Table 5 Ancillary testing confounders/limitations [10, 20,21,22]
From: Quality improvement in the determination of death by neurologic criteria around the world
Test | Confounder/limitationa | Sensitivity/specificity |
|---|---|---|
Brain blood flow | ||
Computed tomography angiography | Requires transport to the scanner | 52–97%/100% |
Image variability based on injection technique | ||
Potential to miss a slow flow state | ||
Risk of nephrotoxicity | ||
Digital subtraction angiographyb | Requires transport to angiography suite | 100%/100% |
Risk of nephrotoxicity | ||
Image variability based on injection technique | ||
Magnetic resonance angiography | Requires transport to the scanner | 93–100%/100% |
Image variability based on injection technique | ||
Radionuclide angiographyb | Limited evaluation of brainstem | 99%/56% |
Radionuclide scintigraphyb | Requires transport to the scanner | Planar: 78%/100% SPECT: 88%/100% |
Planar imaging may have limited evaluation of brainstem | ||
Transcranial Doppler ultrasonographyb | Potential for technical difficulties in performance | 90%/98% |
Potential for lack of windows | ||
Electrophysiological function | ||
Electroencephalography | Risk of environmental artifact | 53–80%/97% |
Confounded by sedation, hypothermia and toxic-metabolic derangements | ||
Predominantly provides information about cortical function | ||
Evoked potentials-auditory | Can be absent in comatose patients with other intact brainstem reflexes | NA/NA |
Confounded by sedation, hypothermia, isolated eighth nerve and brainstem lesions | ||
Only evaluates auditory pathways | ||
Performance/interpretation may be limited by experience | ||
Evoked potentials-somatosensory | Can be absent in comatose patients with ongoing brain function | 100%/78% |
Confounded by cervical spine injury, isolated brainstem lesions, sedation and hypothermia | ||
Only evaluates somatosensory pathways | ||
Performance/interpretation may be limited by experience | ||
Evoked potentials-visual | Can be absent in comatose patients with ongoing brain function | NA/NA |
Confounded by sedation, retinal or optic nerve lesions | ||
Only evaluates visual pathways | ||
Performance/interpretation may be limited by experience | ||