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Effect of hydrogen gas inhalation on patient QOL after hepatectomy: protocol for a randomized controlled trial.

肝切除後患者のQOLに対する水素ガス吸入の効果：無作為化対照試験プロトコル

human randomized controlled trial inhalation not assessed

Abstract

This document describes the protocol for a double-blind, randomized, superiority trial evaluating whether hydrogen gas inhalation improves quality of life (QOL) in patients following hepatectomy. Hepatic resection involves repeated ischemia-reperfusion cycles that generate reactive oxygen species (ROS), potentially impairing liver function. Because molecular hydrogen selectively neutralizes highly toxic ROS, early postoperative inhalation may limit hepatic dysfunction. Participants will be randomly assigned to inhale either hydrogen gas or air after surgery. The primary endpoint is the QoR40 score on postoperative day 3. Secondary endpoints include additional QoR40 assessments, Clavien-Dindo complication grading, pain intensity via Numerical Rating Scale, dietary intake, liver function markers, systemic inflammation indices, urinary 8-hydroxydeoxyguanosine (8-OHdG) as an oxidative stress biomarker, and pedometer-recorded step counts. The trial is registered under jRCTs03220332 and was approved by the Niigata University Central Review Board of Clinical Research.

Mechanism

Molecular hydrogen is proposed to selectively scavenge highly toxic reactive oxygen species generated during hepatic ischemia-reperfusion, thereby limiting oxidative stress-mediated liver dysfunction in the postoperative period.

Bibliographic

Authors
Kaibori M, Kosaka H
Journal
Trials
Year
2021 (2021-10-21)
PMID
34674744
DOI
10.1186/s13063-021-05697-5
PMC
PMC8529823

Tags

Disease:ischemia-reperfusion injury (107) liver disease (56) Delivery:inhalation delivery (196) Mechanism:hydroxyl radical scavenging (352) 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:

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