Reflex hypotension following carotid endarterectomy: mechanism and management

Abstract

✓ Postoperative changes in blood pressure regulation were studied retrospectively in 56 patients and prospectively in 46 patients after carotid endarterectomy. Hypotension, of a degree sufficient to require pressors and/or volume-expanding agents to maintain systolic blood pressure above 100 mm Hg, associated with bradycardia and low central venous pressure occurred in 41% of the retrospectively studied group. In the prospectively studied group, controllable variables were excluded by standardizing fluid management and anesthetic technique. It was found that infusion of colloid preoperatively, intraoperatively, and postoperatively to maintain central venous pressure above zero markedly reduced the incidence of postoperative hypotension. Denervation of the carotid sinus prevented postoperative hypotension. We hypothesize that the atheromatous plaque damps the pressure wave reaching the carotid sinus baroreceptors. Removal of the plaque results in increased stimulation of these baroreceptors, with a resulting bradycardia and hypotension of neurogenic origin. The data indicate that blood pressure usually returns to its previous level within a few hours. Closely monitored infusion of colloid before, during, and after operation is the recommended form of management.