ESOPHAGEAL, RECTAL, AXILLARY, TYMPANIC AND PULMONARY-ARTERY TEMPERATURES DURING CARDIAC-SURGERY

Purpose: The gradient between temperatures measured at different body sites is not constant; one factor which will change this gradient is r apid changes in body temperature. Measurement of this gradient was don e in patients undergoing rapid changes in body temperature to establis h the best site to measure temperature and to compare two brands of co mmercial tympanic thermometers. Method: A total of 228 sets of tempera tures were measured from probes in the oesophagus, rectum, and axilla and from two brands of tympanic thermometer and compared with pulmonar y artery (PA) temperature in 18 adults during cardiac surgery. Results : Measurements from the oesophageal site was closest to PA readings (m ean difference 0.0 +/- 0.5 degrees C) compared with IVAC tympanic ther mometer (mean difference -0.3 +/- 0.5 degrees C), Genius tympanic ther mometer (mean difference -0.4 +/- 0.5 degrees C), axillary (mean diffe rence 0.2 +/- 1.0 degrees C) and rectal (mean difference -0.4 +/- 1.0 degrees C) readings. When data during cooling were analysed separately , all sites had similar gradients from PA except for rectal, which was larger. On rewarming, oesophageal readings were closest to PA reading s; tympanic readings were closer to PA than were rectal or axillary re adings. Readings from the two brands of tympanic thermometer were equi valent. Conclusion: Oesophageal temperature is more accurate and will reflect rapid changes in body temperature better. than tympanic, axill ary, or rectal temperature. When oesophageal temperature cannot be mea sured, tympanic temperature done by a trained operator should become t he reading of choice.