title: Methylene blue as a vasopressor: a meta-analysis of randomised trials.
abstract: OBJECTIVE
  To evaluate the efficacy of methylene blue in raising mean arterial pressure in hypotensive patients.
  
  
  METHODS
  A meta-analysis of randomised controlled trials.
  
  
  METHODS
  We searched BioMedCentral, PubMed, Embase and the Cochrane Central Register of clinical trials.
  
  
  METHODS
  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.
  
  
  RESULTS
  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 blue treated 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.
authors: Department of Anesthesia and Intensive Care, San Raffaele Scientific Institute, Milan, Italy. pasin.laura@hsr.it
authors: Laura
authors: L
authors: Pasin
authors: Michele
authors: M
authors: Umbrello
authors: Teresa
authors: T
authors: Greco
authors: Massimo
authors: M
authors: Zambon
authors: Federico
authors: F
authors: Pappalardo
authors: Martina
authors: M
authors: Crivellari
authors: Giovanni
authors: G
authors: Borghi
authors: Andrea
authors: A
authors: Morelli
authors: Alberto
authors: A
authors: Zangrillo
authors: Giovanni
authors: G
authors: Landoni
mesh_terms: D006801:Humans; D007022:Hypotension / Q000188:drug therapy*; D008751:Methylene Blue / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D014662:Vasoconstrictor Agents / Q000627:therapeutic use*
chemical_list: D014662:Vasoconstrictor Agents; D008751:Methylene Blue