Accuracy of an infrared tympanic thermometer

Background: The use of infrared thermometry to measure temperatures in hosp italized patients is increasing. Although infrared thermometers have been p roven to be accurate when they are used by well-trained personnel, no previ ous studies have examine their accuracy during routine hospital use, Objective: To determine the accuracy and observer variability of temperatur es measured with an infrared tympanic thermometer (TT). Design: Prospective, observational study. Setting: ICUs of a 300-bed teaching community hospital. Patients: Fifty-one critically ill patients. Measurements: The mean of three tympanic temperatures measured with the inf rared TT (tempTTs) was compared to temperatures simultaneously measured wit h the thermistor of right heart catheters and rectal mercury thermometers f or the following three groups of observers who had been certified in the us e of the infrared TT: a single critical care nurse (CCN)/educator (Ed); CCN s, and floor nurses (FNs)/clinical care practitioners (CCPs). Results: Two rounds of measurements were given to 51 patients by 153 observ ers. Temperatures of tbe pulmonary artery (PA) measured with the thermistor of light heart: catheters (tempPAs) ranged from 96.5 to 102.6 degrees F, w ith a mean ( +/- SD) of 99.3 +/- 1.1 degrees F. The intraobserver variabili ties (correlation coefficients) of the tempTTs ranged from 0.90 for those m easured by FNs/CCPs, to 0.92 for those measured by CCNs, to 0.98 for those measured by the CCN/Ed. Accuracy, arbitrarily defined as within a deviation of +/- 0.5 degrees F of the tempPA, was 100% for the rectal mercury thermo meter and 98.0% for the infrared TT when used by the CCN/Ed. The accuracy o f die infrared TT was 80% when measured by CCNs and 61% when measured by FN s/CCPs. Differences between tempPAs and tempTTs measured by the CCN/Ed rang ed front 0 to 0.7 degrees F, with a mean of 0.2 degrees F. Similarly, diffe rences between tempPAs and tempTTs measured by CCNs ranged from 0 to 2.4 de grees F, with a mean difference of 0.3 degrees F. However, differences betw een tempPAs and tempTTs measured by FNs/CCPs ranged from 0 to 3.0 degrees F , with a mean of 0.6 degrees F (greater differences than those obtained by the CCNs; p < 0.01). The accuracy of rectal mercury thermometry tvas 100%. If a temperature greater than or equal to 101.0 degrees F had been consider ed as the threshold at which a fever is present, and if the mean of three m easurements had been used to designate temperature, workups that were eithe r inappropriately performed or omitted would have resulted from 2% of tempT Ts measured by the CCN/Ed, 1% of those measured by CCNs, and 4% of those me asured by FNs/CCPs. Conclusion: When used properly, both tympanic and rectal thermometry are ve ry accurate. However, the infrared TT produced measurements that were both less accurate and less reproducible when used by nurses who routinely used it in clinical practice.