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[Clinical study of value of transcranial Doppler ultrasonography in diagnosing brain death in severe craniocerebral injury].

OBJECTIVE
To assess the clinical value of transcranial Doppler(TCD) ultrasonography in diagnosing brain death in patients with severe craniocerebral injury.


METHODS
Forty patients of severe craniocerebral injury defined by a scene Glasgow coma scale(GCS)≤8, admitted to Department of Neurosurgery of First Central Clinical Hospital of Tianjin Medical University, were divided into two groups based upon the prognosis: the death group(n=15) and the survival group (n=25). All patients were examined dynamically by TCD, and the occurrence of retrograde diastolic flow (RDF) and mean velocity (Vm) of middle cerebral arteries (MCA) were measured as well as the pulse index (PI).


RESULTS
In the survival group, 3 showed partial RDF which was found within 24 hours after injury, and the duration was short lasting for no more than 12 hours, and the RDF wave disappeared very quickly after treatment of drug or operation. These patients were in persistent vegetative state with Glasgow outcome score (GOS) 2, having been followed up for 6 months. In the death group, 12 showed fully RDF, 2 showed very small systolic spike. The characteristic change of 14 patients' cerebral hemodynamics took place 6-40 hours before clinical brain death. Compared with survival group, Vm of MCA was significantly decreased (20.07±13.97 cm/s vs. 56.72±16.87 cm/s), the value of PI was significantly increased (3.95±3.51 vs. 1.25±1.06), and the occurrence of RDF was also elevated (93.3% vs. 12.0%) in the death group, the differences were statistically significant (P<0.05 or P<0.01).


CONCLUSION
TCD with the advantages of easy and bedside operation, noninvasiveness, no disturbance from sedatives and repeatability in cerebral hemodynamic examination is of great clinic practical value in early diagnosing brain death in patients with severe cranial injury.