Methods and Materials:
A retrospective cohort review was performed on all entries in the
Extracorporeal Life Support Organization (ELSO) registry from November
1, 2010 to July 31, 2017 at the Massachusetts General Hospital (MGH), a
large quaternary care center in Boston, Massachusetts (USA). Patients
who were undergoing CPR in hospital at the time of ECMO initiation as
documented in the procedural report were included. Patients who
underwent ECMO cannulation but for whom immediate durable flow through
the ECMO circuit could not be initiated were excluded. Baseline
characteristics were extracted from the medical record. The study was
approved by the Partners Institutional Review Board.
This study’s primary outcome was survival to hospital discharge.
Etiology of cardiac arrest was adjudicated by two reviewers (NM & LXM)
and categorized by cardiac origin ( defined as an etiology of acute
coronary syndrome, primary arrhythmia in the absence of overlapping
etiology, acute heart failure, and tamponade) or non-cardiac origin
(defined as pulmonary embolism, drug toxicity, sepsis, perioperative
shock, or air embolism). When multiple potential etiologies were
present, the primary cause as adjudicated by the care team was selected.
Cardiac arrest rhythm was ascertained from the procedural report and
categorized as either pulseless ventricular tachycardia/ventricular
fibrillation (VT/VF) or pulseless electrical activity (PEA).
ECMO-related complications were assessed. Major bleeding was defined as
Bleeding Academic Research Consortium category 3-527.
Additional outcomes assessed included de novo renal replacement therapy,
cerebrovascular events, limb ischemia, and cerebral performance category
(CPC). CPC scores 1 through 5 correlated to good cerebral performance
(able to work, minor deficits), moderate cerebral disability (persistent
deficits but mostly independent), severe cerebral disability (dependent
on others), coma or vegetative state, and brain death,
respectively28.
Descriptive statistics were used to quantify baseline patient
characteristics, clinical features, ECMO utilization, and survival
rates. Categorical variables were reported as counts and percentages and
compared using the Fisher’s exact test. Continuous variables were
reported as medians with interquartile ranges and compared with the
Wilcoxon two-sample test. Statistical significance was assessed at a
nominal α level of 0.05. All reported P values were 2-sided. Analysis
was performed in R 4.0.0 (R Core Team, 2020).