Improved tympanic thermometer based on a fiberoptic infrared radiometer and an otoscope and its use as a new diagnostic tool for acute otitis media

Clinical diagnosis of Acute Otitis Media (AOM) in children is not easy. It was assumed that there is a difference ΔT between the Tympanic Membrane (TM) temperatures in the two ears in unilateral AOM and that an accurate measurement of ΔT may improve the diagnosis accuracy. An IR transmitting fiber, made of AgClBr, was coupled into a hand held otoscope and was used for the non-contact (radiometric) measurements of T_T, the TM temperature. Experiments were carried out, first, on a laboratory model that simulated the human ear, including an artificial tympanic membrane and an artificial ear canal. Measurements carried out using commercially available tympanic thermometers showed that the temperature T_C of the ear canal affected the results. T_C did not affect the fiberoptic radiometer, and this device accurately measured the true temperature, T_T of the tympanic membrane. A prospective blinded sampling of the TM temperature was then performed on 48 children with suspected AOM. The mean temperature difference between the ears, for children with unilateral AOM was ΔT = (0.68±0.27) °C. For children with bilateral AOM it was ΔT = (0.12±0.08) °C and for children with bilateral normal ears the difference was ΔT = (0.14±0.10) °C (p<0.001). It was demonstrated that for unilateral AOM the difference ΔT was proportional to the systemic temperature. In conclusion, the fiberoptic inferometric measurements of the TM can be a useful non-invasive diagnostic tool for AOM, when combined with other data.