TRANSCRANIAL DOPPLER RECORDINGS IN RAISED INTRACRANIAL-PRESSURE

The pulsatility index (PI) registreted by the transcranial doppler (TC D) was examined in relation to arterial PCO2 (paCO2) and epidural pres sure (ICP). In 10 normal subjects PI was studied during variations in paCO2. In 10 neurosurgical patients with head injuries concomitant mea surements of PI and ICP were obtained. The results showed a negative e xponential correlation between PI and paCO2. PI changed with 3.2% pr m mHg paCO2. A positive exponential correlation between PI and ICP was o bserved. PI changed with 2.4% pr mmHg ICP. In the subgroup of patients with raised ICP (15 mmHg <) PaCO2 was found not to influence the PI-r eflection of the ICP, probably because PaCO2-changes affected PI as we ll as ICP. The results suggest that the noninvasive bedside TCD-regist ration may be a useful marker of the ICP and probably replace the form er invasive methods of measuring ICP.