# Hydrogen gas improves survival rate and organ damage in zymosan-induced generalized inflammation model.
> 水素ガス吸入はザイモサン誘発全身性炎症モデルにおける生存率と臓器障害を改善する


## Abstract

Sepsis and multiple organ dysfunction syndrome represent a leading cause of mortality in critically ill patients. This study examined the effects of 2% H2 inhalation in a mouse model of generalized inflammation induced by zymosan (ZY) injection. Two 60-minute inhalation sessions initiated at 1 and 6 hours post-ZY administration significantly raised the 14-day survival rate from 10% to 70%. At 24 hours after ZY challenge, elevated serum markers of organ injury—including aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine—were substantially reduced by H2 inhalation. Histopathological damage scores in the lung, liver, and kidney were similarly attenuated. Mechanistically, H2 treatment was associated with lower oxidative stress products, enhanced antioxidant enzyme activity, and decreased concentrations of both early- and late-phase proinflammatory cytokines in serum and organ tissues. These findings indicate that H2 inhalation confers protection against multi-organ injury in a ZY-induced systemic inflammation model.

### Mechanism

H2 selectively scavenges hydroxyl radicals, reducing oxidative damage while enhancing antioxidant enzyme activity and suppressing both early- and late-phase proinflammatory cytokine production, thereby limiting multi-organ injury in systemic inflammation.

## Bibliographic

- **Authors**: Xie K, Yu Y, Zhang Z, Liu W, Pei Y, Xiong L, et al.
- **Journal**: Shock
- **Year**: 2010
- **PMID**: [20351628](https://pubmed.ncbi.nlm.nih.gov/20351628/)
- **DOI**: [10.1097/SHK.0b013e3181def9aa](https://doi.org/10.1097/SHK.0b013e3181def9aa)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 2%

## Delivery context

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.

## Safety notes

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:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 20351628. https://h2-papers.org/en/papers/20351628
> **Source**: PubMed PMID [20351628](https://pubmed.ncbi.nlm.nih.gov/20351628/)