Can Acute Inhalation Of Hydrogen Gas Reduce Eucapnic Voluntary Hyperpnoea-induced Fall In Forced Expiratory Volume?

Hydrogen gas inhalation has demonstrated antioxidant and anti-inflammatory effects in animal models of asthma. To date, limited research has been conducted in humans. With no reported side effects, it is a safe and potentially effective therapy in the management of asthma and exercise induced bronchoconstriction (EIB). PURPOSE: To determine whether acute inhalation of hydrogen gas reduces the greatest fall in forced expiratory volume in one second (∆FEV1 max) following an indirect airway provocation (Eucapnic Voluntary Hyperpnoea (EVH)) challenge in people with asthma/EIB. METHOD: Nine participants (age: 26 ± 9 years; height: 174 ± 11 cm; body mass: 80 ± 19 kg; male = 5; female = 4) with asthma/EIB were recruited. As previously prescribed by their physician, throughout the study all participants remained on inhaled short-acting β2-agonists, with six taking daily inhaled corticosteroids. Baseline spirometry and fractional exhaled nitric oxide (FeNO) were measured. In a double-blind crossover design, participants inhaled through a nasal cannula hydrogen gas (HYD) (67% hydrogen and 33% oxygen) or placebo gas (PLA) (atmospheric air) for 60 minutes. Participants then completed a EVH challenge (6 minutes of inhaling 21% oxygen, 5% carbon dioxide, balance nitrogen) at a target ventilation rate of 85% predicted maximal voluntary ventilation ([%MVV] 30 x FEV1). Immediately post-EVH, participants inhaled the same gas (HYD or PLA) while spirometry was measured in duplicate at 3, 5, 7, 10 and 15 minutes. A positive response was deemed a fall in FEV1 ≥ 10% at two consecutive time points. Group comparisons were made using paired samples t-tests and repeated measures ANOVA. RESULTS: Physiological and psychological measures were similar between the conditions (HYD vs PLA, respectively; %MVV: 73 ± 7% vs 69 ± 9%, p = 0.19; ∆FEV1 max post-EVH challenge: -18.88 ± 7.41 vs -17.50 ± 5.48%, p = 0.39; perception of breathlessness post-EVH challenge: 3.56 ± 1.13 vs 3.67 ± 1.66, p = 0.76). CONCLUSION: Acute inhalation of hydrogen gas when used alongside prescribed inhalers does not reduce ∆FEV1 max following an EVH challenge in people with asthma/EIB. Future research should investigate different inhalation timings and the effect on airway inflammation and oxidative stress markers. This work was supported by a grant from Osmio Water, Kent, UK.