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Published on: September 25, 2009
Middle cerebral artery blood flow velocity during beach chair position for shoulder surgery under general anesthesia
Jean-Luc Hanouz1, Anne-Lise Fiant2, Jean-Louis Gérard1
1Pôle 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.
Objectives:
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.
Design:
Prospective observational study.
Setting:
Operating room, shoulder surgery.
Patients:
Fifty-three consecutive patients scheduled for shoulder surgery in beach chair position.
Interventions:
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).
Measurements:
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.
Main 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.
Conclusion:
Beach chair position resulted in transient decrease in MAP requiring fluid challenge and vasopressors and a moderate decrease in VMCA.
