Comparison of rectal and aural core body temperature thermometry in hyperthermic, exercising individuals: a meta-analysis

Abstract

Objective: To compare mean differences in core body temperature (T(core)) as assessed via rectal thermometry (T(re)) and aural thermometry (T(au)) in hyperthermic exercising individuals.

Data sources: PubMed, Ovid MEDLINE, SPORTDiscus, CINAHL, and Cochrane Library in English from the earliest entry points to August 2009 using the search terms aural, core body temperature, core temperature, exercise, rectal, temperature, thermistor, thermometer, thermometry, and tympanic. Study Selection: Original research articles that met these criteria were included: (1) concurrent measurement of T(re) and T(au) in participants during exercise, (2) minimum mean temperature that reached 38°C by at least 1 technique during or after exercise, and (3) report of means, standard deviations, and sample sizes.

Data extraction: Nine articles were included, and 3 independent reviewers scored these articles using the Physiotherapy Evidence Database (PEDro) scale (mean = 5.1 ± 0.4). Data were divided into time periods pre-exercise, during exercise (30 to 180 minutes), and postexercise, as well as T(re) ranges <37.99°C, 38.00°C to 38.99°C, and >39.00°C. Means and standard deviations for both measurement techniques were provided at all time intervals reported. Meta-analysis was performed to determine pooled and weighted mean differences between T(re) and T(au).

Data synthesis: The T(re) was conclusively higher than the T(au) pre-exercise (mean difference [MD] = 0.27°C, 95% confidence interval [CI] = 0.15°C, 0.39°C), during exercise (MD = 0.96°C, 95% CI = 0.84°C, 1.08°C), and postexercise (MD = 0.71°C, 95% CI = 0.65°C, 0.78°C). As T(re) measures increased, the magnitude of difference between the techniques also increased with an MD of 0.59°C (95% CI = 0.53°C, 0.65°C) when T(re) was <38°C; 0.79°C (95% CI = 0.72°C, 0.86°C) when T(re) was between 38.0°C and 38.99°C; and 1.72°C (95% CI = 1.54°, 1.91°C) when T(re) was >39.0°C.

Conclusions: The T(re) was consistently greater than T(au) when T(core) was measured in hyperthermic individuals before, during, and postexercise. As T(core) increased, T(au) appeared to underestimate T(core) as determined by T(re). Clinicians should be aware of this critical difference in temperature magnitude between these measurement techniques when assessing T(core) in hyperthermic individuals during or postexercise.

Figure 1

Selection process for articles included in the systematic review and the rationale for excluding the articles that were not included.

Figure 2

Mean difference (±SD) between rectal (T_re) and aural (T_au) temperatures during exercise in hyperthermic individuals. Pooled weighted mean difference reflects all included articles. ^a Pooled weighted mean (T_re − T_au)  =  0.96°C.

Figure 3

Mean difference (±SD) between rectal (T_re) and aural (T_au) temperatures after exercise in hyperthermic individuals. Pooled weighted mean difference reflects all included articles. ^a Pooled weighted mean (T_re − T_au)  =  0.71°C.

Figure 4

Pooled weighted mean difference between rectal (T_re) and aural (T_au) temperatures at various temperature ranges based on rectal temperatures for studies conducted in a climate chamber (indoor), field setting (outdoor), and all studies combined.