November 29, 2025
Background: Vasoplegia during cardiac surgery is common and is associated with perioperative mortality. Hydroxocobalamin is a catecholamine-sparing approach for treating vasoplegia. However, there is currently limited evidence to inform its use.
Methods: We conducted a single-centre retrospective propensity-matched cohort study of patients who developed vasoplegia after cardiopulmonary bypass. The primary outcome was vasopressor requirement, expressed as norepinephrine equivalents (NEE), at 1, 4, 24, and 48 hours after treatment. The secondary outcome was a composite of in-hospital complications comprising stroke, sternal wound infection, mesenteric ischaemia, renal failure, and death.
Results: We identified 2727 (11%) patients with vasoplegia from 2018 to 2024. The final analysis cohort included 229 matched pairs. Hydroxocobalamin administration was associated with a significant reduction in median NEE infusion rates of -0.04 (95% confidence interval [CI]: -0.07 to -0.02; P = 0.008) mg kg⁻¹ min⁻¹ at 1 hour, -0.05 (95% CI: -0.07 to -0.02; P < 0.001) mg kg⁻¹ min⁻¹ at 4 hours, and -0.04 (95% CI: -0.06 to -0.02; P = 0.004) mg kg⁻¹ min⁻¹ at 24 hours, but not at 48 hours, -0.02 (95% CI: -0.05 to 0.0; P = 0.220) mg kg⁻¹ min⁻¹. Over the initial 24 hours, hydroxocobalamin reduced NEE by 14% compared with the reference group. The risk of in-hospital complications was similar in each group (odds ratio: 1.06; 95% CI: 0.74-1.54; P = 0.745).
Conclusions: Hydroxocobalamin administration was associated with reduced vasopressor requirement over 24 hours, but not thereafter. Robust trials are needed to determine whether this relationship is causal and whether a reduction in vasopressor use improves substantive clinical outcomes.
Keywords: cardiac surgery; cardiopulmonary bypass; hydroxocobalamin; vasoplegia; vasopressor.
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