Published in:
Open Access 01-12-2015 | Original research
The impact of environmental factors in pre-hospital thermistor-based tympanic temperature measurement: a pilot field study
Published in: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine | Issue 1/2015
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Background
Few pre-hospital services have the possibility to accurately measure core temperature (T
core
). Non-invasive estimation of T
core
will improve pre-hospital decision-making regarding the triage and management of hypothermic patients. Thermistor-based tympanic temperature (T
tymp
) correlates well with T
core
in controlled studies; however, little is known about the feasibility of using T
tymp
under field conditions. This study assessed the impact of pre-hospital environmental factors on the accuracy of T
tymp
. Deep rectal temperature (T
rect
) was used as a substitute for T
core
.
Methods
Normothermic volunteers (n = 13) were exposed to four simulated field conditions producing local cooling of the head and ear canal. After exposure, T
tymp
was recorded every 15 s for 10 min and compared with T
rect
. Descriptive analysis and Bland-Altman plots were used to assess agreement.
Results
Immediately after exposure mean T
tymp
was low, but increased rapidly and reached an apparent steady state after 3–5 min. After 5 and 10 min, the mean temperature difference (∆T
rect-tymp
) ranged from 1.5–3.2 °C (SD = 0.5) and 1.2–2.0 °C, respectively. T
rect
remained unchanged throughout the study period.
Conclusions
After surface cooling of head and neck, T
tymp
did not accurately reflect core temperature within the first 10 min of measurement. The variation of ∆T
rect-tymp
was low after 10 min, regardless of the initial degree of cooling. With the risk of over-triage, T
tymp
may at this point provide an indication of T
core
and also exhibit a trend.
Trial registration
ClinicalTrials.gov: NCT02274597