Abstract
Title:
Management of perioperative hypothermia in major surgery: The efficacy of prewarming with Barrier Easy warm blanket and validation of the Spot on thermometry.

Authors:
Elke Van Gerven, Steve Coppens, Arne Neyrinck
Dept. of Anesthesiology, Leuven University Hospital, Leuven, Belgium

Background and Goal of the study:
Perioperative hypothermia (core temperature < 36°C) is a common but preventable complication during surgery and is associated with increased risk of infections, bleeding, postoperative shivering and cardiovascular complications. 1-3
After induction of general anesthesia, the body temperature initially drops due to a redistribution of blood from the cold body surface to the body core 4. Previous studies showed that preoperative skin warming 
(prewarming) 5,6 may be very effective in minimalizing this redistribution hypothermia.
Also, less invasive temperature assessment is needed in case of a prewarming strategy. 
Recently a disposable self-warming blanket was developed (Easy warm). with chemical powder that becomes activated in contact with room air (40-42°C for 10-12 hours )6. In addition, the Spot on thermometry provides a noninvasive temperature assessment (Forehead).

The goal of our study was to evaluate the prewarming strategy combining the Easy warm blanket with the Spot on device in patients scheduled for a esophagectomy.

Material and Methods
40 adult patients included scheduled for a total esophagectomy under general anesthesia were randomized in two groups. Group 1 (intervention) received the Easy warmer 30 minutes before induction of general anesthesia, and group 2 (control) was covered with normal blankets. Patient core temperature was measured with2 devices (bladder, Spot On) at regular intervals during the pre-, per -and postoperative period. All patients got rescue warming with a bair hugger if bladder temperature dropped below 35°C. 

Result and Discussion:
No difference in temperature was seen between group 1 and group 2 during the pre-, per and postoperative period, both with the bladder and Spot on measurements. 
Noninvasive thermometry gives an average fault -0.4 °C compared to bladder temperature. 

Conclusion:
A prewarming strategy with the easy warm did not reduce the incidence of hypothermia. The new Spot On devices was less accurate compared with gold standard bladder temperature measurement to access core temperature.

References

1.	Frank SM, Fleisher LA, Breslow MJ, et al. Perioperative Maintenance of Normothermia Reduces the Incidence of Morbid Cardiac Events: A Randomized Clinical Trial. JAMA. 1997;277(14):1127-1134. doi:10.1001/jama.1997.03540380041029.
2.	Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. N Engl J Med. 1996;334(19):1209-1215. doi:10.1056/NEJM199605093341901.
3.	Rajagopalan S, Mascha E, Na J, Sessler DI. The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology. 2008;108(1):71-77. doi:10.1097/01.anes.0000296719.73450.52.
4.	Menzel M, Grote R, Leuchtmann D, Lautenschläger C, Röseler C, Bräuer A. [Implementation of a thermal management concept to prevent perioperative hypothermia : Results of a 6‑month period in clinical practice]. Anaesthesist. 2016;65(6):423-429. doi:10.1007/s00101-016-0158-3.
5.	Sessler DI, Schroeder M, Merrifield B, Matsukawa T, Cheng C. Optimal duration and temperature of prewarming. Anesthesiology. 1995;82(3):674-681.
6.	Torossian A, van gerven E, Geertsen K, Horn B, Van de Velde M, Raeder J. Active perioperative patient warming using a self-warming blanket (BARRIER EasyWarm) is superior to passive thermal insulation: a multinational, multicenter, randomized trial. J Clin Anesth. 2016;34:547-554. doi:10.1016/j.jclinane.2016.06.030.

Management of perioperative hypothermia in major surgery: the efficacy of prewarming with Barrier Easy warm blanket and validation of the Spot on thermometry