[1] Univ Calif San Francisco, VA Med Ctr, Dept Anesthesia & Perioperat Care, Anesthesiol Serv 129, 4150 Clement St, San Francisco, CA 94121 USA
[2] Univ Alabama Birmingham, Anesthesiol & Perioperat Med, Anesthesia Dept, JT 923,619 19th St South, Birmingham, AL 35249 USA
[3] Katholieke Univ Leuven, Dept Anaesthesiol, Dept Cardiovasc Sci, Univ Hosp Leuven, Herestraat 49B, B-3000 Leuven, Belgium