1. From the Departments of Anesthesia and Perioperative Care (H.K., J.N., W.L.Y.), Epidemiology and Biostatistics (H.K., C.E.M.), and Neurological Surgery (M.T.L., W.L.Y.), University of California, San Francisco; Division of Neuroradiology, Department of Medical Imaging (T.K., K.G.T.), Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada; and Division of Respirology, Keenan Research Centre, and Li Ka Shing Knowledge Institute, St. Michael’s Hospital, University of Toronto, Toronto...