Clinical features, ventilatory management, and outcome of ARDS caused by COVID-19 are similar to other causes of ARDS

Abstract

Purpose: The main characteristics of mechanically ventilated ARDS patients affected with COVID-19, and the adherence to lung-protective ventilation strategies are not well known. We describe characteristics and outcomes of confirmed ARDS in COVID-19 patients managed with invasive mechanical ventilation (MV).

Methods: This is a multicenter, prospective, observational study in consecutive, mechanically ventilated patients with ARDS (as defined by the Berlin criteria) affected with with COVID-19 (confirmed SARS-CoV-2 infection in nasal or pharyngeal swab specimens), admitted to a network of 36 Spanish and Andorran intensive care units (ICUs) between March 12 and June 1, 2020. We examined the clinical features, ventilatory management, and clinical outcomes of COVID-19 ARDS patients, and compared some results with other relevant studies in non-COVID-19 ARDS patients.

Results: A total of 742 patients were analysed with complete 28-day outcome data: 128 (17.1%) with mild, 331 (44.6%) with moderate, and 283 (38.1%) with severe ARDS. At baseline, defined as the first day on invasive MV, median (IQR) values were: tidal volume 6.9 (6.3-7.8) ml/kg predicted body weight, positive end-expiratory pressure 12 (11-14) cmH₂O. Values of respiratory system compliance 35 (27-45) ml/cmH₂O, plateau pressure 25 (22-29) cmH₂O, and driving pressure 12 (10-16) cmH₂O were similar to values from non-COVID-19 ARDS patients observed in other studies. Recruitment maneuvers, prone position and neuromuscular blocking agents were used in 79%, 76% and 72% of patients, respectively. The risk of 28-day mortality was lower in mild ARDS [hazard ratio (RR) 0.56 (95% CI 0.33-0.93), p = 0.026] and moderate ARDS [hazard ratio (RR) 0.69 (95% CI 0.47-0.97), p = 0.035] when compared to severe ARDS. The 28-day mortality was similar to other observational studies in non-COVID-19 ARDS patients.

Conclusions: In this large series, COVID-19 ARDS patients have features similar to other causes of ARDS, compliance with lung-protective ventilation was high, and the risk of 28-day mortality increased with the degree of ARDS severity.

Trial registration: ClinicalTrials.gov NCT04368975.

Keywords: Acute respiratory distress syndrome; Coronavirus; Mechanical ventilation; Outcome.

Fig. 1

Patients flowchart. A total of 742 patients were followed-up for 28 days and stratified as mild, moderate and severe ARDS based on baseline PaO₂/FiO₂. ARDS acute respiratory distress syndrome, PaO₂/FiO₂ partial pressure of arterial oxygen to inspiratory oxygen fraction ration

Fig. 2

Top panel: daily distribution of patients under invasive mechanical ventilation by ARDS severity (mild, moderate, and severe) from day 1 to 28. Mild: PaO₂/FiO₂ < 100 mmHg, moderate: PaO₂/FiO₂ 100–200 mmHg, severe: PaO₂/FiO₂ > 201 and < 300 mmHg. Bottom panel: Daily mean (95% confidence interval) of respiratory system compliance in cmH₂O. Only patients under controlled mechanical ventilation are included. ARDS acute respiratory distress syndrome, PaO₂/FiO₂ partial pressure of arterial oxygen to inspiratory oxygen fraction ration, MV mechanical ventilation

Fig. 3

Time to event curves using Kaplan–Meier with univariable Cox regression. The probability of discontinuation from mechanical ventilation and the probability of ICU discharge increase with decreasing ARDS. The 28-day probability of death was higher in severe ARDS. ICU intensive care unit, ARDS acute respiratory distress syndrome