Transcranial Doppler: A Useful Tool to Predict Brain Death Still Not Confirmed by Clinical Assessment.

Background: Diagnosing brain death (BD) with accuracy and urgency is of great importance because an early diagnosis may guide the clinical management, optimize hospital beds, and facilitate organ transplantation. The clinical diagnosis of nonreactive and irreversible coma can be confirmed with additional tests. Among the complimentary exams that may testify brain circulatory arrest, transcranial Doppler (TCD) can be an option. It is a real-time, bedside, inexpensive, noninvasive method that assesses cerebral blood flow. In patients with suspected BD, especially those who are under sedative drugs, early diagnosis is imperative. The aim of the present study was to evaluate the role of TCD in predicting BD.

Methods: One hundred consecutive comatose patients with a Glasgow Coma Scale score of less than 5, owing to different etiologies, were included. TCD was performed in all patients. The TCD operator was blinded for clinical and neurologic data. This study is in compliance with the Declaration of Helsinki.

Results: Sixty-nine patients with TCD-brain circulatory collapse were diagnosed later with BD. Of the 31 patients with brain circulatory activity, 8 (25.8%) were clinically brain dead and 23 (74.2%) were alive. TCD showing brain circulatory collapse had a sensitivity of 89.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 74.2%.

Conclusion: TCD is highly specific (100%) and sensitive (89.6%) as a method to confirm the clinical diagnosis of BD, even in patients under sedation. The possibility of patients presenting with cerebral circulatory activity and clinical diagnosis of BD was demonstrated to occur.