Effect of Crying on Infrared Tympanic Temperature Measurement in Pediatrics

Thhe newly available in-frared tympanic ther-mometer has become popular because it is easy to use, takes less time to measure tem-perature, and causes little discom-fort to the patient. The ear canal has a temperature gradient, warmest at the tympanic mem-brane and coolest at the auditory meatus. The tympanic membrane is situated close to the internal carotid artery, and its tempera-ture is thought to reflect the tem-perature of the blood flowing into the hypothalamus. The ear canal radiates energy in the form of electromagnetic waves in propor-tion to its temperature. Infrared thermometers detect this thermal radiation, which is in the far-in-frared range in the human body.' The tympanic thermometer is reported reliable and comparable to mercury thermometers.2-5 However, tympanic thermometer measurements (TTM) can be af-fected by several factors, such as whether the patient has been ly-ing on that ear, whether he or she has been exposed to cold or hot temperatures, and whether the in-frared thermometer is positioned closely enough to the tympanic membrane, which is not always possible, owing to small ear canal dimensions in younger children and standard tympanic ther-mometer tip size.67 A patient's crying may also affect readings. When a child cries, the tympanic membrane becomes red, owing to increased blood flow to the area. Many times, this increased red-ness is extreme enough to give the clinician a false-positive sign of ear infection. A medical litera-ture search showed no studies de-scribing the effect of crying on tympanic thermometer measure-ment. The purpose of this study was to determine whether in-creased blood flow to the tym-panic membrane with crying has any significant effect on the accu-racy of measurements taken by the tympanic thermometer