title: Transcranial Doppler for detection of cerebral ischaemia during carotid endarterectomy.
abstract: We evaluated transcranial Doppler sonography (TCD) for the detection of cerebral ischaemia during carotid endarterectomy in 30 male and 14 female patients with ipsilateral focal cerebro-vascular symptoms. Surgery was performed during halothane-nitrous oxide anaesthesia with moderate hypocapnia. Eight patients had a temporary shunt owing to contralateral occlusion or a stump pressure below 40 mmHg, and/or EEG flattening. Transcranial Doppler sonography was followed intra-operatively together with electro-encephalography (EEG), internal carotid artery (ICA) pressures and cerebral blood flow (CBF). Middle cerebral artery mean flow velocity (Vmean) was 38 (22-96) cm s-1 (median and range) and decreased during cross-clamping to 28 (10-60) cm s-1 (p less than 0.0001). After removal of the clamp it increased to 42 (20-102) cm s-1 (p less than 0.0001). AVmean clamp of less than 30 cm s-1 together with a Vmean clamp: Vmean pre-clamp ratio of less than 0.6 showed an accuracy with respect to CBF below 20 ml 100 g-1 min-1 of 89%. AVmeanclamp:Vmean pre-clamp ratio below 0.4 detected all all patients with EEG flattening (n = 3) (accuracy 97%). The corresponding level of accuracy obtained with stump pressure was 80%. The results indicate that middle cerebral flow velocity enables an increase in the accuracy of detecting cerebral ischaemia during carotid endarterectomy.
authors.affiliation: Department of Vascular Surgery, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: L G
authors.initials: LG
authors.lastname: Jørgensen
authors.forename: T V
authors.initials: TV
authors.lastname: Schroeder
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D002343:Carotid Artery, Internal / Q000503:physiopathology / Q000601:surgery; D002560:Cerebrovascular Circulation; D004453:Echoencephalography; D004569:Electroencephalography; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D008875:Middle Aged