There are a number of predisposing factors that can lead to decompression illness even when all of the appropriate guidelines and safety factors are followed. Some factors are at the mercy of the environment, such as water temperature and elevation. Other factors are physiological and pertain to each individual person, which can change from day to day and the techniques you use in the execution of your dive, ascent, and decompression.
The following is a list of factors that can predispose you to DCI and bubble formation:
Thermal stress: If you are cold or overheated, you are more susceptible to DCI. When cold, your body tries to warm itself, shunting blood away from your extremities. This reduces effective circulation and can lead to inefficient gas transfer increasing your susceptibility to DCI.
Depth and pressure change: The deeper you go, the greater the pressure and the more inert gas is absorbed into your tissues. When you ascend, the pressure reduces and if you’re ascending too quickly can allow inert gas to come out of solution and cause bubbles.
Exposure time: The amount of time you spend at depth affects the amount of inert gas absorbed into your tissues. The longer you stay, the more inert gas is absorbed and the more decompression is required. If you push no decompression tables or your computer, a slower ascent and adequate safety stops should be performed.
Exertion and gas uptake on the dive: The harder and more exertion performed during a dive, the more absorption of inert gas into your body’s tissues and the more your body produces carbon dioxide. Increased amounts of carbon dioxide creates a predisposition for DCI because the carbon dioxide combines with any existing inert gas bubbles and can bring the bubbles to critical size.
Drugs, alcohol, caffeine, and nicotine: Any of these can affect your body’s ability to off gas effectively. When diving, especially decompression diving, it’s better to avoid the use of any of these substances.