(166) Comparison of Dosing Strategies of Hydroxocobalamin for Vasoplegic Syndrome After Cardiac Surgery

Introduction: Vasoplegic syndrome following cardiac surgery with or without cardiopulmonary bypass (CPB) is associated with significant morbidity and mortality. Hydroxocobalamin (B12) is utilized off label for refractory vasoplegic syndrome post CPB. Literature describes B12 dosing strategies in this setting either via bolus dosing or as an extended infusion (EI). This study's purpose was to evaluate each B12 dosing strategy on catecholamine requirements in patients with vasoplegic syndrome following cardiac surgery.

Methods: A retrospective, single-center study was conducted in adults admitted to the intensive care unit (ICU) following cardiac surgery who received B12 for vasoplegic syndrome from February 2020 to October 2022. Patients were excluded if they received methylene blue prior to B12, were requiring extracorporeal membrane oxygenation (ECMO) or received B12 in the operating room. The primary outcome was change in norepinephrine equivalents (NEE) over 12 hr following B12 initiation. Secondary outcomes included mean arterial pressure changes following B12 initiation, ICU and hospital length of stay (LOS), hospital survival, and administration of additional scavenging therapy, and ECMO cannulation after B12 administration.

Results: Fifty-five patients received B12 for vasoplegic syndrome of which 13 were included in the study. Of the patients included, 8 patients received B12 as a bolus over 15 min and 5 received an EI given over 6 hrs. The aggregate population was 85% male with a mean age of 59 and weight of 108.5 kg. At baseline, the bolus group had higher NEE requirements compared to the EI cohort (0.28 v 0.16 mcg/kg/min) and mean duration of CPB was longer in the bolus group (217±87 v 179±26 min, p=0.002). The mean NEE change at 12 hours was similar between the bolus and EI groups (0.024 v 0.018 mcg/kg/min, p=0.63). The bolus group received a non-significant increase in additional scavenger therapy compared to EI (62.5% v 20%, p=0.26) but no difference in mean ICU LOS (40 v 24 days), mean hospital LOS (48 v 35 days), or hospital survival (38% v 40%) was observed.

Conclusions: This study found no difference in NEE changes at 12 hrs between bolus and EI B12 dosing strategies in vasoplegic patients following cardiac surgery. Further studies are needed to explore the optimal B12 dosing strategy.