Limitations of infrared ear temperature measurement in clinical practice

PRINCIPLES: Detection of elevated body temperature is critical in the early diagnosis of sepsis. Due to its convenience, infrared ear temperature measurement (IETM) has become the standard of care. Unfortunately, the limitations of this method are largely unexplored.

OBJECTIVE: To evaluate potential limitations of IETM, including the presence of cerumen on otoscopy, depth of penetration, side of measurement, and the impact of acclimatisation to room temperature.

METHODS: In this prospective cohort study, 333 patients presenting to the medical emergency department underwent serial IETM before and after otoscopy and cleaning of the external auditory canal. The primary endpoint was defined as mean change in infrared ear temperature (IET) before and after removal of cerumen. We also tested for the effect of penetration depth, side of measurement and impact of acclimatisation.

RESULTS: Otoscopy revealed cerumen in 98 patients (29%). Cerumen had a weak but statistically significant impact on IETM. The removal of cerumen obturans resulted in a rise in IET of 0.20 °C (95% CI 0.10-0.28 °C, P = 0.03). The effects of penetration depth (P = 0.39), side of measurement (P = 0.78) and impact of acclimatisation (P = 0.82) were not significant.

CONCLUSIONS: Cerumen has a statistically significant, albeit not clinically meaningful, influence on IETM. Thus routine ear inspection prior to the use of IETM is not warranted. IETM provides highly reproducible assessments of IET irrespective of penetration depth, side of measurement and acclimatisation.