1. Division of Trauma and Critical Care and Acute Care Surgery, Department of Surgery, Duke University Medical Center, Durham, NC, USA
2. The Critical Care and Perioperative Epidemiologic Research (CAPER) Unit, Duke University Medical Center, Durham, NC, USA
3. Department of Surgery, Kaweah Delta Health Care District, Medical Center, Visalia, CA, USA
4. Department of Surgery, TCU and UNTHSC School of Medicine, Fort Worth, TX, USA
5. Division of Pulmonary Critical Care, Department of Medicine, Duke University Medical Center, Durham, NC, USA