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Abstract

The results from the studies performed by Evora and colleagues1Evora P.R Should methylene blue be the drug of choice to treat vasoplegias caused by cardiopulmonary bypass and anaphylactic shock?.J Thorac Cardiovasc Surg. 2000; 119: 632-634Abstract Full Text Full Text PDF PubMed Google Scholar, 2Evora P.R Ribeiro P.J Andrade J.C Methylene blue administration in SIRS after cardiac operation.Ann Thorac Surg. 1997; 63: 1212-1213Abstract Full Text PDF PubMed Scopus (36) Google Scholar encouraged us to use methylene blue (MB) as a rescue treatment in catecholamine refractory vasoplegia after cardiopulmonary bypass (CPB).3Leyh R.G Kofidis T Strüber M Fischer S Knobloch K Hagl C et al.Methylene blue the drug of choice for catecholamine-refractory vasoplegia following cardiopulmonary bypass?.J Thorac Cardiovasc Surg. 2003; 6: 1426-1431Abstract Full Text Full Text PDF Scopus (130) Google Scholar We used an intravenous MB dose of 2 mg/kg as an infusion with a positive effect in 92% of our patients. We selected this dose because the majority of MB side effects obviously do not occur when a dose of MB of 2 mg/kg or less is administered.4Cheng X Pang C.C Pressor and vasoconstrictor effects of methylene blue in endotoxaemic rats.Naunyn Schmiedebergs Arch Pharmacol. 1998; 357: 648-653Crossref PubMed Scopus (25) Google Scholar, 5Zhang H Rogiers P Preiser J.C Spapen H Manikis P Metz G et al.Effects of methylene blue on oxygen availability and regional blood flow during endotoxic shock.Crit Care Med. 1995; 23: 1711-1721Crossref PubMed Scopus (65) Google Scholar, 6Weingartner R Oliveira E Oliveira E.S Sant'Anna U.L Oliveira R.P Azambuja L.A et al.Blockade of the action of nitric oxide in human septic shock increases systemic vascular resistance and has detrimental effects on pulmonary function after a short infusion of methylene blue.Braz J Med Biol Res. 1999; 32: 1505-1513Crossref PubMed Scopus (33) Google Scholar We have no experience with continuous MB infusion for more than 48 hours. Continuous MB infusion could be an option for patients not responding to a single dose of MB. However, more scientific evidence is mandatory to define the role of MB in the treatment of catecholamine refractory vasoplegia after CPB (eg, multicenter, prospective, and randomized studies). Even more important is a better understanding of the mechanism triggering vasoplegia after CPB to avoid this potentially lethal complication, because a preoperative selection process to identify patients prone to vasoplegia after CPB could result in prophylactic treatment with guanylate cyclase inhibitors.