Temporal trends in respiratory parameters and their association with mortality in mechanically ventilated patients with COVID-19-related acute respiratory distress syndrome: the importance of driving pressure.
Academic Article
Overview
abstract
BACKGROUND: There are limited data on temporal trends of respiratory parameters and their association with mortality in patients with acute respiratory distress syndrome (ARDS). We sought to describe temporal trends of respiratory parameters in mechanically ventilated patients with COVID-19-related ARDS and their relationship with mortality. METHODS: Patients with COVID-19-related ARDS, undergoing mechanical ventilation, admitted to an intensive care unit (ICU), were included. Data on respiratory parameters were collected on ICU admission (day 1) and on days 3, 5, 10, 14, and 21 thereafter. Linear mixed effects and time-dependent Cox proportional hazards regression analyses were conducted to assess the association between temporal trends of respiratory parameters and mortality. RESULTS: Data from 585 patients [median (IQR) age 70 [60-77] years, 387 (66%) males] were analyzed. All-cause ICU mortality was 57%. Average values of plateau pressure, respiratory rate, P(A-a)O2, and PaCO2 were higher and increased more over time, in non-survivors compared to survivors (regression coefficient r = 1.33, P = 0.005, r = 1.23, P = 0.01, r=67.75, P < 0.001, and r=4.88, P < 0.001, respectively). Average values of respiratory system compliance and PaO2/FiO2 ratio were lower and decreased more over time, in non-survivors compared to the survivors (r=-3.49, P = 0.002, and r=-38.03, P < 0.001, respectively). Finally, the average value of driving pressure was higher across time in non-survivors compared to the survivors (r=1.09, P = 0.005), and was independently associated with ICU mortality (Hazard ratio=1.04, 95% confidence interval: 1.01-1.08, P = 0.044). CONCLUSION: Temporal trends of respiratory parameters were associated with mortality of mechanically ventilated patients with COVID-19-related ARDS. Among respiratory mechanics variables, driving pressure was the only parameter independently associated with mortality when modeled as a time-updated covariate.
