Use of High-Dose Hydroxocobalamin for Septic Shock: A Case Report

Use of Hydroxycobolamin in the Prevention of Vasoplegic Syndrome in Adult Patients Undergoing Cardiopulmonary Bypass: A Controlled Prospective Trial

OBJECTIVE

We hypothesized that the prophylactic use of hydroxocobalamin in patients at high-risk patients to develop vasoplegia after cardiopulmonary bypass (CPB) may decrease its incidence.

DESIGN

This randomized placebo-controlled prospective single-center study was conducted on high-risk patients for vasoplegia who underwent coronary artery bypass grafting (CABG).

SETTING

This study was conducted in Ain Shams University Hospitals from August 2019 to October 2023 in cardiothoracic operative rooms and its intensive care unit.

PARTICIPANTS

Patients included in the study were 18 to 60 years old and undergoing CABG and/or valve surgery on CPB and had 2 or more preoperative risk factors for vasoplegia. They were receiving using preoperative β-blocker or angiotensin-converting enzyme inhibitor with a preoperative ejection fraction of less than 35% and a history of thyroid disease and preoperative diuretics.

INTERVENTIONS

At the end of CPB, the patients were assigned randomly into two groups: group I consisted of 30 patients who received hydroxocobalamin 5 g intravenously via the central venous catheter as a bolus over 15 minutes reconstituted in 200 mL of normal saline, and group II (control) consisted of 30 patients who received 200 mL of normal saline intravenously over 15 minutes.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the change in mean arterial pressure between baseline and all time points (30 and 60 minutes after CPB initiation and 30 and 60 minutes after CPB separation) between the two groups and within the same group. The comparison regarding the change in systemic venous resistance between baseline and all time points (30 and 60 minutes before CPB initiation and 30 and 60 minutes after CPB separation) between the two groups and within the same group is calculated. Cardiac index was calculated 30 min before CPB initiation and 30 min after CPB separation. Doses of norepinephrine and its equivalent, incidence of vasoplegic shock syndrome, serum lactate, number of ventilator days, intensive care unit length of stay, hospital length of stay, incidence of norepinephrine-resistant refractory vasoplegia, acute kidney injury, shock liver and mortality in 1 week were calculated. Results showed that mean arterial pressure and systemic venous resistance at minutes 30 and 60 after CPB separation was significantly higher in group I compared to group II. Cardiac index was significantly lower in group I compared to group II. Norepinephrine requirements (µg/kg/min) at minutes 30 and 60 after CPB separation as well as average total dose norepinephrine equivalent were significantly lower in group I. Serum lactate was also found to be significantly lower in group I. Incidence of vasoplegic shock syndrome, norepinephrine-resistant refractory vasoplegia, number of ventilator days, intensive care unit length of stay, hospital length of stay, acute kidney injury, shock liver, and mortality was less frequent in group I, but the differences were statistically significant only for vasoplegia and refractory vasoplegia.

CONCLUSION

This study showed that prophylactic hydroxocobalamin can be used effectively to decrease the incidence of vasoplegic syndrome, and total vasopressor dose, as well as improve tissue perfusion in high-risk patients in cardiac surgeries.

Hydroxocobalamin for Vasodilatory Hypotension in Shock: A Systematic Review With Meta-Analysis for Comparison to Methylene Blue

Hydroxocobalamin inhibits nitric oxide-mediated vasodilation, and has been used in settings of refractory shock. However, its effectiveness and role in treating hypotension remain unclear. The authors systematically searched Ovid Medline, Embase, EBM Reviews, Scopus, and Web of Science Core Collection for clinical studies reporting on adult persons who received hydroxocobalamin for vasodilatory shock. A meta-analysis was performed with random-effects models comparing the hemodynamic effects of hydroxocobalamin to methylene blue. The Risk of Bias in Nonrandomized Studies of Interventions tool was used to assess the risk of bias. A total of 24 studies were identified and comprised mainly of case reports (n = 12), case series (n = 9), and 3 cohort studies. Hydroxocobalamin was applied mainly for cardiac surgery vasoplegia, but also was reported in the settings of liver transplantation, septic shock, drug-induced hypotension, and noncardiac postoperative vasoplegia. In the pooled analysis, hydroxocobalamin was associated with a higher mean arterial pressure (MAP) at 1 hour than methylene blue (mean difference 7.80, 95% CI 2.63-12.98). There were no significant differences in change in MAP (mean difference -4.57, 95% CI -16.05 to 6.91) or vasopressor dosage (mean difference -0.03, 95% CI -0.12 to 0.06) at 1 hour compared to baseline between hydroxocobalamin and methylene blue. Mortality was also similar (odds ratio 0.92, 95% CI 0.42-2.03). The evidence supporting the use of hydroxocobalamin for shock is limited to anecdotal reports and a few cohort studies. Hydroxocobalamin appears to positively affect hemodynamics in shock, albeit similar to methylene blue.

