Background Data on the lung respiratory mechanics and gas exchange in the time course of COVID-19-associated respiratory failure is limited. This study aimed to explore respiratory mechanics and gas exchange, the lung recruitability and risk of overdistension during the time course of mechanical ventilation. Methods This was a prospective observational study in critically ill mechanically ventilated patients ( n = 116) with COVID-19 admitted into Intensive Care Units of Sechenov University. The primary endpoints were: «optimum» positive end-expiratory pressure (PEEP) level balanced between the lowest driving pressure and the highest SpO 2 and number of patients with recruitable lung on Days 1 and 7 of mechanical ventilation. We measured driving pressure at different levels of PEEP (14, 12, 10 and 8 cmH 2 O) with preset tidal volume, and with the increase of tidal volume by 100 ml and 200 ml at preset PEEP level, and calculated static respiratory system compliance (C RS ), PaO 2 /FiO 2 , alveolar dead space and ventilatory ratio on Days 1, 3, 5, 7, 10, 14 and 21. Results The «optimum» PEEP levels on Day 1 were 11.0 (10.0–12.8) cmH 2 O and 10.0 (9.0–12.0) cmH 2 O on Day 7. Positive response to recruitment was observed on Day 1 in 27.6% and on Day 7 in 9.2% of patients. PEEP increase from 10 to 14 cmH 2 O and VT increase by 100 and 200 ml led to a significant decrease in C RS from Day 1 to Day 14 ( p < 0.05). Ventilatory ratio was 2.2 (1.7–2,7) in non-survivors and in 1.9 (1.6–2.6) survivors on Day 1 and decreased on Day 7 in survivors only ( p < 0.01). PaO 2 /FiO 2 was 105.5 (76.2–141.7) mmHg in non-survivors on Day 1 and 136.6 (106.7–160.8) in survivors ( p = 0.002). In survivors, PaO 2 /FiO 2 rose on Day 3 ( p = 0.008) and then between Days 7 and 10 ( p = 0.046). Conclusion Lung recruitability was low in COVID-19 and decreased during the course of the disease, but lung overdistension occurred at «intermediate» PEEP and VT levels. In survivors gas exchange improvements after Day 7 mismatched C RS . Trial registration ClinicalTrials.gov, NCT04445961 . Registered 24 June 2020—Retrospectively registered. Supplementary Information The online version contains supplementary material available at 10.1186/s12871-022-01600-0.
【저자키워드】 COVID-19, acute respiratory distress syndrome, PEEP, Volutrauma, Lung recruitability, Lung strain, 【초록키워드】 Respiratory failure, mechanical ventilation, prospective observational study, intensive care unit, lung, risk, improvement, Critically ill, Survivors, Gas exchange, Patient, Compliance, Respiratory system, recruitment, university, patients, primary endpoint, Respiratory mechanics, Positive end-expiratory pressure, Volume, supplementary material, Registered, ventilatory, significant decrease, dead, driving, survivor, alveolar, Recruitability, non-survivor, lowest, Course, Result, highest, occurred, the disease, Day, calculated, mechanically ventilated patient, PaO, with COVID-19, 【제목키워드】 Trial, mechanical ventilation, Noninvasive ventilation, lung, risk, Patient, lung recruitment, Potential,