Brain death and transcranial Doppler: Experience in 130 cases of brain dead patients

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Abstract

Background and purpose: Diagnosis of brain death requires confirmation of the clinical diagnosis by appropriate tests, generally electroencephalography (EEG) and angiography. The diagnostic limitations or logistical problems inherent to these tests indicate the need to develop other more appropriate methods. The results obtained with transcranial Doppler (TCD) led us to conduct this prospective study of TCD recordings in brain dead patients. Methods: 130 patients, aged 2–88 years were diagnosed as brain dead between July 1987 and June 1993. Clinical criteria were confirmed in all cases by EEG (n=88) and or angiography (n=64). Intracranial anterior circulation was insonated via temporal windows or, when impossible, via a transorbital approach. The posterior circulation was studied only in more recent patients. Examinations were made as soon as possible after brain death diagnosis and repeated for about 30 min. Vital parameters and treatments were taken into account. Results: There was only one false negative result, in a patient with an extended skull defect, who retained TCD and angiographic intracranial circulation despite confirmed irreversible brain death. All other patients displayed typical ultrasonic patterns of cerebral circulation arrest: an oscillating signal (n=190, 73%), a systolic spike (n=62, 24%) or a unilateral absence of signal (n=5). Despite a total correlation for positive diagnosis, TCD and angiography may differ as to the level of circulation arrest. TCD is useful for patients under sedative drugs. No false positive result was encountered but we were unable to insonate any intracranial artery in 5 patients. Conclusion: Data from previous studies and the results of this study indicate that TCD is a very sensitive and safe method for diagnosing cerebral circulatory arrest. TCD may be used as a confirmatory test alongside EEG and angiography. TCD is more widely applicable than EEG and may be earlier and safer than angiography.

Introduction

In most countries and states the clinical diagnosis of brain death, which is often important for possible organ donation, must be confirmed by appropriate tests, such as EEG, cerebral angiography or radionuclide imaging 1, 2, 3, 4. These confirmatory tests may be the source of major logistical problems, as they are time consuming and require the transportation of critically ill patients. Hence, there is a need to develop other methods. The results obtained during the past few years with transcranial Doppler (TCD) led us to evaluate this non-invasive ultrasonic method, comparing it to standard techniques 5, 6, 7, 8, 9. TCD, demonstrates the arrest of the cerebral circulation with typical intracranial Doppler waveforms. It may thus support the diagnosis of brain death and become a useful alternative to accepted confirmation tests. We have therefore studied, prospectively, patients diagnosed as brain dead by clinical data and accepted confirmation tests, to determine the clinical value of TCD.

Section snippets

Materials and methods

A total of 130 patients hospitalized in the intensive neurosurgical and medical care units, between July 1987 and June 1993 with an established diagnosis of brain death, were evaluated with TCD. They ranged in age from 2 to 88 years (mean: 34). This series includes 13 children below 15 years: aged 2 (n=3), 5 (n=1), 7 (n=2), 8 (n=2), 9 (n=1), 12 (n=1), 15 (n=3). The cause of brain death was known in all the cases. The main cause was head trauma (76 cases, 58.5%) or subarachnoid haemorrhage (27

Results

Two TCD waveform patterns were recorded (Table 1). One was an oscillating, `to and fro', signal (Fig. 1) with a mono or biphasic reverse diastolic signal (190 ICA, 73%) and the second a systolic spike (62 ICA, 24%). The systolic spike was narrow and there was no detectable diastolic flow (Fig. 2). No detectable signal was found on one side in five patients, while the signal was easily identified on the opposite side. In three cases, the systolic component of the Doppler signal was larger,

Discussion

TCD examination of the 130 brain dead patients showed a typical pattern of CCA, confirming on a large prospective series previous findings 5, 6, 7, 8, 13. TCD has been used for 6 years in neurology and neurosurgery intensive care departments in our hospital, and, during that time, no patient displaying a permanent TCD pattern of global circulatory arrest subsequently recovered. Furthermore, in other clinical situations, we never found typical TCD patterns of CCA. The absolute specificity of the

Conclusion

Our experience with TCD in severe comatose and brain dead patients confirms that TCD is a reliable alternative confirmatory test for the diagnosis of brain death. That the examiner should be experienced in ultrasonic methods is an evidence, as should be any person authorized to establish a clinical diagnosis of brain death. As TCD is a non-invasive, bedside, rapid and repeatable method, it should be particularly suitable for diagnosing, especially when EEG is not relevant, as in patients

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