[Clonidine combined with flunitrazepam before carotid endarterectomy decreases cerebrovascular CO2 reactivity].
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.


METHODS
Prospective study, not randomized, the patient being his own "control".


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.


CONCLUSIONS
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.
Laffon
M
M
Service d'anesthésie-réanimation, hôpital Bretonneau, 2 bis, boulevard Tonnelé, 37000 Tours, France. laffon@med.univ-tours.fr
Sauvagnac
X
X
Ferrandière
M
M
Jaber
W
W
Gautier
T
T
Martinez
R
R
Mercier
C
C
Fusciardi
J
J
D000316:Adrenergic alpha-Agonists; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000097:blood / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003000:Clonidine; D016894:Endarterectomy, Carotid; D005260:Female; D005445:Flunitrazepam; D018757:GABA Modulators; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011229:Preanesthetic Medication; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial
D000316:Adrenergic alpha-Agonists; D018757:GABA Modulators; D002245:Carbon Dioxide; D005445:Flunitrazepam; D003000:Clonidine
La clonidine associée au flunitrazépam avant endartériectomie carotidienne diminue la réactivité cérébrovasculaire au CO2.