[Transcranial Doppler sonography as a reliable diagnostic tool in craniocerebral trauma]

Transcranial Doppler sonography (TCD) is a simple, noninvasive bedside procedure that can be repeated any time for the measurement of cerebral blood flow velocity in the great basal cerebral arteries. It is practicable in most severely head-injured patients in critical care. Flow patterns and pulsatility index (PI) resulting from maximal systolic and diastolic flow velocities and representing cerebrovascular resistance give quite an accurate impression of potential intracranial hypertension and the dependent cerebral perfusion pressure (CPP). With increasing intracranial pressure (ICP) and decreasing CCP, diastolic flow is progressively reduced. If ICP reaches the systemic diastolic blood pressure level, diastolic flow disappears. Oscillating (reverberating) flow patterns are seen when ICP increases further up to the arterial mean pressure level. The authors' own studies on 20 comatose patients with raised ICP showed typical changes in TCD parameters following different therapies for intracranial hypertension. Under continuous TCD monitoring of the middle cerebral artery, increases in maximal flow velocity (from 4% up to 102%, on average 27%) and mean flow velocity (from 18% up to 153%, on averaged 73%) were always observed after osmotherapy. In addition, a variable increase in negative frequencies was noted, probably due to increased turbulences. After barbiturate administration (thiopentone bolus of 0.3 g) a flow reduction was always seen [from -2% up to -25% (on average -13%) for maximal flow velocity and from -9% up to -30% (on average -19%) for mean flow velocity].(ABSTRACT TRUNCATED AT 250 WORDS)