SCUBA diving is associated with generation of gas emboli due to gas release from the supersaturated tissues during decompression. Gas emboli arise mostly on the venous side of circulation and they are usually eliminated as they pass through the lung vessels. Arterialization of venous gas emboli (VGE) is seldom reported and it is potentially related to neurological damage and development of decompression sickness. The goal of the current study was to evaluate the generation of VGE in a group of divers using a mixture of compressed oxygen, helium and nitrogen (trimix) and to probe for their potential appearance in arterial circulation. Seven experienced male divers performed three dives in consecutive days according to trimix diving and decompression protocols generated by V-planner, a software program based on the Varying Permeability Model. The occurrence of VGE was monitored ultrasonographically for up to 90 minutes after surfacing and the images were graded on a scale from 0 to 5. The performed diving activities resulted in a substantial amount of VGE detected in the right cardiac chambers and their frequent passage to the arterial side: in 9 out of 21 total dives (42%) and in 5 out of 7 divers (71%). Concomitant measurement of mean pulmonary artery pressure revealed a nearly twofold augmentation, from 13.6±2.8, 19.2±9.2 and 14.7±3.3 mmHg assessed before the first, second and the third dive, respectively, to 26.1±5.4, 27.5±7.3 and 27.4±5.9 mmHg detected after surfacing. No acute decompression-related disorders were identified. The observed high gas bubble loads and repeated microemboli in systemic circulation raise questions about the possibility of long-term adverse effects and warrant further investigation.
- technical diving
- bubble detection
- left ventricular gas emboli
- Copyright © 2009, Journal of Applied Physiology