Efficacy and safety of inhaled molecular hydrogen therapy in patients with respiratory failure due to chronic obstructive pulmonary disease exacerbation in post-COVID period

Molecular hydrogen (H 2 ) is a powerful antioxidant and anti-apoptotic agent. H 2 has been studied in a number of clinical studies in the recent years. The aim of this research was to investigate the efficacy and safety of H 2 inhalation therapy in patients with hypoxemic and hypercapnic respiratory failure (RF) against exacerbation of chronic obstructive pulmonary disease (COPD) in the post-COVID (Corona Virus Disease 2019) period. Methods . The randomized prospective parallel comparative study included patients (n = 60: 40 men aged 71.2 ± 1.8 years, 20 women aged 70.9 ± 2.8 years) with a post-COVID-19 exacerbation of COPD complicated by hypoxemic/hypercapnic RF. The patients were divided into 2 groups: group 1 (main) (n = 30: 18 men, 12 women), group 2 (control) (n = 30: 18 men, 12 women). To maintain arterial blood saturation ≥ 90 %, patients in both groups received respiratory support (non-invasive ventilation) using the Prisma 25ST device (Lowenstein Medical, Germany) in the BiPAP S/T mode (BiLevel Positive Airway Pressure Spontaneous/Time spontaneous/forced mode 20–24/4–6 cm H2O and O 2 , respectively; the fractional oxygen concentration in the inhaled gas mixture was ≥ 24%). In addition to standard treatment, patients in the main group received additional H2 therapy (Suisonia device, Japan) through a nasal cannula for 90 minutes daily for 14 days. Results. In patients of the main group, a decrease in the stiffness index was detected from 14.6 ± 1.2 to 6.2 ± 0.6 m/s, and the arterial blood lactate level – from 2.84 ± 0.1 to 0.02 ± 0.1 mmol/l (p < 0.001), the calculated shunt fraction Qs/Qt (venous admixture) – from 27.21 ± 3.4 to 7.14 ± 1.23 (p < 0.01) and an increase in the following parameters: reflection index – from 42.2 ± 2.0 to 66.2 ± 4.9% (p < 0.05), virus-specific IgG level – from 134 ± 125 to 669 ± 164 (p < 0. 05), blood flow velocity in arterioles – from 473 ± 108 to 868 ± 64 μm/s (p < 0.05), blood flow velocity in venules – from 299 ± 56 to 862 ± 69 μm/s (p < 0.05), the 6-minute walk distance – from 57.1 ± 4.4 to 328.9 ± 33.7 m (p < 0.05). Conclusion. H 2 inhalations were safe and increased the therapeutic effect when added to standard therapy for patients with hypoxemic and hypercapnic RF during exacerbation of COPD in the post-COVID period.