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Description and Validation of Flow-Through Chambers of Respirometry for Measuring Gas Exchange in Animal Trials.

ABSTRACT: Indirect calorimetry (IC) is a widely used method to study animal energy metabolism by measuring gas exchange. The accuracy of IC depends on detecting variations in signals reflecting the metabolic response, which can be challenging due to measurement noise and external factors. This study proposes a methodology to validate IC systems, including an easy-to-use spreadsheet for data computing, to verify accuracy and detect whole-system leaks. We conducted a recovery test using a simulation of CO₂ dynamics in MS Excel and injecting a known CO₂ concentration into four respirometry chambers. The thought flow rate of CO₂ was observed and compared to the expected rate from the simulation. Data filtering and computing, including a detailed calculation of signals calibration, Bartholomew transformation, and noise reduction, was developed to obtain the gas exchange and heat production parameters using an open-circuit IC system. The results from the recovery test in our system show that the proposed methodology is accurate and precise. The proposed methodology and recovery test can be used to standardize the validation of IC systems together with adequate data computing, providing accurate measurements of animal energy metabolism in different environmental conditions and energy utilization from feeds.

SUBMITTER: Lizana RR

PROVIDER: S-EPMC10451871 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Description and Validation of Flow-Through Chambers of Respirometry for Measuring Gas Exchange in Animal Trials.

Lizana Rony Riveros RR Camargos Rosiane de Souza RS Silva Raully Lucas RL Leme Bruno Balbino BB Sakomura Nilva Kazue NK

Animals : an open access journal from MDPI 20230819 16

Indirect calorimetry (IC) is a widely used method to study animal energy metabolism by measuring gas exchange. The accuracy of IC depends on detecting variations in signals reflecting the metabolic response, which can be challenging due to measurement noise and external factors. This study proposes a methodology to validate IC systems, including an easy-to-use spreadsheet for data computing, to verify accuracy and detect whole-system leaks. We conducted a recovery test using a simulation of CO<s ...[more]

PMID: 37627466

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Project description:We assessed the validity, reliability, and transferability of gas exchange and ventilatory variables from two commonly used metabolic measurement systems (COSMED Quark and VO2Master Pro). Two identical devices from each system were independently connected to a metabolic simulator (VacuMed), and 2 min of steady-state data was recorded at simulated oxygen uptake (V̇O2) of 1, 2, 3, and 4 L∙min-1 achieved through minute ventilation (V̇E) of 30, 60, 105, and 150 L∙min-1. Each metabolic analyzer recorded data three times for each "intensity" in a randomized order, and assessments were completed on two separate days. Douglas bag-based measurements were also made once at each simulated "intensity". Measured steady-state data (average of final 1.5 min) for both V̇O2 (STPD) and V̇E (ATPS) were compared with simulated values to assess validity, repeated values between and within days assessed reliability, and between-device comparisons provided transferability. Including both COSMED devices at all intensities, the mean percent error for V̇O2 was 3.5% (range: -2.5%-8.1%) and, for V̇E, was 2.0% (-0.5%-7.6%). For the VO2Master, these values averaged 0.6% (-9.3%-4.8%) and 1.1% (-6.3%-4.0%) for V̇O2 and V̇E, respectively. Mean percent error for Douglas Bag was 1.5%, -3.7%, -3.1%, and -2.0% for 1, 2, 3, and 4 L∙min-1, respectively. Between-day differences (reliability) for V̇O2 of both COSMED devices ranged from -4.1% to 2.2% (mean 0.1%) and, for both VO2Masters, between -1.6% and 11.1% (mean 1.2%). Between-device differences (transferability) ranged from -3.5% to 0.5% (mean 1.3%) for COSMED and from -11.0% to 3.6% (mean 0.0%) for VO2Master. Mean values and ranges for V̇E were similar. When used appropriately in laboratory settings, the COSMED Quark and VO2Master Pro systems provide gas exchange and ventilatory data within an acceptable range for metabolic testing equipment that are both reliable and transferable between optimally performing devices.

Project description:Background: HIV infection is associated with impaired gas transfer in the lung as indicated by a low diffusing capacity (DLCO). Mechanisms for reduced DLCO in the setting of HIV infection are not well understood. We hypothesized that HIV-associated gas exchange impairment is indicative of system-wide perturbations that could be reflected by alterations in peripheral blood gene expression. Methods: A total of 40 HIV-infected (HIV+) and uninfected (HIV-) men with preserved versus reduced DLCO were selected from a larger cohort study of lung function. All subjects were current smokers and those with acute illness, lung diseases other than COPD or asthma were excluded. Total RNA was extracted from peripheral blood leukocytes (PBLs) and hybridized to whole-genome microarrays. Gene set enrichment analysis (GSEA) was performed between HIV+ vs. HIV- subjects with preserved DLCO and those with impaired DLCO to identify differentially activated pathways. Results: Using pathway-based analyses we found that in subjects with preserved DLCO, HIV infection is associated with activation of processes involved in immunity, cell cycle, and apoptosis. When we applied a similar analysis to subjects with low DLCO, we identified a much broader repertoire of inflammatory and immune-related pathways in HIV+ patients relative to HIV- subjects, with up-regulation of multiple interleukin pathways, interferon signaling, Toll-like receptor signaling, and T cell/B cell receptor signaling. We confirmed elevated circulating levels of IL-6 in HIV+ patients with reduced DLCO relative to the other groups. Conclusions: Our findings reveal that PBLs of subjects with HIV infection and low DLCO are distinguished by widespread enrichment of immuno-inflammatory programs. Activation of these pathways may alter the biology of circulating leukocytes and play a role in the pathogenesis of HIV-associated pulmonary gas exchange impairment. Total RNA was isolated from peripheral blood leukocytes in four subject groups: 1. HIV-, low DLCO (N = 11); 2. HIV+, low DLCO (N = 10); 3. HIV-, preserved DLCO (N = 9); 4. HIV+, preserved DLCO (N = 9). Each sample was hybridized to an Affymetrix PrimeView Human Gene Expression microarray for a total of 39 experiments.

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Description and Validation of Flow-Through Chambers of Respirometry for Measuring Gas Exchange in Animal Trials.

Publications

Description and Validation of Flow-Through Chambers of Respirometry for Measuring Gas Exchange in Animal Trials.

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