Accuracy and stability of temperature probes for intracranial application

Intracranial temperature measurement may play a pivotal role for prognosis and treatment of neurological and neurosurgical patients. For reliable clinical application, accurate temperature readings are therefore necessary. We present an independent in vitro study investigating the accuracy and stability of three temperature probes. Eight Neurovent-P Temp (RN), eight Licox temperature sensors (LT) and eight Neurotrend sensors (NT) were placed into a water bath. The temperature was increased in 3 degrees C increments from 30 to 42 degrees C before (accuracy test day 0) and after (accuracy test day 5) a long-term stability test run at 37 +/- 0.2 degrees C. The accuracy tests revealed deviations of <0.25, <0.2 and >0.4 degrees C for the RN, NT and LT probes, respectively, when compared to the reference measurement by a precision Pt100 temperature measuring instrument. All sensor types showed stable readings over the course of 120 h. The high variability of LT probes was due to a malfunctioning Licox monitor. Excluding these values reduced deviation below 0.21 degrees C the standard deviation at each temperature step was below +/-0.08 (RN, NT) and +/-0.12 (LT), laying within the range provided by the manufacturer (RN, NT: +/-0.1; LT: +/-0.2). In general, RN, NT and LT temperature measurement is reliable, but malfunctioning parts may lead to false interpretation of temperature readings. Therefore, validation of temperature probes to a reference temperature prior to clinical use is recommended.