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Am Fam Physician. 1998;57(5):1107-1108

Rectal temperature measurement is considered the most accurate way of assessing temperature in infants, but it may be difficult to obtain correctly. Axillary temperature is easily obtained but is often inaccurate. Tympanic temperature devices are commonly used, but some studies have indicated doubt about their accuracy, especially in infants and young children. Press and Quinn evaluated the accuracy of the electronic pacifier thermometer.

Temperatures obtained rectally and with the pacifier thermometer were compared in 100 children between seven days and 24 months of age who were seen in an emergency department or an inpatient pediatric unit. Sublingual and rectal temperatures were taken sequentially, one immediately after the other. The initial site of measurement was altered from patient to patient. Fever was defined as a rectal temperature of 38.0°C (100.4°F) or greater.

The time for the pacifier to reach a steady-state temperature was measured in the first 30 children and ranged from two minutes and 15 seconds to four minutes and 15 seconds. The mean supralingual temperature was 37.5°C (99.9°F), and the mean rectal temperature was 38.0°C (100.4°F). The mean difference of 0.49°F between the two thermometers was significant. However, when the mean difference between the two readings was adjusted upward by 0.5°F for the pacifier thermometer, the difference was not statistically significant.

Fifty patients had a rectal temperature of 38.0°C (100.4°F) or greater, and fever was identified by the pacifier thermometer in 36 of these 50 children. This number increased to 46 when 0.5°F was added to the supralingual reading. None of the remaining four children in whom fever was missed by the oral reading had a fever of greater than 38.5°C (100.8°F) rectally. The pacifier thermometer was 72 percent sensitive and 97 percent specific in the detection of fever. The sensitivity increased to 92 percent when oral readings were adjusted upward by 0.5°F, but the specificity decreased to 76 percent.

The authors state that the rectal temperature should remain the gold standard for recording temperature, especially in infants younger than three months. However, the pacifier thermometer seems to be a reasonable and easier alternative for parents of older infants and children, especially when exact temperature measurements are less crucial. A disadvantage of the pacifier thermometer is the mean time of more than three minutes that is necessary to reach a steady state. This feature may make it a more feasible option for home use or use in low-volume ambulatory care settings, as opposed to the emergency department or a busy office.

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