What are the evidence-based guidelines for determining brain death in adult patients on Extracorporeal Membrane Oxygenation (ECMO)?

From the Guidelines

The determination of brain death in adult patients on Extracorporeal Membrane Oxygenation (ECMO) should be based on a systematic approach that includes prerequisite conditions, neurological examination, and appropriate ancillary testing, as recommended by the most recent consensus guidelines 1. To determine brain death in adult ECMO patients, clinicians should first establish an irreversible cause of coma, exclude confounders such as hypothermia, severe metabolic or endocrine disturbances, and sedative medications, and ensure adequate blood pressure (typically mean arterial pressure >60 mmHg). The clinical examination should demonstrate absence of all brainstem reflexes, including pupillary, corneal, oculocephalic, oculovestibular, and gag reflexes, as well as absence of spontaneous respiration. For ECMO patients specifically, apnea testing presents unique challenges due to the extracorporeal circuit, and modified apnea testing can be performed by adjusting the sweep gas flow to allow PaCO2 to rise above 60 mmHg while maintaining oxygenation, as suggested by recent guidelines 1. If apnea testing cannot be safely performed, ancillary testing becomes mandatory, and acceptable ancillary tests include cerebral angiography showing absence of intracranial circulation, electroencephalography showing electrocerebral silence, transcranial Doppler showing absent cerebral blood flow, or nuclear medicine perfusion studies demonstrating absence of cerebral perfusion 1. Some key points to consider when determining brain death in ECMO patients include:

• Maintaining hemodynamic stability during testing
• Recognizing that the ECMO circuit itself may complicate interpretation of some tests
• Using a multimodality, multidisciplinary approach for neurological prognostication, including clinical/neurological examination, electrophysiological tests, and neuroimaging 1
• Avoiding the use of any single factor/tool as the sole indicator for patient prognosis 1 The determination should be made by physicians experienced in both neurological assessment and ECMO management, with at least two separate examinations typically performed 6-24 hours apart depending on institutional protocols.

From the Research

Determining Brain Death in Adult Patients on ECMO

• The determination of brain death in adult patients on Extracorporeal Membrane Oxygenation (ECMO) is a complex process, with various challenges and limitations 2, 3, 4, 5, 6.
• Apnea testing is a crucial component of brain death determination, but it can be difficult to perform in patients on ECMO due to the risk of hypoxia and hemodynamic instability 2, 4, 6.
• Several studies have proposed modifications to the apnea test to make it safer and more reliable in patients on ECMO, such as decreasing the ECMO sweep gas flow and increasing oxygen delivery 4, 6.
• Ancillary tests, such as electroencephalogram, computed tomography angiography, and transcranial Doppler ultrasound, are often used to support the diagnosis of brain death in patients on ECMO, especially when the apnea test is nonconfirmatory or cannot be performed 3, 6.
• The use of ancillary tests can help to increase the accuracy of brain death determination in patients on ECMO, but the variability in practice and the lack of standardized protocols can make it challenging to determine brain death in these patients 3, 5, 6.

Apnea Testing in Patients on ECMO

• Apnea testing can be performed in patients on ECMO, but it requires careful consideration of the patient's hemodynamic and respiratory status 2, 4, 6.
• Decreasing the ECMO sweep gas flow and increasing oxygen delivery can help to make the apnea test safer and more reliable in patients on ECMO 4, 6.
• The apnea test should be performed by experienced clinicians who are familiar with the patient's condition and the ECMO equipment 2, 3, 4.
• The use of ancillary tests can help to support the diagnosis of brain death in patients on ECMO, especially when the apnea test is nonconfirmatory or cannot be performed 3, 6.

Ancillary Tests for Brain Death Determination

• Ancillary tests, such as electroencephalogram, computed tomography angiography, and transcranial Doppler ultrasound, can be used to support the diagnosis of brain death in patients on ECMO 3, 6.
• These tests can help to increase the accuracy of brain death determination in patients on ECMO, especially when the apnea test is nonconfirmatory or cannot be performed 3, 6.
• The choice of ancillary test depends on the patient's condition and the availability of equipment and expertise 3, 6.
• The use of ancillary tests should be guided by standardized protocols and clinical guidelines to ensure consistency and accuracy in brain death determination 5, 6.