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Three Part Question

In [neonates] how accurate is [axillary thermometry] compared to [tympanic thermometry] at accurately [measuring core body temperature]?

Clinical Scenario

A previously well, term 10 day old female neonate presents to the emergency department. Her parents say she feels like she is ‘burning up’ and is irritable. On initial inspection you agree that she looks unwell, her temperature as taken with a axillary thermometer is 37.7oC. She has no focus for her fever on examination. You would like to know how accurate axillary temperatures are and whether you should check the temperature using tympanic thermometry.

Search Strategy

Using the Medline database: 1950- week 1 June 2010 via OVID.
Embase database: 1980- week 23 2010 via OVID
CinAHL: CINAHL plus: 1937- June 2010
[axillary thermometer$.mp. OR axilla$ thermometer$.mp.OR axilla temperature.mp.] AND [tympanic thermometer$.mp. OR tympanic temperature$.mp. OR tympanic membrane thermometer.mp. OR tympanic membrane temperature$.mp.] AND [exp Body Temperature OR exp Fever OR febrile.mp. OR exp Hot Temperature OR exp Skin Temperature OR exp Temperature]
LIMIT to [english language and humans and ("all infant (birth to 23 months)" or "newborn infant (birth to 1 month)")]

Search Outcome

Medline: 6 papers, 3 of which were relevant
Embase: 3 papers, 0 of which were additional
CINAHL: 4 papers, 1 of which was additional and relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
El-Radhi AS et al 2006 UK	106 infants attending the paediatric ED in a district general hospital.	Diagnostic study: axillary and tympanic temperatures were measured and compared, using rectal temperature as the gold standard.	sensitivity (temperature <39 degrees)	axillary= 24%, tympanic = 76%	The age of the infants in the study is unknown, the sample size is unjustified and the study was un-blinded.
			sensitivity (temperature >39 degrees)	axillary= 89%, tympanic= 100%
			mean difference compared to rectal temperature (afebrile patients)	axillary= 1.11 degrees, tympanic= 0.38 degrees
			mean difference compared to rectal temperature (febrile patients)	axillary= 1.58 degrees, tympanic= 0.42 degrees
Wilshaw R et al 1999 USA	39 infants (less than 90 days old), 5 of which were febrile, in a community clinic.	Diagnostic study: axillary and tympanic temperatures were measured and compared against rectal temperature (the gold standard)	average temperature	axillary= 36.8 degrees (34.9-39.0), tympanic= 37.5 degrees (36.1-40.3)	This study had a small unjustified sample size with few febrile infants involved. The recruitment method for the study was unknown and the research was un-blinded
			sensitivity (temperature >38 degrees)	axillary= 100%, tympanic= 100%
			sensitivity (temperature >37.6 degrees)	axillary= 80%, tympanic= 80%
			specificity (temperature >38 degrees)	axillary= 58%, tympanic= 34%
			specificity (temperature >37.6 degrees)	axillary= 21%, tympanic= 2%
Yetman RJ et al 1993 USA	200 term well newborn infants (1-2 days old) in a well baby nursery in a teaching hospital.	Observational study	mean temperature	axillary= 36.8 degrees (+/- 0.3 degrees), tympanic= 36.8 degrees (+/-0.4 degrees)
Leick-Rude MK et al 1998 USA	280 sets of data from 220 infants (aged 1-102 days old; mean 17.2 +/- 12.8 days, median 8 days) in a neonatal intensive care unit in a children's hospital.	Observational study: tympanic and digital thermometry were compared to axillary recordings obtained by glass/mercury thermometers (the gold standard).	% of recordings within +/- 0.2 degrees of the gold standard	digital axillary= 51%, tympanic (protected ear)= 13.7 %, tympanic (exposed ear)= 43.3%	The study was un-blinded and involved infants >28 days old (although the median age was 8 days). The study used glass/mercury axillary temperatures as the gold standard. Infants in the study were in NICU, for a variety of reasons, which is a different population to the one posed by the question.
			% of recordings within +/- 0.5 degrees of the gold standard	digital axillary= 89.3%, tympanic (protected ear)= 56.8%, tympanic (exposed ear)=75.1%
			% of recordings within +/- 1 degrees of the gold standard	digital axillary= 100%, tympanic (protected ear)= 95.6%, tympanic (exposed ear)= 97.8%
			mean temperature	glass/mercury axillary= 36.89 degrees (+/- 0.37, range 35.4-38), digital axillary= 37.13 (+/- 0.36, range 36.4-38.1), tympanic (protected ear)= 37.39 (+/- 0.4, range 35.9-38.4), tympanic (exposed ear)= 36.98 (+/- 0.53, range 35.1-38.1)

Comment(s)

The available data on this subject is generally quite conflicting. El-Radhi's paper concludes that tympanic thermometry is more accurate than axillary thermometry and recommends its' use in the paediatric ED. The paper finds tympanic thermometry significantly more sensitive than axillary thermometry, in febrile and afebrile infants. This article is extremely relevant to the question posed but the major weakness is the unknown age of infants in the study, as without this information, the relevance to the under 28 day old neonate must be questioned. Wilshaw et al's study found that the ability to detect fever in both methods is equal, however specificity was poor in both axillary and tympanic thermometry therefore recommended rectal thermometry. Yetman et al's study also found that there was no significant difference between tympanic and axillary methods. Leick-Rude et al's research provided conflicting results and it recommended that axillary thermometry is superior to tympanic thermometry in hospitalised infants. This study however contained 102 readings from infants in radiant warmers, 103 readings from infants in incubators and 75 readings from infants in cribs. It found that the bed environment of the infants affected the infant's tympanic temperature reading as did the medication the infants were on (as dopamine increased tympanic temperature readings and prostaglandins decreased them), also the study included pre-term infants as well. In conclusion the evidence contributed by the Leick-Rude study has limited relevance to the question and clinical scenario posed. The other available studies are more relevant to the question and the scenario of the neonate presenting in the ED.

Clinical Bottom Line

More research is needed into this topic in order to make an accurate conclusion. From the data available tympanic thermometry appears to be slightly superior for providing accurate body temperature readings compared to axillary thermometry in infants presenting to the ED.

References

1. El-Radhi AS and Patel S An evaluation of tympanic thermometry in a paediatric emergency department Emergency Medical Journal 2006; 40-41
2. Wilshaw R, Backstrand R, Waid D et al A comparison of the use of tympanic, axillary and rectal thermometers in infants Journal of Pediatric Nursing 1999; 88-93
3. Yetman RJ, Coody DK, West SM et al Comparison of temperature measurements by an aural infrared thermometer with measurements by traditional rectal and axillary techniques The Journal of Pediatrics 1993; 769-773
4. Leick-Rude MK and Bloom LF A comparison of temperature taking methods in neonates Neonatal Network 1998; 21-37