Health, Exercise, and Sports Sciences ETDs


Doyeon Kim

Publication Date



The purpose of this investigation was to validate a new system of breath-by-breath 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 significantly (p < 0.05) lower for the ParvoMedics system compared to the mixing bag and mixing chamber. The mean temporal distribution of 1 L ventilation maneuvers from the mixing bag turbine was 0.999 ± 0.142 L, with a range of 0.96 to 1.03 L. The mean ventilation (STPD) from the ParvoMedics (pneumotach) was significantly lower (p = 0.0027) than the mixing bag turbine. For VE (p = 0.097), VO2 (p = 0.786), and VCO2 (p = 0.178) were not significantly different in the main effect for method and the Intensity x Method interaction (VE: p = 0.721, VO2: p = 0.059, VCO2: p = 0.406). As expected, there was a significant difference for the intensity main effect (p < 0.0001). For FEO2 (p < 0.0001) and FECO2 (p < 0.0001) there were significant findings for the main effects of intensity. However, the Intensity x Method interaction showed no significant differences in FEO2 and FECO2. RER was significantly different in the main effect for method (p = 0.024), intensity (p = 0.0006), and Intensity x Method interaction (p = 0.005). The expired oxygen and carbon dioxide had significant main effects and interactions (p < 0.001). All mean differences between alveolar and mouth end tidal gas % values across 6 breaths were significant (p < 0.01). The mean individual computed dead space volumes were 2.5 ± 0.13 L. The results suggested that the new 2 L mixing bag is capable of accurately reproducing specific gas fractions from reference calibration gas. The new 2 L mixing bag allowed expired air to wash out through the bag. This system, in combination with including anatomical dead space (ADS) as a factor in the determinations, gives more accurate measurements and calculations than a traditional mixing chamber. Additionally, the new mixing bag method has unique aspects that are advantageous to the operation and validity of the system. Although the new system is not used in commercial systems of expired gas analysis indirect calorimetry (EGAIC), this system provides enhanced accuracy and validity.


Indirect calorimetry, Indirect calorimetry--Equipment and supplies--Evaluation

Document Type




Degree Name

Physical Education, Sports and Exercise Science

Level of Degree


Department Name

Health, Exercise, and Sports Sciences

First Advisor

Robert, Robergs

First Committee Member (Chair)

Len, Kravitz

Second Committee Member

Christine, Mermier

Third Committee Member

Carole, Conn