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-microm 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-microm 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.