title: Cerebral oxygenation in the beach chair position for shoulder surgery in regional anesthesia: impact on cerebral blood flow and neurobehavioral outcome.
abstract: OBJECTIVE
  Beach chair position is considered a potential risk factor for central neurological events particularly if combined with low blood pressure. The aim of this study was to assess the impact of regional anesthesia on cerebral blood flow and neurobehavioral outcome.
  
  
  METHODS
  This is a prospective, assessor-blinded observational study evaluating patients in the beach chair position undergoing shoulder surgery under regional anesthesia.
  
  
  METHODS
  University hospital operating room.
  
  
  METHODS
  Forty patients with American Society of Anesthesiologists classes I-II physical status scheduled for elective shoulder surgery.
  
  
  METHODS
  Cerebral saturation and blood flow of the middle cerebral artery were measured prior to anesthesia and continued after beach chair positioning until discharge to the postanesthesia care unit. The anesthesiologist was blinded for these values. Controlled hypotension with systolic blood pressure≤100mm Hg was maintained during surgery.
  
  
  METHODS
  Neurobehavioral tests and values of regional cerebral saturation, bispectral index, the mean maximal blood flow of the middle cerebral artery, and invasive blood pressure were measured prior to regional anesthesia, and measurements were repeated after placement of the patient on the beach chair position and every 20 minutes thereafter until discharge to postanesthesia care unit. The neurobehavioral tests were repeated the day after surgery.
  
  
  RESULTS
  The incidence of cerebral desaturation events was 5%. All patients had a significant blood pressure drop 5 minutes after beach chair positioning, measured at the heart as well as the acoustic meatus levels, when compared with baseline values (P<.05). There was no decrease in either the regional cerebral saturation (P=.136) or the maximal blood flow of the middle cerebral artery (P=.212) at the same time points. Some neurocognitive tests showed an impairment 24 hours after surgery (P<.001 for 2 of 3 tests).
  
  
  CONCLUSIONS
  Beach chair position in patients undergoing regional anesthesia for shoulder surgery had no major impact on cerebral blood flow and cerebral oxygenation. However, some impact on neurobehavioral outcome 24 hours after surgery was observed.
authors.affiliation: Division of Anesthesiology, Balgrist University Hospital, Zurich, Switzerland. Electronic address: jose.aguirre@balgrist.ch.
authors.forename: José A
authors.initials: JA
authors.lastname: Aguirre
authors.affiliation: Division of Anesthesiology, Balgrist University Hospital, Zurich, Switzerland. Electronic address: oliviam@access.uzh.ch.
authors.forename: Olivia
authors.initials: O
authors.lastname: Märzendorfer
authors.affiliation: Division of Anesthesiology, Balgrist University Hospital, Zurich, Switzerland. Electronic address: Muriel.brada@balgrist.ch.
authors.forename: Muriel
authors.initials: M
authors.lastname: Brada
authors.affiliation: Anaesthesiology Department, Bellinzona Regional Hospital, Bellinzona, Switzerland. Electronic address: Andrea.Saporito@eoc.ch.
authors.forename: Andrea
authors.initials: A
authors.lastname: Saporito
authors.affiliation: Division of Anesthesiology, Balgrist University Hospital, Zurich, Switzerland. Electronic address: alain.borgeat@balgrist.ch.
authors.forename: Alain
authors.initials: A
authors.lastname: Borgeat
authors.affiliation: Division of Anesthesiology, Balgrist University Hospital, Zurich, Switzerland. Electronic address: karlphilippbuehler@gmail.com.
authors.forename: Philipp
authors.initials: P
authors.lastname: Bühler
mesh_terms: D000328:Adult; D000765:Anesthesia, Conduction; D001921:Brain / Q000098:blood supply; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019965:Neurocognitive Disorders / Q000503:physiopathology / Q000517:prevention & control*; D010100:Oxygen / Q000097:blood*; D056888:Patient Positioning / Q000379:methods*; D011183:Postoperative Complications / Q000503:physiopathology / Q000517:prevention & control*; D011187:Posture; D011446:Prospective Studies; D012782:Shoulder / Q000601:surgery*
chemical_list: D010100:Oxygen
keywords: Beach chair position, neurocognitive outcome; Cerebral blood flow; Cerebral oxygenation; Intraoperative monitoring; Near-infrared spectroscopy