Lactate flux during carotid endarterectomy under general anesthesia: correlation with various point-of-care monitors.
OBJECTIVE
The ability to assess the brain-at-risk during carotid endarterectomy (CEA) under general anesthesia remains a major clinical problem. Point-of-care monitoring can potentially dictate changes to management intraoperatively. In this observational study, we examined the correlation between a series of point-of-care monitors and lactate flux during CEA.


METHODS
Both neurosurgeons and vascular surgeons participated in the study. The patients underwent arterial-jugular venous blood sampling for oxygen, carbon dioxide, glucose, and lactate, n = 26; bispectral index (BIS) monitoring ipsilateral to side of surgery, n = 26; raw and processed electroencephalogram (EEG), n = 22; and bi-frontal cerebral oximetry using the Fore-Sight monitor, n = 20.


RESULTS
One patient experienced a new neurological deficit when assessed at 24 hr following surgery. Lactate flux into the brain was correlated with the greatest decrease in cerebral oximetry with carotid cross-clamping; lactate efflux was correlated with the least. The most noticeable changes in processed EEG (density spectral analysis) were also seen with lactate influx, but at a slower time resolution than cerebral oximetry. Loss of autoregulatory behaviour was demonstrated with lactate influx; however, no correlation was seen between lactate flux and BIS monitoring.


CONCLUSIONS
There was a correlation between cerebral oximetry and lactate flux during carotid cross-clamping. The Fore-Sight monitor may be of value as a point-of-care monitor during CEA under general anesthesia. A novel finding of this study is lactate flux into the brain in the presence of a large difference in cerebral oxygenation during cross-clamping of the carotid artery. Registered at clinicaltrials.gov: NCT000737334.
Espenell
Ainsley E G
AE
Department of Anesthesia, University of Manitoba, 227 Harry Medovy House, 671 William Avenue, Winnipeg, MB R3E 0Z2, Canada.
McIntyre
Ian W
IW
Gulati
Harleena
H
Girling
Linda G
LG
Wilkinson
Marshall F
MF
Silvaggio
Joseph A
JA
Koulack
Joshua
J
West
Michael
M
Harding
Gregory E J
GE
Kaufmann
Anthony M
AM
Mutch
W Alan C
WA
D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects / Q000379:methods; D001921:Brain / Q000378:metabolism; D015331:Cohort Studies; D056805:Consciousness Monitors; D004569:Electroencephalography / Q000379:methods; D016894:Endarterectomy, Carotid / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood; D019095:Point-of-Care Systems; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies
D019344:Lactic Acid; D010100:Oxygen