Patient Safety and Methylene Blue-Associated Severe Serotonin Toxicity

Methylene Blue for Refractory Shock in Children: A Systematic Review and Survey Practice Analysis

OBJECTIVES

Shock refractory to fluid and catecholamine therapy has significant morbidity and mortality in children. The use of methylene blue to treat refractory shock in children is not well described. We aim to collect and summarize the literature and define physicians' practice patterns regarding the use of methylene blue to treat shock in children.

DESIGN

We conducted a systematic search of MEDLINE, Embase, PubMed, Web of Science, Cochrane for studies involving the use of methylene blue for catecholamine-refractory shock from database inception to 2019. Collected studies were analyzed qualitatively. To describe practice patterns of methylene blue use, we electronically distributed a survey to U.S.-based pediatric critical care physicians. We assessed physician knowledge and experience with methylene blue. Survey responses were quantitatively and qualitatively evaluated.

SETTING

Pediatric critical and cardiac care units.

PATIENTS OR SUBJECTS

Patients less than or equal to 25 years old with refractory shock treated with methylene blue.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One-thousand two-hundred ninety-three abstracts met search criteria, 139 articles underwent full-text review, and 24 studies were included. Studies investigated refractory shock induced by a variety of etiologies and found that methylene blue was generally safe and increased mean arterial blood pressure. There is overall lack of studies, low number of study patients, and low quality of studies identified. Our survey had a 22.5% response rate, representing 125 institutions. Similar proportions of physicians reported using (40%) or never even considering (43%) methylene blue for shock. The most common reasons for not using methylene blue were unfamiliarity with this drug, its proper dosing, and lack of evidentiary support.

CONCLUSIONS

Methylene blue appears safe and may benefit children with refractory shock. There is a stark divide in familiarity and practice patterns regarding its use among physicians. Studies to formally assess safety and efficacy of methylene blue in treating pediatric shock are warranted.

High-dose hydroxocobalamin in end-stage liver disease and liver transplantation

Distributive shock is a serious complication in patients with chronic or end-stage liver disease, and can be exacerbated by vasoplegia in this patient population. Vasoplegic syndrome (VS) is a state of shock refractory to catecholamines and vasopressin that is often multifactorial in liver failure patients, and can occur in any phase of liver transplantation (LT) [i.e., pre-transplantation, intraoperative, and post-transplantation]. Methylene blue (MB) has been a well-established pharmacologic therapy for VS. However, it has been known to cause dose-related toxicity. Hydroxocobalamin (HXC) is not currently FDA approved for the management of VS, but studies have demonstrated its ability to cause an increase in systolic blood pressure by hypothesized mechanisms with only minimal side effects. To date, only three other reports have demonstrated the use of HXC in LT patients, which highlighted its use both intraoperatively and post-transplantation. Our report illustrates the utility of HXC in four LT patients with VS. Two of these cases illustrate the usefulness of HXC in the pre-transplantation period, which has never been previously reported. HXC is a useful pharmaceutical agent in the management of VS, especially if contraindications to MB exist or in cases of MB-resistant vasoplegia. Further studies with large sample sizes are necessary to ascertain the optimal dosage of HXC in LT patients.

Case report of high-dose hydroxocobalamin in the treatment of vasoplegic syndrome during liver transplantation

A 66-year-old man with cryptogenic cirrhosis secondary to nonalcoholic steatohepatitis presented for orthotopic liver transplantation. Following organ reperfusion, the patient developed vasoplegic syndrome, with arterial blood pressures of approximately 60-70/30-40 mm Hg (mean arterial pressure [MAP] <45 mm Hg) for >90 minutes. He required high-dose norepinephrine and vasopressin infusions, as well as i.v. bolus doses of norepinephrine and vasopressin to reach a goal MAP> 60 mm Hg. There was minimal response to a 2 mg/kg i.v. bolus of methylene blue. Following the administration of 5 g of i.v.hydroxocobalamin, the patient had a profound improvement in arterial blood pressure, with subsequent discontinuation of the vasopressin infusion and rapid reduction of norepinephrine infusion from 20 to 2 μg/min. While there have been several reports of the efficacy of hydroxocobalamin for vasoplegia after cardiopulmonary bypass, there have been only limited cases of hydroxocobalamin used in liver transplantation, and none with high-dose administration. We present a case of vasoplegic syndrome during liver transplantation that was refractory to high-dose vasopressors and methylene blue but responsive to high-dose i.v. hydroxocobalamin.