Failure of intraoperative liquid crystal temperature monitoring.

T he major reason for monitoring intraoperative temperature is for detection of fever, malignant hyperthermia, and hypothermia. Inadvertent hypothermia-defined by an absolute core temperature <36”C-is by far the most common perioperative thermal disturbance. However, hypothermia may be difficult to evaluate using liquid-crystal thermography, because skin temperatures are l-4°C less than core temperature (l-3). Furthermore, the difference between skin and core temperatures varies considerably both between and within individuals (4-12). Liquid-crystal thermography may also fail to detect core hyperthermia. Numerous studies demonstrate that skin-surface thermography often fails to identify clinical fevers, and no published study indicates that liquid-crystal thermography correlates with core temperature during malignant hyperthermia crises in humans. In contrast, the single relevant study showed that changes in forehead and neck skin temperatures failed to identify malignant hyperthermia in swine (13). Despite the lack of validating data, liquid-crystal thermometers are promoted for “trending” core temperature. The term “trend,” in this context, means that an increase in core temperature will produce an increase in the value displayed on the liquid crystal, without any requirement that the increase be comparable-or even a linear function of core temperature. We now present a case in which liquid-crystal skinsurface thermography failed to “trend” core temperature; monitoring failure prompted otherwise unnecessary laboratory evaluations and cancellation of surgery.