The effects of heparin bound surface modification (Carmeda Bioactive Surface) on human platelet alterations during simulated extracorporeal circulation.

To determine if treatment with covalently bound heparin (Carmeda Bioactive Surface (CBAS)) to the synthetic surface of the extracorporeal circuit (ECC) would alter the stereotypic pattern of adverse platelet alterations, 450 ml of heparinized blood (lU/ml) was recirculated at a flow rate of twice the circulating volume (L/min) for 2 hrs at 37 degrees C through either untreated (CONT,n=7) or treated (CBAS,n=7) circuits constructed of identical components including a pediatric (0.8m 2) reversed hollow fiber membrane oxygenator. In CONT circuits, platelet count maintained 88+1% (x+/-SEM) of its initial level in the circuit prime sample, dropped to 36+/-6% after 5 min, and returned to 56+/-2% following 2 hrs of ECC. In CBAS circuits, platelet count in the circuit prime sample demonstrated 90+/-4%, decreased to 68+/-10% after 5 min (p less than 0.05) and declined further to 45+/-5% after 2 hrs (NS). Although platelets from both groups retained reactivity to ADP after priming the circuit, only at 5 min of recirculation did CBAS circuits significantly preserve this responsiveness. In CONT circuits, baseline plasma levels of platelet factor 4 rose from 24+/-3 to 581+/-82 ng/ml in the primed circuit and continued to rise to 2933+/-276 ng/ml by 2 hrs of ECC. In contrast, CBAS circuits markedly reduced this release after 2 hrs (577+/-165 ng/ml). Furthermore by 2 hrs of ECC, plasma levels of thromboxane B 2 in the CBAS circuits were significantly reduced when compared to CONT circuits (3035+/-1529 vs 29916+/-16293 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)