[The use of trans-cranial Doppler sonography in a neurosurgical intensive care unit. Intracranial pressure, intracranial circulatory arrest].

Transcranial Doppler Sonography (TCD) is a noninvasive simple bedside procedure to control continuously cerebral blood flow velocity in basal brain arteries in comatose patients of an intensive care unit (ICU). This measure can already be performed at ICU, to determine timing of angiography for confirming intracranial circulatory arrest when an organ explantation of patients judged clinically brain-dead is intended. TCD is also carried out to assess cerebral circulation in patients with intracranial hypertension. 64 patients are repeatedly evaluated by TCD and have been continuously monitored for ICP at the same time. According to our results a strong correlation between the flow parameters derived from TCD and the ICP exists when the ICP surpasses the level of 25 mmHg. Furthermore repeated control-TCD-examinations of 150 comatose patients in our ICU have elucidated the significant prognostic value of the pulsatility index representing the cerebrovascular resistance. Thereby important informations concerning further clinical course of patients suffering from intracranial hypertension are available. Additionally a clinical example of complete failure of cerebrovascular autoregulation shortly after hypoxic brain damage is demonstrated.