Stroke, Vol 18, 606-611, Copyright © 1987 by American Heart Association
PJ Hoehner, JM Dean, MC Rogers and RJ Traystman
A thermal clearance technique for measuring cerebral blood flow is
described and compared with the radiolabelled microsphere technique. The
thermal technique involves measurement of the rewarming curve generated
after bolus infusion of 4-5 ml of ice-cold saline into the common carotid
artery with a subdural thermistor placed on the parietal cortex. Evaluation
of the biexponential decay curves obtained with this technique demonstrated
a close correlation with total hemispheric, parietal, and parietal gray
blood flow determined by simultaneous microsphere measurement. Despite
significant correlations (p less than 0.001), scatter in the data produced
a broad 95% confidence interval, thus making interpretation of blood flow
with the thermal clearance technique impossible. Furthermore,
instrumentation with the thermal probe, which required opening of the dura,
blunted the cerebral blood flow response to hypercapnia. We conclude that
the major limitations of the thermal clearance technique include:
nonhomogeneous clearance function, significant variability, and depression
of CO2 reactivity. These limitations must be addressed before this
technique can be used reliably in the laboratory.
ARTICLES
Comparison of thermal clearance measurement of regional cerebral blood flow with radiolabelled microspheres
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