Measurement of Body Temperature in Postsurgical Children: Comparisons of Infrared Nonskin Contact Digital Thermometer, Skin Contact Digital Thermometer, and Mercury in Glass Thermometer.

CONTEXT: Postoperative fever is known to occur after all surgical procedures irrespective of the type of anesthesia. Thermometry devices that work without touching or disturbing the child seem to be appreciated more than the conventional skin contact thermometers. However, whether this technology is reliable to be adapted for routine pediatric surgical care is debatable. AIMS: The aim of this study was to study the accuracy of infrared nonskin contact digital thermometer (IRT) compared to the skin contact digital thermometer (DT) and mercury in glass thermometer (MT). SETTINGS AND
DESIGN: A prospective cross-sectional study was done in postoperative patients at a pediatric surgical center over a period of 3 months. SUBJECTS AND METHODS: The forehead temperature was recorded with IRT. This was followed by recording the temperature in one armpit by DT and the other armpit by MT. Readings were promptly documented. STATISTICAL ANALYSIS USED: A sample t-test was done which gave the P value and mean. Linear regression analysis was carried out to find correlation coefficients. Bland-Altman test was used to access the concordance between all readings.
RESULTS: We found a strong correlation between temperature readings taken by DT (mean = -0.03, r = 0.07, slope = -0.04) and IRT (mean = 0.89, r = 0.091, slope = -0.14). However, on comparison of results with the MT, there are wider limits of agreement with the IRT (-0.31-2.09) in comparison to DT (-0.66-0.59).
CONCLUSION: Skin contact digital thermometer are more accurate and suitable for checking body temperature as compared to infrared nonskin contact digital thermometer in postoperative pediatric patients. Copyright:

INTRODUCTION

Fever in a surgical patient is a cause for concern. Postoperative fever is known to occur irrespective of the type of anesthesia. Accurate documentation of the body temperature is mandatory to help the clinician make a decision regarding investigating the child or making a modification in the line of management. Irrespective of the technique used, the temperature should accurately reflect the core body temperature and should not be affected by any external factor. Body temperature in pediatric patients is commonly recorded in the axilla. This is being done using either a skin contact digital thermometer (DT) or a mercury in glass thermometer (MT). Body temperature record by the MT has been considered as a gold standard to ascertain core body temperature. However, the time taken to achieve an accurate reading is around 5 min, which is quite difficult to achieve in pediatric patients.[1] Mercury is a known hazard to humankind, and hence, the World Health Organization has been suggesting health-care professionals to move from the mercury in glass thermometers to DTs for recording body temperature.[2] Studies have been done and recommendations rolled out, suggesting that axillary temperature measurement with DT is as acceptable as mercury in glass thermometer.[34] The DT has also been shown to be easy to use for health-care workers. Over the past few years, infrared nonskin contact DTs (IRT) have emerged as a new option for recording body temperature. This study was carried out to determine the accuracy of infrared nonskin contact DTs (IRT) compared to the axillary skin contact digital thermometer and Mercury in glass thermometer (MT) in postoperative children.

SUBJECTS AND METHODS

A prospective study was carried out over a period of 3 months on all postsurgical patients at a pediatric surgical center from July 1, 2019, to August 31, 2019. A total of 152 readings were taken. Patients' temperature was recorded with IRT (Braun NTF 3000) followed by DT (Dr. Morepen MT-222) in one armpit and MT (Hicks Clinical Thermometer) in another armpit.

IRT was aimed at the forehead area between eyebrows after making sure that the skin was free of sweat or dirt. DT was kept in armpit till beep sound was made by thermometer. MT was kept in the opposite armpit for 5 min.[1] All readings were taken by trained nursing staff with vision of 6/6. The aid of a magnifying glass was taken when required to reduce bias. All readings were recorded in degree Fahrenheit and promptly documented. To study all the values obtained by IRT and DT, a similar and statistically significant sample t-test was done which gave the P value and mean.[5] Following this, linear regression analysis was carried out to find correlation coefficients to provide information about the strength and direction of the relationship between two continuous variables.[6] To assess the concordance between the MT with DT and IRT readings, the Bland–Altman test was used.[7] This is an exploratory diagnostic test between the differences of the two temperature readings of each patient. It is plotted on the Y-axis against the means of the two temperatures plotted on the X-axis. There are two parameters of interest. The first is the overall mean difference for the paired readings of each patient. A value of zero implies perfect concordance. The second and more important parameter is the 95% limits of agreement (LOAs) between the two paired readings across the range of temperatures. It is a range within which we would expect 95% of the differences to lie. The tighter the LOAs, the better the concordance. The wider the range, the lesser would be the concordance in the two readings.

