Applicability of laser-Doppler flowmetry for cerebral blood flow monitoring in neurological intensive care.

Laser Doppler flowmetry (LDF) is a technique for real-time assessment of cerebral blood flow (CBF) changes with potential clinical applicability. Experimental studies have validated that LDF allows accurate measurement of changes in CBF due to physiological and pathophysiological stimuli. Absolute quantitation of flow in ml/100 g min by LDF is not possible. The technique may be used in patients during open brain surgery and postoperatively for bedside CBF monitoring. Disadvantages of the technique are that the flow measurement is highly localized (about 1 mm3) and artifacts may be produced by movement, light or probe placement over large surface vessels. The fibre optic probes for LDF are small enough to be introduced into routinely used intraventricular pressure catheters. We suggest that simultaneous monitoring of CBF and intracranial pressure by such a device holds promise for improved management of patients with critical brain injury.