The case against confirmatory tests for determining brain death in adults

Abstract

The determination of brain death is based on a comprehensive clinical assessment. A confirmatory test-at least, in adult patients in the United States-is not mandatory, but it typically is used as a safeguard or added when findings on clinical examination are unwontedly incomplete. In other countries, confirmatory tests are mandatory; in many, they are optional. These tests can be divided into those that test the brain's electrical function and those that test cerebral blood flow. A false-positive result (i.e., the test result suggests brain death, but clinically the patient does not meet the criteria) is not common but has been described for tests frequently used to determine brain death. A false-negative result (i.e., the test result suggests intact brain function, but clinically the patient meets the criteria) in one test may result in more confirmatory tests and no resolution when the test results diverge. Also, pathologic studies have shown that considerable areas of viable brain tissue may remain in patients who meet the clinical criteria of brain death, a fact that makes these tests less diagnostic. Confirmatory tests are residua from earlier days of refining comatose states. A comprehensive clinical examination, when performed by skilled examiners, should have perfect diagnostic accuracy.

Guidelines for the Determination of Brain Death in Infants and Children: An Update of the 1987 Task Force Recommendations

“…It is also important to note that spontaneous ventilation has been falsely reported to occur while patients were maintained on CPAP despite having the trigger sensitivity of the mechanical ventilator reduced to minimum levels. 48 Physician(s) performing apnea testing should continuously monitor the patient's heart rate, blood pressure, and oxygen saturation while observing for spontaneous respiratory effort throughout the entire procedure. PaCO 2 , measured by blood gas analysis, should be allowed to rise to Ն 20 mm Hg above the baseline PaCO 2 level and Ն 60 mm Hg.…”

“…Low to mid therapeutic levels of barbiturates should not preclude the use of EEG testing. 48 Evidence suggests that radionuclide CBF study can be used in patients with high dose barbiturate therapy to demonstrate absence of CBF. 52,53 Diagnostic Yield of the EEG in Suspected Brain Dead Children Appendix 4 summarizes EEG data from 12 studies in 485 suspected brain dead children in all age groups.…”

Unconsciousness state identification using phase information extracted by Wavelet and Hilbert transform

“…Particularly, extracting systematic features to distinguish coma and quasi brain death (QBD) states using wavelet convolution or Hilbert transform-based phase synchrony on group analysis EEG records is, to our knowledge, a new area of research. The point is to improve the diagnosis processes (variant from countries) for brain death by using less intrusive and heavy methods [2]. On a near real time basis, the algorithm can be used to monitor the evolution of the patients brain state and eventually detect significant brain state changes as it is not humanly possible to individually monitor 24/7 each patient in an intensive care unit (ICU).…”

Protracted cerebral circulatory arrest and cortical electrical silence coexisting with preserved respiratory drive and flexor motor response

“…1 The topic remains highly controversial. 2 It is our opinion that the reported specificity of tests confirming cerebral circulatory arrest may be overestimated. Only patients who already fulfil BSD criteria are usually tested.…”