Discussion
The main finding of the current study was a positive correlation between axillary and tympanic methods of measuring body temperature. This study positively answered the question ‘How well does tympanic membrane temperature measurement agree with standard axillary measuring technique?’, or can the new device substitute for the old? Infrared tympanic membrane thermometers take seconds to measure the natural emission of infrared thermal radiation from the tympanic membrane. However, doubts have been expressed about the accuracy of tympanic membrane thermometry and differences have been observed when measurements are made in both ears. Ear infections e.g. otitis media can influence the true temperature of the tympanum. A further study comparing rectal temperature measurement with infrared tympanic thermometer measurement did not find excellent agreement of results. Similar results to the present study were obtained by Chue et al., 2012 who compared tympanic and oral mercury thermometers in 201 patients on the Thai-Myanmar border, and found the mean difference in the two devices for all observers/devices to be 0.09°C (95% CI: 0.07–0.12). More than one reading was used by Chue et al., and only one reading was used in the current study. Likewise, Rabbani et al., 2010 reached the same conclusion, especially in young patients, where both tympanic membrane and oral cavity temperatures were recorded, as well as oral temperature as standard. However, Edelu et al., 2011 compared infrared tympanic thermometer in oral mode with mercury glass thermometer readings for measuring the temperature in febrile and afebrile children less than 5 years old, and found a mean difference of 0.41 ± 0.37°C (P < 0.001) in the febrile group and 0.47 ± 0.39°C (P < 0.001) in the afebrile group. Although tympanic membrane thermometers have a fairly good sensitivity and specificity, the study concluded that they may not be reliable in estimating ‘core’ body temperature in children.
Findings from the present study support the use of infrared tympanic membrane thermometers, because of their safety, ease of use and the fast speed for obtaining temperature readings. Moreover, the hazards of mercury toxicity makes infrared thermometers preferable to the old mercury glass thermometers, although some might prefer the latter based on their low cost compared with tympanic membrane thermometers.
One of the limitations of the present study was the use of axillary temperature as a measurement of core temperature rather than the rectal one. Axillary temperature is easy to use, commonly used in our setting and might be acceptable by the traditions and customs in this setting. Pulmonary artery temperature correlates best with core temperature, but to measure this requires an invasive procedure which is unsuitable for use in routine emergency care practice. Furthermore, this study did not include patients with hypothermia, and so its findings cannot be extrapolated to newborns or to patients with hypothermia. Further studies including these groups should be carried out to support the wider use of tympanic membrane thermometers.
Acknowledgments
The authors would to thank the National Science Council of the Republic of China for financially supporting this research under Contract No NSC – 95 – 2313 – B – 005 - 019.
Competing interests
The authors declare that they have no competing interests.
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