Methodology
The Nebraska ECMO Research Database (NERD) is a collection of data points for all ECMO patients at our institution since 2006, with data collected in a retrospective fashion. After institutional review board at the University of Nebraska Medical Center approved this study, data was collected from NERD for ECMO patients supported between 2006-2017. PC-ECMO support was defined as ECMO instituted within 72 hours of cardiotomy. Patients who were status post orthotopic heart transplant or left ventricular assist device placement were excluded. The type of support was defined as either veno-arterial (VA) or veno-venous (VV) ECMO, with subgroup analysis performed between these cohorts. The VV ECMO group included the temporary percutaneous right ventricular assist device configuration with an in-line oxygenator. Basic demographic information was collected. Operative data including type of operation performed, overall time in the operating room, cross-clamp (XC) and cardiopulmonary bypass (CPB) times, and red blood cell transfusions during the index operation were recorded. Frozen mediastinum status was defined as prior cardiac surgery or mediastinal radiation. Cannulation site (peripheral or central), time to cannulation (immediately versus delayed by up to 72 hours), and reoperation for hemorrhage were all examined.
Primary outcomes were ability to wean from ECMO and hospital survival. Secondary outcomes included hospital and intensive care lengths of stay and long-term survival status. Fisher’s exact test or the Mann-Whitney test, as appropriate to the data, was used to compare patient characteristics and outcomes between subsets of patients. Overall survival for patients discharged from the hospital was defined as the time from discharge to death from any cause and was determined by the Kaplan-Meier method. Comparisons of survival curves was done using the log-rank test All analyses were done using SAS Version 9.4 and a p-value < 0.05 was considered statistically significant.