1 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Department of Epidemiology and Public Health, Universidad Panamericana School of Medicine, Mexico City, Mexico.
2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
3 Department of Pharmacy, Brigham and Women's Hospital, Boston, MA.
4 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
5 Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
6 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115. Electronic address: mfarber@bwh.harvard.edu.