P014: MOLECULAR STRUCTURE AND PROPOSED MECHANISM OF HYDROXOCOBALAMIN IN VASOPLEGIC SYNDROME: A REVIEW OF INTRAOPERATIVE USE OF VITAMIN B12
Fritz-Gerald Charles, BS, Chris Giordano, MD, Bruce Spiess, MD; University of Florida College of Medicine- Dept. of Anesthesiology
Background: Vasoplegic syndrome which is a common condition seen following cardiopulmonary bypass, is a very dangerous condition characterized by severe hypotension that is resistant to catecholamines. Due to the high mortality rate associated with vasoplegia, there have been growing interests in finding a drug to manage it. Methylene blue which is the current standard therapy used to treat catecholamine-resistant vasoplegia has been falling out of favor as multiple recent studies have reported that the drug is associated with high morbidity, and possibly increased mortality rate when used at the high dose required to treat vasoplegia. Hydroxocobalamin which was approved by the U.S. FDA for treatment of cyanide poisoning has been shown to produce a consistent increase in blood pressure when used for this purpose. Roderique et al reported the first case of hydroxocobalamin use in vasoplegia in 2014. Since, there have been multiple reports of successful use of hydroxocobalamin to treat the hypotension and morbidities associated with vasoplegia. To our knowledge, the mechanism by which hydroxocobalamin exerts its action has not been decisively established. In this review, we highlight the proposed mechanism by which B12 is believed to produced it hemodynamic actions, as well as enlighten the molecular structure of B12, which is very similar to hemoglobin, to further clarify the chemical properties that allows this drug to be useful. We also underline the importance of the core cobalt atom at the center of hydroxocobalamin which allows it to scavenge unwanted gasotransmitters in the blood, such as nitric oxide, hydrogen sulfide, and carbon monoxide. We performed a literature search and identified all the cases of intraoperative B12 use to date in order to make preliminary assessments of the effectiveness and side effect profile of the drug.
Method: To make preliminary assessment of the effectiveness and to identify possible complications resulting from the use of hydroxocobalamin in vasoplegic syndrome, we performed a literature search of PubMed, Cochrane, and Web of Science to identify all cases of intraoperative use of B12 to date.
Result: Our search identified eleven (11) reported cases of intraoperative hydroxocobalamin use in vasoplegia. We have calculated based on doses of B12 use to date, that the drug has produced an average increase in mean arterial pressure (MAP) of 28mmHg. The range of increase in MAP was between 2 to 40mmHg. There has not been any reported adverse effect from the use of B12, except body fluid discoloration which may affects lab values and cause a false blood leak alarm in some cases of hemodialysis used in the immediate postoperative period
Conclusion: This review has made tentative preliminary assessments of the effectiveness and risk profile of B12 in vasoplegia based on cases reported to date. We proposed a novel hypothesis for the mechanism of action of B12 by emphasizing that the core cobalt atom in hydroxocobalamin plays a crucial role in the mechanism of action of the drug.