[1] Univ Nice, Dept Anesthesia & Intens Care, F-06202 Nice, France
[2] Univ Nice, Archet Hosp, Dept Orthopaed Surg, F-06202 Nice, France
[3] Univ Aix Marseille 1, UPRES, F-13331 Marseille 3, France
[4] Univ Calif San Francisco, San Francisco Gen Hosp, Dept Anaesthesia, San Francisco, CA 94143 USA