CEREBRAL BLOOD-FLOW ALTERATION BY ACETAZOLAMIDE DURING CAROTID BALLOON OCCLUSION - PARAMETERS REFLECTING CEREBRAL PERFUSION-PRESSURE IN THEACETAZOLAMIDE TEST

Background and Purpose We attempted to clarify the role of the acetazo lamide-reactive mechanism in cerebral hemodynamic autoregulation and t o establish a useful method of estimation using the acetazolamide test . Methods We examined 18 patients whose cerebral hemodynamics were con sidered to be normal and whose cerebral blood flow (CBF) was maintaine d during the balloon occlusion test (BOT) of the internal carotid arte ry. We measured the mean stump pressure (MSTP) and the mean CBF in the middle cerebral arterial territory using a xenon-enhanced CT system d uring BOT with and without acetazolamide activation. We obtained the a symmetry ratio (AR=occluded CBF/contralateral CBF) and the increased C BF parameters caused by acetazolamide activation expressed as an absol ute value (Delta CBF) and a percentage (%Delta CBF) for the occluded s ide. Results AR during BOT with and without acetazolamide activation d iffered significantly (P<.001, paired t test) despite the lack of sign ificant MSTP changes. Furthermore, although there was no significant c orrelation between MSTP and AR without acetazolamide activation, a pos itive significant correlation was detected with acetazolamide activati on (r=.634, P=.005, linear regression analysis). There were significan t correlations between Delta CBF and MSTP (r=.574, P=.013) and %Delta CBF and MSTP (r=.640, P=.004). Conclusions We consider that the acetaz olamide-reactive mechanism functions as autoregulation at the lower en d of the autoregulatory range. The acetazolamide Lest, using %Delta CB F or Delta CBF as parameters (which both directly reflect MSTP), is us eful for estimating the cerebral perfusion pressure decrease and prese nce of hemodynamic compromise.