Validation of Improved Hardware and Software for Expired Gas Analysis Indirect Calorimetry

The purpose of this investigation was to validate a new system of breath-bybreath expired gas analysis to both an artificial working model of lung ventilation and gas exchange as well as to the Douglas bag technique. In addition, comparisons will be made between expired fractions, ventilation, and computations of VO2, VCO2, and RER between the new system and a commercial mixing chamber system (ParvoMedics) for repeated measurements at rest, steady state and non-steady state cycle ergometry exercise. Post acquisition processing involved custom developed software (LabVIEW), where time to gas equilibration within the mixing bag was determined, as well as differences in equilibrated gas fractions. All testing procedures were repeated 5 times for parametric statistical analyses. Gas concentration (%) results for the compliant 2 L mixing bag was the only method to yield data not significantly different between alveolar and measured. Alveolar % oxygen was significantly lower than mixing bag, mixing chamber, and ParvoMedics. The most responsive method was the mixing bag, with significantly lower % gas data for oxygen for breaths 2 to 5 compared to the mixing chamber and ParvoMedics. The ParvoMedics and mixing bag yielded similar results after breath 6, but data were significantly higher than for alveolar air. The slope data for breaths 0 to breaths 2 was