# Molecular hydrogen exposure improves functional state of red blood cells in the early postoperative period: a randomized clinical study.
> 心肺バイパス手術における分子水素吸入が赤血球機能状態および心機能指標に与える影響：無作為化臨床試験


## Abstract

This randomized clinical trial enrolled 24 patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) for acquired valve disease at a specialized cardiosurgical hospital in Nizhny Novgorod, Russia. Twelve patients inhaled 1.5–2.0% molecular hydrogen via facemask through a ventilator breathing circuit from tracheal intubation through the end of surgery, while 12 control patients received no hydrogen. Blood samples were collected at four time points: immediately after anesthesia induction, before CPB initiation, immediately after CPB termination, and 24 hours postoperatively. Compared with controls, the hydrogen group showed increased erythrocyte electrophoretic mobility, enhanced red blood cell metabolic activity, and reduced erythrocyte aggregation. Markers of oxidative stress were most markedly reduced at 24 hours after surgery. Statistically significant differences in myocardial contractile function were observed on postoperative days 1 and 3. These findings indicate that hydrogen inhalation during CPB surgery is associated with improved red blood cell functional status and a more favorable early postoperative course.

### Mechanism

Molecular hydrogen is thought to reduce oxidative stress during cardiopulmonary bypass, thereby improving erythrocyte membrane charge and metabolic activity, decreasing red blood cell aggregation, and contributing to enhanced myocardial contractile function in the early postoperative period.

## Bibliographic

- **Authors**: Deryugina AV, Danilova DA, Brichkin YD, Taranov EV, Nazarov EI, Pichugin VV, et al.
- **Journal**: Med Gas Res
- **Year**: 2023
- **PMID**: [36204784](https://pubmed.ncbi.nlm.nih.gov/36204784/)
- **DOI**: [10.4103/2045-9912.356473](https://doi.org/10.4103/2045-9912.356473)
- **PMC**: [PMC9555031](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9555031/)
- **Study type**: human randomized controlled trial
- **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 36204784. https://h2-papers.org/en/papers/36204784
> **Source**: PubMed PMID [36204784](https://pubmed.ncbi.nlm.nih.gov/36204784/)