Estimating the time of death with infrared tympanic thermometer: a new prospective study in France

Very few studies are available on the use of infrared tympanic thermometer to estimate the postmortem interval. The purpose is to observe the decrease of the infrared tympanic temperature according to the postmortem interval under standardized conditions and to compare with the gold standard (rectal temperature). One hundred seventeen cadavers are included at the mortuary of the University Hospital of Nancy from 1 June 2015 to 1 June 2016. The infrared tympanic temperature is measured twice in each ear for each cadaver with a control of these measurements and the taking of rectal temperature for the part of them. In our experiments, the reproducibility of the measurements was excellent between both the ears of one body [intra class coefficient correlation [ICC] = 0.952], the right ear and the left ear with a same observer [ICC = 0.853] and the different observers [ICC = 0.830]. The postmortem interval is correlated with the infrared tympanic temperature (rho = - 0.483; p < 0.0001) with an average of 3.79 h +/- 2.38 h. A calculation method is developed (postmortem interval = 16.14 - 0.39 x infrared tympanic temperature). Even if the correlation with the gold standard was correct (rho = 0.505), it is not associated with the postmortem interval (p = 0.0702) due to weakness of the sample. Despite early and only time point postmortem measurements, these results are promising and might impact the forensic science community by drawing the attention of researchers to the estimation of the time period since death and by developing a simple and non-invasive method, even for non-medical investigators at the scene.