Decompression practice

To prevent or minimize decompression sickness, divers must properly plan and monitor decompression. Divers follow a decompression model to safely allow the release of excess inert gases dissolved in their body tissues, which accommodated as a result of breathing at ambient pressures greater than surface atmospheric pressure. Decompression models take into account variables such as depth and time of dive, breathing gasses, altitude, and equipment to develop appropriate procedures for safe ascent.

Decompression may be continuous or staged, where the ascent is interrupted by stops at regular depth intervals, but the entire ascent is part of the decompression, and ascent rate can be critical to harmless elimination of inert gas. What is commonly known as no-decompression diving, or more accurately no-stop decompression, relies on limiting ascent rate for avoidance of excessive bubble formation. Staged decompression may include deep stops depending on the theoretical model used for calculating the ascent schedule. Omission of decompression theoretically required for a dive profile exposes the diver to significantly higher risk of symptomatic decompression sickness, and in severe cases, serious injury or death. The risk is related to the severity of exposure and the level of supersaturation of tissues in the diver. Procedures for emergency management of omitted decompression and symptomatic decompression sickness have been published. These procedures are generally effective, but vary in effectiveness from case to case.

The procedures used for decompression depend on the mode of diving, the available equipment, the site and environment, and the actual dive profile. Standardized procedures have been developed which provide an acceptable level of risk in the circumstances for which they are appropriate. Different sets of procedures are used by commercial, military, scientific and recreational divers, though there is considerable overlap where similar equipment is used, and some concepts are common to all decompression procedures. In particular, all types of surface oriented diving benefited significantly from the acceptance of personal dive computers in the 1990s, which facilitated decompression practice and allowed more complex dive profiles at acceptable levels of risk.