Effect of blood and microbubble oxygen and nitrogen content on perfluorocarbon-filled dextrose albumin microbubble size and efficacy: in vitro and in vivo studies.

We hypothesized, on the basis of in vitro observations, that a higher oxygen partial pressure within perfluorocarbon-containing microbubbles (PCMB) would enhance inward nitrogen diffusion after venous injection, leading to improved myocardial contrast. The in vitro studies measured PCMB size and concentration after injection into arterial blood that was obtained during inhalation of either room air or 100% oxygen. We then compared the myocardial contrast produced from PCMB sonicated in the presence of either a nitrogen-free environment (100% oxygen) or room air in three closed chest dogs. PCMB exposed to oxygenated blood in vitro were significantly smaller after insonation than PCMB exposed to arterial blood obtained during room air inhalation, confirming the important role of dissolved nitrogen in stabilizing PCMB size. In vivo studies demonstrated that intravenous PCMB sonicated with 100% oxygen produced significantly greater anterior and posterior myocardial contrast than PCMB sonicated in the presence of room air.