Non-invasive zero-heat-flux technology compared with traditional core temperature measurements in the emergency department.

INTRODUCTION

Core temperatures (T) are often invasive, and can be underutilized. Peripheral temperatures are easier to obtain, but are often less accurate. A zero-heat-flux thermometer (ZHF) is a non-invasive method to obtain core temperatures (T), and has been accurate when compared to T in the operating room. We aimed to determine whether T accurately and reliably measures T in emergency department (ED) patients when compared to rectal, bladder or esophageal temperatures.

METHODS

We conducted a prospective observational quality improvement project, with concurrent T and T measurements. The primary outcome was whether one device detected a fever (≥38.1 °C) when the other device did not. Unadjusted linear regression was used to determine the relationship between temperature differences between devices.

RESULTS

268 patients were included. Mean temperatures were 36.6 °C for T and 36.3 °C for T. 16 of 52 patients with fever identified by T were not detected by T, 13 with an infectious etiology. The mean temperature difference between T and T increased as the patient's temperature increased; the difference was 0.2 °C in afebrile patients, but 0.7 °C in febrile patients.

CONCLUSION

While we found overall concordance between T and T, the ZHF did not detect fever in 25% of patients presenting with fever of infectious origin. Measurements between T and T varied more as temperatures increased, with T consistently reporting lower values. Although more study is needed, these findings call into question the use of T in the ED where detection of fever frequently guides patient evaluation and management.