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GASEOUS EXCHANGE AND THE EXPRESSION OF DECOMPRESSION SICKNESS

Conclusions

The formation of bubbles in tissue depends on several factors. From the outset, the volume of inert gas dissolved in tissue interacts with rates of decompression to dictate whether bubbles will form. With gradual decompression, safe off-gassing may reflect the simple and uneventful perfusion-limited transfer of inert gas from loaded tissues to the venous blood to the heart to the lungs to the environment. With more rapid decompression, however, the ambient pressure may no longer be sufficient to maintain the gas in solution, thus permitting the formation of bubbles. The simple formation of bubbles, however, is not necessarily sufficient for the expression of decompression sickness: It is clear, for example, that asymptomatic bubbling in the blood may be a normal nonpathological mechanism by which some inert gas exits the body during and after decompression. For this reason, the sites and rates of bubbling are key factors that dictate both whether decompression sickness will emerge and the form that the illness will assume. After all, decompression sickness is not a unitary phenomenon characterized by a limited and easily recognizable array of signs and symptoms. To the contrary, a bewildering variety of signs and symptoms may indicate the pathological expression of bubbles associated with decompression sickness.