Embolism bubble adhesion force in excised perfused microvessels.

BACKGROUND The mechanics of gas embolism bubble adhesion to the vessel wall is poorly understood. New strategies to treat gas embolism may result from an understanding of adhesion forces, including the molecular determinants of bubble adhesion. The authors conducted experiments to measure the adhesion force of bubbles contacting the vessel wall. METHODS Microbubbles were injected into excised arterioles. Bubbles resided for 5, 10, 20, or 30 min with the endothelium intact or damaged and with a physiologic salt solution, physiologic salt solution with 5% bovine serum albumin, or rat serum as the perfusate. Inflow pressure was raised until the bubble dislodged. The differential pressure across the microbubble, deltaP, was recorded at the moment of bubble movement. Bubble diameter, D, and length, L, were determined by videomicroscopy. The adhesion force per unit surface area of a bubble contacting the vessel wall, K = deltaPD/4 L, was calculated for each experiment. RESULTS K at 10 min contact time (physiologic salt solution, 141 +/- 29; serum, 153 +/- 57 dyne/cm2) was higher than at 5 min (physiologic salt solution, 56 +/- 22; serum, 71 +/- 29 dyne/cm2), 20 min (physiologic salt solution, 46 +/- 29) and 30 min (physiologic salt solution, 14 +/- 5) (P < 0.05). Endothelium removal reduced K at 10 min (physiologic salt solution, 68 +/- 46; serum, 60 +/- 14 dyne/cm2) (P < 0.05). K was higher with 5% bovine serum albumin present at 10 min (349 +/- 149, P < 0.05), correlating with in vivo estimates. CONCLUSIONS The adhesion force developed between a microbubble and the vessel wall depends on multiple factors, including bubble residence time, presence of the endothelium, and perfusion solution.