Long-Term Variation in Oxygen Consumption Rate in Preterm Infants

Roberts, Susan B.; Murgatroyd, Peter R.; Crisp, J.A.; Nohria, Virinder; Schlingenseipen, K.-H.; Lucas, Alan

doi:10.1159/000242677

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…Accurate measurement of energy expenditure has important implications in the determination of energy requirements in preterm infants. Previous studies examining EE using flowthrough indirect calorimetry (IC) have yielded variable results (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). The extent to which this reflects differences in methodology, biologic variability, and/or factors such as dietary intake, age, weight, weight gain, etc., is not entirely clear.…”

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confidence: 99%

“…Infants may also be placed on a balance collection mattress containing holes, which although used to ensure complete urine and stool collection may limit the accuracy of gas sampling. Studies suggest that 24-h EE can be estimated from a 6-h EE measurement (14,16) but EE varies on a day-to-day basis (9,17) and the extent to which a 6-h EE reading can be extrapolated to a 48-h EB collection has not been determined.…”

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Factors Affecting the Measurement of Energy Expenditure during Energy Balance Studies in Preterm Infants

2000

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Our objective was to examine factors that affect the accuracy of energy expenditure measurements (EE), when using flow-through indirect calorimetry (IC), to determine the minimum length of time needed to measure 24- and 48-h EE and to compare cross-over and parallel designs as methods of investigation during energy balance collections (EB) in preterm infants. A baby doll manikin was used to determine equilibration times and to compare VCO(2) and VO(2) as measured by flow meter and indirect calorimetry under different study conditions, one of which simulated an EB. "Continuous" EE was measured to determine the minimum length of time needed to accurately reflect 24- and 48-h EE and to compare parallel and cross-over studies as methods of study design in a group of "normal" enterally fed preterm infants. The mean (+/-SD) errors between flow meter and indirect calorimetry determinations for VCO(2) and VO(2) were -1.9 +/- 2.5 and -1.8 +/- 4.3% under conditions that simulated an EB. Cumulative 6-h EE accurately predicted 24- and 48-h EE. Expressed in absolute terms (kcal/d), EE did not change on a day-to-day basis but did increase over the 2-wk study period. Expressed on body weight basis (kcal/kg/d), EE did not change on a day-to-day or week-to-week basis. The variance in EE due to biologic variability; i.e. the parallel design, was approximately 6 times greater than that due to age, weight, and weight gain; i.e. the cross-over design. Indirect calorimetry, therefore, accurately measures EE in conditions simulating an energy balance collection. Six-hour EE determinations are valid estimate of EE during a 48-h balance collection, while cross-over studies may be the preferred method of study design during short-term studies of EE in preterm infants.

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confidence: 99%

Factors Affecting the Measurement of Energy Expenditure during Energy Balance Studies in Preterm Infants

2000

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“…These measurements can be carried out on the entire human age range from pre-term infants (Roberts et al, 1987) to the elderly (Fuller et al, 1996), and can be obtained during almost all states of disease.…”

Section: Discussionmentioning

confidence: 99%

Precision and accuracy in a metabolic monitor for indirect calorimetry

Wells

Fuller

1998

Eur J Clin Nutr

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Objective: To determine within-machine and between-machine precision (reproducibility) and accuracy, of the Deltatrac Mk 1 Metabolic Monitor. Design: Within-machine and between-machine comparison for gas exchange (VO 2 and VCO 2 ), respiratory quotient (RQ) and energy expenditure (EE). Subjects: 3 Deltatrac Mk 1 Metabolic Monitors. Methods: Within-machine and between-machine reproducibility were assessed by ®ve successive 10 min gas infusion tests in each machine. Accuracy was assessed by measuring independently the gas content of the infusion mixture. The Deltatrac¯owmeters were evaluated by further infusion tests. Results: Within-study reproducibility was`1 ml/min for VCO 2 ,`2.5 ml/min for VO 2 ,`5 kcal/d for EE and 0.01 for RQ. Between-study reproducibility was`0.2% for RQ,`1% for VCO 2 and`2% for VO 2 and EE. Between-machine reproducibility was`0.1% for RQ and`1% for VO 2 , VCO 2 and EE. Accuracy in all three machines was within 3% for VO 2 , VCO 2 and EE, and within 0.2% for RQ. Conclusions: The Deltatrac Mk 1 is a very precise metabolic monitor, and is accurate within 3% for gas exchange and EE. RQ is measured with greatest reproducibility and accuracy (within 0.2%), making the monitor particularly suitable for studies of substrate utilisation. Descriptors: oxygen consumption; carbon dioxide production; energy expenditure; respiratory quotient IntroductionMeasurement of minimal metabolism in the form of basal (BMR), resting (RMR) or sleeping (SMR) metabolic rate is used increasingly in both research and clinical care. Although minimal metabolism can be predicted from anthropometry, predictive equations are inevitably subject to a degree of error, and are unsuitable for many patient groups and disease states. Consequently, there is a strong case for measuring minimal metabolism wherever possible (Kaplan et al, 1995; Journal of Pediatrics Editorial, 1995).Several commercially-produced machines are now available for such measurements. Furthermore, these machines are able to measure separately oxygen (O 2 ) consumption, carbon dioxide (CO 2 ) production, and by derivation substrate utilisation, which are useful measurements in their own right. However, although commercial machines have been used for up to ten years, the success with which they measure respiratory gas exchange has not received adequate attention. We have therefore assessed precision (reproducibility) and accuracy, both within-machine and between-machine, in a metabolic monitor that is widely used in research and hospital environments. MethodsThree Deltatrac Mk 1 Metabolic Monitors (Datex, Helsinki) were set up in close proximity to each other, in order to minimise environmental differences or ambient¯uctua-tions. Carbon dioxide and nitrogen (N 2 ) were infused simultaneously to simulate physiological rates of CO 2 production and O 2 consumption respectively. N 2 alone was infused to simulate physiological rates of O 2 consumption in order to assess machine¯ow rate. For each series of tests the monitors were warmed up for over an hour before th...

