(1448) Methylene Blue or Hydroxocobalamin and Risk for Cardiac Surgery-Associated Acute Kidney Injury

Introduction: Patients undergoing cardiothoracic surgery are at high risk for experiencing acute kidney injury (AKI) as well as vasoplegic syndrome. Methylene blue or hydroxocobalamin are utilized off-label for vasoplegic syndrome in adult cardiothoracic surgery, however their impact on renal outcomes is unknown. The purpose of this study is to determine the association of these medications on AKI in this population.

Methods: A retrospective, single-center cohort study was performed in adult cardiothoracic surgical patients undergoing cardiopulmonary bypass (CPB) who received methylene blue or hydroxocobalamin for vasoplegic syndrome during the index operation or in the ICU up to 24 hours after CPB separation between July 2013 and May 2020. Patients were excluded if dialysis dependent at the time of study medication administration or received both study medications. Incidence of AKI was measured by the KDIGO AKI stage and new dialysis requirement post study dose.

Results: Of the 390 patients screened, 127 were analyzed, of which 107 received methylene blue and 20 received hydroxocobalamin. The baseline norepinephrine equivalent requirement was similar between groups (0.32 mcg/kg/min [IQR 0.23-0.49] methylene blue vs 0.34 mcg/kg/min [IQR 0.25-0.42] hydroxocobalamin, p = 0.976). The baseline mean arterial pressure was lower in those who received methylene blue (59 mmHg [IQR 52-70] vs 74 mmHg [IQR 65-82], p = 0.0006). Patients receiving hydroxocobalamin were more likely to have AKI (75% vs 58.9%, p= 0.047), stage 3 AKI (70% vs 37.4%, p = 0.012), a new dialysis requirement (70% vs 29%, p < 0.001), a longer ICU length of stay (median 18.8 days [IQR 10-35] vs 7.2 days [IQR 3-20.7], p = 0.005), and a longer hospital length of stay (median 51.2 days [IQR 28-83] vs 22.8 days [IQR 11.8-40], p < 0.001).

Conclusions: In adult cardiothoracic surgical patients with perioperative vasoplegic syndrome, hydroxocobalamin administration was associated with increased AKI and dialysis requirement as compared to methylene blue.