Use of Intravenous Hydroxocobalamin without Methylene Blue for Refractory Vasoplegic Syndrome After Cardiopulmonary Bypass.

BACKGROUND Cardiac vasoplegic syndrome is a form of vasodilatory shock characterized by profound vasodilation and low systemic vascular resistance, which results in significant hypotension despite high cardiac output and appropriate fluid resuscitation. In up to 45% of patients, cardiopulmonary bypass (CPB) can precipitate vasoplegic syndrome. Vasoplegic syndrome after CPB that is refractory to other vasopressors, such as catecholamine and vasopressin, has been successfully treated with inhibitors of the nitric oxide (NO) system, such as methylene blue and hydroxocobalamin. Methylene blue has been the treatment of choice because of its effectiveness for both prevention and rescue therapy. Hydroxocobalamin has demonstrated efficacy in combination with methylene blue, and also on its own when vasoplegic syndrome is refractory to methylene blue. CASE REPORT We present 2 cases that expand upon the existing evidence supporting the efficacy of hydroxocobalamin as a first-line option for inhibiting the NO system in vasoplegic syndrome that is refractory to other vasopressors. Specifically, we demonstrate the appropriate and successful use of hydroxocobalamin alone to treat refractory vasoplegic syndrome after CPB. CONCLUSIONS Refractory vasoplegic syndrome that occurs after CPB has been successfully treated with inhibitors of the NO system, such as methylene blue and hydroxocobalamin. The present cases expand upon the scant existing evidence of the efficacy of hydroxocobalamin as an appropriate option for refractory vasoplegic syndrome.