Correlation Between Core Temperature and Skin Temperature Measured by 3M SpotOn

Core temperature should be monitored under general anesthesia. Because patients are prone to hypothermia during surgery. Conventional core temperature is monitored at esophagus, rectum, nasopharynx. But some of them are invasive and impossible in sometimes. Recently developed 3M Spoton skin temeprature which is applied on temporal artery is correlated with core temperature measured by esophageal prove in several studies. Its mechanism is making zero heat flux on skin applied. But it also cannot apply in head or facial surgery. Other studies showed conventional skin temperature over carotid artery is also correlated with core temperature. The investigators hypothesized using Spoton on carotid artery could be alternative method measuring core temperature. The purpose of this study is comparing 3 methods of temperature monitoring. First, conventional core temperature measure by esophageal stethoscope. Second, 3M Spoton applying on temporal artery. Third, 3M Spoton applying on carotid artery