Evidence-Based Guidelines for Prevention of Perioperative Hypothermia Shawn S Forbes, MD, Cagla Eskicioglu, MD, Avery B Nathens, MD, FACS, Darlene S Fenech, MD, Claude Laflamme, MD, Richard F McLean, MD, Robin S McLeod, MD, FACS; for the Best Practice in General Surgery Committee, University of Toronto* Burden of illness Perioperative hypothermia (PH), defined as a tempera- ture 36.0°C at any point in the perioperative period, has been identified as a cause of considerable morbidity in the surgical population, and its effects on surgical-site infections (SSIs) and cardiac morbidity have been clearly documented. 1-4 PH has been shown to affect many aspects of the im- mune system, including leukocyte migration, neutrophil phagocytosis, and cytokine and antibody production. 5 The end result is a decreased resistance to SSIs. SSIs account for approximately 15% of all hospital-acquired infections and are the most common nosocomial infection in surgical pa- tients, accounting for nearly 40% of infectious complica- tions in this group. 6 SSIs have been associated with an increased risk of death (relative risk [RR]: 2.2; 95% CI, 1.1–4.5), an increase in hospital length of stay (median 6.5 days; 95% CI, 5–8), and an increase in direct hospital costs measured in the thousands of dollars per patient affected. 7 Estimates suggest that in SSI-related deaths, one-third can be directly attributed to the SSI itself. 8 PH has also been demonstrated to lead to an increase in circulating catecholamine levels, systemic vasoconstriction, and systemic blood pressure. 9 The consequences of these changes are an increase in cardiac demand and, subse- quently, an increased risk of cardiac morbidity. In a review of the literature on perioperative cardiac events, Devereaux and colleagues 10 reveal the magnitude of this disease. It was reported that with a rate of approximately 1.4% in uns- elected, elective surgery patients older than 50 years of age, up to 900,000 people worldwide would experience a peri- operative cardiac event annually. Hospital length of stay was found to be increased an average of 11 days in these patients, and the in-hospital mortality rate was estimated to be as high as 15% to 25%. Those patients who survive a postoperative cardiac event continue to be at considerable risk of cardiovascular death in the first 6 months after dis- charge (hazard ratio: 18; 95% CI, 6–57). 10 Despite the link between hypothermia and poor postop- erative outcomes, PH continues to be a common occur- rence. In the early 1980s, PH was documented in as many as 60% of all patients on arrival to the postanesthetic care unit (PACU) and in almost 20% of patients on arrival to the ward. 1 Nearly 30 years later, even with an abundance of evidence to support its prevention, PH rates remain unac- ceptably high. Currently, as many as 46% of general sur- gery patients undergoing abdominal operations have a temperature 36°C at the start of operation and more than one-third will be hypothermic on arrival in the PACU. 11,12 Rationale for guideline development These guidelines are for the prevention of unplanned PH in patients undergoing abdominal operations, including gen- eral, vascular, gynecologic, and obstetric procedures. They were prepared for surgeons and anesthesiologists in order to consolidate the evidence supporting avoidance of un- planned PH. These guidelines focus on how avoidance of PH prevents SSIs and cardiac morbidity, how best to mon- itor perioperative temperature, and what devices readily available in North American hospitals are most effective at preventing PH. METHODS A systematic review of the medical literature from January 1950 to January 2008 was performed. The objective of the literature search was to address three questions: Disclosure Information: Nothing to disclose. Reviewed and endorsed by the Canadian Association of General Surgeons, September 2008. Abstract presented at the Canadian Surgical Forum, Halifax, Nova Scotia, September 2008. *See Appendix 1 for Members of the Best Practice in General Surgery Com- mittee, University of Toronto. Received May 22, 2009; Revised June 29, 2009; Accepted July 7, 2009. From the Departments of Surgery (Forbes, Eskicioglu, Nathens, Fenech, McLeod), Health Policy, Management, and Evaluation (Forbes, Eskicioglu, Nathens, Fenech, McLeod), and Anesthesia (Laflamme), University of To- ronto,Toronto, Ontario, Canada, Dr. Zane Cohen Digestive Diseases Clin- ical Research Centre, Mount Sinai Hospital, Toronto, Ontario, Canada (Forbes, Eskicioglu, Fenech, McLeod), Department of Anesthesia, McMaster University, Hamilton, Ontario, Canada (McLean), and Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada (McLeod). Correspondence address: Robin S McLeod, MD, FACS, Mount Sinai Hos- pital, 600 University Avenue, Suite 449, Toronto, ON. email: rmcleod@ mtsinai.on.ca 492 © 2009 by the American College of Surgeons ISSN 1072-7515/09/$36.00 Published by Elsevier Inc. doi:10.1016/j.jamcollsurg.2009.07.002