RESULTS

After analyzing data of all 152 readings, we found that DT had a smaller mean difference value compared to IRT. Both, however, had a strong positive correlation ship when compared with MT. Analysis also showed that IRT had a higher slope and wider LOA in comparison to DT. The data are depicted in Table 1 and Figures 1 and 2.

Table 1

Statistical significance, correlation, and concordance of DT and IRT data against MT

	MT versus DT	MT versus IRT
Mean	−0.03	0.89
95% CI	−0.08-0.01	0.79-0.99
R	0.074	0.091
Slope	−0.04	−0.14
Limits of agreement	−0.66-0.59	−0.31-2.09

MT: Mercury in glass thermometer, DT: Skin contact digital thermometer, IRT: Infrared nonskin contact digital thermometer, CI: Confidence interval

Figure 1

Bland - Altman chart - mercury in glass thermometer Vs skin contact digital thermometer

Figure 2

Balnd - Altman chart - mercury in glass thermometer Vs infrared nonskin contact digital thermometer

A comparison of mean, maximum, and minimum temperature for MT, DT, and IRT is depicted in Tables 2 and 3.

Table 2

Summary measurements of temperatures

Thermometer	Observations	Minimum (°F)	Maximum (°F)
Mercury	152	97	104.5
Digital	152	97	104.5

Table 3

Summary measurements of temperatures

Thermometer	Observations	Minimum (°F)	Maximum (°F)
Mercury	152	97	104.5
Infrared	152	96	103.9

DISCUSSION

Early postoperative fever is common in children. Most of these occurrences are benign and their incidence reduces between 24 and 72 h of the surgery.[8] Whatever the cause, it is prudent that an accurate documentation of the body temperature is made. Recording of the axillary skin temperature by the mercury in glass thermometers has been used for many years. Because of the hazards of mercury and the possibility of injury to the child following the breakage of the glass thermometers, DTs came into existence. Studies showed them to be as acceptable as their mercury counterparts in measuring the temperature. A child following surgery is always psychologically upset and cranky. Managing these children and their anxious parents is a daunting task for health-care workers. Something as simple as recording the body temperature may cause disturbance to the sleeping child and in turn can agitate both the patient and the parents. Placement of rectal or esophageal thermometer probes for continuous temperature monitoring can be very uncomfortable for children. Skin sensors on the other hand are not a reliable indicator of the core body temperature in the pediatric age group. Over the past few years, the infrared nonskin contact DTs (IRT) have emerged as a new option for recording body temperature. The nontouch method of measuring temperature may reduce the infection rate and discomfort in postoperative children. It has also been shown to be easy to use for health-care workers. There have been no studies comparing the results of MT, DT, and IRT in pediatric patients, and hence, this study was undertaken to evaluate the feasibility of IRT in postoperative children.

In our study, we saw a wide LOA between MT versus IRT (−0.31–2.09). Chiappini et al. in their study done on children more than 1 month reported a very narrow LOA (−0.62–0.76).[9] The sample size taken by Chiappini et al. was 250 patients where they had taken 3 readings with IRT of the same patient. In our study, the temperature readings were taken in every time the child had a fever until the time of discharge. This can be one of the reasons for this discrepancy. Hajela studied rectal mercury thermometer versus IRT on 260 neonates.[10] They found LOA to be −2.09–2.40, which is a bit higher than our study.[10] This can be attributed to the effect of warmer care in neonatal patients compared to no such care in pediatric patients in the present study. Berksoy et al. reported LOA of DT versus MT −1.5–2.6 which is equivalent to −0.66–0.59 LOA in our study.[11] Considering wider LOAs for IRT in comparison to DT, they are not optimal to replace or substitute DT.

CONCLUSION

Through this study we will like to conclude that skin contact digital thermometers are more accurate and suitable for checking body temperature as compared to infrared nonskin contact digital thermometer in postoperative pediatric patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.