The aim of this investigation was to study the effect of environmental pressure and surface tension on the size of gas bubbles in tissues and on their inner pressure. Due to the action of surface tension, the pressure inside the bubbles is always greater than the surrounding pressure. This phenomenon is the more marked, the smaller are the bubbles. Therapeutic compression leads to diminution of the volume of gas bubbles and thus to a rise of that portion of their inner pressure which is due to surface tension. In small bubbles the surface tension may cause their dissolution and disappearance. It is therefore correct to implement therapeutic compression in decompression sickness as soon as possible before the fusion of a significant number of small bubbles into larger ones occurs.
The surface tension of blood assessed in a group of 71 healthy subjects (24 men and 47 women) by the drop method at a temperature of 22 °C was 55.89 . 10~3 N.m-1, S.D. = 3.57 . 10~3 N.m-1. It did not correlate with age or sex of the examined subjects nor with any of the following variables: red cell sedimentation rate, blood haemoglobin levels, number of erythrocytes, total serum cholesterol, total serum triacylglycerols, creatinine blood levels, ALT and AST activity. The surface tension of blood and other body fluids can play an important part not only in the genesis and development of decompression sickness but also in other processes in the organism.