title: Middle cerebral artery blood flow velocity during beach chair position for shoulder surgery under general anesthesia.
abstract: OBJECTIVE
  The goal of the present study was to examine changes of middle cerebral artery (VMCA) blood flow velocity in patients scheduled for shoulder surgery in beach chair position.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Operating room, shoulder surgery.
  
  
  METHODS
  Fifty-three consecutive patients scheduled for shoulder surgery in beach chair position.
  
  
  METHODS
  Transcranial Doppler performed after induction of general anesthesia (baseline), after beach chair positioning (BC1), during surgery 20minutes (BC2), and after back to supine position before stopping anesthesia (supine).
  
  
  METHODS
  Mean arterial pressure (MAP), end-tidal CO2, and volatile anesthetic concentration and VMCA were recorded at baseline, BC1, BC2, and supine. Postoperative neurologic complications were searched.
  
  
  RESULTS
  Beach chair position induced decrease in MAP (baseline: 73±10mm Hg vs lower MAP recorded: 61±10mm Hg; P<.0001) requiring vasopressors and fluid challenge in 44 patients (83%). There was a significant decrease in VMCA after beach chair positioning (BC1: 33±10cm/s vs baseline: 39±14cm/s; P=.001). The VMCA at baseline (39±2cm/s), BC2 (35±14cm/s), and supine (39±14cm/s) were not different. The minimal alveolar concentration of volatile anesthetics, end-tidal CO2, SpO2, and MAP were not different at baseline, BC1, BC2, and supine.
  
  
  CONCLUSIONS
  Beach chair position resulted in transient decrease in MAP requiring fluid challenge and vasopressors and a moderate decrease in VMCA.
authors.affiliation: Pôle Réanimations Anesthésie SAMU, CHU de Caen, Avenue Côte de Nacre, 14033 Caen cedex, France; Laboratoire de Signalisation, Électrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA 4650, Université Caen Basse Normandie, France. Electronic address: hanouz-jl@chu-caen.fr.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Hanouz
authors.affiliation: Pôle Réanimations Anesthésie SAMU, CHU de Caen, Avenue Côte de Nacre, 14033 Caen cedex, France.
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Fiant
authors.affiliation: Pôle Réanimations Anesthésie SAMU, CHU de Caen, Avenue Côte de Nacre, 14033 Caen cedex, France; Laboratoire de Signalisation, Électrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA 4650, Université Caen Basse Normandie, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Gérard
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General / Q000379:methods*; D062186:Arterial Pressure / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016343:Monitoring, Intraoperative / Q000379:methods; D056888:Patient Positioning / Q000379:methods*; D011187:Posture / Q000502:physiology; D011446:Prospective Studies; D012782:Shoulder / Q000601:surgery*; D012785:Shoulder Joint / Q000601:surgery; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods
keywords: Beach chair position; Cerebral blood flow; Shoulder surgery; Transcranial Doppler