Letter to the Editor

Iran J Public Health, Vol. 49, No.2, Feb 2020, pp.411-413

Usefulness of Non-Contact Infrared Thermometer for Early
Neonatal Period Using Bland-Altman Analysis
Saori SUGAWARA, *George IMATAKA, Shigemi YOSHIHARA
Department of Pediatrics, Dokkyo Medical University, Tochigi, Japan*Corresponding Author: Email: geo@dokkyomed.ac.jp(Received 24 Jun 2019; accepted 19 Jul 2019)

Dear Editor-in-Chief
It is impossible to measure central body temperature in a living body. Therefore, usually, bodytemperature is measured in the oral cavity (sublingual temperature), anus (rectal temperature),ear (tympanic temperature), armpit (axillary temperature) and others. In most cases, oral and rectal temperatures are usually used. On the other
hand, in Japan in order to respect hygiene
measures, body temperature is often measured in
the axilla (1).
There are three types of thermometers that areused for temperature readings in Japan: mercury
thermometer, ear thermometer, and electronic
thermometer. Mercury thermometer that havebeen used for a long time is the most accurate(2). However, the measurement can take about 5minutes. In addition, the use of mercury is on
decline due to environmental pollution. Ear
thermometer measure the body temperature using infrared rays emitted from the eardrum. The
measurement time of this thermometer is a few
seconds. However, measurement errors are likely
to occur in newborns and infants because theexternal auditory canal is narrow and the amountof exudate is large. At the Japanese pediatric hospital electronic thermometers are often used fornewborns and infants.
In recent years, in addition to these three thermometers, non-contact infrared thermometershave begun to spread mainly in East Asia such as
Japan and Korea. The new thermometer has the411

shortest measurement time (less than 1 second).
However, because this type of thermometer is
non-contact type, measurement errors may occur
depending on the environmental temperature andhumidity. Furthermore, there are few basic datain early postnatal neonates with a lot of vernix on
the skin (3-7).
Therefore, we examined the usefulness of a noncontact infrared thermometer for normal neonates in the neonatal room of obstetrics in KoikeLadies Clinic in Japan. This study was approvedby the hospital and informed consent was takenfrom the parents of participants before the study.
Eighteen healthy early neonates from 0 to 6 days
after birth were enrolled in this study. The neonatal gestational age was 38.1-41.0 weeks(mean±SD=39.5weeks±0.7
days,
median[IQR]=39.5 weeks). The birth weight was 2,650 g
to 3,306 g, (mean±SD= 2,952.7±172. g, median[IQR]= 2,988.5 g). The body temperature wasmeasured at the center of the forehead and theaxilla. Non-contact infrared thermometer (Thermo Finder Pro FS-300 manufactured by HuBDIC- Global CO., LTD, Korea) was used at thedistance of 2 cm from the center of forehead.
A contact-type electronic thermometer (TerumoThermometer C205 manufactured by TerumoCorporation, Japan) was used for the axilla. Bothnon-contact and contact thermometers weremeasured at the same time, 3 times a day, for a
total of 67 times. All of newborns were examined

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Iran J Public Health, Vol. 49, No.2, Feb 2020, pp. 411-413

in the supine position on a newborn cot. Theroom temperature was 23 to 26 degrees, and thehumidity was 40 to 60%. Comparison of measurements using both thermometers was statistically analyzed using Bland-Altman analysis (8).

The software used for data analysis was SPSS
version 22.0 (IBM Japan, Ltd., Tokyo, Japan).
The measurement results (contact and noncontact) were analyzed using Bland-Altman plots(Fig. 1).

Fig. 1: Bland-Altman analysis of our study relation between contact type of electrical thermometer at the axilla andnon-contact type of infrared type of thermometer at the center of forehead in early neonate

The X-axis in the figure is the average temperature measured at the axilla and forehead. The Yaxis was plotted by subtracting the forehead temperature from the axilla temperature. In order toconfirm the fixed error, the average value obtained by subtracting the forehead value from theaxilla was shown as “Mean” on the horizontal
line in the figure. Analysis of mean body temperature showed that the axilla body temperature
was 0.053 ℃ higher than the forehead temperature. The 95% confidence interval was 0.0160.091. Since this confidence interval does notcross 0, it was judged that the analysis was a significant fixed error. In addition, since the correlation coefficient was 0.079 and the P value was0.431, there was no proportional error.

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Temperature measurements in the axilla weresignificantly 0.053 ℃ higher than forehead. The
0.053 ℃ difference is clinically acceptable. So,
both contact-type electronic thermometer andnon-contact-type infrared thermometer in newborns have no clinical problems in measuring
temperature.
One of the difficulties we encountered whenmeasuring the body temperature was horizontal
infection mainly due to MRSA and Pseudomonas
aeruginosa due to skin contact. Furthermore, it wasdifficult to keep a newborn baby with a long
sleep time resting. Non-contact thermometers
did not directly contact the skin, so there was norisk of skin infection.
In conclusion, the non-contact infrared thermometer using in the neonatal room of obstetrics
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Sugawara et al.: Usefulness of Non-Contact Infrared Thermometer …

was not only practical but also very useful. Thismethod was hygienic, had a short measurement
time and did not disturb the quality of daily lifeof the newborns.

4.

Conflict of interests
The authors declare that there is no conflict ofinterests.

References

6.

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