Elevated Driving Pressure and Elastance Does Not Increase In-Hospital Mortality Among Obese and Severely Obese Patients With Ventilator Dependent Respiratory Failure.

Existing recommendations for mechanical ventilation are based on studies that under-sampled or excluded obese and severely obese individuals.
Objective: To determine if driving pressure (DP) and total respiratory system elastance (E _rs ) differ among normal/overweight (body mass index [BMI] < 30 kg/m ² ), obese, and severely obese ventilator-dependent respiratory failure (VDRF) patients and if there any associations with clinical outcomes.
Design Setting and Participants: Retrospective observational cohort study during 2016-2018 at two tertiary care academic medical centers using electronic health record data from the first 2 full days of mechanical ventilation. The cohort was stratified by BMI classes to measure median DP, time-weighted mean tidal volume, plateau pressure, and E _rs for each BMI class.
Setting and Participants: Mechanically ventilated patients in medical and surgical ICUs.
Main Outcomes and Measures: Primary outcome and effect measures included relative risk of in-hospital mortality, ventilator-free days, ICU length of stay, and hospital length of stay with multivariable adjustment.
Results: The cohort included 3,204 patients with 976 (30.4%) and 382 (11.9%) obese and severely obese patients, respectively. Severe obesity was associated with a DP greater than or equal to 15 cm H ₂ O (relative risk [RR], 1.51 [95% CI, 1.26-1.82]) and E _rs greater than or equal to 2 cm H ₂ O/(mL/kg) (RR, 1.31 [95% CI, 1.14-1.49]). Despite elevated DP and E _rs , there were no differences in in-hospital mortality, ventilator-free days, or ICU length of stay among all three groups.
Conclusions and Relevance: Despite higher DP and E _RS among obese and severely obese VDRF patients, there were no differences in in-hospital mortality or duration of mechanical ventilation, suggesting that DP has less prognostic value in obese and severely obese VDRF patients.
Competing Interests: The authors have disclosed that they do not have any potential conflicts of interest.
(Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)