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“…Indirect calorimetry in these infants over 8 h is therefore supposed to give a good representation of measure ments lasting 24 h or longer [11,12], al though considerable variation of results is found in some studies [1]. The aim of our present study was to investigate if a 5-day estimate of energy expenditure of normally growing preterm infants could be made satis factory using a single IDC study of 8 h in comparison with the same measurement per formed 5 days later and in comparison with measurement of the energy expenditure us ing the DLW method over 5 days.…”

Section: Discussionmentioning

confidence: 99%

“…This measurement of gas exchange, so-called indirect calorimetry (IDC), must be applied over a period of at least 6-8 h in order to allow the results to be representative for a period of 24 h or longer. According to some investigations however this extrapolation of results over periods longer than 1 day, for instance 5-7 days, may create considerable mistakes [1]. Re cently estimation of energy expenditure was described in preterm infants using the dou bly-labeled water (2H2I80 ) method (DLW) [2,3], This technique has the advantage that it allows measurement over an extended pe riod and only requires accurate sampling of urine or saliva after oral administration of the stable isotope that is free of any radia tion hazards.…”

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Comparison of Short Term Indirect Calorimetry and Doubly Labeled Water Method for the Assessment of Energy Expenditure in Preterm Infants

Lafeber¹,

Sulkers²,

Sauer³

1991

Neonatology

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The accuracy of 8-hour indirect calorimetry (IDC) as an estimate of energy expenditure was investigated in 8 healthy preterm infants (birth weight 1,270 ± 193 g, gestational age 32 ± 3 weeks, mean ± SD) in comparison with an analysis over 5 days using the doubly-labeled water (²H₂¹⁸O) method (DLW). The infants that were fed continuously by nasogastric drip with 120 kcal/kg/day of special infant formula were measured twice under thermoneutral conditions in a closed system indirect calorimeter during 8 h with a 4-day interval; simultaneously isotope decay was measured by isotope ratio mass spectrometry in urine samples collected daily during 5 days from 6 h after an oral dose of 2H2180 on the first day of IDC, all during the 4th postnatal week. The mean differences between carbon dioxide production rate (rCO₂) measured either by single 8-hour IDC or by duplicate 8-hour IDC and the 5-day DLW method, using the two-point analysis or the multipoint analysis were not significantly different from zero. The rCO₂ calculated from the DLW method using the two-point analysis differed ––1.4 ± 1.7% from that measured by the multipoint analysis. The mean differences between the metabolic rate estimated from 8 h of IDC and from the 5-day DLW method based on a measured RQ of 0.90 was ––6.7 ± 6.2% and based on the RQ of the feeding ––4.5 ± 6.0%. These differences were not significantly different from zero. We conclude that IDC over 8 h and two-point DLW measurement over 5 days, both methods that can be applied with relative ease in practice, offer an adequate average estimate of energy expenditure in continuously fed preterm infants under thermoneutral conditions.

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Long-Term Variation in Oxygen Consumption Rate in Preterm Infants

Cited by 15 publications

References 8 publications

Factors Affecting the Measurement of Energy Expenditure during Energy Balance Studies in Preterm Infants

Factors Affecting the Measurement of Energy Expenditure during Energy Balance Studies in Preterm Infants

Precision and accuracy in a metabolic monitor for indirect calorimetry

Comparison of Short Term Indirect Calorimetry and Doubly Labeled Water Method for the Assessment of Energy Expenditure in Preterm Infants

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