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Updated: Oct 4, 2026
Bilateral Common Carotid Artery Occlusion as an Adequate Preconditioning Stimulus to Induce Early Ischemic Tolerance to Focal Cerebral Ischemia
Published on: May 9, 2013
[Clonidine combined with flunitrazepam before carotid endarterectomy decreases cerebrovascular CO2 reactivity]
M Laffon1, X Sauvagnac, M Ferrandière
1Service d'anesthésie-réanimation, hôpital Bretonneau, 2 bis, boulevard Tonnelé, 37000 Tours, France. laffon@med.univ-tours.fr
Objective:
Assess cerebrovascular CO2 reactivity changes using transcranial Doppler sonography (TCD) after oral premedication associating clonidine (2 micrograms.kg-1) and flunitrazepam (70 micrograms.kg-1) in patients scheduled for carotid stenosis surgery.
Study Design:
Prospective study, not randomized, the patient being his own "control".
Patients And Methods:
Thirteen patients undergoing carotid endarterectomy under cervical plexus block were included. The monitoring included: automated arterial pressure cuff, ECG, radial artery catheter, TCD with probe secured in temporal window. The study of the cerebrovascular CO2 reactivity was performed with TCD recording on the side of operation, on the day before, and on the day of carotid endarterectomy, 90 min after the premedication, immediately before surgery. To change PaCO2, four ventilatory states were successively performed: (1) normoventilation, (2) hyperventilation, (3) hypoventilation, (4) "breath-holding test". At each state, it was noted: HR, MAP, PaCO2, mean blood flow velocity in the middle cerebral artery (Vm-MCA), resistance index of Pourcelot (RI), cerebrovascular reactivity (slope Vm-MCA/PaCO2). The results (+/- SEM) were analyzed by Wilcoxon test or t test.
Results:
After premedication, cerebrovascular CO2 reactivity decreased (0.043 +/- 0.019 vs 0.034 +/- 0.013; p < 0.05) without modification of RI (0.578 +/- 0.291 vs 0.612 +/- 0.025; NS). No complication during carotid clamping was reported.
Conclusion:
Inclusion of clonidine in premedication before carotid stenosis surgery must be questioned because a decrease of cerebrovascular CO2 reactivity could be deleterious in case of intraoperative stroke.
