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Transcranial Doppler for detection of cerebral ischaemia during carotid endarterectomy
1Department of Vascular Surgery, Rigshospitalet, University of Copenhagen, Denmark.
Insights
Transcranial Doppler sonography effectively detects cerebral ischemia during carotid endarterectomy. Middle cerebral artery flow velocity monitoring improves accuracy over traditional stump pressure measurements.
Area of Science:
- Neurology
- Vascular Surgery
- Medical Imaging
Background:
- Cerebral ischemia is a risk during carotid endarterectomy.
- Accurate intraoperative monitoring is crucial for patient outcomes.
Purpose of the Study:
- To evaluate transcranial Doppler sonography (TCD) for detecting cerebral ischemia during carotid endarterectomy.
- To compare TCD accuracy with electroencephalography (EEG) and internal carotid artery (ICA) stump pressures.
Main Methods:
- TCD was used to monitor middle cerebral artery mean flow velocity (Vmean) in 144 patients undergoing carotid endarterectomy.
- Vmean changes during cross-clamping were analyzed.
- EEG, ICA pressures, and cerebral blood flow (CBF) were used as comparison metrics.
Main Results:
- A Vmean decrease during cross-clamping indicated cerebral ischemia.
- A Vmean clamp: Vmean pre-clamp ratio below 0.6 showed 89% accuracy for detecting CBF below 20 ml 100 g-1 min-1.
- A ratio below 0.4 detected all patients with EEG flattening with 97% accuracy, outperforming stump pressure (80% accuracy).
Conclusions:
- Middle cerebral artery flow velocity monitoring via TCD significantly enhances the accuracy of detecting cerebral ischemia during carotid endarterectomy.
- TCD offers a more reliable method for intraoperative cerebral ischemia detection compared to stump pressure.
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.