Noninvasive transcranial Doppler to manage CBF/CPP at the bedside. Example of transcranial Doppler in a patient with acute hydrocephalus and increased intracranial pressure (ICP). A. Before extraventricular drainage, TCD in the middle cerebral artery (MCA) shows cerebral ischemia with low diastolic CBF velocities (<20 cm/sec) and elevated pulsatility index (PI > 1.4). B. After extraventricular drainage, normalization of ICP was associated with normalization of diastolic velocities and PI, reflecting increased CBF.