A retrospective analysis of initial ventilator settings and lung mechanics in COVID-19 patients requiring mechanical ventilation

Abstract

Background: During the COVID-19 pandemic, variability in lung mechanics challenged the conventional management of COVID-19-related hypoxemic respiratory failure, particularly on initial presentation. This study evaluated the association between respiratory system mechanics and ventilator settings on day 1 of intubation and mechanical ventilation with mortality in a large cohort of patients with COVID-19-related hypoxemic respiratory failure.

Methods: A multicenter, retrospective analysis of 1,563 mechanically ventilated patients with COVID-19 admitted to the ICU across sixteen hospitals in North Texas between 2020 and 2023. Demographics, treatments, respiratory system mechanics, and ventilator settings on day 1 were collected. All-cause hospital mortality was reported.

Results: Overall mortality in the study population was 54.4% with higher mortality observed in patients with increasingly abnormal respiratory system mechanics and gas exchange. We also observed a higher mortality with PP >30 cmH2O (64.5% vs. 50.0%, p<0.001) and DP >14 cmH2O (56.8% vs. 49.5%, p<0.007). Unexpectedly, we observed lower mortality with higher TV: 43.4% in patients receiving >8 cc/kg PBW and 59.4% mortality in patients receiving <8 cc/kg (p<0.001).

Conclusion: Our retrospective study confirmed the relationship between abnormal respiratory mechanics and gas exchange with mortality reported by many others in COVID-19 respiratory failure. Exposure to mechanical ventilation parameters exceeding established injury thresholds (PP >30 cmH2O and DP >14 cmH2O) was also associated with increased mortality. The lower mortality in patients receiving TVs >8 cc/kg PBW likely reflected initial clinician judgment prioritizing minute ventilation needs in patients perceived to be at lower risk for ventilator-induced lung injury.