Small amounts of venous gas embolism cause delayed impairment of endothelial function and increase polymorphonuclear neutrophil infiltration

Abstract

Gas bubbles from decompression and gas embolization lead to endothelial dysfunction and mechanical injury in the pig, rabbit and lamb. In the study presented here, 0.01 ml air/min/kg was infused through a catheter into the jugular vein in 12 rabbits for 60 min. The endothelial response was measured using tension measurements in the blood vessel wall, and morphological changes where quantified using light microscopy and image processing. Percent lung water content was calculated and used to estimate the severity of pulmonary oedema. The infusion led to a significant decrease in the acetylcholine-mediated endothelial-dependent vasodilatation in the pulmonary artery 6 h after the infusion (6-h group, n = 6). A decrease in substance-P-mediated endothelial-dependent vasodilatation was also detected. No changes where seen in a group of rabbits examined 1 h after infusion (l-h group, n=6). The impaired endothelial-dependent vasodilatation caused by the bubbles is probably biochemical in origin, since no visible changes were seen in the endothelial layer. A significant increase in polymorphonuclear neutrophils was observed in the 6-h group compared to the l-h group. This study demonstrates that small numbers of bubbles, corresponding to "silent bubbles", lead to an impairment of the endothelial-dependent vasoactive response.

Effect of in-water recompression with oxygen to 6 msw versus normobaric oxygen breathing on bubble formation in divers

“…The body regards bubbles as foreign surfaces and responds to them some time after the gas bubbles have been formed. Rapid removal of the bubbles could prevent some of these secondary eVects (Nossum et al 1999(Nossum et al , 2002. Despite a recompression treatment, Mollerlokken et al (2007) found no signiWcant diVerence in survival time between the experimental and control groups with, however, a trend towards better survival in experimental group.…”

“…It was hypothesized that due to this latency before the start of treatment, the endothelial function has already been impaired to a point where recompression to 160 kPa with oxygen for 60 min has little eVect. Indeed, previous Wndings showed a relationship between gas bubbles and mechanical endothelial damage related to biochemical or immunological responses developed with time (Nossum et al 1999(Nossum et al , 2002.…”

Microparticle enlargement and altered surface proteins after air decompression are associated with inflammatory vascular injuries

“…DCS has been associated with endothelial dysfunction, platelet activation, occasional alterations in coagulation pathways, and rare reduction of circulating platelet counts (2, 18 -20). Neutrophil activation and perivascular adherence are associated with functional deficits postdecompression in animal models (14,17). DCS is a risk associated with deep-sea SCUBA diving, high-altitude aviation, and space exploration.…”

Anti-C5a monoclonal antibodies and pulmonary polymorphonuclear leukocyte infiltration – endothelial dysfunction by venous gas embolism

“…Small amounts of venous gas emboli (VGE) lead to impaired endothelial function and increases polymorphonuclear leukocyte (PMN) infiltration in the lung (Nossum et al 2002). Intravascular gas bubbles develop in the venous system during decompression (Brubakk et al 1986;Eckenhoff et al 1990), following laparoscopy, by accidental injection and during cardiopulmonary bypass (Johnston et al 1993;Hoka et al 1997;Webb et al 1997) and may lead to endothelial damage (Warren et al 1973;Philp 1974;Nossum et al 1999).…”

“…gas bubbles, we evaluated whether i.v. injection of a monoclonal antibody (MAb) against C5a affects endothelial dysfunction and pulmonary PMN infiltration caused by low-grade VGE (Nossum et al 2002).…”