Holter monitoring of central and peripheral temperature: possible uses and feasibility study in outpatient settings.

Background: Conventional clinical thermometry has important limitations. A continuous monitoring of temperature may offer significant advantages, including the use of chronobiological and complexity analysis of temperature profile and eventually the identification of a "pre-febrile" pattern.

Objective: We present a clinical model designed to measure, store and/or transmit in real time a central and a peripheral temperature reading. The results of its use in a healthy, free-living population is reported.

Methods: Thirty subjects (15 women, 15 men, 20-70 years old), were monitored for 24 h while following their normal life. Temperatures were recorded every minute at the external auditory channel (EAC) and on the skin, at the intersection of the 5th intercostal space and the anterior axillary line. A Cosinor analysis and Approximate Entropy (ApEn) (m = 2, r = 0.15*SD, N = 180) were calculated for both temperatures.

Results: Median temperature was 35.55 degrees C [interquartile range (IR) 0.77 degrees C] in the external auditory channel (EAC) and 34.62 degrees C (IR 1.61) in the specified skin location. Median gradient between AEC and skin was 0.93 (IR 1.57). A circadian rhythm was present both in EAC and skin temperature, with a mean amplitude of 0.44 degrees C and an acrophase at 21:02 for the EAC and 0.70 degrees C and 00:42 for the skin. During the night there was a sizable increase in peripheral temperature, with a decrease in gradient and a loss of complexity in the temperature profile, most significantly in the peripheral temperature.

Conclusions: Continuous monitoring of central and peripheral temperature may be a helpful tool in both ambulatory and admitted patients and may offer new approaches in clinical thermometry.