Abstract
BackgroundEpitympanic temperature (Tty) measured with thermistor probes correlates with core body temperature (Tcore), but the reliability of measurements at low ambient temperature is unknown. The aim of this study was to determine if commercially-available thermistor-based Tty reflects Tcore in low ambient temperature and if Tty is influenced by insulation of the ear.MethodsThirty-one participants (two females) were exposed to room (23.2 ± 0.4 °C) and low (−18.7 ± 1.0 °C) ambient temperature for 10 min using a randomized cross-over design. Tty was measured using an epitympanic probe (M1024233, GE Healthcare Finland Oy) and oesophageal temperature (Tes) with an oesophageal probe (M1024229, GE Healthcare Finland Oy) inserted into the lower third of the oesophagus. Ten participants wore ear protectors (Arton 2200, Emil Lux GmbH & Co. KG, Wermelskirchen, Switzerland) to insulate the ear from ambient air.ResultsDuring exposure to room temperature, mean Tty increased from 33.4 ± 1.5 to 34.2 ± 0.8 °C without insulation of the ear and from 35.0 ± 0.8 to 35.5 ± 0.7 °C with insulation. During exposure to low ambient temperature, mean Tty decreased from 32.4 ± 1.6 to 28.5 ± 2.0 °C without insulation and from 35.6 ± 0.6 to 35.2 ± 0.9 °C with insulation. The difference between Tty and Tes at low ambient temperature was reduced by 82 % (from 7.2 to 1.3 °C) with insulation of the ear.ConclusionsEpitympanic temperature measurements are influenced by ambient temperature and deviate from Tes at room and low ambient temperature. Insulating the ear with ear protectors markedly reduced the difference between Tty and Tes and improved the stability of measurements. The use of models to correct Tty may be possible, but results should be validated in larger studies.
Highlights
Epitympanic temperature (Tty) measured with thermistor probes correlates with core body temperature (Tcore), but the reliability of measurements at low ambient temperature is unknown
Epitympanic temperature (Tty) measured with a thermistor probe in the ear canal correlates with Tcore in hypothermic patients [5, 6] and may be a non-invasive alternative for diagnosing the severity of Strapazzon et al Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine (2015) 23:90 hypothermia in victims of accidental hypothermia [7, 8]
Case reports of deep hypothermic patients have shown that temperature [3]. Epitympanic temperature (Tty) measured prehospitally was comparable to Tcore measured invasively at hospital admission [9,10,11], but there is still a lack of data on the reliability of epitympanic measurements at low ambient temperature
Summary
Epitympanic temperature (Tty) measured with thermistor probes correlates with core body temperature (Tcore), but the reliability of measurements at low ambient temperature is unknown. Epitympanic temperature (Tty) measured with a thermistor probe in the ear canal correlates with Tcore in hypothermic patients [5, 6] and may be a non-invasive alternative for diagnosing the severity of Strapazzon et al Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine (2015) 23:90 hypothermia in victims of accidental hypothermia [7, 8]. Case reports of deep hypothermic patients have shown that Tty measured prehospitally was comparable to Tcore measured invasively at hospital admission [9,10,11], but there is still a lack of data on the reliability of epitympanic measurements at low ambient temperature. The aim of this study was to determine if commercially-available thermistor-based Tty reflects Tcore in low ambient temperature and if Tty is influenced by insulation of the ear
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