COMPARISON OF INFRARED EAR THERMOMETER DERIVED AND EQUILIBRATED RECTAL TEMPERATURES IN ESTIMATING PULMONARY-ARTERY TEMPERATURES

Objectives: To investigate the clinical accuracy of infrared ear therm ometer derived and equilibrated rectal temperatures in estimating core body temperature. The clinical bias (i.e., mean difference between bo dy sites), and variability (so of the differences) of simultaneous tem peratures were compared with pulmonary artery temperatures. Clinical r epeatability (pooled SD of triplicate reading differences) was also ex amined for three ear infrared thermometers. Design: Prospective clinic al study. Setting: A multidisciplinary, adult intensive care unit. Pat ients: Twenty patients with an existing pulmonary artery catheter were studied in a multidisciplinary, adult intensive care unit. Interventi ons: A single operator using optimum ear infrared technique and masked to ear and rectal temperatures recorded triplicate measurements with each of three infrared ear thermometers, each over a 4-min period with each infrared thermometer, while an assistant recorded temperatures. Infrared and rectal temperatures were compared with a simultaneous pul monary artery temperature. Measurements and Main Results: Infrared ear thermometers and rectal thermometers were calibrated daily, and pulmo nary artery catheters were calibrated on removal from the patient. Pat ients were grouped into afebrile and febrile groups, based on initial pulmonary artery temperature. Bias and variability were compared betwe en thermometers using analysis of variance. Clinical bias, but not var iability, was significantly different between three ear infrared therm ometers (0.16+/-0.46 degrees C, 0.07+/-0.38 degrees C, and -0.22+/-0.4 7 degrees C). The repeatability was not different between ear infrared thermometers (range 0.13 degrees C to 0.14 degrees C). Rectal tempera ture had a significantly greater bias (average 0.3 degrees C), but les s variability (average 0.2 degrees C). Bias was increased, and variabi lity decreased for both rectal and infrared ear temperatures when pulm onary artery temperature was increased. Conclusions: The three infrare d ear thermometers studied provided a closer estimate of core body tem perature than equilibrated rectal temperature. Clinical bias was great est in febrile vs. afebrile intensive care unit patients.