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Accuracy of ear temperature questioned

LIVERPOOL, UNITED KINGDOM. A precise and accurate measurement of body core temperature is essential in order to determine the presence of fever. Rectal temperature has traditionally been considered to be the best approximation of core temperature and is still the gold standard when an accurate measurement is required. Taking a rectal temperature is, however, uncomfortable and time-consuming so the idea of measuring core temperature by infrared ear thermometry has gained wide acceptance. It is estimated that 64 per cent of pediatricians and 65 per cent of family physicians in the USA now use an infrared ear thermometer to measure temperature with the practice being particularly widespread when it comes to children.

Medical researchers at the University of Liverpool have just completed a review of 31 studies (involving 4441 individuals [75 per cent children]) aimed at evaluating the correlation between infrared ear temperature and standard rectal temperature. The infrared ear thermometers all had an electronic feature that adjusted the actual measurement to correspond to a rectal temperature. The researchers found that the rectal temperature calculated from infrared ear thermometry was on average 0.29 degrees C (0.46 degrees F) lower than the actual rectal temperature. However, the extent of discrepancy was quite wide. For example, for a true rectal temperature of 38 degrees C, the "rectal temperature" measured at the ear could be anywhere between 37.0 and 39.2 degrees C. The researchers conclude that in children infrared ear thermometry cannot be used as an accurate approximation of rectal temperature.
Craig, Jean V., et al. Infrared ear thermometry compared with rectal thermometry in children: a systematic review. The Lancet, Vol. 360, August 24, 2002, pp. 603-09
Akinyinka, O.O. Infrared ear thermometry versus rectal thermometry in children. The Lancet, Vol. 360, August 24, 2002, p. 584 (commentary)

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