ABSTRACT
I. INTRODUCTION Decompression sickness (DCS), arterial gas embolism (AGE), and barotrauma are syndromes precipitated by a rapid change in pressure to which the body is exposed. It has been proposed that the term decompression illness (DCI) should be used to encompass all manifestations of decompression barotraumas and/or DCS (Table 1) [1-3]. The most frequent cause for this pathology, which is caused by a change in pressure (dysbarism), is an insufficient decompression time after exposure to elevated pressures, such as after diving underwater or a similar sudden reduction of environmental pressure at high altitude in aviators who fly in compressed cabins. Astronauts can also be exposed to very low pressure in their habitat aboard a space capsule, both in preparation for and by accident during extravehicular activities. In all cases, the pathology of dysbarism is similar and is caused by the elevated partial pressure of inert gas in tissues, usually nitrogen, coming out of solution and forming bubbles in tissues or even in the bloodstream. For such a bubble formation to happen in oversaturated tissue the pressure must rapidly be reduced by 50%, therefore a strict distinction between DCS and AGE might be blurred during the clinical exposure. It has been hypothesized that both diseases are often present simultaneously, but with different manifestations. Barotrauma occurs when there is sufficient pressure differential across a tissue-air interface within the body to cause injury. Gas-containing spaces in the body shrink with compression and expand during decompression according to Boyle’s law, and the largest volume variations occur near the surface, as shown in Figure 1.
