Cerumen occlusion lowers infrared tympanic membrane temperature measurement.

OBJECTIVE: To examine the effect that cerumen occlusion of the ear canal has on infrared tympanic membrane temperature measurement.

METHODS: A prospective, randomized, single-blind human study was carried out in a university hospital observation unit. The subjects were a convenience sample of human volunteers ages 18 years or older who did not have cerumen occlusion or scarred tympanic membranes. A paraffin-coated human cerumen plug was placed in one randomly chosen ear, and after 20 minutes of equilibration the temperature of each ear was measured with an infrared thermometer. Analysis of the difference in mean temperature between the occluded and nonoccluded ears was by Student's paired t-test.

RESULTS: Infrared tympanic membrane temperatures were measured in 43 subjects aged 21 to 58 years. The mean temperature of the occluded ear canal was 0.3 degrees C lower than that of the opposite ear canal (p = 0.0001, 95% CI 0.16-0.45 degrees C).

CONCLUSION: Cerumen occlusion of the ear canal causes underestimation of body temperature measure by infrared tympanic membrane thermometry.