Comparison of Wireless Continuous Axillary and Core Temperature Measurement after Major Surgery

Abstract

Background: Temperature is considered one of the primary vital signs for detection of complications such as infections. Continuous wireless real-time axillary temperature monitoring is technologically feasible at the general ward, but no clinical validation studies exist.

Methods: This study compared axillary temperature with a urinary bladder thermometer in 40 major abdominal postoperative patients. The primary outcome was changes in axillary temperature registrations. Secondary outcomes were mean bias between the urinary bladder and the axillary temperatures. Intermittent frontal and tympanic temperature recordings were also collected.

Results: Forty patients were monitored for 50 min with an average core temperature of 36.8 °C. The mean bias was -1.0 °C (LoA -1.9 to -0) after 5 min, and -0.8 °C (LoA -1.6 to -0.1) after 10 min when comparing the axillary temperature with the urinary bladder temperature. After 20 min, the mean bias was -0.6 °C (LoA -1.3-0.1). During upper arm abduction, the axilla temperature was reduced to -1.6 °C (LoA -2.9 to -0.3) within 1 min. Temporal skin temperature measurement had a resulted in a mean bias of -0.1 °C (LOA -1.1 to -1.0) compared with central temperature. Compared with the mean tympanic temperature, it was -0.1 °C (LoA -0.9 to -1.0) lower than the urinay bladder temperature.

Conclusions: Axillary temperature increased with time, reaching a mean bias of 1 °C between axillary and core temperature within 5 min. Opening the axillary resulted in rapidly lower temperature recordings. These findings may aid in use and designing corrections for continuous axillary temperature monitoring.

Keywords: axillary; fever; temperature; validation; vital signs; wireless monitoring.

Figure 1

Showing how the temperature changes in Celsius in relation to how long the arm is kept close to the body and after opening the axilla. Data points are including standard deviation.

Figure 2

Boxplots showing the difference between axillary and bladder temperature at different time intervals with closed axillae; y axis is the temperature difference in Degrees Celsius (°C).

Figure 3

Bland and Altmann plots of agreement between measurements of axillary and urinary bladder temperatures after 1 min with closed axilla. Upper dotted line shows the upper limit of agreement, the middle dotted line the mean bias, and the lowest dotteld line the lower limits of agreement.

Figure 4

Bland and Altmann plots of agreement between measurements of axillary and urinary bladder temperatures after 5 min with closed axilla. Upper dotted line shows the upper limit of agreement, the middle dotted line the mean bias, and the lowest dotteld line the lower limits of agreement.

Figure 5

Bland and Altmann plots of agreement between measurements of axillary and urinary bladder temperatures after 10 min with closed axilla. Upper dotted line shows the upper limit of agreement, the middle dotted line the mean bias, and the lowest dotteld line the lower limits of agreement.

Figure 6

Bland and Altmann plots of agreement between measurements of axillary and urinary bladder temperatures after 20 min with closed axilla. Upper dotted line shows the upper limit of agreement, the middle dotted line the mean bias, and the lowest dotteld line the lower limits of agreement.