OBJECTIVE: To review practices of brain death (BD) determination in patients on 
extracorporeal membrane oxygenation (ECMO).
METHODS: A systematic search was applied to PubMed and 6 electronic databases 
from inception to May 22, 2019. Studies reporting methods of BD assessment in 
adult patients (>18 years old) while on ECMO were included, after which data 
regarding BD assessment were extracted.
RESULTS: Twenty-two studies (n = 177 patients) met the inclusion criteria. 
Eighty-eight patients (50%) in 19 studies underwent the apnea test (AT); most 
commonly through decreasing the ECMO sweep flow in 14 studies (n = 42, 48%), 
followed by providing CO2 through the ventilator in 2 studies (n = 6, 7%), and 
providing CO2 through the ECMO oxygenator in 1 study (n = 1, 1%). The details of 
the AT were not reported in 2 studies (n = 39, 44%). In 19 patients (22%), the 
AT was nonconfirmatory due to hemodynamic instability, hypoxia, insufficient CO2 
rise, or unreliability of the AT. A total of 157 ancillary tests were performed, 
including electroencephalogram (62%), computed tomography angiography (22%), 
transcranial Doppler ultrasound (6%), cerebral blood flow nuclear study (5%), 
cerebral angiography (4%), and other (1%). Forty-seven patients (53% of patients 
with AT) with confirmatory AT still underwent additional ancillary for BD 
confirmation. Only 21 patients (12% of all patients) were declared brain-dead 
using confirmatory ATs alone without ancillary testing.
CONCLUSIONS: Performing AT for patients with ECMO was associated with high 
failure rate and hemodynamic complications. Our study highlights the variability 
in practice in regard to the AT and supports the use of ancillary tests to 
determine BD in patients on ECMO.