title: The effect of deliberate hypercapnia and hypocapnia on intraoperative blood loss and quality of surgical field during functional endoscopic sinus surgery.
abstract: BACKGROUND
  Anesthetic management during functional endoscopic sinus surgery is aimed at minimizing bleeding and establishing a near-perfect surgical field. We investigated whether deliberate intraoperative hypercapnia and hypocapnia may affect blood loss and quality of surgical field through a proposed modulating effect of different carbon dioxide (CO2) tension levels on nasal vasculature.
  
  
  METHODS
  One hundred and eighty patients were randomly assigned to normocapnia (end-tidal CO2 [ETco2] 37 +/- 2 mm Hg), hypercapnia (ETco2 60 +/- 2 mm Hg), and hypocapnia (ETco2 27 +/- 2 mm Hg) groups. Anesthetic management was with propofol and remifentanil infusions, nitrous oxide, and moderate controlled hypotension. Blood loss and operating conditions were assessed by the surgeon who was blinded to group assignment. Differences among the study groups, the effect of the study group and time on ETco2 levels and hemodynamic variables, and the association of blood loss with surgical covariates were analyzed.
  
  
  RESULTS
  There were no differences in blood loss and quality of surgical field among the study groups. Patients in the hypocapnia group demonstrated the highest, and in the hypercapnia group, the lowest, requirements for remifentanil, labetalol, and administration of the antihypertensive medications in general. The computed tomography-graded severity of sinonasal disease and duration of surgery were the only independent predictors of intraoperative blood loss.
  
  
  CONCLUSIONS
  CO2 management during functional endoscopic sinus surgery does not influence operating conditions or blood loss.
authors.affiliation: Stanford University School of Medicine, Stanford, California 94305-5640, USA. nek@.stanford.edu
authors.forename: Vladimir
authors.initials: V
authors.lastname: Nekhendzy
authors.forename: Hendrikus J M
authors.initials: HJ
authors.lastname: Lemmens
authors.forename: Winston C
authors.initials: WC
authors.lastname: Vaughan
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Hepworth
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Chiu
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Church
authors.forename: John G
authors.initials: JG
authors.lastname: Brock-Utne
mesh_terms: D000328:Adult; D016063:Blood Loss, Surgical / Q000503:physiopathology / Q000517:prevention & control*; D004724:Endoscopy / Q000009:adverse effects / Q000379:methods* / Q000592:standards*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D016857:Hypocapnia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012852:Sinusitis / Q000503:physiopathology / Q000601:surgery