Validation of the 13C-bicarbonate tracer technique for determination of CO2 production and energy expenditure in ponies by indirect calorimetry

Objective To determine longitudinal measurements of resting energy expenditure (REE) by indirect calorimetry (IC) in healthy term infants during the first 2 months of life. Study Design An outpatient prospective pilot study was performed in healthy term infants to estimate REE by measuring expired gas fractions of oxygen (O2) and carbon dioxide (CO2) with IC in a respiratory and metabolic steady state. Results A total of 30 measurements were performed. Fourteen subjects completed measurements at both 1 and 2 months of life, and two subjects had only measurements made at 1 month of life. Mean REE values were 64.1 ± 12.7 and 58.4 ± 14.3 kcal/kg/d at 1 and 2 months of age, respectively. Mean O2 consumption and CO2 production measurements were 9.3 ± 2.0 and 7.7 ± 1.2 mL/kg/min and 8.1 ± 2.2 and 6.4 ± 1.1 mL/kg/min at 1 and 2 months of age, respectively. Conclusion This pilot study demonstrates longitudinal measurements of REE by IC in healthy term infants during the first 2 months of life. We also demonstrate that, overall, there is consistency in REE values in this population, with a likely decrease in individual longitudinal measurements over the first 2 months of life.

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Breath water-based doubly labelled water method for the noninvasive determination of CO2 production and energy expenditure in mice

Isotopes in Environmental and Health Studies ◽

10.1080/10256016.2018.1531855 ◽

2018 ◽

Vol 54 (6) ◽

pp. 561-572 ◽

Cited By ~ 2

Author(s):

Peter Junghans ◽

Solvig Görs ◽

Martina Langhammer ◽

Cornelia C. Metges

Keyword(s):

Energy Expenditure ◽

Co2 Production ◽

Doubly Labelled Water ◽

Water Based

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Determining energy expenditure in preterm infants: comparison of 2H(2)18O method and indirect calorimetry

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1992.263.3.r685 ◽

1992 ◽

Vol 263 (3) ◽

pp. R685-R692 ◽

Cited By ~ 1

Author(s):

C. L. Jensen ◽

N. F. Butte ◽

W. W. Wong ◽

J. K. Moon

Keyword(s):

Heart Rate ◽

Energy Expenditure ◽

Preterm Infants ◽

Indirect Calorimetry ◽

Water Flux ◽

High Ratio ◽

Individual Variability ◽

Study Time ◽

Co2 Production ◽

Turnover Rates

The doubly labeled water (2H(2)18O) method used to estimate total energy expenditure (EETotal) is particularly sensitive to analytic error in preterm infants, because of their high percentage of body water and the high ratio of water flux to CO2 production. To evaluate further use of this method, the EE of 12 preterm infants was measured by indirect calorimetry and 2H(2)18O simultaneously and continuously for 5 days. Initial infant weight, age, and postconceptional age were (means +/- SD) 1,674 +/- 173 g, 4.4 +/- 2.6 wk, and 34.6 +/- 1.6 wk, respectively. The indirect calorimeter system included an air-temperature-controlled chamber and heart rate monitor. EE was measured by indirect calorimetry for 85.6 +/- 4.7% of study time and estimated from the linear regression of heart rate on EE for 14.4 +/- 4.7% of study time. The 2H(2)18O method entailed an initial dose of 100 mg 2H2O and 250 mg 18O/kg and a final dose of 75 mg 18O/kg; urine was collected twice daily. 2H and 18O enrichments were measured by gas-isotope-ratio mass spectrometry. EE was calculated from measured 2H and 18O dilution spaces (NH, NO), turnover rates (kH, kO), and measured respiratory quotient. The ratio of 2H to 18O dilution spaces was 1.01 +/- 0.01 and the ratio of kO to kH was 1.16 +/- 0.04. Estimation of EE from 2H(2)18O and indirect calorimetry agreed within 1%, although individual variability in methods was large.

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Indirect calorimetry with a hood: flow requirements, accuracy, and minute ventilation measurement

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.1.485 ◽

1993 ◽

Vol 74 (1) ◽

pp. 485-491 ◽

Cited By ~ 8

Author(s):

B. E. Pennock ◽

M. Donahoe

Keyword(s):

Water Vapor ◽

Indirect Calorimetry ◽

Respiratory Exchange Ratio ◽

Minute Ventilation ◽

Co2 Concentration ◽

Patient Comfort ◽

Co2 Production ◽

O2 Concentration ◽

Expired Gas

Flow-dilution-based hood systems for indirect calorimetry eliminate the conventional mouthpiece or mask of sealed-circuit systems allow measurements with improved patient comfort. This feature is particularly relevant when measurements are made over long periods of time or are repeated often. The flow of air pulled through the hood into the calorimeter in these systems is necessary to clear CO2 from inside the hood. The errors in these systems are greater than those in the sealed-circuit systems and are proportional to the flow. We show that the CO2 concentration within the hood at steady state does not depend on hood size. We describe the accuracy in determination of O2 consumption (VO2), CO2 production, and respiratory exchange ratio with a hood system as a function of the accuracy of the O2 and CO2 analyzers and the water vapor in collected gas. For example, we show that if there is a 1% error in O2 concentration, the percent error in VO2 changes from 5% in a sealed circuit to 51% when a cleansing flow of 50 l/min is introduced. The error in VO2 caused by a 5% error in CO2 determination is 10.6% at this cleansing flow. Removal of 90% of the water vapor (instead of 100%) before analysis of the expired gas introduces a 15.8% error in VO2. By use of the equations described, the accuracy of any measurement system can be determined. In addition, we demonstrate that the measurement of ventilation, usually lost in a hood system, can be preserved using dual pneumotachographs and a sealed hood.

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