Michael J Walters1, Marianne Tanios1, Onur Koyuncu1, Guangmei Mao2, Michael A Valente3, Daniel I Sessler4. 1. Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, United States. 2. Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, United States. 3. Department of Colorectal Surgery, Digestive Disease and Surgery Institute, Cleveland Clinic, Cleveland, United States. 4. Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, United States. Electronic address: DS@OR.org.
Abstract
STUDY OBJECTIVE: Moderate hypothermia (e.g., 34.5 °C) causes surgical site infections, but it remains unknown whether mild hypothermia (34.6 °C-35.9 °C) causes infection. Therefore, the objective of this study was to evaluate the relationship between intraoperative time-weighted average core temperature and a composite of serious wound and systemic infections in adults having colorectal surgery over a range of near-normal temperatures. DESIGN: Retrospective, single center study. SETTING: The operating rooms of the Cleveland Clinic Foundation from January 2005 to December 2014. PATIENTS: Adult patients having colorectal surgery at least 1 h in length who received both general anesthesia and esophageal core temperature monitoring. INTERVENTION(S): Time weighted average intraoperative core temperature. MEASUREMENTS: Our primary outcome was a composite of serious infections obtained from a surgical registry and billing codes. Average intraoperative esophageal temperatures and the composite of serious 30-day complications were assessed with logistic regression, adjusted for potential confounding factors. MAIN RESULTS: A total of 7908 patients were included in the analysis. A 0.5 °C decrease in time-weighted average intraoperative core temperature ≤ 35.4 °C was associated with an increased odds of serious infection (OR = 1.38, P = .045); that is, hypothermia below 35.4 °C progressively worsened infection risk. Additionally, at higher core temperatures, the odds of serious infection increased slightly with each 0.5 °C increase in average temperature (OR = 1.10, P = .047). CONCLUSIONS: Below 35.5 °C, hypothermia was associated with increased risk of serious infectious complications. Why composite complications increased at higher temperatures remains unclear, but the highest temperatures may reflect febrile patients who had pre-existing infections. Avoiding time-weighted average core temperatures <35.5 °C appears prudent from an infection perspective, but higher temperatures may be needed to prevent other hypothermia-related complications.
STUDY OBJECTIVE: Moderate hypothermia (e.g., 34.5 °C) causes surgical site infections, but it remains unknown whether mild hypothermia (34.6 °C-35.9 °C) causes infection. Therefore, the objective of this study was to evaluate the relationship between intraoperative time-weighted average core temperature and a composite of serious wound and systemic infections in adults having colorectal surgery over a range of near-normal temperatures. DESIGN: Retrospective, single center study. SETTING: The operating rooms of the Cleveland Clinic Foundation from January 2005 to December 2014. PATIENTS: Adult patients having colorectal surgery at least 1 h in length who received both general anesthesia and esophageal core temperature monitoring. INTERVENTION(S): Time weighted average intraoperative core temperature. MEASUREMENTS: Our primary outcome was a composite of serious infections obtained from a surgical registry and billing codes. Average intraoperative esophageal temperatures and the composite of serious 30-day complications were assessed with logistic regression, adjusted for potential confounding factors. MAIN RESULTS: A total of 7908 patients were included in the analysis. A 0.5 °C decrease in time-weighted average intraoperative core temperature ≤ 35.4 °C was associated with an increased odds of serious infection (OR = 1.38, P = .045); that is, hypothermia below 35.4 °C progressively worsened infection risk. Additionally, at higher core temperatures, the odds of serious infection increased slightly with each 0.5 °C increase in average temperature (OR = 1.10, P = .047). CONCLUSIONS: Below 35.5 °C, hypothermia was associated with increased risk of serious infectious complications. Why composite complications increased at higher temperatures remains unclear, but the highest temperatures may reflect febrile patients who had pre-existing infections. Avoiding time-weighted average core temperatures <35.5 °C appears prudent from an infection perspective, but higher temperatures may be needed to prevent other hypothermia-related complications.