(Bennett-Guerrero) Department of Anesthesiology, The Mount Sinai Medical Center, New York, New York; Departments of (Dunn, Young, Wahl, Diers, Newman) Anesthesiology and (Phillips-Bute) Biostatistics, Duke University Medical Center, Durham, North Carolina; and (Welsby, Mythen) Department of Anaesthesia, University College London Hospitals, London, England.Accepted for publication April 14, 1999.Address correspondence and reprint requests to Elliott Bennett-Guerrero, MD, Department of Anesthesiology, P&S Box 46, College of Physicians and Surgeons of Columbia University, 630 West 168th St., New York, NY 10032.