Objective Prehospital induction of therapeutic hypothermia after cardiac arrest may require temperature monitoring in the field. Tympanic temperature is non-invasive and frequently used in clinical practice. Nevertheless, it has not yet been evaluated in patients undergoing mild therapeutic hypothermia (MTH). Therefore, a prospective observational study was conducted comparing three different sites of temperature monitoring during therapeutic hypothermia.

Methods Ten consecutive patients admitted to our medical intensive care unit after out-of-hospital cardiac arrest were included in this study. During MTH, tympanic temperature was measured using a digital thermometer. Simultaneously, oesophageal and bladder temperatures were recorded in a total of 558 single measurements.

Results Compared with oesophageal temperature, bladder temperature had a bias of 0.019°C (limits of agreement ±0.61°C (2SD)), and tympanic measurement had a bias of 0.021°C (±0.80°C). Correlation analysis revealed a high relationship for tympanic versus oesophageal temperature (r=0.95, p<0.0001) and also for tympanic versus bladder temperature (r=0.96, p<0.0001).

Conclusions That tympanic temperature accurately indicates both oesophageal and bladder temperatures with a very small discrepancy in patients undergoing MTH after cardiac arrest is demonstrated in this study. Although our results were obtained in the hospital setting, these findings may be relevant for the prehospital application of therapeutic hypothermia as well. In this case, tympanic temperature may provide an easy and non-invasive method for temperature monitoring.