Precision of DLW energy expenditure measurements: contribution of natural abundance variations

1996 ◽  
Vol 270 (1) ◽  
pp. E164-E169 ◽  
Author(s):  
P. Ritz ◽  
T. J. Cole ◽  
C. Couet ◽  
W. A. Coward
Keyword(s):  
Linear Regression ◽  
Energy Expenditure ◽  
Coefficient Of Variation ◽  
Natural Abundance ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Product Model ◽  
Group Of Seven ◽  
Accuracy And Precision ◽  
Abundance Variation

Accuracy and precision of the the doubly labeled water (DLW) measurements of energy expenditure are commonly estimated with models that do not account for 2H and 18O natural abundance variation. A new and simple treatment that completes the ratio-product model is derived in the present study. It uses both linear regression of multipoint data with time and information on within-subject 2H and 18O natural abundance variation. Use of this treatment is demonstrated in a group of seven subjects in whom 2H and 18O natural abundance variation was assessed by collecting predose samples for 6-8 days before dosing. In this set of 16 measurements, the precision (coefficient of variation) of individual DLW estimates of CO2 production was 4.90 +/- 2.14%, of which 3.23 +/- 1.20% arose from natural abundance variation.

Interactions between 2H and 18O natural abundance variations and DLW measurements of energy expenditure

1996 ◽  
Vol 271 (2) ◽  
pp. E302-E308 ◽  
Author(s):  
P. Ritz ◽  
T. J. Cole ◽  
P. S. Davies ◽  
G. R. Goldberg ◽  
W. A. Coward
Keyword(s):  
Energy Expenditure ◽  
Dose Level ◽  
Meteoric Water ◽  
Natural Abundance ◽  
Doubly Labeled Water ◽  
Water Line ◽  
Optimal Ratio ◽  
Meteoric Water Line ◽  
Within Subjects

Appropriate corrections for 2H and 18O natural abundance are necessary in energy expenditure measurements with the doubly labeled water (DLW) method. The contribution of natural abundance variations to errors in the method is generally ignored if an appropriate dose level is given. Calculation of the appropriate dose level assumes that 2H and 18O natural abundance values are covariant and have a fixed slope. This study has investigated the between- and within-subject natural abundance variations, the latter over periods of time similar to those used in DLW experiment. Although 2H and 18O natural abundance values are covariant between subjects, the slope of their relationship is different from that of the Meteoric Water Line. Within subjects there is no such demonstrable covariance. It is concluded that: 1) the determinants of 2H and 18O natural abundance are different within and between subjects; 2) the concept of an optimal ratio of doses is not valid, and a safer strategy is probably to use a ratio > 10; 3) natural abundance variations may contribute significantly to the magnitude of error in the DLW measurements of energy expenditure.

Total energy expenditure in burned children using the doubly labeled water technique

1990 ◽  
Vol 259 (4) ◽  
pp. E576-E585 ◽  
Author(s):  
M. I. Goran ◽  
E. J. Peters ◽  
D. N. Herndon ◽  
R. R. Wolfe
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Resting Energy Expenditure ◽  
Total Energy Expenditure ◽  
High Rate ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Water Turnover ◽  
Activity Factor ◽  
Basal Energy Expenditure

Total energy expenditure (TEE) was measured in 15 burned children with the doubly labeled water technique. Application of the technique in burned children required evaluation of potential errors resulting from nutritional intake altering background enrichments during studies and from the high rate of water turnover relative to CO2 production. Five studies were discarded because of these potential problems. TEE was 1.33 +/- 0.27 times predicted basal energy expenditure (BEE), and in studies where resting energy expenditure (REE) was simultaneously measured, TEE was 1.18 +/- 0.17 times REE, which in turn was 1.16 +/- 0.10 times predicted BEE. TEE was significantly correlated with measured REE (r2 = 0.92) but not with predicted BEE. These studies substantiate the advantage of measuring REE to predict TEE in severely burned patients as opposed to relying on standardized equations. Therefore we recommend that optimal nutritional support will be achieved in convalescent burned children by multiplying REE by an activity factor of 1.2.

