Pulsatile cerebral echo in diagnosis of brain death

Abstract

Conclusive diagnosis of brain death can be made by the demonstration of prolonged cessation of cerebral blood flow. A simple method is described to determine the presence or absence of the blood flow in the brain by recording the pulsatile midline echo on 1 channel of the EEG or on any 4-channel monitoring system in the intensive care unit. A firm transducer holder was developed to eliminate artifacts caused by transducer motion. The pulsations of the midline echo are assumed to be the result of displacement of the midline structures by the arterial injection of each cardiac systole. The absence of these midline pulsatile echoes correlates with the absence of cerebral blood flow and, if the absence persists over 30 min in the presence of normal blood pressure, then the result is brain death. In clinical brain death 28 cases with electrocerebral silence of EEG and 18 obtunded patients with various types of cerebral pathology were examined by the echo-pulsation technique. Of the 28 cases, 26 showed no pulsation of the midline echo. The validity of the technique was documented in 4 cases by 4-vessel cerebral angiogram.