Homogeneous nucleation of gas bubbles in vivo.

Several current theories of decompression sickness (DCS) presume the preexistence of gas bubble nuclei in tissue, because the de novo nucleation of gas bubbles in the body is thought to be theoretically impossible. Reexamination of nucleation theory reveals the overwhelming importance of two parameters: gas supersaturation and tissue surface tension (gamma). For the high gamma of pure water nucleation theoretically requires more than 1,000 ATA supersaturation. Lower values of gamma allow nucleation to occur with vastly smaller supersaturations. Application of homogeneous nucleation theory can provide reasonable fits to both rat and human pressure-reduction data with values of gamma within the range reported for biological fluids (below 5 dyn/cm). The initial bubble sizes predicted are 0.1 micron or less. The presence of heterogeneous sites, for example crevices and lipid surfaces, makes nucleation even more likely.