Methylene blue as a vasopressor: A meta-analysis of randomised trials

Objective: To evaluate the efficacy of methylene blue in raising mean arterial pressure in hypotensive patients. Design: A meta-analysis of randomised controlled trials. Data sources: We searched BioMedCentral, PubMed, Embase and the Cochrane Central Register of clinical trials. Data extraction: Inclusion criteria were random allocation to treatment and comparison of methylene blue versus any comparator. Exclusion criteria were duplicate publications, non-adult studies and no data on main outcomes. The primary end point was mean arterial blood pressure value 1 hour after the study drug administration; the secondary end points were mortality at the longest follow-up available, and cardiac index. Data synthesis: Data from 174 patients in five randomised controlled studies were analysed. Mean arterial pressure rose in patients receiving methylene blue (weighted mean difference = 6.93 mmHg; 95% CI, 1.67 to 12.18; P for effect = 0.01; P for heterogeneity = 0.17; I² = 41%). Only two studies reported the values of cardiac index with a non-statistically significant improvement in the methylene blue group (mean difference = 0.76 L/min/m²; 95% CI, -0.32 to 1.84; P for effect = 0.2). The overall mortality rate was 16% (14/88) among methylene bluetreated patients and 23% (20/86) in the control group (odds ratio = 0.65; 95% CI, 0.21 to 2.08; P for effect = 0.5). Conclusions: Methylene blue increases arterial blood pressure and systemic vascular resistances in vasoplegic patients without a detrimental effect on survival.