The effect of prostacyclin infusion on platelet hemostatic function in patients undergoing cardiopulmonary bypass

Prostacyclin (PGI₂) infusion was studied in patients during cardiopulmonary bypass for coronary artery bypass grafting to assess its capacity to protect platelet hemostatic function. Twelve patients received PGI₂ at doses ranging from 20 to 70 ng/kg/min by continuous infusion directly into the bubble oxygenator. Nine control patients were also studied. Platelet counts were not different in the two groups; the platelet count at the completion of the operation was decreased by a mean of 29% in treated patients and 40% in control patients (p > 0.15). Bleeding times were uniformly greater than 30 minutes following 30 minutes on bypass in both groups (p > 0.5). Also there was no difference in the bleeding times between the treated and untreated groups in the immediate postbypass period (p > 0.05). In addition, no difference in transfusion requirements was observed between the treated and control groups. However, plasma levels of platelet factor 4 were lower in the treated patients (p < 0.05), and, more significantly, blood pressure was lower at all time points in the treated patients (p < 0.001) despite the greater use of vasopressors. We conclude that PGI₂ infusion in this study was of no hemostatic benefit but produced significant hypotension, a potential source of morbidity.