MONITORING OF REGIONAL CEREBRAL BLOOD-FLOW (CBF) IN ACUTE HEAD-INJURYBY THERMAL-DIFFUSION

During the last few years continuous measurements of CBF by means of a thermal diffusion blood flow probe have been proposed as a possible m eans for monitoring the patient's CBF in a clinical setting. Also, it has been suggested that continuous CBF data from head injured patients can be correlated with other continuously recorded clinical parameter s, such as ICP and blood pressure, in order to clarify pathophysiologi cal mechanisms such as ''plateau-waves''. We measured regional cortica l blood flow continuously with a thermal diffusion flow probe in 13 co matose head injured patients after undergoing craniotomy for evacuatio n of a traumatic intracranial mass lesion in order to assess the relia bility and usefulness of the method. In seven patients stable Xenon-CT CBF studies were performed with the flow probe in place, in order to compare the two methods. The continuous blood flow values did not corr elate with regional or global stable Xenon-CT values. These results in dicate that continuous monitoring of CBF with the thermal diffusion me thod as currently used cannot be used in the clinical management of th e patient. Further research will have to be directed to the question a s to whether changes in CBF are reliably measured with this method. If this is true, the thermal diffusion flow probe with its high temporal resolution may still be useful in investigating pathophysiological me chanisms such as interaction between CBF, ICP, mean arterial blood pre ssure (MABP), and endexpiratory CO2 (etCO2).