Effect of weaning on accuracy of doubly labeled water method in infants

1988 ◽  
Vol 254 (4) ◽  
pp. R622-R627 ◽  
Author(s):  
S. B. Roberts ◽  
W. A. Coward ◽  
G. Ewing ◽  
J. Savage ◽  
T. J. Cole ◽  
...  
Keyword(s):  
Breast Milk ◽  
Energy Expenditure ◽  
Loading Dose ◽  
Doubly Labeled Water ◽  
Water Influence ◽  
Naturally Occurring ◽  
Accuracy And Precision ◽  
Doubly Labeled Water Method ◽  
The Relationship

Variations in background 2H and 18O abundances in body water influence the accuracy and precision of the 2H218O method for determination of energy expenditure. To investigate the effect of weaning during infancy on background 2H and 18O abundances, urine samples from 44 breast- or formula-fed infants aged 5-16 wk were analyzed. 2H and 18O abundances were significantly higher (P less than 0.001) in breast- than in formula-fed infants. The relationship between 2H and 18O abundances was linear and independent of diet [slope, 4.16 +/- 0.43 (SE)]. By use of this information, the effect of weaning on the accuracy of the 2H218O method was evaluated, taking into account the effect of 2H-18O abundances in the isotope loading dose. In infants weaned completely from breast milk to formula during the measurement, energy expenditure can be overestimated by 18.0%, even if 2H-18O abundances in the isotope dose equal the ratio of naturally occurring background changes. However, this error can be reduced to less than 3.0% by manipulating the study duration and isotope dose. During gradual weaning, the overestimation of energy expenditure is only 0.3-2.0%.

Field use of D2 18O to measure energy expenditure of soldiers at different energy intakes

1989 ◽  
Vol 67 (5) ◽  
pp. 1922-1929 ◽  
Author(s):  
J. P. DeLany ◽  
D. A. Schoeller ◽  
R. W. Hoyt ◽  
E. W. Askew ◽  
M. A. Sharp
Keyword(s):  
Energy Expenditure ◽  
Coefficient Of Variation ◽  
Fat Free Mass ◽  
Field Conditions ◽  
Base Line ◽  
Doubly Labeled Water ◽  
Special Operations ◽  
Energy Expenditures ◽  
Before And After ◽  
Ad Libitum

To test the application of doubly labeled water under adverse field conditions, energy expenditures of 16 special operations soldiers were measured during a 28-day field training exercise. Subjects were matched by fat-free mass and divided equally between an ad libitum ready-to-eat meal diet and a 2,000 kcal/day lightweight ration. Subjects recorded intakes daily, and body composition was measured before and after the exercise. At the beginning of the study, subjects moved to a new northerly location and, therefore, a new water supply. To compensate for this, a group of soldiers who did not receive heavy water was followed to measure isotopic base-line changes. Energy expenditure by doubly labeled water was in agreement with intake/balance (3,400 +/- 260 vs. 3,230 +/- 520 kcal/day). The overall coefficient of variation of energy expenditure by doubly labeled water was half that of intake/balance (7.6 vs. 16.1%). The coefficient of variation of repeat measures with doubly labeled water was 7.3%. Energy expenditure of the ready-to-eat meal group, 3,540 +/- 180 kcal/day, was not significantly different from the lightweight ration group, 3,330 +/- 301 kcal/day. Doubly labeled water was valid under field conditions.

Measurement of energy expenditure in humans by doubly labeled water method

1982 ◽  
Vol 53 (4) ◽  
pp. 955-959 ◽  
Author(s):  
D. A. Schoeller ◽  
E. van Santen
Keyword(s):  
Energy Expenditure ◽  
Coefficient Of Variation ◽  
Body Water ◽  
Ratio Analysis ◽  
Doubly Labeled Water ◽  
Water Output ◽  
Isotope Ratio Analysis ◽  
Doubly Labeled Water Method ◽  
Total Body

The utility of the doubly labeled water method for the determination of energy expenditure and water output was investigated in humans. Approximately 10 g of 18O and 0.5 g of 2H as water was orally administered to four healthy adults. Total body water was determined from the isotope dilution, and the ensuing 18O and 2H disappearance rates from body water were determined for 13 days by mass spectrometric isotope ratio analysis of the urinary water. During this period, subjects were maintained on a measured diet to determine energy and water intake. The energy expenditure from the doubly labeled water method differed from dietary intake plus change in body composition by an average of 2%, with a coefficient of variation of 6%. The water outputs determined by the two methods differed by 1%, with a coefficient of variation of 7%. The doubly labeled water method is noninvasive, and the subjects could maintain their daily activities without restriction.

