Effects of a single bolus of methylene blue on 24-hour hemodynamics in vasodilatory shock

Background Methylene blue (MB) can cause transient hypertension in healthy subjects, but studies examining its efficacy over time in persistent shock states are lacking. Methods Adults in shock who received methylene blue from 2017 to 2021 were analyzed retrospectively. Hourly hemodynamics from 12 hours (h) before and after treatment were collected, and the difference and hourly change of mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), and norepinephrine-equivalent dose (NED) were examined in mixed-effect models. Results This study included hemodynamic data points from 58 patients. In the linear mixed effects model, significant differences in MAP and NED existed 12-h after MB administration (EFE 4.0, p = 0.01 and EFE − 0.12 ug/kg/min, p = .04, respectively). However, the two-piecewise mixed model found that the hourly change in MAP, SBP, and DBP was not different from zero in either the pre-administration or post-administration segments. Conclusions MB administration has been observed to increase MAP and decrease vasopressor requirements in shock. Our results suggest that in refractory vasoplegia, MB may improve MAP and vasopressor requirement over 12 hours in the linear mixed model, but not the piecewise mixed model, suggesting that the positive hemodynamic changes of MB may not be uniform. Clinically, these findings reinforce that bolus-dose MB likely has an impactful, though transient, physiological effect when given in addition to standard pharmaceutical management of refractory shock. MB should be considered as an adjunct therapy in refractory shock.