Study Design and Participants

This is a secondary analysis of a prospective observational study of neonatal and pediatric patients <18 years who were cannulated onto ECMO for any indication within an academic, urban, quaternary care pediatric intensive care unit between July 2010 and June 2015. Details on the parent two-center prospective cohort have been published.⁷ Briefly, written informed consent was obtained from guardians within 24 hours of cannulation. We excluded patients cannulated at an outside hospital, patients on ECMO for less than 6 hours, those with limitation of care discussions within 24 hours of cannulation, non-index ECMO cannulations during the same hospitalization, and patients in foster care or wards of the state. For this secondary analysis, we further excluded those on venovenous ECMO support, those with no echocardiogram studies around the time of cannulation and separation from ECMO, and those with ECMO courses <48 hours and only one plasma sample collected. This study was approved by the Johns Hopkins Institutional Review Board.

Demographic and clinical data were collected prospectively.⁷ We reviewed echocardiograms obtained for clinical purposes that were closest to cannulation and time of separation from ECMO. If a patient had multiple echocardiograms within 24 hours of cannulation or separation from ECMO, the echocardiogram indicating the most severe dysfunction was included in the analysis. We reviewed clinical echocardiogram reports and two coauthors (MG and MN) further reviewed images to achieve consensus for qualitative assessment of right ventricular or left ventricular function (mild, moderate, or severe dysfunction).

The primary outcome was inability to separate from ECMO defined as mortality on ECMO, transition to ventricular assist device, or cardiac transplant. The secondary outcome was presence of any left or right cardiac dysfunction at the end of the ECMO course.

The ECMO circuits during the study period consisted of custom-packed 1/4- or 3/8-inch flexible PVC tubing (Medtronic, Minneapolis, MN) with a silicone reservoir, a bladderbox (Johns Hopkins Hospital, Baltimore, MD), a 0.8 m² to 4.5 m² membrane oxygenator (Medtronic), a heat exchanger (Medtronic), and a roller pump (Sorin Cardiovascular USA, Arvada, CO) up to January 2011, and the Quadrox-ID oxygenator (Maquet Cardiopulmonary, Rastatt, Germany), the Better Bladder (Coastal Life Systems Inc, San Antonio, TX), and a roller pump (for infants <10 kg) or centrifugal pump (for children ≥10 kg) (Sorin), thereafter.