Current Evidence Does Not Support the Accuracy of Aural Thermometry for Core Body Temperature as Compared to Rectal Thermometry

Data Sources: Sources from PubMed, Ovid, MEDLINE, SPORTDiscus, CINAHL, and the Cochrane Library databases were searched from 2009 to present with the following search terms: aural, core body temperature, core temperature, exercise, rectal, temperature, thermistor, thermometer, thermometry, and tympanic.

Study Selection: Studies that involved human participants who reached a core temperature of 38°C or higher while exercising and were assessed via rectal and aural temperature simultaneously were included. Excluded studies involved research on animals, disuse of indwelling thermistors, or use of passive methods as opposed to exercise to induce hyperthermia.

Data Extraction: To aid in the comparison between rectal and aural temperatures, the following key components were identified from the nine research articles included: rectal and aural temperature before, during, and after exercise; the specifics of the measurement devices; conditions of the exercise environment; and the study design and number of participants.

Main Results: Initial results of the search yielded 2,044 studies; 1,918 were not included due to irrelevance. Sixty-three articles were further analyzed for criteria compliance. Following cross-referencing, 9 studies were included for the meta-analysis of differences in temperature between rectal and aural thermometry. These studies were appraised for validity and quality through use of the Physiotherapy Evidence Database (PEDro) scale.

The collected baseline results from 138 individuals indicated a weighted mean difference of 0.27°C (95% confidence interval [CI] = 0.15°C to 0.39°C) and a range of 0.04°C to 0.41°C, showing the rectal temperatures to be consistently higher than the aural temperatures. Temperatures assessed during exercise showed a pooled weighted mean difference of 0.96°C (95% CI = 0.84°C to 1.08°C). Temperatures taken after 15 minutes of exercise had a mean difference of .80°C, whereas temperatures ranged from 0.55°C to 1.70°C when taken after 60 minutes of exercise. Pooled data following exercise indicated a mean difference of 0.71°C (95% CI = 0.65 C° to 0.78°C). For each reference point of temperature measurement, the rectal temperature was higher than the aural temperature.

Conclusion: The importance of establishing the core body temperature of exercising, hyperthermic individuals has been established, thus necessitating the need to determine valid and reliable means to assess core temperature. Although rectal thermometry has been shown to be the most valid and reliable means of assessment of core body temperature, there are still many practicing health care professionals who consistently use alternate means such as aural thermometry. Findings from the meta-analysis revealed that as core body temperature increases, the degree of separation of assessment increases up to almost 1°C, which could be significant in the diagnosis and treatment of exertional heat stroke.

Summary: Exertional heat illness has continued to be a relevant topic of discussion during recent years due to several deaths reported related to complications from exertional heat stroke. In July 2014, the National Athletic Trainers' Association published an updated position statement reporting that deaths from exertional heat stroke can be 100% avoided if recognized, diagnosed, and treated in an appropriate manner.1 The deteriorating function of the central nervous system along with assessment of a core body temperature of 105°F are the two main signs and symptoms associated with exertional heat stroke.1 However, numerous stakeholders, including clinicians, patients, and families of physically active individuals, debate whether the invasive nature of obtaining a rectal temperature is indeed a necessary method to diagnose exertional heat stroke. Therefore,… 

Autor / Fonte:Huggins R, Glaviano N, Negishi N, Casa D, Hertel J. J Athl Train. 2012;47:329–338.