• Andrew G Percy, Garrett Keim, Anoopindar K Bhalla, and Nadir Yehya.
• Department of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.
• Anesthesiology. 2024 Aug 27.

BackgroundMechanical power (MP) is a summary variable quantifying the risk of ventilator-induced lung injury (VILI). The original MP equation was developed using square flow ventilation. However, most children are ventilated using decelerating flow. It is unclear whether MP differs according to mode of flow delivery. We compared MP in children with acute respiratory distress syndrome (ARDS) who received both square and decelerating flow ventilation.MethodsThis was a secondary analysis of a prospectively enrolled cohort of pediatric ARDS. Patients were ventilated on decelerating flow, and then placed in square flow and allowed to stabilize. Ventilator metrics from both modes were collected within 24 hours of ARDS onset. Paired t-tests were used to compare differences in MP between the modes.ResultsWe enrolled 185 subjects with a median oxygenation index of 9.5 (IQR 7, 13) and median age 8.3 years (IQR 1.8, 14). MP was lower in square flow (mean 0.46 J・min-1·Kg-1, SD 0.25, 95% CI 0.42-0.50) than in decelerating flow modes (mean 0.49 J・min-1·Kg-1, SD 0.28, 95% CI 0.45-0.53) with a mean difference of 0.03 J・min-1·Kg-1 (SD 0.08, 95% CI 0.014-0.038) (p<0.001). This result remained statistically significant when stratified by age < 2 years in square flow compared to decelerating flow and also when stratified by age >/= 2 years in square flow compared to decelerating flow. The elastic contribution in square flow was 70% and the resistive contribution was 30%.ConclusionsMP was marginally lower in square flow than in decelerating flow, although the clinical significance of this is unclear. Upward of 30% of MP may go towards overcoming resistance, regardless of age. This is nearly three-fold greater resistance compared to what has been reported in adults.Copyright © 2024 American Society of Anesthesiologists. All Rights Reserved.

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