H₂ Papers

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Promising novel therapy with hydrogen gas for emergency and critical care medicine.

救急・集中治療領域における水素ガスの医療応用に関するレビュー

review inhalation not assessed

Abstract

Hydrogen gas has been reported to exert beneficial effects across a broad spectrum of conditions, ranging from acute disorders such as ischemia-reperfusion injury and hemorrhagic shock to chronic conditions including metabolic syndrome, rheumatoid arthritis, and neurodegenerative diseases. Antioxidant and anti-inflammatory mechanisms have been proposed, yet the precise molecular target of hydrogen gas remains unidentified. This review summarizes findings from research conducted through an industry-academia collaborative center focused on hydrogen medicine, covering areas such as acute myocardial infarction, cardiopulmonary arrest syndrome, contrast-induced acute kidney injury, and hemorrhagic shock within the context of emergency and critical care medicine.

Mechanism

Hydrogen gas is proposed to act via antioxidant and anti-inflammatory pathways, though its specific molecular target has not yet been identified.

Bibliographic

Authors
Sano M, Suzuki M, Homma K, Hayashida K, Tamura T, Matsuoka T, et al.
Journal
Acute Med Surg
Year
2018
PMID
29657720
DOI
10.1002/ams2.320
PMC
PMC5891106

Tags

Disease:ischemia-reperfusion injury (107) kidney disease (45) myocardial infarction (28) Delivery:inhalation delivery (196) Mechanism:anti-inflammatory (743) oxidative stress (899) reactive oxygen species (774)

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.

→ Evidence by delivery route

Safety notes

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.

See also:

Other papers on the same disease / condition