Methods and Devices of Temperature Measurement in the Neonate: A Narrative Review and Practice Recommendations

Peripheral thermometry: Agreement between non-touch infrared versus traditional modes in an adult population

AIM

To test whether infrared non-touch forehead thermometry (FNTT) obtains comparable temperature readings in adults compared with common, non-invasive thermometry methods such as axillary (DAT), oral (DOT) and infrared tympanic (ITT).

DESIGN

A prospective, repeated-measures comparative diagnostic test study design was used for this study.

METHODS

Data were collected from a convenience sample of 169 nursing students over 3 months (March 2019 to May 2019). Participants had their temperature measured once with each of the four thermometers. Agreement between thermometers was assessed using repeated-measures analysis of variance with Bonferroni post hoc testing.

RESULTS/FINDINGS

One hundred and sixty-one participants were included in the final analysis. A repeated-measures ANOVA showed statistically significant differences between the four thermometer temperature readings. Post hoc pairwise comparisons with Bonferroni adjustment revealed infrared non-touch forehead thermometry demonstrated statistically significant higher mean temperatures compared with digital oral thermometry MD = 0.466℃ (95% CI, 0.357-0.576, p < .001) and digital axillary thermometry MD = 0.897℃ (95% CI, 0.752-1.043, p < .001), but not with infrared tympanic MD = 0.069℃ (95% CI, -0.025-0.162, p = .307).

CONCLUSIONS

This study found that infrared non-touch forehead thermometry consistently produced higher temperature readings in adults compared with other common forms of peripheral thermometry. Caution should be taken when using forehead non-touch thermometer readings interchangeably with digital oral and digital axillary readings unless corrections for bias are made. More research is needed into whether infrared non-touch forehead thermometry and infrared tympanic could be used interchangeably.

IMPACT STATEMENT

This study aimed to address whether non-touch forehead could be used interchangeably with other common forms of non-invasive thermometry. Our result revealed inconsistencies in temperature readings between the different thermometers. Consequently, healthcare professionals should exercise caution when monitoring temperature trends where readings have been taken by different types of peripheral thermometers. This study could impact healthcare clinicians responsible for the monitoring and recording of peripheral temperatures.

Comparison of Axillary and Temporal Artery Thermometry in Preterm Neonates

OBJECTIVE

To compare the accuracy of infrared temporal artery thermometry with axillary thermometry in a cohort of preterm neonates between 28 and 36 weeks postmenstrual age.

DESIGN

Descriptive repeated measures design with randomization to temperature measurement order.

SETTING

Level III NICU in the Central/Southeastern United States.

PARTICIPANTS

Sixty-eight neonates born between 28 weeks and 36 weeks postmenstrual age cared for in incubators or open cribs.

METHODS

Neonates were randomly assigned to temperature measurement order (axillary followed by temporal artery or temporal artery followed by axillary). Temperature pairs were taken once during the day shift and once during the night shift. Behavioral states were assessed before, during, and after temperature measurement.

RESULTS

Neonates were predominantly female (64.7%) with a mean age of 6.6 days and a mean gestational age of 32.7 weeks, and most were cared for in incubators (n = 55). Noninferiority was observed between the two temperature methods (Holm-Bonferroni criterion = .025, p < .001). There was no statistically significant difference in the behavioral states of the neonates between the two temperature methods. It took nurses significantly longer to use the axillary thermometer than to use the temporal artery thermometer (p < .001).

CONCLUSION

Temporal artery temperature measurements were as accurate as axillary temperature measurements in low-birth-weight neonates in the NICU. Nurses spent less time measuring with the temporal artery method than with the axillary method.

Remote biomonitoring of temperatures in mothers and newborns: design, development and testing of a wearable sensor device in a tertiary-care hospital in southern India

Objective

Newer technologies such as wearables, sensors, mobile telephony and computing offer opportunities to monitor vital physiological parameters and tackle healthcare problems, thereby improving access and quality of care. We describe the design, development and testing of a wearable sensor device for remote biomonitoring of body temperatures in mothers and newborns in southern India.

Methods

Based on client needs and technological requirements, a wearable sensor device was designed and developed using principles of ‘social innovation’ design. The device underwent multiple iterations in product design and engineering based on user feedback, and then following preclinical testing, a techno-feasibility study and clinical trial were undertaken in a tertiary-care teaching hospital in Bangalore, India. Clinical trial phases I and IIa for evaluation of safety and efficacy were undertaken in the following sequence: 7 healthy adult volunteers; 18 healthy mothers; 3 healthy babies; 10 stable babies in the neonatal care intensive unit and 1 baby with morbidities. Time-stamped skin temperature readings obtained at 5 min intervals over a 1-hour period from the device secured on upper arms of mothers and abdomen of neonates were compared against readings from thermometers used routinely in clinical practice.

Results

Devices were comfortably secured on to adults and neonates, and data were efficiently transmitted via the gateway device for secure storage and retrieval for analysis. The mean skin temperatures in mothers were lower than the axillary temperatures by 2°C; and in newborns, there was a precision of –0.5°C relative to axillary measurements. While occasional minimal adverse events were noted in healthy volunteers, no adverse events were noted in mothers or neonates.

Conclusions

This proof-of-concept study shows that this device is promising in terms of feasibility, safety and accuracy (with appropriate calibration) with potential for further refinements in device accuracy and pursuit of further phases of clinical research for improved maternal and neonatal health.

Using axillary temperature to approximate rectal temperature in newborns

AIM

Various factors have been shown to potentially affect the difference between axillary and rectal temperature measurements in newborns. We aimed to explore their roles and, if possible, to construct a formula that explained the difference.

METHODS

The study was based on a consecutive sample of 175 infants, with a gestational age of 24-42 weeks, whose rectal and axillary temperatures were measured simultaneously at the neonatal unit at Skaraborg Hospital in Sweden. Data were analysed using multiple regressions.

RESULTS

Premature infants had a significantly smaller mean difference (0.33°C) between rectal and axillary temperatures than full-term infants (0.43°C). Significant associated factors for premature infants were chronological age (p = 0.025), time of day (p = 0.004) and axillary temperature (p < 0.001). For full-term infants, the only significant associated factor was axillary temperature (p = 0.015).

CONCLUSION

Although it is possible to construct a formula that estimates neonate rectal temperature based on axillary temperature with a slightly higher reliability than simply adding a fixed value like 0.4°C, such a formula would be too complex to apply in practice. Adding 0.3°C or 0.4°C to the measured axillary temperature for premature infants or full-term infants, respectively, yields acceptable approximations in most cases.