LAUSR

Background: Hydrogen-oxygen mixture (H₂-O₂) may reduce airway resistance in patients with acute severe tracheal stenosis, yet data supporting the clinical use of H₂-O₂ are insufficient. Objectives: To evaluate the efficacy and safety of breathing H₂-O₂ in acute severe tracheal stenosis. Methods: Thirty-five consecutive patients with severe acute tracheal stenosis were recruited in this prospective self-control study. Air, H₂-O₂ and O₂ inhalation was given in 4 consecutive breathing steps: air for 15 min, H₂-O₂ (6 L per min, H₂:O₂ = 2: 1) for 15 min, oxygen (3 L per min) for 15 min, and H₂-O₂ for 120 min. The primary endpoint was inspiratory effort as assessed by diaphragm electromyography (EMGdi); the secondary endpoints were transdiaphragmatic pressure (Pdi), Borg score, vital signs, and impulse oscillometry (IOS). The concentration of H₂ in the ambient environment was obtained with 12 monitors. Adverse reactions during the inhalation were recorded. Results: The mean reduction in the EMGdi under H₂-O₂ was 10.53 ± 6.83%. The EMGdi significantly decreased during 2 H₂-O₂ inhalation steps (Steps 2 and 4) compared with air (Step 1) and O₂ (Step 3) (52.95 ± 15.00 vs. 42.46 ± 13.90 vs. 53.20 ± 14.74 vs. 42.50 ± 14.12% for Steps 1 through 4, p < 0.05). The mean reduction in the Pdi under H₂-O₂ was 4.77 ± 3.51 cmH₂O. Breathing H₂-O₂ significantly improved the Borg score and resistance parameters of IOS but not vital signs. No adverse reactions occurred. H₂ was undetectable in the environment throughout the procedure. Conclusions: Breathing H₂-O₂ may reduce the inspiratory effort in patients with acute severe tracheal stenosis and can be used for this purpose safely.