To compare changes in vasopressor requirements and hemodynamic responses after hydroxocobalamin or methylene blue administration for vasoplegic shock (VS).

Retrospective cohort analysis.

Single-center, academic medical center.

Cardiothoracic surgery adult patients.

Hydroxocobalamin or methylene blue.

The primary outcome was a change in vasopressor requirements over the first 24 hours (1, 3, 6, 12, and 24 hours) after hydroxocobalamin or methylene blue initiation. Secondary outcomes included changes in mean arterial pressure (MAP), systemic vascular resistance, and lactate.

A total of 120 adult patients who received hydroxocobalamin (n = 77) or methylene blue (n = 43) were included. Vasopressor requirements at baseline were 0.34 µg/kg/min (95% CI 0.28-0.4) norepinephrine equivalent (NEE) in the hydroxocobalamin group, and 0.59 µg/kg/min (95% CI 0.52-0.66) NEE in the methylene blue group; p < 0.001. Vasopressor requirements decreased significantly at each time point within each group (hour 1 mean [95% CI] NEE, hydroxocobalamin 0.27 µg/kg/min [0.21-0.33]; methylene blue 0.44 µg/kg/min [0.38-0.51]; p < 0.001). The mean MAP at baseline was 65 mmHg (95% CI 63-67) in the hydroxocobalamin group, and 57 mmHg (95% CI 54-59) in the methylene blue group; p < 0.001. The mean MAP increased significantly from baseline at each time point within each group (hour 1 mean [95% CI] hydroxocobalamin 73 mmHg [71-75]; methylene blue 67 mmHg [65-70]; p < 0.001). After adjusting for baseline characteristics, a significantly greater reduction in vasopressor requirements and an increase in MAP were noted in the hydroxocobalamin group compared with the methylene blue group.

Hydroxocobalamin was associated with a greater reduction in vasopressor requirements than methylene blue in treating VS associated with cardiopulmonary bypass.