Methylene blue for postcardiopulmonary bypass vasoplegic syndrome: A cohort study

Background: Methylene blue (MB) has been used to treat refractory hypotension in a variety of settings. Aims: We sought to determine whether MB improved blood pressure in postcardiopulmonary bypass (CPB) vasoplegic syndrome (VS) in a complex cardiac surgery population. Furthermore, to determine variables that predicted response to MB. Setting and Design: This was conducted in a tertiary care medical center; this study was a retrospective cohort study. Materials and Methods: Adult cardiac surgery patients who received MB for post-CPB VS over a 2-year period were studied. Mean arterial blood pressure (MAP) and vasopressor doses were compared before and after MB, and logistic regression was used to model which variables predicted response. Results: Eighty-eight patients received MB for post-CPB VS during the study period. MB administration was associated with an 8 mmHg increase in MAP (P = 0.004), and peak response occurred at 2 h. Variables that were associated with a positive drug response were deep hypothermic circulatory arrest during surgery and higher MAP at the time of drug administration (P = 0.006 and 0.02). A positive response had no correlation with in-hospital mortality (P = 0.09). Conclusions: MB modestly increases MAP in cardiac surgery patients with VS. Higher MAP at the time of drug administration and surgery with deep hypothermic circulatory arrest predict a greater drug response.