Validation of jugular venous flow as an index of total cerebral blood flow.

Abstract

Values of total cerebral blood flow in man measured by the indicator dilution method are compared with values of total internal jugular venous flow measured by the thermal dilution method. Except in the case of an extremely labile cerebral hemodynamic state, the results agree within the accuracy of the two methods, suggesting that for the supine patient total internal jugular venous flow provides a good index of total cerebral flow. The relatively short measurement time associated with nondiffusible indicators (dye or thermal dilution) facilitates detection of transient changes in total CBF or differential jugular flow that would tend to be averaged out with diffusible indicator methods. A mathematical analysis of the potential errors in the computation of total flow using the average of bilateral jugular venous dilution curves from a unilateral internal carotid injection is presented. This error can be partially corrected if the ratio of flow in one internal jugular to total flow is known. An analysis of potential computational errors under nonsteady state flow conditions (change in flow during the period between alternate carotid injections) is presented. Such flow changes can effect substantial errors in the computation of individual hemispheric or internal jugular flow and smaller errors in the computation of total flow.