The Durability of Intravenous Hydroxocobalamin in Vasoplegia

Objectives Refractory distributive shock (vasoplegia) has been treated with intravenous (IV) hydroxocobalamin (B12), but its use is poorly characterized. The objective of this study was to quantify the duration of hemodynamic improvement after B12 administration. Materials and methods This was a retrospective chart review of adult patients who received IV B12 while on vasopressors in the intensive care unit. Patients were divided into two groups: responders (≥10% decrease in baseline vasopressor requirements within 60 minutes of B12 administration) and non-responders. Results A total of 16 patients were included, and five (31%) met the 'responder' criteria. The median time to respond was 15 minutes, and the response was maintained for a median of 210 minutes. The baseline median norepinephrine equivalent (NEE) rate was 32.9 mcg/min in responders and 24.7 mcg/min in non-responders. Responders' NEE requirements decreased to 16.7 mcg/min after 15 minutes and 14.8 mcg/min after 60 minutes. All responders and 10 (91%) non-responders were mechanically ventilated; both groups were mostly male (60% and 91%) and had a median age of 54 years and 58 years, respectively. A total of 4 (80%) responders and 10 (91%) non-responders died while hospitalized. IV B12 was administered as 5 g over 15 minutes in all but two patients (one responder and one non-responder), who each received 5 g of B12 over 360 minutes. Conclusion Vasopressor requirements decreased rapidly in 31% of patients after B12 administration and remained so for a median of 210 minutes.

High-Dose IV Hydroxocobalamin (Vitamin B12) in Septic Shock: A Double-Blind, Allocation-Concealed, Placebo-Controlled Single-Center Pilot Randomized Controlled Trial (The Intravenous Hydroxocobalamin in Septic Shock Trial)

BACKGROUND

Elevated hydrogen sulfide (H₂S) contributes to vasodilatation and hypotension in septic shock, and traditional therapies do not target this pathophysiologic mechanism. High-dose IV hydroxocobalamin scavenges and prevents H₂S formation, which may restore vascular tone and may accentuate recovery. No experimental human studies have tested high-dose IV hydroxocobalamin in adults with septic shock.

RESEARCH QUESTION

In adults with septic shock, is comparing high-dose IV hydroxocobalamin with placebo feasible?

STUDY DESIGN AND METHODS

We conducted a phase 2 single-center, double-blind, allocation-concealed, placebo-controlled, parallel-group pilot randomized controlled trial comparing high-dose IV hydroxocobalamin with placebo in critically ill adults with septic shock. Patients meeting Sepsis 3 criteria were randomized 1:1 to receive a single 5-g dose of high-dose IV hydroxocobalamin or equivalent volume 0.9% saline solution as placebo. The primary outcome was study feasibility (enrollment rate, clinical and laboratory compliance rate, and contamination rate). Secondary outcomes included between-group differences in plasma H₂S concentrations and vasopressor dose before and after infusion.

RESULTS

Twenty patients were enrolled over 19 months, establishing an enrollment rate of 1.05 patients per month. Protocol adherence rates were 100% with zero contamination. In the high-dose IV hydroxocobalamin group, compared to placebo, there was a greater reduction in vasopressor dose between randomization and postinfusion (-36% vs 4%, P < .001) and randomization and 3-h postinfusion (-28% vs 10%, P = .019). In the high-dose IV hydroxocobalamin group, the plasma H₂S level was reduced over 45 mins by -0.80 ± 1.73 μM, as compared with -0.21 ± 0.64 μM in the placebo group (P = .3).

INTERPRETATION

This pilot trial established favorable feasibility metrics. Consistent with the proposed mechanism of benefit, high-dose IV hydroxocobalamin compared with placebo was associated with reduced vasopressor dose and H₂S levels at all time points and without serious adverse events. These data provide the first proof of concept for feasibility of delivering high-dose IV hydroxocobalamin in septic shock.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03783091; URL: www.

CLINICALTRIALS

gov.

The pharmacotherapeutic options in patients with catecholamine-resistant vasodilatory shock

INTRODUCTION

Septic and vasoplegic shock are common types of vasodilatory shock (VS) with high mortality. After fluid resuscitation and the use of catecholamine-mediated vasopressors (CMV), vasopressin, angiotensin II, methylene blue (MB) and hydroxocobalamin can be added to maintain blood pressure.

