Vogel, S R

Prostacyclin (PGI2) and Ibuprofen (IP) may preserve platelet integrity and function during cardiopulmonary bypass (CPB). Platelet consumption on bubble and membrane oxygenator, platelet lysis, and platelet microembolism were studied in 7 control, 6 PGI2-, and 5 IP-treated dogs undergoing CPB. At 18 hours after I.V. administration of autologous In-Ill-labeled platelets (300 μCi), 7 heparinized dogs (300 u/kg), and 6 dogs treated with I.V. infusion of PGI2 (25 ng/kg/min) and heparin (100 u/kg), and 5 dogs with I.V. IP (12.5 mg/kg) 15 min prior to bypass procedure underwent CPB for 1 hour. In-111 in plasma obtained from platelet lysis was determined by centrifugation at 200,000 G of serial blood samples at 5-min intervals during CPB. Hemodilution was measured with I-125-labeled serum albumin (10 μCi). Platelet deposition on oxygenator was imaged with a gamma camera and quantitated with an ionization chamber. An insignificant amount of platelet (<0.2%) was found in the heat exchanger. In-111-labeled platelet level in blood of control dogs 20 min after CPB initiation decreased to 23 ± 5% of prebypass level, 38 ± 5% in PGI2 group, and 25 ± 5% in the IP group. Plasma In-111 increased to 34±7% in control, 15±5% in PGI2 group, and 17±3% in IP group (p< 0.01). Platelet deposition on the oxygenator amounted to 20±5% of In-111 platelets in control, 11±3% of PGI2, and 13±4% in IP group (p< 0.01). These results indicate that both PGI2 and IP significantly reduce platelet consumption in oxygenator and platelet lysis during CPB. Thus PGI2 may reduce postoperative bleeding. Ibuprofen, although preserving platelet function, has a longer duration of action and, hence, systemic administration prior to CPB is not practical. Surface coating of extracorporeal surfaces with IP might be beneficial.