Introduction to barotrauma in diving

Barotrauma results from the changes in pressure that a diver experiences with descent or ascent. As a diver descends, the column of water above them adds 1 atmosphere of pressure for every 10 metres of seawater descended. This exerts increased pressure over the whole of a diver’s body. Air-filled spaces in the body are subject to Boyle’s Law—as the atmospheric pressure increases, the volume of gases in these spaces decreases. The greatest relative pressure change that a diver experiences is near the surface.

Barotrauma occurs when the pressure of an air-filled space (middle ear, sinuses, lungs) within the body cannot, or does not, equilibrate with changes in ambient pressure of the environment. This is one of the most common causes of diving-related illness, affecting any space that may have entrapped air. Barotrauma can present during, or after, even very short and shallow dives. It can occur on descent (as the atmospheric pressure increases and gas volume decreases) or on ascent (as air trapped in spaces increases in volume). Establishing the dive phase (ascent or descent) in which the symptoms started helps to determine the likely precipitating event. Check, as part of presenting history, whether the diver followed good diving practices designed to prevent barotrauma, such as exhaling on ascent, and performing any decompression stops that were recommended by their diving tables or dive computer.