Hydrogen Gas Inhalation Treatment in Acute Cerebral Infarction: A Randomized Controlled Clinical Study on Safety and Neuroprotection.
急性脳梗塞に対する水素ガス吸入の安全性と神経保護効果：無作為化対照臨床試験
Abstract
This randomized controlled clinical trial enrolled 50 patients with acute cerebral infarction of mild-to-moderate severity (NIHSS scores 2–6) within a 6–24 hour therapeutic window. Twenty-five patients inhaled 3% H2 gas for one hour twice daily over 7 days, while 25 controls received standard intravenous medications. Assessments included daily vital signs, weekly blood chemistry, NIHSS scores, Barthel Index, and brain MRI over a 2-week period. No significant adverse events were observed in the H2 group, and oxygen saturation improved. Compared with controls, the H2 group demonstrated significant improvements in MRI relative signal intensity at the infarction site, NIHSS scores, and physical therapy outcomes as measured by the Barthel Index. These findings indicate that 3% H2 gas inhalation is both safe and associated with neurological benefit in the acute phase of cerebral infarction.
Mechanism
H2 gas is proposed to exert antioxidant effects by selectively neutralizing reactive oxygen species at the infarction site, thereby reducing oxidative damage to neural tissue and limiting infarct progression.
Bibliographic
- Authors
- Ono H, Nishijima Y, Ohta S, Sakamoto M, Kinone K, Horikosi T, et al.
- Journal
- J Stroke Cerebrovasc Dis
- Year
- 2017
- PMID
- 28669654
- DOI
- 10.1016/j.jstrokecerebrovasdis.2017.06.012
Tags
Delivery context
In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.
Safety notes
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