Differential Effect of PEEP on Overweight Individuals in a Pediatric ARDS Cohort

Background: There is limited data regarding mechanical ventilation practices in overweight patients with PARDS. Our study aims to understand the differences in ventilator management and its effect on clinical outcomes in overweight and non-overweight PARDS patients. We hypothesize that the use of PEEP had a differential effect on overweight vs non-overweight PARDS patients. Methods: This study analyzed patients recruited based on the PALICC 2015 definition of PARDS. Correlation between ventilator settings and BMI Z-score were studied using Spearman correlation. Overweight status was defined as BMI Z-score ≥ +1. Ventilator settings were analyzed in overweight vs. non-overweight groups and the association between PEEP with PICU mortality and 28-day ventilator free days was studied using multivariable regression, adjusting for age and oxygenation index and stratified by overweight status Results: 132 patients with PARDS were included in this study. There were no clinical or statistical differences in ventilator settings comparing overweight vs non-overweight patients, though there was a trend towards the use of higher PEEP with patients of higher BMI Z-scores (r = 0.19, P = .056). Among patients who were not overweight, there was a significant difference in mortality comparing patients who were adherent vs. not adherent to the PEEP/FIO2 grid [0 (0%), vs 9 (17.5%); P = .053], however, this effect was missing in the overweight group. Similarly, VFD was also improved comparing patients who were adherent vs. not adherent [21 (18.5, 23) vs. 15 (0, 21); P = .007] only in the non-overweight group. In the multivariable analysis, adherence to the PEEP/FIO2 grid was only associated with improved VFD [adjusted beta 6.05 (95% confidence interval 0.43, 11.66); P = .035] in non-overweight patients. Conclusions: The beneficial effects of the PEEP/FIO2 grid were only observed in non-overweight patients. A larger cohort is required to confirm these findings and to determine the mechanism of this effect.