Development of an Individual Device for Exhaled Breath Temperature Measurement

Abstract

Different thermometers have been constructed over the decades to measure the temperature of the body to help detect and monitor morbid states. They yield slightly different estimates of the core body temperature depending on the proximity of the measurement site to the internal milieu of the organism, the principle of temperature assessment, and the specific characteristics of the gauging devices. Evaluation of the exhaled breath temperature (EBT) has been recently suggested as a new method to detect inflammatory processes in the conducting airways due to changes in the blood flow perfusion of their walls and adjacent structures. While the first reported EBT experiments required sealed laboratory environment and sophisticated equipment, we designed a simple handheld instrument for EBT measurement and proven its precision, reproducibility and validity in subjects with asthma. We now describe the construction principles of our instrument, the procedure to test the fitness for purpose of the separate units and the novel features of the newest prototypes outfitted with microprocessor and memory. We also outline the potential clinical applications of an individual device for EBT measurement.Index Terms-Airway inflammation, clinical applications, core body temperature, exhaled breath temperature, thermometry.

Human exhaled breath analysis

“…Several research teams have investigated the assumption that inflammation of the airways would influence the temperature of the air coming from the alveoli of the lungs and that this added signal could be picked by appropriate means. [47][48][49] In previous experiments it was demonstrated that in asthmatic adults and children there was correlation between the temperature of the exhaled breath and the bronchial blood flow, the FeNO levels, and the number of sputum eosinophils. 50,51 Although the first experiments were made in sealed chambers with sophisticated equipment requiring extensive training of the patients to take the measurements, a specially designed, handheld instrument was built that allowed measurements to be taken in regular indoor environments without special requirements from the tested patients.…”

Tidal‐breathing measurement of exhaled breath temperature (EBT) in schoolchildren

“…Tidal‐breathing EBT was measured by means of a portable device (X‐halo breath thermometer, Delmedica Investments, Singapore) validated and fully described elsewhere . This technique allows the subject's exhaled air to pass into a thermally isolated chamber across an inflow valve, then into a copper tube with a thermal sensor, while outflow valves discard the excess air at every exhalation.…”

Development of a Breath Analyzer for O2 and CO2 Measurement

“…The physiological parameters of heat, humidity and CO 2 production and O 2 consumption calculated by Eqs. (3)(4)(5)(6) are in Table 2.…”

“…Popov et al [4,6] adopted a resistive thermometer to measure EBT. The advantages of this resistive sensing element are reliability and accuracy.…”

“…A thermal chamber was used to eliminate the effect of surrounding conditions, and the resistive thermometer was selected. The authors then constructed the second and third type of devices for EBT measurement [5,6]. Then, the requirement of the portable EBT and the utilization of this device to detect a pathological process in the respiratory system were introduced in detail [7].…”