Carotid artery stump pressure and associated neurological changes in predominantly symptomatic carotid artery disease patients undergoing awake carotid endarterectomy

AIM To determine the mean carotid artery stump pressure (SP) at which patients develop neurological changes while undergoing awake carotid artery endarterectomy (CEA) under cervical block anaesthesia (CBA). METHODS A prospective analysis was carried out of patients undergoing awake CEA under CBA between February 2004 and April 2007. All patients had mean SP measured, with selective shunting on those who developed neurological symptoms on carotid artery clamping regardless of stump pressure. A ball connected to a pressure sensor was put in the patient inverted exclamation mark s contra-lateral hand. RESULTS Fifty-nine patients had awake CEA, 40 were males with a mean age of 64 years. Indications for CEA were asymptomatic high-grade stenosis in 12 (20%) patients and symptomatic stenosis in 47 (80%). Seven (12%) patients required shunting, one for transient ischaemic attack (TIA) and six for loss of consciousness. Six of these patients had presented with symptomatic disease. Taking the threshold of mean carotid SP of 50 mmHg as an indication for shunting, 22% (6/27) of patients with a mean SP of < 50 mmHg required shunting and only 3% (1/32) with a mean carotid SP of > 50 mmHg needed a shunt. This was not statistically significant. Using a mean carotid SP of < or = 40 mmHg as the threshold for shunting, 40% (4/10) of patients required shunting and 3% (1/31) with a mean carotid SP of > 40 mmHg required shunting. This was statistically significant. Thirteen (22%) patients were complicated by transient hoarseness of voice. One (2%) had a haematoma that required re-exploration. None of these patients had any major postoperative neurological or cardiological complications. CONCLUSION Even though the sample in this study was small, awake CEA under local anaesthesia was seen as a safe procedure. It would appear to be safe to use the mean SP of 40 mmHg as a threshold for selective shunting in CEA under general anaesthesia.