Intraoperative monitoring of cerebral function and carotid hemodynamics during carotid endarterectomy

The authors investigated the hemodynamics and monitored the cerebral function to perform the carotid endarterectomy (CEA) safely. The hemodynamics were investigated by measurements of carotid arterial blood flow by an electromagnetic flow meter before and after CEA. And a doppler flow meter applied directly to the carotid arteries to analyze the flow parameters such as peak frequencies (PF), mean frequencies (MF), mode frequencies (Mo F) and % window. We used routinely our specially designed shunt system during surgery, by which stump pressure of the ICA could be measured easily. The cerebral function was evaluated by the amplitude of N20-P25 component of somatosensory evoked potential (SEP). Flow parameters of doppler sounds demonstrated significant changes such as inversion of MF and Mo F, decrease in % window at the poststenotic ICA in the severe stenosis group. By these doppler sounds the extension of stenotic lesion could be detected clearly. The ICA flow showed evidently low values in patients with more than 80% stenosis, which was improved by CEA. With our specially designed T-tube shunt system, stump pressure, side pressure and direct pressure of the ICA could be monitored easily. The mean stump pressure was 52 mmHg and systemic arterial blood pressure was 99 mmHg on the average. SEP revealed evident changes during temporary occlusion in 10 out of 41 patients, which improved following the reflow with the shunt system. Mean stump pressure in the 11 patients was 33 mmHg, and that in the remaining patients were 59 mmHg on the average.(ABSTRACT TRUNCATED AT 250 WORDS)