Study designs of evaluations included in the review
Prospective studies were eligible for inclusion. Case reports and reviews were excluded.
Specific interventions included in the review
Studies that assessed TCD flow patterns and specified a persistent intracranial flow pattern specific for cerebral circulatory arrest (oscillating flow or systolic spikes) were eligible for inclusion. Studies that only examined extracranial vessels were excluded. The vessels examined by the included studies were the middle cerebral artery, basilar artery, vertebral artery and internal carotid artery.
Reference standard test against which the new test was compared
Studies that included a specified reference standard and in which brain death was defined as non-reactive coma with complete loss of the brain-stem reflexes and apnoea were eligible for inclusion. The reference standards used in the included studies were clinical criteria alone or in combination with cerebral angiography, electroencephalogram or radionuclide scan.
Participants included in the review
Studies of neonates or infants (age under 1 year) were excluded. Details were only provided of patients who received a false-positive diagnosis.
Outcomes assessed in the review
Studies had to report extractable data for patients classified as brain dead or non-brain dead. The outcomes reported in the review were the sensitivity and specificity. Some studies only reported data on sensitivity.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.