[Cerebral Blood flow velocity spectrum by transcranial doppler ultrasound in patients with brain death clinical criteria]. / Espectro de velocidad del flujo sanguíneo cerebral por ultrasonido Doppler transcraneal en pacientes con criterios clínicos de muerte cerebral.

OBJECTIVE: To evaluate cerebral blood flow (CBF) direction, speed, and shape of Doppler profile in patients with clinical criteria of brain death (BD). PATIENTS: A total of 42 consecutive patients with clinical criteria for BD were included. MEASUREMENTS AND INTERVENTIONS: After anemia, hypothermia and hypocapnia were ruled out; confirmatory electroencephalogram (EEG) and a complete transcranial Doppler ultrasonography (TCDU) profile of circle of Willis and basilar arteries were done in all patients. Patients continued with mechanical ventilation and support in the Intensive Care Unit. RESULTS: All EEG reported generalized theta and delta waves, which were associated with a TCDU profile showing small systolic peaks without diastolic wave. CBF velocities of < 10 cm/sec were recorded in all patients. Only four patients had reverberating flow. At follow-up, cardiac arrest occurred in all patients at a mean of 2 +/- 0.84 days. CONCLUSIONS: Patients with clinical criteria of BD frequently have slow wave neuronal electrical activity on EEG that anticipates cardiac arrest. In these patients, TCDU detects an early and severe drop in CFB that is incompatible with life. TCDU should be done when other confirmatory tests like EEG suggest some retention of brain function.