Validation of whole room indirect calorimeters: refinement of current methodologies. Issue 22 (28th November 2017)

• Record Type: Journal Article
• Authors: Rising, Russell; Foerster, Thomas; Arad, Avigdor D.; Albu, Jeanine; Pi‐Sunyer, Xavier
• Is Part Of: Physiological reports. Volume 5:Issue 22(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-11-28
• Subjects: Blender -- energy -- infusion and combustion -- propane -- validation; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.13521
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: Whole room indirect calorimeter (WRIC) validation techniques consist of propane combustion (PC) or infusion of mixed carbon dioxide (CO2 ) and nitrogen (N2 ) by a precision blender (PB). To determine the best method, PC of 6, 10, 22‐h and PB infusions of 6, 10, and 14‐h, were conducted. The 14‐h infusion consisted of two metabolic settings. Energy expenditure (EE; kJ), ventilation (V; liters/min) of oxygen (VO2 ), VCO2, and respiratory quotient (VCO2 /VO2 ) obtained from the WRIC were extrapolated to the respective test durations and compared to similarly calculated values. Moreover, accurate equations (AE) were derived to correct infusions for additional N2 . As a final evaluation of a PC validated WRIC, weight maintenance (WM), energy balance (EB), respiratory quotient (RQ), and food quotients (FQ) were determined in 22 subjects who had repeat 24‐h EE measurements. Statistical analyses ( P < 0.05) were conducted (SPSS, version 23). Significant differences in RQ existed between PC and stoichiometry after 6‐h. Errors for the rest of the PC tests ranged from −1.5 ± 2.4 (VCO2 ) to 2.8 ± 4.6% (EE). When compared with the WRIC, all uncorrected metabolic parameters for six and 10‐h PB infusions were significantly different with errors from −12.8 ± 1.6 (VO2 ) to 6.0 ± 2.8% (RQ). The AE reduced the magnitude of errors to −12.4 ± 1.5 (RQ) to 2.2 ± 3.0% (RQ). The PB infusion with two settings showed similar performance. No differences in WM, EB, RQ, or FQ existed in the subjects. In conclusion, 10‐h PC tests are sufficient for validating WRICs. Abstract : Propane gas combustions of various durations was compared to precision gas blending tests of similar lengths to determine the best methodology for validating whole room indirect calorimeters. It was found that a 10‐h propane combustion test was sufficient for validating whole room indirect calorimeters utilized for 24‐h metabolic studies verses that of precision gas blending and best emulated the metabolic processes of a human subject.