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.