高齢者の膝関節症に対する水素・酸素混合ガス吸入と在宅運動の併用効果：オープンラベル・盲検エンドポイント無作為化対照試験
This randomized controlled trial enrolled 121 elderly patients with knee osteoarthritis (mean age 81.2 years; 80.2% female) and assigned them to either a hydrogen-oxygen (H-O) inhalation group (60 min/day for 2 weeks, alongside a 12-week home-based exercise program) or an exercise-only control group. The primary endpoint, the WOMAC total score, improved significantly from baseline in both groups, but the between-group difference at week 12 was −5.2 (95% CI −12.1 to 1.7; P = 0.140), falling short of statistical significance. A significant group-by-time interaction (P < 0.001) indicated that H-O inhalation produced more pronounced symptom relief during the initial 2-week period. No between-group differences were detected in inflammatory markers (hs-CRP, NLR, PLR, LMR), physical performance tests, SF-36 quality-of-life scores, exercise adherence, or adverse event rates at week 12. The findings suggest a transient benefit of H-O inhalation in the early phase of a combined exercise regimen, without sustained superiority over exercise alone.
Molecular hydrogen is proposed to scavenge reactive oxygen species and suppress inflammatory mediators, thereby reducing oxidative stress and inflammation in articular tissues, which may underlie the transient symptom relief observed in the early intervention phase.
For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.
See also:
https://h2-papers.org/en/papers/39950118