title: Limitations of infrared ear temperature measurement in clinical practice.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Internal Medicine, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland. rtwerenbold@uhbs.ch
authors.forename: Raphael
authors.initials: R
authors.lastname: Twerenbold
authors.forename: Andreas
authors.initials: A
authors.lastname: Zehnder
authors.forename: Tobias
authors.initials: T
authors.lastname: Breidthardt
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.forename: Miriam
authors.initials: M
authors.lastname: Reiter
authors.forename: Nora
authors.initials: N
authors.lastname: Schaub
authors.forename: Roland
authors.initials: R
authors.lastname: Bingisser
authors.forename: Gerd
authors.initials: G
authors.lastname: Laifer
authors.forename: Christian
authors.initials: C
authors.lastname: Mueller
mesh_terms: D000368:Aged; D001831:Body Temperature; D004423:Ear; D005260:Female; D006801:Humans; D007259:Infrared Rays; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013817:Thermography