Accelerated arteriolar gas embolism reabsorption by an exogenous surfactant

Abstract

Background: Cerebrovascular gas embolism can cause profound neurologic dysfunction, and there are few treatments. The authors tested the hypothesis that an exogenous surfactant can be delivered into the bloodstream to alter the air-blood interfacial mechanics of an intravascular gas embolism and produce bubble conformations, which favor more rapid bubble absorption. Methods: Microbubbles of air were injected into the rat cremaster microcirculation after intravascular administration of either saline (control, n = 5) or Dow Corning Antifoam 151OUS (surfactant, n = 5). Embolism dimensions and dynamics were directly observed after entrapment using intravital microscopy. Results: To achieve embolization, the surfactant group required twice as many injections as did controls (3.2 ± 1.3 vs. 1.6 ± 0.9; P < 0.05). There was no difference in the initial lodging configuration between groups. After bubble entrapment, there was significantly more local vasoconstriction in the surfactant group (24.2% average decrease in diameter) than in controls (3.4%; P < 0.05). This was accompanied by a 92.7% bubble elongation in the surfactant group versus 8.2% in controls (P < 0.05). Embolism shape change was coupled with surfactant-enhanced breakup into multiple smaller bubbles, which reabsorbed nearly 30% more rapidly than did parent bubbles in the control group (P < 0.05). Conclusions: Intravascular exogenous surfactant did not affect initial bubble conformation but dramatically increased bubble breakup and rate of reabsorption. This was evidenced by both the large shape change after entrapment and enhancement of bubble breakup in the surfactant group. These dynamic surfactant-induced changes increase the total embolism surface area and markedly accelerate bubble reabsorption.