# Application of Molecular Hydrogen in Heart Surgery under Cardiopulmonary Bypass.
> 人工心肺下心臓手術における分子状水素吸入が酸化ストレスマーカーに与える影響


## Abstract

This prospective study examined the influence of inhaled molecular hydrogen on lipid peroxidation during cardiac valve surgery performed under cardiopulmonary bypass (CPB). Twenty patients were divided into a hydrogen inhalation group (n=11; 1.5–2.0% H2 delivered via ventilator circuit from intubation through surgery) and a control group (n=9; no H2). Blood samples were collected at four time points: after anesthesia induction, before CPB, after CPB termination, and 24 hours postoperatively. Lipid peroxidation was assessed via diene conjugates (DC), triene conjugates (TC), and Schiff bases (SB). In the hydrogen group, arterial TC and SB levels declined relative to baseline before CPB initiation and at 24 hours postoperatively, while venous DC elevation before CPB normalized by the post-CPB stage. The control group showed progressive increases in arterial SB and elevated venous TC and SB at 24 hours. The most pronounced reduction in oxidative stress markers in the hydrogen group occurred on postoperative day one, supporting the potential of intraoperative H2 inhalation as a safe antioxidant adjunct in cardiac surgery.

### Mechanism

Inhaled molecular hydrogen is proposed to scavenge reactive oxygen species generated during cardiopulmonary bypass, thereby reducing lipid peroxidation end-products such as triene conjugates and Schiff bases in both arterial and venous blood.

## Bibliographic

- **Authors**: Danilova DA, Brichkin YD, Medvedev AP, Pichugin VV, Fedorov SA, Taranov EV, et al.
- **Journal**: Sovrem Tekhnologii Med
- **Year**: 2021
- **PMID**: [34513069](https://pubmed.ncbi.nlm.nih.gov/34513069/)
- **DOI**: [10.17691/stm2021.13.1.09](https://doi.org/10.17691/stm2021.13.1.09)
- **PMC**: [PMC8353690](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8353690/)
- **Study type**: human observational study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 1.5–2%

## 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 34513069. https://h2-papers.org/en/papers/34513069
> **Source**: PubMed PMID [34513069](https://pubmed.ncbi.nlm.nih.gov/34513069/)