Background: Up to 20% of patients experience unintended perioperative hypothermia (UPH) defined as a core temperature below 36°C (2). The peripheral compartment is usually 2-4 °C cooler than the central compartment (3). This temperature gradient is maintained by central regulation in the hypothalamus of peripheral arteriovenous shunts in the fingers and toes. General Anesthesia reduces the threshold for centrally modulated vasoconstriction by 2°C.Thermoregulatory vasoconstriction decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissues results in an increase in surgical site infections as well as other complications, all of which results in postoperative morbidity and mortality with an increased length of hospitalization. Methods: Forty-eight patients undergoing abdominal, gynecological, breast and head and neck surgery were randomly assigned to two groups. The control group used a Forced Air Warming Device (FAWD), (3M™ Bair Hugger™ warming unit, 3M, Maplewood, MN) and the study group using a pajama-type garment with gloves and socks containing air-activated heating packs (HEATMAX INC. Dalton, GA). The patients’ anesthetic care was standardized. Core temperature measurements were made in the admissions area, at 15 minute intervals during general anesthesia and in the Post Anesthesia Care Unit (PACU). Additional measurements were recorded of ambient operating room temperature, temperature one meter from the patient’s head, dorsal hand temperature in admissions area, at the start of general anesthesia and 60 minutes thereafter. Core temperature was measured on admission to the PACU and at 15 minute intervals until patient was normothermic. Results: Mean (±SE) intraoperative core temperature at 120 minutes, 35.27 °C (± 0.45) in study group and 36.09 °C in control group. (± 0.13), (P-Value 0.0656). Mean (±SE) intraoperative core temperature at 150 minutes, 35.33 °C (± 0.18) in the study group and 36.26 °C in control group. (± 0.21), (P-Value 0.0007) see Table 2. The mean (±SE) PACU admission core temperature was 36.5 °C (± 0.11) in the study group and 36.79 °C in the control group. (± 0.09), (P-Value 0.04). All patients from both groups were normothermic on admission to the PACU. Conclusions: This study was designed primarily as a proof of concept study to show that an integrated heat-pack garment was effective in maintaining normothermia during the perioperative period as compared to a FAWD. The findings were that there was no statistical significance between the two groups for before or after surgery and for the first 120 minutes of anesthesia. Thereafter the Control group had significantly higher temperatures although there were more participants in the control group after 120 minutes (Table2). All of the patients in both groups were normothermic on admission to the PACU, conforming with the NICE guidelines. No patient felt cold or experienced clinical or ECG manifestations of shivering in the PACU.
