The Surgical Care Improvement Project (SCIP) identified immediate postoperative normothermia for colorectal surgery patients as one of seven infection control measures after discovering that mild hypothermia triples surgical site infections after colon surgery and increases the hospital stay by 20%.1 Dr. Daniel Sessler studied the efficacy of preoperative warming in a 1995 study. He noted a significant reduction in hypothermia when redistribution hypothermia was prevented via preoperative warming lasting at least 30 minutes with the ideal time being 1 hour or longer.2
A randomized clinical trial was conducted on patients undergoing surgery who had a surgical wound classification of clean. During the trial, systemic preoperative warming was compared with preoperative local warming or no preoperative warming. Results revealed a significant decrease in postoperative infection rate in groups that received preoperative warming, and the greatest in the systemic group.3 Relevant studies showed that 30 to 60 minutes of preoperative, skin-surface warming can prevent heat redistribution associated with anesthesia induction. When combined with intraoperative warming techniques, this could potentially avoid hypothermia and associated complications altogether.4
Forced-air warming devices
Warming patients with a forced-air warming device with an attached blanket has become commonplace in many institutions during surgical procedures expected to last at least 1 hour. A comparison study between using a forced-air warming device or cotton blankets showed the warming device was a more effective tool for warming patients during the perioperative period. The results found that the forced-air warming group had significantly higher temperatures upon arrival to the postanesthesia care unit compared with the blanket group.5
Another modality to prevent and treat perioperative hypothermia is the fluid warmer. One study found that warming I.V. fluid during orthopaedic surgeries resulted in a 0.5° C and 0.6° C greater final core and skin temperature compared with room temperature fluids. The study concluded that hemodynamic parameters (core and skin temperature, mean arterial pressure), shivering, and recovery time was less in the group receiving warm I.V. fluids when compared to the group receiving fluids at room temperature.6 However, another study concluded that the delivery of 1.1 L of I.V. fluids at 38° C to 39° C can't transfer enough heat to rewarm patients who are already hypothermic. Thus, patients who don't need an excess amount of fluid would have to receive more than their requirements in an attempt to achieve normothermia.7
REFERENCES
1. The Joint Commission. SCIP-INF-7: Colorectal surgery patients with immediate postoperative normothermia. Specifications Manual for National Hospital Inpatient Quality Measures. http://manual.jointcommission.org/pub/Manual/MIF0058/SCIPInf7_Algorithm.pdf . [Context Link]
2. Sessler DI, Schroeder M, Merrifield B, et al. Optimal duration and temperature of prewarming. Anesthesiology. 1995; 82(3):674–681. [Context Link]
3. Melling A, Bagar A, Scott E, Leaper D. Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomized controlled trial. Lancet. 2001;358:876–880. [Context Link]
4. Kiekkas P, Pouplopoulou M, Papahatzi A, et al. Effects of hypothermia and shivering on standard PACU monitoring of patients. Am Assoc Nurs Anesthetist J. 2005;73:47–53. [Context Link]
5. Ng S, Oo CS, Loh KH, et al. A comparative study of three warming interventions to determine the most effective in maintaining perioperative normothermia. Anesth Analg. 2003;96:171–176. [Context Link]
6. Hasankhani H, Mohhammadi E, Nighizade MM, et al. The effects of warming intravenous fluid on perioperative hemodynamic status, postoperative shivering and recovery in orthopedic surgery. Shiraz-E Med J. 2004;5(3):1–8. [Context Link]
7. Smith CE, Sidhu RS, Lucas L, Mehta D, Pinchak AC. Should patients undergoing ambulatory surgery with general anesthesia be actively warmed? Int J Anesth. 2007;12(1). [Context Link]
