Table 3 The Epistemic Problems with brain death, and outline of objections with their main replies

Argument 1: Bedside tests do not confirm the loss of all brain functions: ongoing EEG, EP, and hypothalamic functions, stress responses, breathing at higher PaCO2, brainstem reflexes (often incorrectly labelled as ‘spinal’)

BD has withstood the test of time

-Circular: BD inevitably leads to withdrawal of life support.

-False: cases of reversibility are reported (see Table 4)

-Wrong question: not about the prognosis of BD, but about whether BD is death

Residual functions are not critical or clinical

-Ad hoc: why are pupillary reaction and corneal reflexes critical (reflecting ongoing integrative unity of the organism), while EEG and EP functions, neuroendocrine control, and breathing at PaCO2 well over 60mmHg are not?

-Circular: “critical functions are necessary for life, and death is the loss of critical functions”

-False: neuroendocrine control is a clinical function (just observe urine output)

-Self-defeating: only an argument for higher BD [the only function that cannot be replaced mechanically is consciousness]

Argument 2: bedside tests cannot diagnose the loss of all brain functions due to: confounders in all or an unknown number of cases [spinal cord injury during brain herniation; possible total locked-in syndrome; central thyroid and adrenal insufficiency; possible global ischemic penumbra; vaguely described other confounders]; apnea testing being contraindicated, self-fulfilling, and not fit for purpose [does not diagnose loss of medullary function]

Similar to BD, other diagnoses are made according to clinical judgment

-Not appropriate for the diagnosis of death: a final irreversible state with implications that leave no room for error

An ancillary test can confirm the diagnosis of BD

-EEG: only tests for superficial cortical function

-Radionuclide CBF test: poorly studied in terms of specificity for diagnosis of BD versus other severe brain/brainstem injuries. Cases reported of absent CBF with retained brain functions [including EEG, posturing, head-turning, and breathing].

-Unknown prevalence of global ischemic penumbra: Jahi McMath had absent CBF, but lack of brain destruction on MRI and may have emerged to the minimally conscious state.

Similar to epistemic claims about methods to diagnose death by circulatory criteria

-Tests to diagnose circulatory death are not debated; rather, when the irreversibility of circulatory death occurs is debated