Materials and methods
expiratory occlusion
SECONDARY
The primary objective of this study was to characterize the correlation between ∆Pes and each of the following: Pocc, P0.1, PMI in mechanically ventilated children. Secondary objectives focused on finding the respective thresholds for Pocc, P0.1, and PMI that detect excessively high and low inspiratory effort.We performed secondary analysis of physiologic data from children on pressure control (PC) or pressure support (PS) ventilation, enrolled in an ongoing randomized trial testing a lung and diaphragm protective ventilation strategy (REDvent, R01HL124666) (Clinical Trials. gov NCT03266016) that uses esophageal manometry at Children’s Hospital Los Angeles (CHLA) [Physiologic waveforms of flow, esophageal pressure (Pes) and airway pressure (Paw) were recorded once daily. All patients were intubated with a cuffed endotracheal tube. For each day the patient remained intubated, a target of 3 inspiratory and 3 expiratory hold maneuvers were performed by using occlusion buttons on the ventilators. For analysis, all patients had to have evidence of spontaneous breathing, measured by negative deflection of the esophageal pressure waveform during inspiration. We used median values of the measures obtained from up to 3 inspiratory and expiratory occlusion maneuvers and the median ΔPes in up to 3 spontaneous PC and/or PS breaths at a time point near the occlusion maneuvers per test day. Data were selected for analysis at the waveform level, and inappropriate waveforms were excluded (Additional file Physiologic waveforms of airway pressure and esophageal pressure during the end-inspiratory (