[1] CHUM, Hop St Luc, Dept Anesthesiol, Montreal, PQ H2X 3J4, Canada
[2] CHUM, Hop St Luc, Dept Epidemiol & Biostat, Montreal, PQ H2X 3J4, Canada
[3] Univ Alberta, Dept Anesthesiol & Pain Med, Edmonton, AB, Canada
[4] CHUM, Hop St Luc, Dept Surg, Hepatobiliary Serv, Montreal, PQ H2X 3J4, Canada