Effect of Hydrogen Gas on Hyperbaric Oxygen Toxicity

Summary

The goal of this trial is to investigate whether adding a small fraction of hydrogen gas to an oxygen-enriched breathing mixture can reduce pulmonary oxygen toxicity (POT) in healthy and active divers from the Swedish Armed Forces. The main questions it aims to answer are:

* Does hydrogen gas reduce oxidative stress and changes in pulmonary function associated with prolonged hyperbaric oxygen exposure?
* What are the underlying pathophysiological mechanisms of pulmonary oxygen toxicity?

Researchers will compare oxygen-enriched breathing gas with 1-2% hydrogen to oxygen-enriched gas with 1-2% nitrogen (control) to see if hydrogen provides protective effects against POT during hyperbaric exposure.

Participants will:

* Complete two hyperbaric exposure sessions (hydrogen vs. nitrogen), each lasting 240 minutes at 1.75 ATA
* Undergo pulmonary function tests and sampling of blod and urin before and after each session
* Serve as their own controls in a double-blind, randomized, crossover study design

Conditions

• Oxygen Toxicity
• Oxidative Stress
• Hyperoxia
• Hyperbaric Oxygen
• Healthy Subjects (HS)
• Diving Medicine
• Hydrogen-oxygen Gas

Interventions

OTHER

Inhaled Hydrogen-Enriched Oxygen Gas

Participants will inhale a gas mixture consisting of 98-99% oxygen and 1-2% hydrogen via a breathing circuit during a single hyperbaric exposure. The exposure will be conducted at a partial pressure of 1.75 ATA for 240 minutes. The intervention aims to evaluate the protective effect of hydrogen gas against pulmonary oxygen toxicity.

OTHER

Inhaled Nitrogen-Enriched Oxygen Gas

Participants will inhale a gas mixture consisting of 98-99% oxygen and 1-2% nitrogen via a breathing circuit during a single hyperbaric exposure. The exposure will be conducted at a partial pressure of 1.75 ATA for 240 minutes. The intervention aims to evaluate the protective effect of hydrogen gas against pulmonary oxygen toxicity.

Sponsors & Collaborators

• Karolinska Institutet

  collaborator OTHER

• Göteborg University

  collaborator OTHER

• Lund University

  collaborator OTHER

• Swedish Armed Forces Diving and Naval Medicine Centre

  collaborator OTHER

• Blekinge Institute of Technology

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Model

CROSSOVER

Eligibility

Min Age

20 Years

Max Age

64 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-01-31

Primary Completion

2029-12-31

Completion

2030-12-31

Countries

• Sweden

Study Locations