![]() ![]() Our primary measures of the effects of hydroxocobalamin were MAP and infusion rates of other vasoactive agents. Administration of hydroxocobalamin took place within the first 24 hours post-operatively in all patients. All patients were administered the same dose of 5 g IV hydroxocobalamin, diluted in 200 mL of 0.9% sodium chloride solution, infused over 15 minutes. The available form of hydroxocobalamin was Cyanokit (Meridian Medical Technologies, Columbia, MD, USA), containing 5 g of powdered hydroxocobalamin for IV administration. In all cases, its use was a consensus decision between the treating cardiac surgeon and intensivist for patients requiring high or increasing doses of two or more vasoactive drugs to maintain adequate MAP (aiming over 65 mmHg). No specific institutional policy exists for selecting patients to receive hydroxocobalamin for treatment of vasoplegia. ![]() A total of seven patients were identified, all of whom received it following cardiac surgery. Therefore, we aimed to assess the use of high-dose hydroxocobalamin within our unit as rescue therapy for post-cardiotomy refractory vasoplegic shock and to compare this experience with the existing international data.įollowing review and approval by our Institutional Human Research Ethics Committee, pharmacy dispensing records were used to identify patients who had been administered high-dose hydroxocobalamin in our hospital's ICU following cardiac surgery from Januto October 1, 2021. ![]() Targeted therapies such as methylene blue and hydroxocobalamin are thought to interrupt the cascade of events leading to vasoplegia through their activity on nitric oxide (NO) pathways, which play a key role in the systemic vasodilation seen in vasoplegic and septic shock. However, combination therapy using multiple agents with differing mechanisms of action (for example, adrenaline and vasopressin) was shown to be beneficial when a single agent failed to maintain the target blood pressure. A 2007 systematic literature review did not demonstrate a clear benefit in the use of any single agent. ![]() Other vasoactive drugs used include arginine vasopressin (vasopressin receptor agonist), phenylephrine (alpha-1 receptor agonist), and angiotensin II (angiotensin II receptor type 1 agonist, causing vasoconstriction and upregulating endogenous vasopressin secretion). Ĭatecholamine vasopressors are the most common first-line agents used to manage vasoplegia. No single strict definition exists, but many studies use parameters of low mean arterial pressure (MAP) 2.2L/kg/m2. Predisposing factors include preoperative antihypertensive use (specifically angiotensin-converting enzyme inhibitors and beta-blockers), low preoperative left ventricular ejection fraction, recent myocardial infarction, and diabetes mellitus. While in most patients, it resolves without sequelae, the outcome in refractory vasoplegic states is poor, with an estimated mortality of 25% in patients not responsive to first-line vasopressors. It affects 5-25% of patients during or following cardiopulmonary bypass (CPB), with an incidence as high as 50% in patients with predisposing risk factors. Vasoplegia is not uncommon following cardiac surgery. Our observations show that high-dose hydroxocobalamin is a safe and effective rescue therapy in refractory vasoplegic shock post cardiopulmonary bypass (CPB). No deaths or adverse effects attributable to hydroxocobalamin administration occurred in our cohort. Administration of hydroxocobalamin in seven patients was associated with an improvement in mean arterial blood pressure or reduction in vasopressor requirements, which were both immediate and sustained throughout our observational period. This study describes our experience in treating refractory vasodilatory shock following cardiac surgery with high-dose hydroxocobalamin. This is an uncommon but potentially life-threatening complication following cardiac surgery and carries a poor prognosis, particularly when patients fail to respond to first-line therapy with catecholamine vasopressors. Administration of high-dose hydroxocobalamin, or vitamin B12, is an emerging, targeted rescue therapy for the treatment of refractory vasoplegic shock. ![]()
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