From the Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
Accepted for publication April 26, 2014.
The authors declare no conflicts of interest.
Reprints will not be available from the authors.
Address correspondence to Mary Ellen Warner, MD, Department of Anesthesiology, Mayo Clinic, 200 1st St. S.W., Rochester, MN 55905. Address e-mail to firstname.lastname@example.org.