Validity and reliability of a new portable telemetric calorimeter designed to measure oxygen consumption and carbon dioxide production.

OBJECTIVE

The purpose of the present study was to evaluate the precision and the accuracy of a new portable telemetric calorimeter developed for the measurement of oxygen consumption, carbon dioxide production and pulmonary ventilation.

DESIGN

An in vitro validation study.

METHODS

An experimental protocol was designed to generate a series of tidal volumes (from 100 ml to 6000 ml at 200 ml steps) at different respiratory rates (5, 8, 14, 20, 40, 60, 75 breaths-min(-1)). For this purpose, a standardized pulmonary waveform generator system was utilized. Moreover, in order to evaluate the measure of O2 and CO2 concentrations at different temperatures (-10 degrees, 0 degrees, 15 degrees, 25 degrees, 40 degrees C), the instrument was placed inside an adjustable temperature and humidity chamber.

RESULTS

The accuracy of flow measurements was within +/-3% in respect to the real values throughout the entire range of physiological values, whereas the measurements of gas concentrations were within +/-1% between 0 and 25 degrees C.

CONCLUSIONS

The new portable telemetric calorimeter represents an easy to use instrument for the measure of energy expenditure during the activities of daily living.