(J. Benumof) Professor of Anesthesia.(Dagg) Hewlett-Packard Information Technology Engineer.(R. Benumof) Professor Emeritus of Physics.Received from the Department of Anesthesiology, University of California at San Diego Medical Center, San Diego, California. Submitted for publication January 22, 1997. Accepted for publication June 19, 1997.Address reprint requests to Dr. Benumof: Department of Anesthesia (0801) UCSD Medical Center, 402 Dickinson Street, San Diego, California 92103–0801.