A TCD TEST FOR CLINICAL-ASSESSMENT OF CEREBRAL AUTOREGULATION

Description of a TCD test designed for the clinical investigation of cerebral autoregulation. The Doppler shift frequency of the middle cerebral artery is recorded using of a transducer fixed to the patient's head by an elastic ribbon and a ball joint type probe-holder, and on-line digitally analysed to calculate the TCD flow index (signal power times velocity). Blood pressure is measured every 30 seconds at the right index hold at the level of the heart, using a special sphygmomanometer. The patient sits on a foot-stool. After 1.5 minutes of measurement he rises to remain in upright position for another 2 minutes. The flow index normalised to its average over the sitting period quantitatively indicates the evolution of volume flow brought about by the change of the body position. The change in arterial blood pressure is off-line calculated from its periodic measurements. In a pilot study this test has been successfully used in 30 healthy volunteers and 2 patients suffering from orthostatic dysregulation of blood pressure.