The Study Of Transcranial Doppler's Value Of Clinic Utility For Diagnosing Of Brain Death

[Objective]To investigate clinical value of transcranial Doppler(TCD)cerebral hemodynamics in the determination of brain death in patients with severe craniocerebral trauma.[Methods]The condition of cerebral blood flow were detected using TCD in 40 severe craniocerebral trauma severely comatose patients with Glasgow Scores≤8. The waveforms and the cerebral blood flow velocities in the bilateral middle cerebral arteries(MCA)were considered as the chief observation index,meanwhile the corresponding index of anterior cerebral artery(ACA),posterior cerebral artery(PCA) and vertebra-basal artery considered as ancillary data.According to MCAVm, clinical manifestation and prognosis of patients,a control trial was made.The condition of cerebral blood flow were detected by Gemany DML Multi-Doppler.The waveforms in middle cerebral arteries(MCA),anterior cerebral artery(ACA)and posterior cerebral artery(PCA)were detected by 2MHz probe through temporal window.Eye window was used when temporal window was closed.Vertebra-basal artery were detected through occipital window in a few patients.TCD examination were performed 1 time per day at least for a week or till death.It were performed 1 time per 2～6 h when the index of clinical brain death was reached.The cerebral hemodynamics index including:the waveforms,the systolic flow velocities(Vs),the diastolic flow velocities(Vs),the mean flow velocities(Vm),pulse index(PI),resistance index(RI),retrograde diastolic flow(RDF)and direction of flow index(DFI).According to prognosis of patients,the brain death group and the living group were divided,the statistical analysis was made.[Results]Comparing the brain death group to the living group,MCA-Vm decreased,PI and the persistence rate of retrograde diastolic flow(RDF)raised,they all had statistical significance.The mean flow velocity was lower than 10cm/s in bilateral MCA,and the persistence of full retrograde diastolic flow(RDF)or small systolic forward flow in above two cerebral vessels,and direction of flow index (DFI)＜0.8 in MCA in severely comatose patients,was a reliable indicator for confirming brain death.It was awfully index for prognosis that PI exceed 2. Characteristic change of cerebral hemodynamics took place in 6～40 h before clinical brain death.[Conelusion]Cerebral hemodynamics monitoring-transcranial Doppler was a technique with higher value of clinic utility for predicting and confirming of brain death in severely comatose patients.It was awfully index for prognosis that the persistence of full retrograde diastolic flow(RDF).The treatment was worthless once the persistence of full retrograde diastolic flow(RDF)or small systolic forward flow.For economizing the medical resourse and providing better donor for organ transplantation,further examinations should be made to diagnosis brain death as early as possible.