Neuromonitoring in carotid surgery: are the results obtained in awake patients transferable to patients under sevoflurane/fentanyl anesthesia?
BACKGROUND
Diagnostic accuracy studies of neuromonitoring devices during carotid endarterectomy in awake patients are limited by the question of the transferability to anesthetized patients. This study was designed to compare the different neuromonitoring parameters in patients under regional and general anesthesia with stump pressure as the primary endpoint and the courses of cerebral blood flow velocity (Vmca) measured by transcranial Doppler sonography, regional cerebral oxygen saturation (rSO2) measured by near-infrared spectroscopy, and the amplitude of somatosensory evoked potentials (SEP) as the secondary endpoints.


METHODS
Ninety-six patients undergoing carotid endarterectomy were randomized to regional (n=48) or sevoflurane/fentanyl anesthesia (n=48) group. Absolute and relative changes of Vmca and rSO2 and the SEP amplitude were recorded at baseline, during carotid artery clamping, and after declamping. Intergroup differences (ß) were calculated by generalized estimation equations and linear regression analysis.


RESULTS
Mean arterial pressure (P<0.001) and heart rate (P<0.001) were significantly higher in the regional anesthesia group. SP did not differ between both the groups (ß=-1.6; P=0.71). Vmca (ß=9.2; P<0.01) and rSO2 (ß=4.1; P<0.01) values were higher in the awake patients. After adjustment for mean arterial pressure, the differences of Vmca remained consistent (ß=9.3; P<0.01) whereas these of rSO2 during clamping (ß=2.9; P=0.105) and during reperfusion (ß=2.7; P=0.095) disappeared. No significant differences were found for Vmca(%) (ß=-1.0; P=0.80), rSO2(%) (ß=-1.4; P=1.8) and SEP (ß=-2.6; P=0.29).


CONCLUSIONS
Carotid artery clamping leads to similar results of stump pressure and similar relative changes of transcranial Doppler sonography, near-infrared spectroscopy, and SEP monitoring in patients under regional and sevoflurane/fentanyl anesthesia.
Moritz
Stefan
S
Department of Anesthesiology, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany. moritz.stefan@yahoo.de
Schmidt
Christoph
C
Bucher
Michael
M
Wiesenack
Christoph
C
Zimmermann
Markus
M
Schebesch
Karl-Michael
KM
Kasprzak
Piotr
P
Metz
Christoph
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D002339:Carotid Arteries / Q000601:surgery*; D002560:Cerebrovascular Circulation; D003250:Constriction; D023381:Endpoint Determination; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D005283:Fentanyl; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008738:Methyl Ethers; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000097:blood; D000077149:Sevoflurane; D019265:Spectroscopy, Near-Infrared; D017585:Ultrasonography, Doppler, Transcranial; D014851:Wakefulness
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D000077149:Sevoflurane; D010100:Oxygen; D005283:Fentanyl