title: Lactate flux during carotid endarterectomy under general anesthesia: correlation with various point-of-care monitors.
abstract: 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.
authors.affiliation: Department of Anesthesia, University of Manitoba, 227 Harry Medovy House, 671 William Avenue, Winnipeg, MB R3E 0Z2, Canada.
authors.forename: Ainsley E G
authors.initials: AE
authors.lastname: Espenell
authors.forename: Ian W
authors.initials: IW
authors.lastname: McIntyre
authors.forename: Harleena
authors.initials: H
authors.lastname: Gulati
authors.forename: Linda G
authors.initials: LG
authors.lastname: Girling
authors.forename: Marshall F
authors.initials: MF
authors.lastname: Wilkinson
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Silvaggio
authors.forename: Joshua
authors.initials: J
authors.lastname: Koulack
authors.forename: Michael
authors.initials: M
authors.lastname: West
authors.forename: Gregory E J
authors.initials: GE
authors.lastname: Harding
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Kaufmann
authors.forename: W Alan C
authors.initials: WA
authors.lastname: Mutch
mesh_terms: 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
chemical_list: D019344:Lactic Acid; D010100:Oxygen