The role of intra-vascular bubbles and the vascular endothelium in decompression sickness

Although decompression procedures have been improved over the years, decompression still remains a significant problem in diving. While there is universal agreement that the basic problem of decompression is gas coming out of solution, forming bubbles when pressure is reduced, the exact mechanism of decompression injury is not known. Furthermore, the wide variety of clinical symptoms and the significant difference in individual susceptibility makes identification of the mechanisms involved difficult. Using ultrasound, vascular gas bubbles have been detected in most decompressions, and these bubbles can act on the endothelial lining of blood vessels resulting in impaired endothelial function. Normal endothelial function is a major indicator of cardiovascular health and thus a reduction in vascular bubble formation and hence the risk of endothelial injury is an important goal in decompression. Even if vascular gas bubbles may not be the only adverse effect of decompression, vascular gas bubbles and their adverse effects on the endothelium may be a useful model for decompression injury. This review claims that endothelial dysfunction may be a possible main mechanism for neurological decompression injuries and describes some of the effects of vascular gas bubbles on the endothelium. Furthermore, as the formation of vascular gas bubbles can be significantly influenced by physical exercise and the use of nitric oxide, a novel approach to reducing the risk of decompression injury is suggested.