Comparison of distal oesophageal temperature with “deep” and tracheal temperatures

Abstract

Comparison oesophageal with "deep" of distal temperature and tracheal temperaturesPurpose: ~ compare distal oesophageal (reference) temperature with "deep-sternal," "deep-forehead," and tracheal temperatures, establishing the accuracy and precision of each. Methods: We studied 20 patients undergoing general anaesthesia for gynaecological surgery. Their lungs were mechanically ventilated with a circle systgm, at a fresh-gas flow rate of 6 L-min -~ Respiratory gases were not warmed or humidified. Tracheal temperatures were recorded from a Trachelon e tube inserted =21 cm. Deepbody temperatures were measured at the sternum and forehead Using a Coretemp | thermometer. The principle of the method is to null thermal flux through a cutaneous dgk, thus obliterating thermal gradients between the sides of the disk, skin surface, and subcutaneous tissues. Distal oesophageal temperatures were measured from thermocouples incorporated into oesophageai stethoscopes. Tracheal and deep-tissue temperatures were compared with oesophageal temperature using regression and Bland and Altman analyses. Results: Tracheal, sternal, and forehead temper:atums correlated similarly with distal oesophageal temperature, correlation coefficients (r 2) being 0.7 in each case. The offset (oesophageal temperature minus study site) was considerably larger for tracheal temperature (0.7~ than for the other sites (0.2~ However, the precision was only 0.3~ at each site. Conclusion: Our data suggest that tracheal temperatures may not be an adequate substitute for conventional core-temperature monitoring sites, In contrast, the accuracy and precision of deep-tissue temperature monitoring at the sternum and forehead was sufficient for clinical use.Objectif : Comparer la temperature oesophagienne distale (rEfErence) avec la temperature sternale profonde, frontale profonde et trachEale, darts le but de verifier !'exactitude et la precision de chacune des m&hodes. M&hodes : Vingt patientes subissant un i'nteruention gyn&ologique ont EtE EtudiEes. Elles &aient ventilEes m&aniquement ~ I'aide d'un circuit circulaire, av, ec un debit de'gaz frais de 6 L.min-'. Les gaz respiratoires n'&aient e ni r&hauff& r,i humidifies. La temp&ature trach~ale &ait enregistr& sur un tube Trachelon insErE ~ =21 cm. Les temperatures corporelles profondes Etaient mesure'es au sternum et sur le front avec un thermomEtre Coretemp e. Le principe de la m&hode est d'annuler le flux thermique ~ travers un disque cutanE, et d'oblitErer ainsi les gradients thermiques ertre les c6t& du disque, la surface cutanEe et le tissu sous<utanC La temperature oesophagienne distale Etait mesur& ~ raide de thermocouples incorpor& dans des stethoscopes oesophagiens. La temperature trachEale et celle des tissus profonds &aient comparEes par analyse de regression et par la m&hode de Bland et Altman. R~sttltats : Les temperatures distale, stemale et frontale &aient en correlation identique avec la temperature oesophagienne distale, le coefficient de correlation (r 2) Etant 017 dans chaque cas. La temperatu...

“Deep-forehead” temperature correlates well with blood temperature

“…14 Good accuracy and precision with this device, compared with esophageal temperature, has been reported previously. 14,17 Our study confirmed these results, and revealed that the accuracy was excellent, comparable to tympanic membrane temperature, and that the precision was clinically sufficient as good as rectal temperature, with reference to blood temperature.…”

“…The "deep-forehead" and "deep-sternum" temperatures have similar accuracy and precision, and either site can be used depending upon the position of the patient and the site of the surgery. 14 In conclusion, we have demonstrated that"deepforehead" temperature has excellent accuracy and has sufficient clinical precision as three other core temperature measurements, compared with blood temperature. The "deep-forehead" temperature is suitable to monitor body temperature non-invasively and continuously during anesthesia.…”

“…10 In addition to these temperature monitoring sites, "deep-forehead" and "deep sternal" temperatures measured by the "deep-tissue" thermometer (Coretemp® CTM-205, Terumo corp., Tokyo, Japan) which was developed by Fox 11 and refined by Togawa 12 has been shown to have sufficient accuracy, compared with esophageal temperature. [13][14][15] In this study, we evaluated the accuracy and precision of "deep-forehead" temperature with rectal, esophageal, and tympanic membrane temperatures, compared with blood temperature, which is considered to be the most reliable estimate of core temperature.…”

“…We determined an accuracy (mean difference between reference and test temperatures) and precision (standard deviation of the difference) of 0.5°C to be clinically acceptable as our previous studies. 14,15 Results The patients' height was 158 ± 8 cm (mean ± SD), weight 54 ± 10 kg, and age 66 ± 10 yr. Four hundreds and fifty one temperature sets were recorded. Blood temperatures ranged from 33.3°C to 37.7°C.…”

“…Then, skin temperature is equilibrated both with the temperature of the sensor element and with the tissue temperature under the skin. 14 Since it takes approximately 15 min for the equilibration, we started the temperature measurements 20 min before the induction of anesthesia. Good correlation (r 2 =0.87) has been shown between the temperature measured by the Coretemp and the temperature at 18-mm-depth from skin surface.…”