Efficacy and safety of methylene blue in patients with vasodilatory shock: a systematic review and meta-analysis

Abstract

Background The role of methylene blue (MB) in patients with vasodilatory shock is unclear. The purpose of this systematic review and meta-analysis was to evaluate the efficacy and safety of MB in patients with vasodilatory shock. Methods We searched MEDLINE at PubMed, Embase, Web of Science, Cochrane, CNKI, CBM and Wanfang Medical databases for all observational and intervention studies comparing the effect of MB and control in vasodilatory shock patients. This study was performed in accordance with the PRISMA statement. There were no language restrictions for inclusion. Results A total of 16 studies with 864 patients were included. Pooled data showed that MB as an adjunct to vasopressors significantly reduced mortality (odds ratio (OR) 0.54, 95% confidence interval (CI) 0.34 to 0.85, P = 0.008; I2 = 7%). Subgroup analyses found a significant difference in mortality between groups, favoring continuous infusion MB in septic shock patients. Moreover, the vasopressor requirement was significantly reduced in the MB group (mean difference (MD) -0.77, 95%CI -1.26 to -0.28, P = 0.002; I2 = 80%). For hemodynamics, MB increased the mean arterial pressure, heart rate and peripheral vascular resistance. For oxygen metabolism, MB reduced the level of lactate but had no effect on oxygen supply and oxygen consumption. MB had no effect on the other outcomes. No serious side effects were found. Conclusions Adjunct administration of MB was associated with lower mortality in patients with vasodilatory shock. This may be due to the ability of MB to decrease vasopressor requirements and the level of lactate and its ability to increase mean arterial pressure, heart rate, and peripheral vascular resistance.