Study objective: To determine normal body temperature with an infrared emission detection ear thermometer.
Design: Cross-sectional convenience sample.
Setting: Four acute and long-term health care facilities.
Participants: Subjects who denied recent potentially febrile illness and ingestion of medications affecting normal body temperature.
Results: Two thousand four hundred forty-seven subjects aged 12 hours to 103 years were enrolled. Ear temperatures were normally distributed for each of eight age groups. There were differences in mean temperature among different age groups (P < .001, by ANOVA) and a striking cutoff at adolescence; the mean temperature for children aged 3 days to 10 years was 36.78 +/- 0.47 degrees C, as compared to 36.51 +/- 0.46 degrees C for subjects 11 years and older (P < .001, by t test). Temperatures were higher in female subjects and showed the characteristic diurnal variation of normal body temperature in five subjects studied longitudinally. The reproducibility of the ear thermometer was better than that of a commonly used electronic thermometer at the oral and axillary sites.
Conclusion: The infrared emission detection ear thermometer is an accurate means of assessing normal body temperature without using corrective offsets to estimate temperature at other body sites. On the basis of these data, the 95th percentile for infrared emission detection temperature in children younger than 11 years old was 37.6 degrees C. The 99th percentile was 37.9 degrees C for children younger than 11 years old and 37.6 degrees C for people 11 years or older. Because only 1% of normal people have an infrared emission detection temperature higher than these values, these may represent appropriate cutoffs for fever screening using this device.