Effects of Optison® on pulmonary gas exchange and hemodynamics

Optison® is a contrast-enhancing agent used in myocardial contrast echocardiography. It consists of small albumin spherules (approximately 4-μm diameter) containing a fluorocarbon gas, octafluoropropane. It is injected IV and, thus, may cause pulmonary manifestations of microembolism. To determine if any such effects do occur, we injected sequential doses of 1, then 3 and then 5 mL Optison® IV into 25 kg anesthetized dogs, and measured pulmonary hemodynamic and gas exchange variables frequently for 30 min after each dose. This was done in both 6 healthy and 6 pulmonary hypertensive animals, the latter produced by acute IV injection of 676-μm diameter polystyrene beads, raising pulmonary artery pressure from normal (15 mmHg) to 33 mmHg. Optison®-injected animals were compared with albumin-injected controls. Two animals developed severe hypotension in response to albumin and could not be used. Lung compliance and wet/dry weight ratio were unaffected by Optison® and no effects on gas exchange were seen at any dose or time in either group of dogs. In the healthy group, there was slight (1 mmHg per mL Optison®), transient and delayed pulmonary hypertension without change in cardiac output, suggesting a vasoconstrictor rather than mechanical basis for these small effects. No such changes occurred in the pulmonary hypertensive group. These results imply that usual human doses of Optison® (0.5 mL) will produce no significant hemodynamic or gas exchange effects in either healthy or pulmonary hypertensive dogs.