A validation study of the KB1-C portable metabolic measurement system using the autocalibration feature

Abstract

The purpose of this study was to determine the validity of the Aerosport KBI-C portable metabolic measurement system (Aerosport, Ann Arbor, MI) using the autocalibration feature against the Quinton QMC metabolic measurement cart. Twenty healthy 18-30 year old men and women volunteered to participate in this study. All subjects were students, faculty, or staff of the University of Wisconsin-Lacrosse. Volume and gas calibrations were completed according to the specifications of the manufacturer. Validation of the QMC ventilation measurements was determined by the subjects performing an exercise test on a treadmill consisting of a standard warm-up at 3.5 mph and 10% grade, followed by 3, 5 minute workloads at a self-selected speed at inclines of 0,2.5, and 5% grade. During this test, exhaled air was routed into the QMC and out the exhaust port into a Tissot spirometer during the final minute of each stage. Once the minute sample was collected in the Tissot, the air was forced out the exhaust port of the Tissot spirometer and through the mouthpiece of the KBl-C. Ventilation (VE) values measured by the KBI-C (STPD), QMC (BTPS), and Tissot spirometer (ATPS) were then converted to a standard volume (STPD) for comparison purposes. Comparison of physiological measures between the KBI-C and QMC was accomplished by each subject performing the same exercise test protocol as described above. During this test, exhaled air was routed into the QMC and out the exhaust port through the mouthpiece of the KBI-C for gas analysis. Repeated measures with appropriate post-hoc tests indicated no significant (p > 0.05) differences existed between the VE measures of the QMC and Tissot spirometer up to 46.8 1-min; however, there were significant (p < 0.05) differences between the Tissot vs KBI -C at all workloads. When physiological measures were compared between the KB1-C and QMC, VE data were not significantly (p > 0.05) different. No significant (p > 0.05) differences were found for measures of FE02; however, FECO2 values were significantly( p < 0.05) different with both FE02a nd FEC02 values produced by the KB1-C consistently lower than the QMC. Oxygen consumption and VCO2 data were both found to be significantly (p < 0.05) different, which produced similar RER values as the reference system, but cannot be termed accurate due to the error in both VO2 and VC02. It was concluded that the KBI-C should not be utilized using the autocalibration procedure in a research capacity due to significant inaccuracy in measurements provided by the unit.