Study Design and Data Source
This was a retrospective analysis of a single-center prospective cohort study as previously described13 who were admitted with PARDS between July 1, 2012, and April 30, 2018, requiring conventional invasive mechanical ventilation, and who had a clinically indicated echocardiogram performed within 24 hours of PARDS onset. Other inclusion criteria were availability of paired end tidal PetCO2and PaCO2 measurements as well as echocardiogram images of sufficient quality to perform RV strain analyses. Patients were excluded for PARDS onset outside of the study center PICU, chronic invasive mechanical ventilation, invasive mechanical ventilation >7 days, and for respiratory failure primarily secondary to congestive heart failure, fluid overload, or exacerbation of chronic lung disease. Patients with paired PetCO2 and PaCO2 values that yielded a negative AVDSf were also excluded. The study was approved by the Children’s Hospital of Philadelphia’s (CHOP) Institutional Review Board with a waiver of the need for informed consent.