Utility of transcranial doppler ultrasonography for confirmatory diagnosis of brain death: two sides of the coin.

BACKGROUND

Although the clinical examination and documentation of the clinical signs of brain death are very uniform, there are significant differences in the guidelines for using technical confirmatory tests to corroborate the clinical signs. The current study examined the utility of transcranial Doppler ultrasonography (TCD) for confirmation of brain death.

METHODS

After 19 patients were excluded from the study because of lack of bone window or because an apnea test could not be performed because of desaturation, 100 patients (61 patients with clinical brain death, and 39 control patients with Glasgow Coma Score<5) were included in the study. The following TCD findings were accepted as confirmatory of brain death when they were found bilaterally or in at least three different arteries for at least 3 minutes within the same examination: (1) brief systolic forward flow or systolic spikes and diastolic reverse flow, (2) brief systolic forward flow or systolic spikes and no diastolic flow, or (3) no demonstrable flow in a patient in whom flow had been clearly documented in a previous TCD examination.

RESULTS

The sensitivity and specificity of the first TCD examination for confirmation of brain death were 70.5% and 97.4%, respectively. Eighteen patients with clinical brain death required repeat TCD examinations because of detection of forward systolo-diastolic flow or a diastolic to-and-fro flow pattern, which were not confirmatory for the diagnosis of brain death. Brain death was confirmed ultrasonographically in 12 of 18 patients in a second examination after 12.6 +/- 8.3 hours of clinical brain death, in 2 patients in a third TCD examination, and in 1 patient in a fourth examination. Three clinically brain-dead patients had died before the diagnosis was confirmed by repeat TCD examinations. The sensitivity of TCD reached 100% in our study population after the fourth examination.

CONCLUSION

The sensitivity of TCD is increased with repeat examinations and should be repeated in cases in which systolo-diastolic forward flow is demonstrated after the first TCD. TCD may prolong or shorten the time to declaration of brain death. The necessity of demonstrating cerebral circulatory arrest in patients with clinical brain death is debatable.