Late Breaking Abstract - Efficacy and safety of hydrogen-oxygen mixture in the emergency management of tracheal stenosis

Background: A medical hydrogen generator has been developed which allows for production of high concentration hydrogen gas to reduce airway resistance in the emergency management of acute severe tracheal stenosis, but evidences for clinical practice is insufficient. Aims: To evaluate the efficacy and safety of breathing a hydrogen-oxygen mixture (H 2 -O 2 ) in the emergency management of tracheal stenosis. Methods: 35 patients with acute severe tracheal stenosis were studied in four consecutive periods: breathing Air (O 2 : 21%) 15 min, H 2 -O 2 (H 2 : 66%) 15 min, N 2 O 2 (O 2 : 33%) 15 min, and H 2 -O 2 120 min. Effort to breathe, assessed by the diaphragm electromyography (EMGdi) was the main end point. Transdiaphragmatic pressure (Pdi), Borg score, vital signs, and impulse oscillometry (IOS) parameters were the secondary end points. The concentration of H 2 in the environment was obtained by a sensor. The adverse inhalation reaction was recorded. Results: All the patients presented a decrease in EMGdi under H 2 -O 2 . The mean reduction of the EMGdi was 10.53±6.83%, ranging from 1.34-25.89%. EMGdi differed significantly between H 2 -O 2 and N 2 O 2 (52.95±15.00 versus 42.46±13.90 versus 53.20±14.74 versus 42.50±14.12% for the four consecutive periods; F=3.41, P 2 -O 2 was 4.77±3.51cmH 2 O, ranging from 0.18-14.22 cmH 2 O. Breathing H 2 -O 2 significant improved Borg score and resistant parameters of IOS, whereas vital signs ware not modified. No adverse reaction occured in any patients. H 2 were undetectable in the environment during the whole procedure. Conclusions: Breathing H 2 -O 2 improves inspiratory effort in patient with acute severe tracheal stenosis, and the process is safe.