(1527) A "Shot" in the Dark: Hydroxycobalamin for Refractory Vasoplegia Post Cardiopulmonary Bypass

Introduction: Refractory vasoplegia following cardiopulmonary bypass (CPB) is thought to be partly due to excess vasodilatory molecules, specifically nitric oxide and hydrogen sulfide. Vasopressin and methylene blue have been the mainstay of treatment. Adult case reports have demonstrated the use of hydroxocobalamin in patients with refractory vasoplegia despite standard therapies. To the authors' knowledge, this is the first case report of hydroxocobalamin for refractory vasoplegia in a pediatric cardiac surgical patient.

Description: A 62 day old term infant with severe pulmonary atresia with intact ventricular septum and RV dependent coronary sinusoids underwent heart transplantation on day of life (DOL) 43. Following transplant, he developed primary graft dysfunction requiring ECMO. Upon return of myocardial graft function, he was decannulated from ECMO on postoperative day (POD) 7. Post decannulation, he suffered from profound vasoplegia refractory to conventional therapies including methylene blue and vasopressin which required ECMO recannulation on POD 8. The patient remained on ECMO for 11 days with resolution of vasoplegia and was decannulated on POD 18. He again experienced profound vasoplegia refractory to vasopressin, methylene blue, and steroids. He required intermittent epinephrine boluses to maintain adequate blood pressure. The patient was given IV hydroxocobalamin (1 mg/kg). Within seven minutes of hydroxycobalamin administration, the patient’s mean arterial pressure increased from 49 mmHg to 112 mmHg which allowed for progressive reduction and discontinuation of inotropes.

Discussion: CPB and ECMO lead to cytokine release which activates inducible nitric oxide synthetase leading to an excess of nitric oxide. Hydroxocobalamin likely improves vasoplegia by inhibiting nitric oxide and hydrogen sulfide which is also an endogenous vasodilator. Hydroxocobalamin may be a useful therapy for refractory vasoplegia following cardiopulmonary bypass in pediatric patients.