From the Division of Pulmonary and Critical Care Medicine (P.E.M.), the Department of Obstetrics and Gynecology (L.A.P.), and the Department of Anesthesiology (L.A.P.), Thomas Jefferson University, Philadelphia. Address reprint requests to Dr. Marik at Pulmonary and Critical Care Medicine, Thomas Jefferson University, 834 Walnut St., Suite 650, Philadelphia, PA, 19107, or at paul.marik@ jeffers...