Background: Hydroxocobalamin increases systemic blood pressure through nitric oxide pathway suppression. However, its effects on hypotension during extracorporeal membrane oxygenation (ECMO) are unknown. The objective of this study was to assess the hemodynamic effects of hydroxocobalamin during ECMO support.

Methods: This was a 5-year retrospective study of adults (> 18 years) on ECMO who received hydroxocobalamin 5-gram i.v. bolus over 15 minutes. Hemodynamic response was defined as mean arterial pressure (MAP) increase of at least 10% at 1-hour following hydroxocobalamin. Continuous data were presented as medians with interquartile range. The intraindividual changes in hemodynamic parameters from baseline (paired differences) were assessed with the Wilcoxon signed rank test.

Results: Forty-nine patients on ECMO received hydroxocobalamin. Most (86%) were venoarterial configuration for postcardiotomy (n = 27) or cardiogenic (n = 14) shock. The baseline MAP was 66 (60, 75) mmHg with a vasopressor dose in norepinephrine equivalence of 0.28 (0.26, 0.38) mcg/kg/min. Twenty-five patients (51%) met criteria for hemodynamic response. These responders had a greater reduction in vasopressor dose at 1-hour (-25% vs. 0%, p = 0.008) and 2-hours (-29% vs. -2%, p = 0.007) post-hydroxocobalamin. Hydroxocobalamin was administered sooner after ECMO initiation in responders (14 hours) than non-responders (37 hours), but this was not significant (p = 0.92). The overall hospital mortality rate of 69% was similar between the groups.

Conclusion: Hydroxocobalamin produces a favorable MAP raising effect in approximately half of recipients during ECMO, which confers greater vasopressor sparing than in non-responders. Its effects on clinical outcomes are unclear.