Introduction: Modern whole room indirect calorimeters (WRIC) consist of large chambers of similar volumes. Quality control is difficult due to the diverse characteristics and requirements of the associated gas analysis instrumentation from various manufacturers. Moreover, software code is specific for a single sized chamber.
Methods: The WRIC lab at St. Luke’s Hospital Obesity Research Center (New York City, USA) consists of a MAIN, Exercise (EX) and RMR chambers with volumes of 23,000, 10,000 and 4,500 liters, respectively. Our aim was to determine the accuracy of the new Sable Systems International Promethion Integrated (SSPI) instrumentation for WRIC of various volumes utilizing propane combustion. Propane burns at 11.92 kcal/g with a respiratory quotient [RQ] of 0.60. Propane burn rate (g/min) was recorded for each test. Comparisons (p<0.05) between propane stoichiometry and the SSPI instrumentation for energy expenditure (EE; kcal), RQ, VO2 and VCO2 (l/min) were determined by independent t-test (SPSS v. 13).
|
Chamber |
N |
Dur (h) |
EE propane |
EE SSPI |
RQ SSPI |
VO2 Propane |
VO2 SSPI |
VCO2 Propane |
VCO2 SSPI |
|
MAIN |
10 |
23 |
2069.6 ± 313.2 |
2047.2 ± 314.5 |
0.60 ± 0.01 |
442.1 ± 66.6 |
447.8 ± 70.2 |
265.3 ± 39.9 |
267.8 ± 38.3 |
|
MAIN |
10 |
6 |
464.6 ± 110.5 |
459.6 ± 108.9 |
0.61 ± 0.01 |
99.2 ± 24.5 |
99.4 ± 23.8 |
59.5 ± 14.7 |
60.9 ± 14.0 |
|
RMR |
15 |
1 |
77.8 ± 12.1 |
77.3 ± 12.3 |
0.61 ± 0.01 |
16.7 ± 2.6 |
16.7 ± 2.7 |
10.0 ±1.6 |
10.2 ± 1.7 |
|
EX |
15 |
1 |
81.7 ± 15.0 |
81.7 ± 15.4 |
0.61 ± 0.02 |
17.6 ± 3.2 |
17.6 ± 3.4 |
10.5 ± 1.9 |
10.7 ± 2.1 |
Results:
No differences existed between propane stoichiometry and the SPPI instrumentation for any of the parameters compared.
Conclusion: The SSPI instrumentation is accurate without regard to the WRIC volume, and can also be used with hoods and masks.