AREAS COVERED

VS treatment utilizes a phased approach with secondary vasopressors added to vasopressor agents to maintain an acceptable mean arterial pressure (MAP). This review covers additional vasopressors and adjunctive therapies used when fluid and catecholamine-mediated vasopressors fail to maintain target MAP.

EXPERT OPINION

Evidence supporting additional vasopressor agents in catecholamine resistant VS is limited to case reports, series, and a few randomized control trials (RCTs) to guide recommendations. Vasopressin is the most common agent added next when MAPs are not adequately supported with CMV. VS patients failing fluids and vasopressors with cardiomyopathy may have cardiotonic agents such as dobutamine or milrinone added before or after vasopressin. Angiotensin II, another class of vasopressor is used in VS to maintain adequate MAP. MB and/or hydoxocobalamin, vitamin C, thiamine and corticosteroids are adjunctive therapies used in refractory VS. More RCTs are needed to confirm the utility of these drugs, at what doses, which combinations and in what order they should be given.

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

Case series

Patients: Male, 71-year-old • Male, 71-year-old

Final Diagnosis: Vasoplegic syndrome

Symptoms: Refractory hypotension

Medication: —

Clinical Procedure: Cardiopulmonary bypass

Specialty: Anesthesiology

Hydroxocobalamin in Refractory Septic Shock: A Retrospective Case Series

Objectives:

Refractory septic shock is associated with high morbidity and mortality. Hydroxocobalamin is used to treat postoperative vasoplegia; however, data supporting its use in the setting of refractory septic shock is limited and restricted to case reports. This study evaluates the effect of hydroxocobalamin on mean arterial pressure and vasopressor requirements in a series of patients with refractory septic shock.

Design:

Single-center, retrospective analysis.

Setting:

Urban, tertiary-care ICU.

Patients:

Adult ICU patients with refractory septic shock treated with hydroxocobalamin between August 2018 and January 2020.

Interventions:

Hydroxocobalamin 5 g IV infusion.

MEASUREMENTS AND MAIN RESULTS:

Twenty-six patients were included for the analysis. Administration of hydroxocobalamin was associated with an increase in mean arterial pressure at 1, 6, and 24 hours postdose (+16.3, +14.3, and +16.3 mm Hg, respectively; p < 0.001). Increase in mean arterial pressure from baseline remained statistically significant when controlling for sex, age, and comorbid conditions. There was no change in the norepinephrine equivalents patients required 1 hour following hydroxocobalamin administration, but a statistically significant decrease in norepinephrine equivalent was observed at 6 and 24 hours postdose (p < 0.001).

Conclusions:

Hydroxocobalamin provides sustained hemodynamic benefit at 24 hours in patients with refractory septic shock.

Extended Duration Infusion of Hydroxocobalamin for Vasoplegic Rescue in Septic Shock

Nitric oxide (NO) is a gaseous signaling molecule and a key endogenous mediator of vascular tone. Hydroxocobalamin (HCB) affects NO-mediated vasoplegia as (1) a direct inhibitor of nitric oxide synthase (NOS), thereby decreasing its production, and (2) by binding directly to NO and acting as a scavenger. HCB has been increasingly used in the treatment of refractory vasoplegia, particularly in cardiac surgery and liver transplant patients. Sepsis and septic shock are characterized by an increase in inducible NOS expression and activity with excessive NO production, resulting in endothelial dysfunction and profound systemic vasodilation. Therefore, a careful sustained reduction in NO burden represents a potential therapeutic target. Here, we present a case of refractory septic shock, which resolved after an extended duration infusion of high-dose HCB. We hope to foster further exploration regarding the safety, dosing, and efficacy of HCB when administered for vasopressor refractory septic shock.

Another Role for Angiotensin II?: Vasopressin-Refractory Shock After Pheochromocytoma Resection: A Case Report

A patient presented with multiple unrelated tumors and was found to have a small but functional adrenal pheochromocytoma. After pheochromocytoma resection, shock developed unresponsive to vasopressin in recommended doses (0.04 U/min infusion plus repeated 1-U boluses) but responded dramatically to an angiotensin II infusion (20 ng/kg/min) with a mean arterial pressure >100 mm Hg. The patient's blood pressure was maintained for 42 hours postoperatively with an infusion rate that ranged from 2 to 38 ng/kg/min. Because vasopressin may not always be effective for postresection shock in people with pheochromocytomas, angiotensin II may prove to be an effective alternative.