Accuracy of Infrared Ear Thermometry and Traditional Temperature Methods in Young Children

Objective: To compare the accuracy of ear-based, rectal, and axillary temperature measurements in comparison to bladder temperature as a core reference.

Design: Repeated-measures comparison study.

Settings: Pediatric critical care settings in two tertiary care hospitals.

Patients: Thirty children, 1 to 45 months old (mean 16.6 months), who required bladder catheters for their care.

Outcome Measures: Correlation and agreement (mean offset +/- SD) of ear-based, rectal, and axillary temperature measurements with bladder temperature.

Procedure: Ear-based measurements were made with three infrared thermometers in the core mode, both with and without an ear tug. All six readings were made in the same ear in randomized order. Bladder, rectal, and axillary temperatures were read from continuous digital displays immediately after each ear-based measurement.

Results: Ear-based readings correlated relatively well with bladder temperature (r = 0.80 to 0.87), but were lower by means of -0.3 degrees to -0.7 degrees C with moderately high variation (SD = 0.4 degrees to 0.5 degrees C) between children. Use of an ear tug did not affect the readings. Rectal temperature correlated well with bladder values (r = 0.93 to 0.97) and was usually slightly higher (mean offset = 0.2 +/- 0.2 [SD] degrees C), while axillary temperature correlated rather poorly (r = 0.59 to 0.64), with much lower and more variable readings (mean offset = 0.9 degrees +/- 0.6 degrees C). In regard to sensitivity, specificity, and predictive value in screening for fever, rectal readings performed very well, ear-based readings moderately well with some variation, and axillary readings poorly.

Conclusions: The findings suggest that the additive core-mode adjustments in infrared ear thermometers are too low for young children, an ear tug is not an essential part of measurement technique, rectal temperature closely reflects bladder temperature, and axillary temperature is low and highly variable.