Critical Care Explorations (Dec 2022)

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

  • Charles Terry, MD, MSCR,
  • Daniel Brinton, PhD,
  • Annie N. Simpson, PhD,
  • Katie Kirchoff, MS,
  • D. Clark Files, MD,
  • George Carter, MD,
  • Dee W. Ford, MD, MSCR,
  • Andrew J. Goodwin, MD, MSCR

DOI
https://doi.org/10.1097/CCE.0000000000000811
Journal volume & issue
Vol. 4, no. 12
p. e0811

Abstract

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Importance:. 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 (Ers) differ among normal/overweight (body mass index [BMI] < 30 kg/m2), 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 Ers 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 H2O (relative risk [RR], 1.51 [95% CI, 1.26–1.82]) and Ers greater than or equal to 2 cm H2O/(mL/kg) (RR, 1.31 [95% CI, 1.14–1.49]). Despite elevated DP and Ers, 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 ERS 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.