1. *Clinical Associate, Anesthesiology Department. National Institutes of Health, Bethesda, Maryland 20014. Present address: Department of Anesthesia, Indiana University School of Medicine, Indian-apolis, Indiana 46202.† Surgery Clinic, National Heart and Lung Institute, Bethesda, Maryland 20014. Present adadress: Department of Surgery, University of Kansas School of Medicine, Kansas City, Kansas 66