all lead to higher inert gas loads, greater bubble formation and consequently less accurate decompression calculations. Divers need to be aware that deeper diving is associated with a higher risk of DCI and the resulting DCI is more likely to affect the nervous system. Very long dives also carry a higher risk of DCI.

A diver explores the Yonaguni Monument © Wikimedia Commons

A diver explores the Yonaguni Monument © Wikimedia Commons

Bubbles can often be found in a diver’s venous blood after surfacing from a dive and this is common after recreational dives. These bubbles are usually detectable within the first hour after diving and can continue to appear in peak numbers for several hours. Therefore, in most circumstances, it is a good idea to extend surface intervals as long as possible between dives. Although it is often convenient and relatively common on dive boats to have surface intervals of around one hour or so, it is probably safer to extend these to at least two – three hours, preferably longer, especially after deeper dives.

In reality, relatively few divers suffer DCI given the enormous amount of diving that takes place around the world. However, for those that do, it can be a very unpleasant, disruptive and, in some cases, life-changing experience. Therefore, it is wise to balance the benefits of the extra depth, dive times and dives against the potential problems that can arise, and make an informed choice about the level of risk one is willing to take.

By DAN AP’s John Lippmann