Abstract
Emerging evidence suggests the potential importance of inspiratory driving pressure (DP) and respiratory system elastance (E(RS)) on outcomes among patients with the acute respiratory distress syndrome. Their association with outcomes among heterogeneous populations outside of a controlled clinical trial is underexplored. We used electronic health record (EHR) data to characterize the associations of DP and E(RS) with clinical outcomes in a real-world heterogenous population. DESIGN: Observational cohort study. SETTING: Fourteen ICUs in two quaternary academic medical centers. PATIENTS: Adult patients who received mechanical ventilation for more than 48 hours and less than 30 days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: EHR data from 4,233 ventilated patients from 2016 to 2018 were extracted, harmonized, and merged. A minority of the analytic cohort (37%) experienced a Pao(2)/Fio(2) of less than 300. A time-weighted mean exposure was calculated for ventilatory variables including tidal volume (V(T)), plateau pressures (P(PLAT)), DP, and E(RS). Lung-protective ventilation adherence was high (94% with V(T) < 8.5 mL/kg, time-weighted mean V(T) = 6. 8 mL/kg, 88% with P(PLAT) ≤ 30 cm H(2)O). Although time-weighted mean DP (12.2 cm H(2)O) and E(RS) (1.9 cm H(2)O/[mL/kg]) were modest, 29% and 39% of the cohort experienced a DP greater than 15 cm H(2)O or an E(RS) greater than 2 cm H(2)O/(mL/kg), respectively. Regression modeling with adjustment for relevant covariates determined that exposure to time-weighted mean DP (> 15 cm H(2)O) was associated with increased adjusted risk of mortality and reduced adjusted ventilator-free days independent of adherence to lung-protective ventilation. Similarly, exposure to time-weighted mean E(RS) greater than 2 cm H(2)O/(mL/kg) was associated with increased adjusted risk of mortality. CONCLUSIONS: Elevated DP and E(RS) are associated with increased risk of mortality among ventilated patients independent of severity of illness or oxygenation impairment. EHR data can enable assessment of time-weighted ventilator variables and their association with clinical outcomes in a multicenter real-world setting.