Intraoperative Warming Comparison of Devices

Hypothermia is a common and serious complication during anesthesia and surgery.
Anesthetic-induced hypothermia results from the inhibition of thermoregulatory control and
exposure to cold operating room environment.

Various warming methods, such as warm blankets, forced-air warmers and circulating water
mattresses, are currently used to prevent and treat mild perioperative hypothermia. All are
cutaneous approaches that rely on heating the peripheral tissues in order to increase the
thermal core temperature. 5, 6 Application of cutaneous warming system blankets/pads are
limited by location/extent of operative site; for example, in certain procedures such as
laparatomies, reconstructive plastic surgery or orthopedic surgery, only a limited amount of
skin surface is available for warming application. 7, 8, 9 The Dynatherm vitalHEAT
technology takes advantage of the body's natural thermoregulatory system to channel thermal
energy to the body's core non-invasively at a rapid rate. The vH2 system is designed to
treat hypothermia during the peri-operative period through a combination of localized heat
and vacuum application to one hand & forearm; this application 1) opens the arteriovenous
anastamoses located in the palm of the hand and 2) conductively warms the extremity thus
effectively warming the blood flow to the body's core. The vH2 system is a portable and
compact warming device which provides a non-invasive approach to warming patients during
surgery.

The primary objective of this study is to determine if the Dynatherm Medical vitalHEAT (vH2)
Temperature Management System is as effective as the forced-air warming Bair Hugger™
(Arizant Healthcare, Eden Prairie, MN) for maintenance of intraoperative body temperature in
patients undergoing abdominal surgery under general anesthesia. The critical endpoints to
be evaluated in making this determination are 1) % of subjects with an average
intraoperative esophageal temperature of ≥ 36º C and 2) % of subjects with an initial PACU
sublingual temperature of ≥ 36º C. Secondary objectives include 1) comparison of the core
body temperatures @ 60 minutes post anesthesia induction, 2) comparison of temperature
trends during surgery and 3) comparison of the subjects' PACU temperature trends and
hypothermic symptoms such as shivering.