Nitric oxide in the oxygenator sweep gas reduces platelet activation during experimental perfusion

Hemorrhage is a major complication experienced in 10% to 35% of neonates treated with extra-corporeal life support (ECLS). The increased bleeding tendency is partly due to an ECLS-induced thrombocytopenia and impaired platelet function. In the present study, we evaluated the effect of nitric oxide on the ECLS-induced platelet consumption and activation. Two identical in vitro ECLS circuits were primed with fresh, heparin-treated human blood and circulated for 24 hours. Nitric oxide (15, 40, or 75 ppm) was added to one of the oxygenators in each pair. Eight paired experiments were performed. Platelet count, plasma β-thromboglobulin, platelet serotonin content, plasma nitrate, plasma cyclic guanosine monophosphate, and platelet membrane glycoprotein Ib were assayed before the start and at 0.5, 1, 3, 12, and 24 hours of perfusion. Plasma nitrate and plasma cyclic guanosine monophosphate levels were significantly higher in the nitric oxide circuits than in the control circuits ( p < 0.01). Higher platelet counts ( p < 0.01) and lower β-thromboglobulin levels ( p < 0.01) were observed in the nitric oxide circuits compared with the control circuits. However, no significant differences in platelet serotonin content or platelet membrane glycoprotein Ib density were noted between the circuits. Nitric oxide probably reduces platelet consumption and platelet activation during ECLS.