1. F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
2. Department of Anesthesia, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
3. Department of Anesthesia, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
4. Department of Vascular Surgery, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA