THE ROLE OF PROPHYLACTIC METHYLENE BLUE IN MANAGEMENT OF POST CARDIOPULMONARY BYPASS VASOPLEGIA IN HIGH RISK PATIENTS

Abstract

Low systemic vascular resistance commonly occurs during and after cardiopulmonary bypass and is easy to accept as a bothersome side effectof bypass Treatment is usually required to maintain adequate perfusion pressure during CPB and to establish satisfactory haemodynamics. Ocassionaly patients may develop a more severe and persistent fall in systemic vascular resistance named Vasoplegic syndrome. This hypotension occurring during cardiopulmonary bypass is in part because of induction of the inflammatory response for which nitric oxide and guanylate cyclase play a central role. Metghylene blue is believed to act through competition with nitric oxide in binding to the iron heme moiety of soluble guanylate cyclase resulting in enzyme activation.This inhibits the increase in the levels of c GMP,and therby precludes the vasorelaxant effect of nitric oxide. Several studies have used the methylene blue drug with different doses ranging from (1.5-3mg)and at different times during the course of the CPB (pre,on bypass and post bypass) with favorable results in almost every and each studies it is worth saying that this drug has been used in treatment of vasoplegic syndromes associated with liver transplantation, sepsis and evevn as a compassionate therapy in children developing severe sepsis.