BALLOON TEST OCCLUSION OF THE INTERNAL CAROTID-ARTERY - CHANGE IN STUMP PRESSURE OVER 15 MINUTES AND ITS CORRELATION WITH XENON CT CEREBRALBLOOD-FLOW

PURPOSE: To determine whether stump pressure changes significantly ove r time during temporary internal carotid artery (ICA) occlusion via an endovascular balloon, and to examine correlations between stump press ure changes and cerebral blood flow (CBF) as measured by xenon CT. MET HODS: Seventy candidates for ICA sacrifice were evaluated preoperative ly with a test occlusion of the cervical ICA using an endovascular bal loon. Measurements of ICA stump pressure above the occlusive balloon t hrough a distal lumen in the balloon catheter were made throughout the 15-minute test. During occlusion, CBF was measured with stable xenon CT techniques. Patients were then categorized according to CBF results . RESULTS: The stump pressure changed significantly (P < .001) during the occlusive period. On average, stump pressure increased 7.7 mmHg (1 2%). Patients determined by xenon CT to have an asymmetric decrease in CBF with balloon occlusion did not display the upward trend in stump pressures and were significantly different (P = .013) in that respect from patients who demonstrated either no CBF change or only minimal bi laterally symmetric decreases in CBF. CONCLUSIONS: Large overlaps amon g the groups prohibit the use of stump pressure changes as an accurate predictor of CBF or of stroke risk in an individual patient. However, these data suggest an autoregulatory mechanism in the cerebral circul ation that evolves over a period of minutes in contrast to the traditi onal concept of cerebral autoregulation which is thought to occur in a matter of seconds.