Ventilatory Parameters Measured After One Week of Mechanical Ventilation and Survival in COVID-19–Related ARDS

BACKGROUND: Ventilatory parameters measured soon after initiation of mechanical ventilation have limited ability to predict outcome of COVID-19–related ARDS. We hypothesized that ventilatory parameters measured after one week of mechanical ventilation might differ between survivors and non-survivors. METHODS: One hundred twenty-seven subjects with COVID-related ARDS had gas exchange and lung mechanics assessed on the day of intubation and one week later. The main parameters of interest were PaO2 /FIO2, ventilatory ratio (VR), respiratory system compliance (CRS), and a composite score that was calculated as (PaO2 /FIO2 /100) 3 CRS/VR. The primary outcome was death in the ICU. RESULTS: Of the 127 subjects, 42 (33%) died in the ICU and 85 (67%) were successfully extubated. On the day of intubation, PaO2 /FIO2, CRS, and composite score of survivors and non-survivors were similar, but survivors had a lower VR. At one week, as compared to survivors, non-survivors had a significantly higher VR (2.04 6 0.76 vs 1.60 6 0.43, P < .001), lower CRS (27.4 6 6.4 mL/cm H2O vs 32.4 6 9.3 mL/cm H2O, P 5 .002), and lower composite score (20.6 6 11.9 vs 34.5 6 18.6, P < .001), with no statistically significant difference in PaO2 /FIO2 (137 6 49 vs 155 6 48, P 5 .08). CONCLUSIONS: In subjects with COVID ARDS, parameters that reflect dead space (VR), lung mechanics (CRS), and a combined score that included PaO2 /FIO2, VR, and CRS differed between survivors and non-survivors after one week of mechanical ventilation but with considerable overlap of values between survivors and non-survivors.