Abstract PR610

Abstract

Background & Objectives: Anaesthesia alters normal body thermoregulation control leading to perioperative hypothermia. Monitoring intra-operative body temperature is frequently reinforced and can be achieved with various methods. We performed a correlation study between infrared tympanic membrane temperature (TMT) and nasopharyngeal temperature (NT) to the core oesophageal temperature (OT). Materials & Methods: Seventy seven patients aged 18 to 60 years requiring general anaesthesia with endotracheal intubation was recruited. A set of three temperatures (TMT, NT and OT) were taken after induction, at one hour and at the second hour intraoperatively on each patient. Bland-Altman plots were utilized to assess agreement of temperatures, with the OT taken as the reference or gold standard method. Results: The mean TMT, NT and OT were 36.84 ± 0.45 °C, 36.24 ± 0.50 °C and 36.20 ± 0.48 °C respectively. The correlation (r) between TMT with OT was 0.819 (p<0.0001), NT with OT was 0.911 (p<0.0001) and NT with TMT was 0.773 (p<0.0001). The mean difference (bias) between NT and OT was found to be -0.064° C with 95% limits of agreement (LOA) of -0.467 to 0.34° C and SD ± 0.40. The mean difference between TMT and OT was found to be -0.023° C with 95% LOA of -0.577 to 0.531° C and SD ± 0.55. The agreement between TMT and OT was outside the acceptable limits of ± 0.5° C via a Bland-Altman plot. The agreement between NT and OT was within acceptable limits at ± 0.40° C. Conclusion: NT showed a higher correlation with OT, although both NT and TMT had strong positive correlations with OT measurement. NT measurement also accurately reflects the lower OT. Our study supports the use of NT monitoring as a simpler and less invasive method to measure the core body temperature.