Brain death is the irreversible loss of all activity in the brain, brainstem, and cerebellum, the part of the central nervous system that remains inside the skull. The clinical diagnosis of brain death should be supported by ancillary tests that provide information about cerebral blood flow or electrical activity in the brain. Some of the ancillary tests that evaluate cerebral blood flow include transcranial Doppler ultrasonography (TDUS), computed tomography (CT) angiography (CTA), and catheter-based cerebral angiography. This study hypothesized that Orbital Doppler ultrasonography (ODUS) alone is more effective than TDUS in detecting intracranial blood flow in diagnosing brain death. To this end, the investigators examined the results of ODUS in patients diagnosed as brain dead who underwent CT angiography.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
66
During measurement, Doppler settings were adjusted to detect low flow and the smallest available Doppler gate was used for all ODUS examinations. The imaging probe position for ODUS was used transversely and axially, and mean values were recorded. ODUS 10-18 MHz linear probe was used.
During the measurement, Doppler settings were adjusted to detect low flow, and the minor available Doppler gate was used for all TDUS examinations. For TDUS, a temporal window was used approximately 1 cm above the midpoint of the line joining the lateral palpebral fissure and the external auditory meatus. Transcranial Doppler ultrasonography ( TDUS) 3-5 MHz convex array probe was used.
Cranial Computed Tomography Angiography
University of Health Sciences,,Bursa Yuksek Ihtisas Training and Research Hospital,
Bursa, Turkey (Türkiye)
ODUS
Orbital artery Doppler ultrasound (ODUS) ODUS measurements: T1; when brain death testing started; T2; 12 hours after the first measurement, T3; before CT angiography, T4; after CT angiography Peak systolic velocity (PSV) cm/s , end-diastolic velocity (EDV) cm/s measurement results. The absence of diastolic flow, reverse diastolic flow (oscillatory flow), and resistive index \>1 were considered brain death.
Time frame: 30 minutes
Resistive index (RI)
The resistive index (RI) is a calculated flow parameter in ultrasound, derived from the maximum, minimum, and mean Doppler frequency shifts during a defined cardiac cycle. Along with the pulsatility index (PI), it is typically used to assess the resistance in a pulsatile vascular system.resistive index \>1 were considered brain death. RI measurements: T1; when brain death testing started; T2; 12 hours after the first measurement, T3; before CT angiography, T4; after CT angiography . RI = (PSV - EDV) / PSV PSV = peak systolic velocity and EDV = end-diastolic velocity.
Time frame: 30 minutes
Transcranial Doppler ultrasound (TDUS)
Transcranial Doppler ultrasound (TDUS) ultrasonography involves the use of a low-frequency (≤2 MHz) transducer, placed on the scalp, to insonate the basal cerebral arteries through relatively thin bone windows and to measure the cerebral blood flow velocity (CBFV) normal flow: mean = 55cm/sec. mild: \> 120cm/sec. moderate: \> 160cm/sec. s
Time frame: 30 minutes
Cerebral blood flow (CTA)
Transcranial Computed Tomography Angiography
Time frame: 40 minutes
Optic nerve diameter
Optic nerve diameter (mm) Orbital artery Doppler was performed simultaneously with ultrasound. The imaging probe position was used transversely and axially and mean values were recorded.
Time frame: 30 minutes
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