The differing effects of regional and general anaesthesia on cerebral metabolism during carotid endarterectomy.
OBJECTIVE
To examine the effects of either regional (RA) or general (GA) anaesthesia upon parameters of cerebral metabolism (near infrared spectroscopy, continuous jugular venous oximetry) during carotid endarterectomy.


METHODS
Prospective, non-randomised, observational study.


METHODS
Sixty-five consecutive patients (33 RA; 32 GA) undergoing carotid endarterectomy.


METHODS
(i) Near infrared spectroscopy: measurement of concentrations of cerebral oxyhaemoglobin (HbO2), deoxyhaemoglobin (HHb) and oxidised cytochrome oxidase (caa3). (ii) Continuous jugular venous oximetry: O2 saturation of jugular venous blood (SJvO2). (iii) Stump pressure in internal carotid artery.


RESULTS
A reduction in SJvO2 (RA: 13% (95% CI-3 to 29%) GA: 9% (95% CI-2 to 20%), p < 0.08) and a fall in caa3 levels (RA vs. GA: 25/31 vs. 19/31, p = 0.2) was more likely in patients given a RA following application of the carotid clamps. When HbO2 and caa3 did fall however spontaneous recovery occurred more often (RA vs. GA; caa3: 18/25 vs. 5/19, p < 0.005; HbO2: 30/31 vs. 4/28, p < 0.001).


CONCLUSIONS
Although GA may offer a degree of cerebral protection by reducing cerebral metabolic rate (lower falls in SJvO2 and caa3) RA preserved cerebral autoregulation as judged by the spontaneous recovery in caa3 and HbO2 levels.
McCleary
A J
AJ
Department of Vascular Surgery, General Infirmary, Leeds, U.K.
Dearden
N M
NM
Dickson
D H
DH
Watson
A
A
Gough
M J
MJ
D000368:Aged; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002045:Bupivacaine; D003576:Electron Transport Complex IV / Q000032:analysis; D016894:Endarterectomy, Carotid; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007530:Isoflurane; D008297:Male; D016343:Monitoring, Intraoperative; D009407:Nerve Block; D009609:Nitrous Oxide; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000032:analysis; D011318:Prilocaine; D011446:Prospective Studies; D013055:Spectrophotometry, Infrared / Q000379:methods
D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D006454:Hemoglobins; D010108:Oxyhemoglobins; D011318:Prilocaine; C100003:deoxyhemoglobin; D007530:Isoflurane; D003576:Electron Transport Complex IV; D009609:Nitrous Oxide; D010100:Oxygen; D002045:Bupivacaine