During ascent in a standard diving (‘hard hat’) suit, the expanding gas must be able to escape. If it does not, then the whole suit will expand like a balloon and cause increased buoyancy and a rapid and uncontrolled ascent to the surface (Figure 9.4). This may result in barotrauma of ascent, decompression sickness, imprisonment of the diver and physical trauma.
With the decreasing use of standard diving suits, this emergency is now not often encountered, but a variant is likely with divers who use a drysuit. It also can occur with other inflatable objects, such as a buoyancy vest or salvage/lift bag if inflated excessively or from failure to deflate during ascent.
A clinically dissimilar and relatively minor manifestation is noticed by divers in an upright position who are using rebreathing equipment that has a counterlung, or breathing bag, positioned below the head and neck. The pressure gradient from the bag to the diver’s head results in a sensation of head and neck distension and bulging of the eyes.