HEPARIN NEUTRALIZATION WITH METHYLENE-BLUE, HEXADIMETHRINE, OR VANCOMYCIN AFTER CARDIOPULMONARY BYPASS

There are no clinically available alternatives for reversing heparin i n protamine-allergic patients. This study examined the ability of meth ylene blue, hexadimethrine, and vancomycin to reverse circulating hepa rin so that these compounds can be carefully examined in future placeb o-controlled studies in humans. Heparin activity in blood obtained fro m extracorporeal circuits was reversed by adding protamine (13.5, 27.0 , 81.1, 135.1, and 270.3 mu g/mL), methylene blue (13.5, 27.0, 135.1, 202.7, 270.3, 337.8, 405.4, 473.0, 540.5, and 810.8 mu g/mL), hexadime thrine (6.8, 13.5, 20.3, 27.0, 81.1, and 135.1 mu g/mL), or vancomycin (13.5, 27.0, 135.1, 270.3, 540.5, and 810.8 mu g/mL), and activated c lotting times (ACTs) were measured with kaolin (n = 18). Heparinase-AC T was obtained to determine complete reversal. Heparin concentrations were 3.3 +/- 0.3 U/mL with ACT values of 485 +/- 97 s. The ACT at a pr otamine concentration of 81.1 mu g/mL and at hexadimethrine concentrat ions of 81.1 and 135.1 mu g/mL was not statistically different from he parinase-ACT; however, methylene blue or vancomycin did not reverse th e anticoagulation at any concentrations. Hexadimethrine can reverse he parin-induced anticoagulation after cardiopulmonary bypass as well as protamine, although methylene blue or vancomycin did not neutralize he parin in vitro.