Hydrogen Gas + Cooling Therapy Improves Brain Recovery After Cardiac Arrest

Authors
Journal
Critical Care Medicine
Year
DOI
10.1097/CCM.0000000000006395
Study Type
Human
Outcome
Positive
Peer Reviewed
Yes
Country
Japan
Health Condition
Cardiac Arrest
Body System
Cardiovascular

TL;DR

Breathing in hydrogen gas along with undergoing mild hypothermia treatment may improve brain function after a heart stops beating outside of a hospital.

Key Finding

In cardiac arrest patients treated with moderate therapeutic hypothermia (32-34°C), adding hydrogen gas inhalation was associated with good neurologic outcomes in 68% of patients versus 38% without hydrogen.

Summary

This study examined whether adding hydrogen gas to standard treatment improved outcomes in people who survived out-of-hospital cardiac arrest. The standard treatment involved cooling the body to 32-34°C (a technique called therapeutic hypothermia). Researchers compared patients who received hydrogen gas plus cooling versus those who received cooling alone. Among patients treated with the cooler temperature range, 68% of those receiving hydrogen had good neurologic recovery at 90 days, compared to 38% in the cooling-only group. However, hydrogen did not improve overall survival rates.

Practical Takeaway

This post hoc analysis of a clinical trial suggests that hydrogen inhalation combined with therapeutic hypothermia may help protect the brain after cardiac arrest, though the study was relatively small (72 patients) and did not show improved survival. More research is needed to confirm these findings and determine whether hydrogen could become a standard addition to cardiac arrest treatment protocols.

Abstract

Objective: The Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During Post-Cardiac Arrest Care (HYBRID) II trial (jRCTs031180352) suggested that hydrogen inhalation may reduce post-cardiac arrest brain injury (PCABI). However, the combination of hypothermic target temperature management (TTM) and hydrogen inhalation on outcomes is unclear. The aim of this study was to investigate the combined effect of hydrogen inhalation and hypothermic TTM on outcomes after out-of-hospital cardiac arrest (OHCA). Design: Post hoc analysis of a multicenter, randomized, controlled trial. Setting: Fifteen Japanese ICUs. Patients: Cardiogenic OHCA enrolled in the HYBRID II trial. Interventions: Hydrogen mixed oxygen (hydrogen group) versus oxygen alone (control group). Measurements and main results: TTM was performed at a target temperature of 32-34°C (TTM32-TTM34) or 35-36°C (TTM35-TTM36) per the institutional protocol. The association between hydrogen + TTM32-TTM34 and 90-day good neurologic outcomes was analyzed using generalized estimating equations. The 90-day survival was compared between the hydrogen and control groups under TTM32-TTM34 and TTM35-TTM36, respectively. The analysis included 72 patients (hydrogen [ n = 39] and control [ n = 33] groups) with outcome data. TTM32-TTM34 was implemented in 25 (64%) and 24 (73%) patients in the hydrogen and control groups, respectively ( p = 0.46). Under TTM32-TTM34, 17 (68%) and 9 (38%) patients achieved good neurologic outcomes in the hydrogen and control groups, respectively (relative risk: 1.81 [95% CI, 1.05-3.66], p < 0.05). Hydrogen + TTM32-TTM34 was independently associated with good neurologic outcomes (adjusted odds ratio 16.10 [95% CI, 1.88-138.17], p = 0.01). However, hydrogen + TTM32-TTM34 did not improve survival compared with TTM32-TTM34 alone (adjusted hazard ratio: 0.22 [95% CI, 0.05-1.06], p = 0.06). Conclusions: Hydrogen + TTM32-TTM34 was associated with improved neurologic outcomes after cardiogenic OHCA compared with TTM32-TTM34 monotherapy. Hydrogen inhalation is a promising treatment option for reducing PCABI when combined with TTM32-TTM34.