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Table 1 Recommended ancillary testing

From: Brain death: a clinical overview

Test Procedure Comments
Digital subtraction angiography (DSA) Lack of arterial contrast opacification where the carotid and vertebral arteries enter the skull correlates to absence of perfusion
External carotid circulation will appear intact
Historically considered the gold/reference standard. Limited by available expertise, skill, cost, and transfer to an operating room/angio suite
Limited by decompressive procedures that may lower intracranial pressure
Radionuclide imaging Lipophobic or lipophilic technetium-based compounds produce signal as they circulate intracranially (lipophobic), or pass through the blood–brain barrier and are metabolized by metabolically active parenchyma (lipophilic) Lipophobic compounds inadequately demonstrate flow through the posterior fossa, thus lipophilic preferred
Tomographic processing of lipophilic compounds is commonly known as single photon emission computed tomography (SPECT) and is increasingly used as a reference standard, but cannot be done at the bedside
Transcranial Doppler (TCD) Allows measurement of dynamic changes to brain blood flow and confirms circulatory arrest when performed in the anterior and posterior circulations
Systolic spokes and oscillating flow appearance indicate obstruction to blood flow
Portable, easily performed at the bedside
10% of patients have inadequate bone windows, thus the absence of a waveform necessitates reference to a previous study that demonstrated perfusion
2 exams suggested at least 30 min apart
Limited by decompressive procedures that may lower intracranial pressure
Not suggested in pediatric patients