Hydroxocobalamin Versus Methylene Blue for Treatment of Vasoplegic Shock Following Cardiopulmonary Bypass: A Systematic Review and Meta-analysis

Objectives: To summarize the evidence of the hemodynamic effects and vasopressor requirements of adult cardiac surgery patients with vasoplegic shock treated with hydroxocobalamin or methylene blue.

Design: Systematic review and meta-analysis.

Setting: Multi-institutional.

Participants: Adult cardiac surgery patients with vasoplegic shock.

Interventions: Administration of hydroxocobalamin or methylene blue.

Measurements and main results: A total of 263 patients in four retrospective observational studies were included in a pooled analysis. There was no significant difference in the primary outcome, vasopressor requirement at 1 hour (mean difference [MD]: 0.00 mcg/kg/min norepinephrine equivalent [NEE], 95% confidence interval [CI]: -0.09 to 0.08). Hydroxocobalamin was associated with a significant improvement in mean arterial pressure at 1 hour (MD: 5.30 mmHg, 95% CI: 2.98 to 7.62), total vasopressor dose at 1 hour (MD: -0.13 mcg/kg/min NEE, 95% CI: -0.25 to -0.01), total vasopressor at 6 hours (MD: -0.15 mcg/kg/min NEE, 95% CI: -0.21 to -0.08). No differences were observed in systemic vascular resistance or mortality between groups. Three studies were deemed at moderate risk of bias and one at serious risk.

Conclusions: Hydroxocobalamin has been shown to have a beneficial effect on hemodynamics and vasopressor requirements in vasoplegic cardiac surgery patients compared with methylene blue, although evidence is limited, and further well-powered randomized controlled trials are required.