The use of apnea test and brain death determination in patients on extracorporeal membrane oxygenation: A systematic review

The Challenges of Apnea Tests in the Determination of Brain Death in Child Patient on Extracorporeal Membrane Oxygenation

“…Apnea test is an essential component to confirm BD. In patients on ECMO support, however, the AT as described in the American Academy of Neurology practice guidelines is inapplicable (11). The primary goal of AT is to induce hypercapnia to a threshold high enough to stimulate the respiratory drive.…”

“…It is difficult to perform an apnea test and increase arterial CO 2 partial pressure (PaCO 2 ) during ECMO, because carbon dioxide removal is performed, to a great degree, by the membrane of ECMO. Methods of inducing hypercapnia reflect the factors affecting PaCO 2 in patients on ECMO, which include decreasing the ECMO sweep flow, adding CO 2 to the gas mixture, and providing CO 2 through the ventilator (11). A systematic review reported exposures that 88 patients in 19 studies were evaluated using the AT while on ECMO.…”

Commentary: How to say goodbye

“…Neurologic complications during extracorporeal membrane oxygenation (ECMO) can be devastating. In this issue of the Journal, Migdady and colleagues 1 provide valuable insight into the vexing problem of determining brain death (BD) in patients on ECMO, which we increasingly encounter with the expanding use of ECMO for cardiopulmonary resuscitation (CPR) and other salvage applications. The authors systematically review 22 studies (with 177 patients) of BD determination when conventional apnea testing (AT) cannot sufficiently confirm BD, which is the case in about 20% of patients supported by ECMO.…”

How I do a brain death examination: the tools of the trade

“…Conventionally, time of death is the time of the second blood gas result. Complications, usually minor with good preparation, become major with bad or non-standard preparation [7][8][9][10]. Our decades-long experience with this oxygen diffusion technique has been safe and aborted in only 3% of 212 tests [9].…”

“…If blending is not available, CO 2 can only be increased by markedly diminishing sweep gas, but this technique risks hypoxia. Additionally, reducing the sweep gas increases the number of expensive blood gasses; it is anyone's guess where PaCO 2 will end up [8,10].…”