title: Effect of ventilation on cerebral oxygenation in patients undergoing surgery in the beach chair position: a randomized controlled trial.
abstract: BACKGROUND
  Surgery in the beach chair position (BCP) may reduce cerebral blood flow and oxygenation, resulting in neurological injuries. The authors tested the hypothesis that a ventilation strategy designed to achieve end-tidal carbon dioxide (E'(CO₂)) values of 40-42 mm Hg would increase cerebral oxygenation (Sct(O₂)) during BCP shoulder surgery compared with a ventilation strategy designed to achieve E'(CO₂) values of 30-32 mm Hg.
  
  
  METHODS
  Seventy patients undergoing shoulder surgery in the BCP with general anaesthesia were enrolled in this randomized controlled trial. Mechanical ventilation was adjusted to maintain an E'(CO₂) of 30-32 mm Hg in the control group and an E'(CO₂) of 40-42 mm Hg in the study group. Cerebral oxygenation was monitored continuously in the operating theatre using near-infrared spectroscopy. Baseline haemodynamics and Sct(O₂) were obtained before induction of anaesthesia, and these values were then measured and recorded continuously from induction of anaesthesia until tracheal extubation. The number of cerebral desaturation events (CDEs) (defined as a ≥20% reduction in Sct(O₂) from baseline values) was recorded.
  
  
  RESULTS
  No significant differences between the groups were observed in haemodynamic variables or phenylephrine interventions during the surgical procedure. Sct(O₂) values were significantly higher in the study 40-42 group throughout the intraoperative period (P<0.01). In addition, the incidence of CDEs was lower in the study 40-42 group (8.8%) compared with the control 30-32 group (55.6%, P<0.0001).
  
  
  CONCLUSIONS
  Cerebral oxygenation is significantly improved during BCP surgery when ventilation is adjusted to maintain E'(CO₂) at 40-42 mm Hg compared with 30-32 mm Hg.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01546636.
authors.affiliation: Department of Anesthesiology and dgmurphy2@yahoo.com.
authors.forename: G S
authors.initials: GS
authors.lastname: Murphy
authors.affiliation: Department of Anesthesiology and.
authors.forename: J W
authors.initials: JW
authors.lastname: Szokol
authors.affiliation: Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron Street F5-704, Chicago, IL 60611, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Avram
authors.affiliation: Department of Anesthesiology and.
authors.forename: S B
authors.initials: SB
authors.lastname: Greenberg
authors.affiliation: Department of Anesthesiology and.
authors.forename: T D
authors.initials: TD
authors.lastname: Shear
authors.affiliation: Department of Anesthesiology and.
authors.forename: J S
authors.initials: JS
authors.lastname: Vender
authors.affiliation: Department of Surgery, NorthShore University HealthSystem (an affiliate of University of Chicago Pritzker School of Medicine), 2650 Ridge Ave., Evanston, IL 60201, USA.
authors.forename: S D
authors.initials: SD
authors.lastname: Levin
authors.affiliation: Department of Surgery, NorthShore University HealthSystem (an affiliate of University of Chicago Pritzker School of Medicine), 2650 Ridge Ave., Evanston, IL 60201, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Koh
authors.affiliation: Department of Anesthesiology and.
authors.forename: K N
authors.initials: KN
authors.lastname: Parikh
authors.affiliation: Department of Anesthesiology and.
authors.forename: S S
authors.initials: SS
authors.lastname: Patel
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D023381:Endpoint Determination; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D056888:Patient Positioning / Q000379:methods*; D010656:Phenylephrine / Q000627:therapeutic use; D011183:Postoperative Complications / Q000453:epidemiology; D012121:Respiration, Artificial / Q000379:methods*; D012782:Shoulder / Q000601:surgery; D019265:Spectroscopy, Near-Infrared; D014662:Vasoconstrictor Agents / Q000627:therapeutic use
chemical_list: D014662:Vasoconstrictor Agents; D002245:Carbon Dioxide; D010656:Phenylephrine
keywords: patient positioning; spectroscopy, near-infrared; ventilation