01 Mar Core Temperature Accuracy Accuracy Study: Cleveland Clinic & Peking Union
The following is the abstract from our clinical trial with Peking Union Hospital and The Cleveland Clinic. Lijian Pei was our principal investigator and she collaborated with Dr. Sessler of the Cleveland Clinic to finalize the study. The study results are soon to be published in the journal of Anesthesia & Analgesia.
BACKGROUND: Core temperature can be accurately measured from the esophagus or nasopharynx during general anesthesia, but neither site is suitable for neuraxial anesthesia. We therefore determined the precision and accuracy of a novel wireless axillary thermometer, the iThermonitor, to determine its suitability for use during neuraxial anesthesia and other patients who are not intubated.
METHODS: We enrolled 80 adults having upper-abdominal surgery with endotracheal intubation. Intraoperative core temperature was measured in distal esophagus, and estimated at the axilla with a wireless iThermonitor WT701 (Raiing Medical, Boston MA) at 5-minute intervals. Pairs of axillary and reference distal esophageal temperatures were compared and summarized using linear regression and repeated-measured Bland and Altman methods. We apriori determined that the iThermonitor would have clinically acceptable accuracy if most estimates were within ±0.5°C of the esophageal reference, and suitable precision if the limits-of-agreement were within ±05°C.
RESULTS: There were 3,339 sets of paired temperatures. Axillary and esophageal temperatures were similar, with a mean difference (esophageal minus axillary) of only 0.14°C ± 0.26°C (standard deviation). The Bland-Altman 95% limits-of- agreement were reasonably narrow, with the estimated upper limit at 0.66°C and the lower limit at -0.38°C, thus ±0.52°C, indicating good agreement across the range of mean temperatures from 34.9°C to 38.1°C. The absolute difference was within 0.5°C in 91% of the measurements (95% CI: 88%, 93%).
CONCLUSIONS: Axillary temperature, as recorded by the iThermonitor WT701, well represents core temperature in adults having non-cardiac surgery and thus appears suitable for clinical use.