NITRIC-OXIDE GAS INFUSION TO THE OXYGENATOR ENHANCES THE BIOCOMPATIBILITY OF HEPARIN-COATED EXTRACORPOREAL BYPASS CIRCUITS

Heparin coated bypass circuits have been reported to improve the bioco mpatibility of extracorporeal circulation, although it is still insuff icient and improvable. Nitric oxide (NO) is known to inhibit platelet activation and inflammatory reactions. In this study, the authors eval uated exogenous NO infusion in enhancing the effect of a heparin coate d bypass circuit on the biocompatibility of an extracorporeal circuit, especially in view of the attenuation of the inflammatory response. A miniature closed bypass circuit, including an oxygenator (BioActive s urface; Carmeda, Stockholm, Sweden) was primed with fresh human hepari nized blood and perfused with a centrifugal pump. Either pure N-2 gas (control group: n = 7) or NO gas (NO group [100 ppm in N-2]: n = 7) wa s infused to the oxygenator. NO metabolites (nitrite and nitrate), pla telet count, thrombin-antithrombin III complex (TAT), alpha(2)-plasmin -plasminogen inhibitor complex (PIC), beta-thromboglobulin (beta-TG), platelet factor 4 (PF4), serotonin, complement 3 activation products ( C3a), granulocyte elastase, and bradykinin were measured at 0, 30, 60, 120, and 180 min after starting perfusion. At every sampling point, p latelet counts were significantly higher, and TAT, beta-TG, and bradyk inin were lower in the NO group than in the control group. PF4, C3a, a nd granulocyte elastase were significantly lower in the NO group at 60 , 120, and 180 min. These results suggest that NO gas infusion to the oxygenator enhances the biocompatibility of heparin coated extracorpor eal circuits.