Mykleburst J: Continuous quantitative local cerebral blood flow measurement: Calibration of chemical conductivity measurements by the hydrogen clearance method. Stroke 11: 661664

SUMMARY The capability of a miniaturized probe to measure local cerebral blood flow in a continuous and quantitative manner is described. The incorporation of thermal conductivity measurements using the isothermal principle with the hydrogen clearance method allows calibration of the thermal conductivity compo-nent in absolute terms. Evaluation of this system in 14 cats showed a linear relationship between both measure-ment methods. The major limitation of this combination probe system is the need for routine intermittent recalibration in order that changes of tissue thermal conductivity induced by physiologic alterations during the experimental procedure may be recognized and resolved. Stroke, Vol 11, No 6, 1980 MOST METHODS used for measuring cerebral blood flow (CBF) in experimental animals are derived from Kety and Schmidt's development of the Fick principle.1 Although a variety of freely diffusible gas-eous and non-gaseous tracers have been used, many investigators favor measuring the clearance of the in-ert gas. Hydrogen can measure CBF in discrete re