NCT07263399
Not yet recruiting
Not Applicable
Effect of Hydrogen Gas on Hyperbaric Oxygen Toxicity - A Randomized Controlled Cross-Over Trial
Blekinge Institute of Technology2 sites in 1 country32 target enrollmentStarted: January 1, 2026Last updated:
Overview
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Blekinge Institute of Technology
- Enrollment
- 32
- Locations
- 2
- Primary Endpoint
- Change in Vital Capacity (ΔVC)
Overview
Brief 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
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Crossover
- Primary Purpose
- Basic Science
- Masking
- Triple (Participant, Investigator, Outcomes Assessor)
Eligibility Criteria
- Ages
- 20 Years to 64 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Military divers actively serving, aged 20-64 years
- •Meeting the Swedish Armed Forces physical standards for diving
Exclusion Criteria
- •Ongoing infection or illness that may impact pulmonary function
- •Use of alcohol or smoking cigarettes within 48 hours
- •Diving with any breathing gas within 48 hours
- •Diving with oxygen-enriched gas (100% O₂) within 2 weeks
- •Use of medications that could affect oxidative stress, lung function, or neurological status
- •Medical history of serious diving-related injuries or long-term complications
Outcomes
Primary Outcomes
Change in Vital Capacity (ΔVC)
Time Frame: Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.
Absolute change in vital capacity (VC), calculated as the difference in liters (L) between pre-exposure and post-exposure spirometry values, measured after each hyperbaric oxygen exposure session.
Secondary Outcomes
- Forced Expiratory Volume in One Second (FEV₁)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure)
- Change in FEV₁/FVC ratio(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure)
- Change in Forced Expiratory Flow 25-75% (FEF25-75%)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Peak Expiratory Flow (PEF)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Inspiratory Capacity (IC)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Total Lung Capacity (TLC)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Residual Volume (Δ RV)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Functional Residual Capacity (Δ FRC)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Diffusing Capacity for Carbon Monoxide (ΔDLCO)(Pre-exposure, 30-120 minutes post-exposure and 24-36 hours post-exposure.)
- Airway Resistance (Impulse Oscillometry, Tremoflo™)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Index of Oxygen Stress (ΔiOS)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Fractional Exhaled Nitric Oxide (ΔFeNO)(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Change in Exhaled Breath Particle Analysis (ΔPExA)(Pre-exposure and follow-up 24-36 hours post-exposure after each intervention.)
- Blood and Urinary Biomarkers of Oxidative Stress and Inflammation(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
- Biomarkers of Neuronal Injury(Pre-exposure, 30-120 minutes post-exposure, and 24-36 hours post-exposure.)
Investigators
Study Sites (2)
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