TYMPANIC INFRARED AND THERMOCOUPLE THERMO METRY - A COMPARATIVE-STUDY

Objective: To compare tympanic temperatures obtained with an infrared thermometer Core Check 2090A(TM) (IVAC), non in contact with the tympa nic membrane, to values obtained with a thermocouple thermometer Mon-A -Therm(TM) (Mallinckrodt) in contact with it, and to assess whether th e differences depend on the person measuring the temperature. Study de sign : Prospective comparative open study Patients: The study included 150 adults in whom the tympanic temperatures were measured at their a dmission to recovery room by 10 nurse anaesthetists. Methods: Each the rmometer was inserted in the same patient into an external acoustic me atus. The median and range of the temperature differences were used to assess the bias and the accuracy of the measures. Their reliability w as analyzed with consideration of the measuring person and the presenc e of irrelevant values, defined as a temperature difference over 0.3 d egrees C. Results: The temperatures obtained with both devices were si milar (36.2 +/- 0.7 degrees C with IVAC thermometer vs 36.2 +/- 0.8 de grees C with Mallinckrodt thermometer). The median value of the differ ences was 0 degrees C, with a range of 2.5 degrees C (maximum value 1.5 degrees C, minimum value: -1 degrees C). Nineteen patients could b e qualified as hypothermic (temperature < 36.5 degrees C) with one the rmometer and normothermic (temperature greater than or equal to 36.5 d egrees C) with the other. Among them, only 9 (6%) had temperature diff erences above 0.3 degrees C. The temperature differences were not diff erent according to the measuring nurse. Nevertheless two of them obtai ned major differences or irrelevant figures. Conclusions: As compared to the thermocouple thermometry, infrared thermometry has no bias but a low precision. The measurement error does not allow the recognition of hypothermia in 6% of patients. The error may be made by the measuri ng person and/or related to the anatomy and the patency of the externa l acoustic meatus. Tympanic infrared thermometry seems to be a conveni ent method for temperature measurements at short time intervals in the recovery room, provided its limitations are kept in mind.