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Biomedical subjects

D E Yount

Publications and source records attributed to D E Yount.

4 recordsLinked to original sources
PubMed1979

Application of a bubble formation model to decompression sickness in rats and humans.

Although decompression sickness results from bubble formation in blood or tissue, pressure schedules currently in use are essentially empirical and contain little input from cavitation theory. The recent convergence of three lines of investigation suggests that a synthesis of practice and theory may now be possible. The data consist of pressure reduction limits for gelatin, rats, and humans following steady-state exposures. From the gelatin studies, a model has been developed in which bubble formation is initiated by spherical gas nuclei stabilized by surface-active skins of varying gas permeability. We demonstrate that the model is also in good agreement with data on rats and humans over a wide range of pressures and that the model parameters assume sensible values in each case. This suggests that cavitation theory can provide a rationale for current diving practice and can serve to secure, consolidate, and extend this practice.

Animals↗
PubMed1977

Bubble formation within decompressed hen's eggs.

Decompression sickness follows a reduction in ambient pressure and is a result of bubble formation in blood or tissues. The origin of such bubbles is the subject of considerable controversy, and a number of mechanisms have been proposed to account for them. In testing these mechanisms, freshly-laid hen's eggs provide a particularly intriguing model--namely, an intact biological system in which bubbles form readily and many of the proposed processes are excluded.

Animals↗
PubMed1977

Stabilization of gas cavitation nuclei by surface-active compounds.

Gas bubbles are the primary agent in producing the pathogenic effects of decompression sickness. Numerous experiments indicate that bubbles originate in water, and probably also in man, as pre-existing gas nuclei. This is surprising considering that gas phases larger than 1 micron should rise to the surface of a standing liquid, whereas smaller ones should dissolve rapidly due to surface tension. Several stabilizing mechanisms have been suggested, and each has been refuted on experimental grounds. In this article, we propose a new model that arises out of a systematic study of the earlier theories. We review these theories and conclude that gas cavitation nuclei must be held intact by surface-active skins that are initially permeable. The first quantitative analysis of bubble formation data from supersaturated gelatin is summarized and leads to the further conclusion that skins can become impermeable if the ambient pressure is increased rapidly by a sufficient amount. Our model owes much to Sirotyuk, who "demonstrated experimentally that stabilization of gas bubbles acting as cavitation nuclei in water is always attributable to the presence of surface-active substances in the water".

Chemical Phenomena↗