COMPARISON OF TWO SYSTEMS FOR MEASURING ENERGY EXPENDITURE: A STUDY IN INDIRECT CALORIMETRY
Health care professionals typically use resting metabolic rate (RMR) via indirect calorimetry to determine a person’s energy expenditure. RMR via indirect calorimetry is determined by either by oxygen consumption (VO2) or oxygen consumption and carbon dioxide production (VCO2). Traditional indirect calorimetry measurements involve an expensive, heavy piece of equipment that requires careful calibration. The recent development of a handheld indirect calorimeter makes it easier to measure RMR at a lower cost. Few investigators have compared the effectiveness of the new handheld device to traditional indirect calorimetry equipment. PURPOSE: To validate the accuracy and precision of the handheld indirect calorimetry device by simultaneously comparing its measurements to those from a traditional indirect calorimeter. METHODS: Healthy, free-living subjects (n=50), ages 18 years and older, were tested simultaneously with both indirect calorimeters. All subjects breathed through the handheld device using a mouthpiece and noseclips were applied to prevent leaks. The handheld indirect calorimetry device was placed inside a canopy with the exhaled gas from the handheld positioned directly over the inlet to the port delivering gases to the traditional device’s mixing chamber. All expired gases were simultaneously collected into the traditional device via a canopy. During the measurement, VO2 and RMR were continuously recorded to a personal computer. RESULTS: Mean oxygen consumption and RMR did not significantly differ between the two devices, with a mean difference of .58 ± 15.33 ml per min (p = 0.790) and 4.66 ± 113.39 kcal per day (p = 0.773) and an absolute difference of 12.3 ± 8.99 ml per min and 86.58 ± 72.32 kcal per day, respectively. Correlation coefficients for oxygen consumption and RMR were 0.945 and 0.941, respectively. CONCLUSION: No significant difference was found between the measurements obtained from both indirect calorimetry devices. These findings suggest that the handheld indirect calorimetry device provides an accurate and reliable measure of oxygen consumption and RMR measurements for spontaneously breathing subjects.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:resting metabolic rate med gem indirect calorimetry nutrition assessment delta trac
Date of Publication:01/01/2003