ABSTRACT
Objectives:
To evaluate the factors associated with mortality in mechanically ventilated patients with acute respiratory distress syndrome due to COVID-19.
Methods:
This was a retrospective, multicenter cohort study that included 425 mechanically ventilated adult patients with COVID-19 admitted to 4 intensive care units. Clinical data comprising the SOFA score, laboratory data and mechanical characteristics of the respiratory system were collected in a standardized way immediately after the start of invasive mechanical ventilation. The risk factors for death were analyzed using Cox regression to estimate the risk ratios and their respective 95%CIs.
Results:
Body mass index (RR 1.17; 95%CI 1.11 - 1.20; p < 0.001), SOFA score (RR 1.39; 95%CI 1.31 - 1.49; p < 0.001) and driving pressure (RR 1.24; 95%CI 1.21 - 1.29; p < 0.001) were considered independent factors associated with mortality in mechanically ventilated patients with acute respiratory distress syndrome due to COVID-19. Respiratory system compliance (RR 0.92; 95%CI 0.90 - 0.93; p < 0.001) was associated with lower mortality. The comparative analysis of the survival curves indicated that patients with respiratory system compliance (< 30mL/cmH2O), a higher SOFA score (> 5 points) and higher driving pressure (> 14cmH2O) were more significantly associated with the outcome of death at 28 days and 60 days.
Conclusion:
Patients with a body mass index > 32kg/m2, respiratory system compliance < 30mL/cmH2O, driving pressure > 14cmH2O and SOFA score > 5.8 immediately after the initiation of invasive ventilatory support had worse outcomes, and independent risk factors were associated with higher mortality in this population.
Keywords:
Respiratory distress syndrome; COVID-19; Coronavirus infections; SARS-CoV-2; Respiration; artificial; Respiratory mechanics; Mortality
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SARS-CoV-2 - severe acute respiratory syndrome coronavirus 2; MV - mechanical ventilation; ARDS - acute respiratory distress syndrome; OTI - orotracheal intubation; ICU - intensive care unit; SOFA - Sequential Organ Failure Assessment; VCV - volume controlled ventilation; Vt - tidal volume; NMB - neuromuscular blocking agent; PEEP - positive end-expiratory pressure; RR - respiratory rate; PaCO2 - partial pressure of carbon dioxide; FiO2 - fraction of inspired oxygen; PaO2 - partial pressure of oxygen; SaO2 - oxygen saturation.
Patients were stratified into groups of low compliance, intermediate compliance and high respiratory system compliance.Vt - tidal volume; 95%CI - 95% confidence interval; LC - low compliance; IC - intermediate compliance; HC - high compliance; rs - respiratory system.
SOFA - Sequential Organ Failure Assessment.
* Patients with SOFA ≥ 5 points had significantly lower 28-day and 60-day survival than did patients with SOFA < 5 points.SOFA - Sequential Organ Failure Assessment.
* Patients with a driving pressure ³ of 14 cmH2O had significantly lower 28-day survival and 60-day survival than did patients with a driving pressure < 14cmH2O.
Crs - respiratory system compliance.
Comparisons were established using the log rank test, considering p < 0.05 as significant and with the differences between the Kaplan-Meier estimators contained within the 95% confidence interval. * Patients with respiratory system compliance < 36mL/cmH2O had significantly lower 28-day and 60-day survival than did patients with Crs ≥ 36mL/cmH2O.Crs - respiratory system compliance.
* The low compliance group had significantly lower 28-day and 60-day survival than did the IC group; † The intermediate compliance group had significantly lower 28-day and 60-day survival than did the high compliance group. rs - respiratory system; LC - low compliance; IC - intermediate compliance; HC - high compliance.