ASSESSMENT OF CEREBROVASCULAR REACTIVITY BY DOPPLER CO2 AND DIAMOX TESTING - WHICH IS THE APPROPRIATE METHOD

Cerebrovascular reserve capacity can be estimated by Doppler CO2 or ac etazolamide (Diamox) stimulation. These two methods were compared in 1 8 normal subjects. The variability of CO2 reactivity (mean 27.4 +/- 3. 8%/vol% CO2) was markedly lower than that of Diamox reactivity (mean 4 1.2 +/- 21.3%), which was partly caused by reactive hyperventilation. Unexpectedly, there was no positive correlation between CO2 and acetaz olamide challenge (r = -0.14). A maximum dilation of the cerebral arte rioles after acetazolamide administration could not be achieved as dem onstrated by a diminished, but still existing CO2 reactivity during Di amox testing. Compared to CO2 stimulation, Diamox testing was more tim e-consuming and caused numerous, though reversible side effects. Thus, using transcranial Doppler sonography for assessing cerebrovascular r eserve capacity, CO2 stimulation seems preferable to acetazolamide adm inistration in most cases.