1. Department of Anesthesiology, Brooke Army Medical Center , Fort Sam Houston, TX 78234-6200, USA
2. Department of Anesthesiology, Uniformed Services University , Bethesda, MD 20814, USA
3. Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. , Rockville, MD 20852, USA
4. Department of Anesthesiology, Mike O’Callaghan Military Medical Center , Nellis AFB, NV 89191, USA
5. Department of Anesthesia and Operative Services, Womack Army Medical Center , Fort Bragg, NC 28310, USA
6. US Navy Bureau of Medicine and Surgery (BUMED) , Falls Church, VA 22042-5113, USA