Hydrogen Gas + Cooling Therapy Improves Brain Recovery After Cardiac Arrest
Combination of Hydrogen Inhalation and Hypothermic Temperature Control After Out-of-Hospital Cardiac Arrest: A Post hoc Analysis of the Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During PostCardiac Arrest Care II Trial
Research hubs: Cardiovascular System · Brain & Nervous System
- Evidence type
- Randomized controlled trial · Human study
- Authors
- Tomoyoshi Tamura, Hiromichi Narumiya, Koichiro Homma, Masaru Suzuki
- Journal
- Critical Care Medicine
- Year
- 2024
- PMID
- 39133068
- Study Type
- Human
- Participants
- 72
- Delivery
- Gas
- Dose
- Hydrogen mixed oxygen inhalation
- H₂ concentration
- 2% hydrogen mixed oxygen
- Duration
- 3 months
- Funding
- Taiyo Nippon Sanso Corporation; Japanese Society for Promotion of Science; Marumo Memorial Foundation Grant for Emergency Medicine Research
- Conflicts of interest
- Dr. Tamura's institution received funding from Taiyo Nippon Sanso Corporation, Japanese Society for Promotion of Science, and Marumo Memorial Foundation; Drs. Tamura and Suzuki disclosed off-label use of hydrogen gas; Dr. Narumiya disclosed work for hire.
- Outcome
- Positive
- Peer Reviewed
- Yes
- Cited by
- 18 (OpenAlex, as of November 2026)
- Country
- Japan
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 (excerpt)
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…