title: Mannitol increases cerebral arteriovenous oxygen difference in patients undergoing craniotomy.
abstract: BACKGROUND
  Monitoring the jugular venous oxygen saturation (SjVO2) and cerebral arteriovenous oxygen difference (AVDO2) is valuable in detecting cerebral ischemia. In the present study, we investigated the effect of mannitol on SjVO2 and AVDO2 in patients undergoing craniotomy.
  
  
  METHODS
  We studied 25 ASA class II-III patients undergoing craniotomy. Anesthesia was induced with thiopental, fentanyl and vecuronium. Immediately after induction, a 16-gauge central venous catheter was placed in the internal jugular vein, ipsilateral to the lesion side with cephalic insertion and anchorage in the jugular bulb. Anesthesia was maintained with continuous infusion of fentanyl (10 micrograms/kg/h), 0.5-1% isoflurane in 60% oxygen (oxygen/air) and supplemental dose of vecuronium for muscle relaxation as needed. Samples of arterial and jugular venous blood were obtained for the measurements of SjVO2 and AVDO2 in the following time intervals: (1) normocapnia (PaCO2 38-40 mmHg); (2) hypocapnia (PaCO2 28-30 mmHg); and (3) 30 min after mannitol (0.5 g/kg) infusion.
  
  
  RESULTS
  Hyperventilation resulted in a significant decrease in SjVO2 (96% patients) and increase in AVDO2 (88% patients). Hypocapnia followed by mannitol administration led to a further decrease and increase of SjVO2 and AVDO2 in 72% and 68% patients, respectively.
  
  
  CONCLUSIONS
  Mannitol may produce a further reduction in SjVO2 accompanied by an increase in AVDO2, suggesting a reduction of cerebral blood flow (CBF) during hyperventilation. Therefore, it should be given cautiously in neurosurgical patients under hyperventilation.
authors.affiliation: Department of Anesthesiology, Veterans General Hospital-Taipei, Taiwan, R.O.C.
authors.forename: J T
authors.initials: JT
authors.lastname: Liou
authors.forename: P W
authors.initials: PW
authors.lastname: Lui
authors.forename: C C
authors.initials: CC
authors.lastname: Shu
authors.forename: S H
authors.initials: SH
authors.lastname: Lin
authors.forename: C L
authors.initials: CL
authors.lastname: Shen
authors.forename: S R
authors.initials: SR
authors.lastname: Lee
authors.forename: T Y
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D003399:Craniotomy; D005260:Female; D006801:Humans; D008297:Male; D008353:Mannitol / Q000494:pharmacology*; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000187:drug effects
chemical_list: D008353:Mannitol; D010100:Oxygen