Daily Energy Expenditure of Savannah Sparrows: Comparison of Time-Energy Budget and Doubly-Labeled Water Estimates

The Auk ◽  
1984 ◽  
Vol 101 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Joseph B. Williams ◽  
Kenneth A. Nagy
Keyword(s):  
Energy Expenditure ◽  
Energy Budget ◽  
Mean Value ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Daily Energy Expenditure ◽  
Passerculus Sandwichensis ◽  
Daily Energy ◽  
The Mean ◽  
Savannah Sparrows

Abstract Using the doubly-labeled water (DLW) technique, we measured the CO2 production of six free-living male Savannah Sparrows (Passerculus sandwichensis, mean mass 19.1 g) and found a mean (±1 SD) of 7.28 ± 1.36 ml ${\rm CO}_{2}/{\rm h}$. Assuming an R.Q. of 0.85 and 24 J/ml CO2, we calculated a mean $\dot{H}_{TD}$ (daily energy expenditure) of 80.3 ± 16.6 kJ/day. Simultaneously to our DLW measurements, we constructed time budgets for the sparrows during their normal activities with the intent of exploring the agreement between predictions of a number of time-energy budget (TEB) models from the literature and DLW measurements. Our results reveal that several models yield reasonable results, the mean value for the models of Kendeigh et al. (1977), Walsberg (1977), and Mugaas and King (1981) differing from DLW measurements by only +4.7, -5.6%, and +5.7%, respectively. Comparisons of $\dot{H}_{TD}$ as predicted by these TEB models between species and within species between nesting phases might be made with some confidence. However, the variation in TEB estimates is not related to variation in DLW measurements within our study. This precludes statements about differences between individuals.

Revision of calculations in the doubly labeled water method for measurement of energy expenditure in humans

1994 ◽  
Vol 267 (6) ◽  
pp. E805-E807 ◽  
Author(s):  
W. A. Coward ◽  
P. Ritz ◽  
T. J. Cole
Keyword(s):  
Experimental Study ◽  
Energy Expenditure ◽  
Recent Work ◽  
Isotope Dilution ◽  
Rate Constants ◽  
Isotope Fractionation ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Doubly Labeled Water Method ◽  
The Difference

In the doubly labeled water (DLW) method for the measurement of energy expenditure in humans, the basis of the calculation for CO2 production is the difference between the products of the rate constants for the disappearance of 18O and 2H from body water (KO, and KD, respectively) and the matching isotope dilution spaces (NO and ND, respectively). Thus, omitting corrections for isotope fractionation, CO2 production = 0.5 (KONO-KDND). In this calculation, it is also customary to normalize observed NO and ND values to a fixed value for ND/NO. The increasing use of the method has resulted in the generation of substantially more information on the normal value for ND/NO than existed at the time the method was first developed, and recent work has suggested that revisions of the originally used value of 1.03 may now be deemed appropriate. Values of 1.034 or 1.0427 have recently been suggested, but when applied in energy expenditure studies these estimates would lead to significantly different expenditure measurements. It can, however, be shown from published work and direct experimental study that ND/NO values are method dependent, and for these reasons the lower revised value of 1.034 appears to be more acceptable. The possibility that particular populations may ultimately be shown to be different from 1.034 should not, however, be dismissed entirely, and for this reason we suggest that information derived in individual experiments could be used in a Bayesian fashion to generate new ND/NO estimates. The appropriate techniques are described.

Energy expenditure by doubly labeled water: validation in humans and proposed calculation

1986 ◽  
Vol 250 (5) ◽  
pp. R823-R830 ◽  
Author(s):  
D. A. Schoeller ◽  
E. Ravussin ◽  
Y. Schutz ◽  
K. J. Acheson ◽  
P. Baertschi ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Isotope Dilution ◽  
Isotope Ratio Mass Spectrometry ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Adult Males ◽  
Doubly Labeled Water Method ◽  
The Difference ◽  
Total Body ◽  
Atom Percent Excess

To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.

Revised equations for calculating CO2 production from doubly labeled water in humans

1993 ◽  
Vol 264 (6) ◽  
pp. E912-E917 ◽  
Author(s):  
J. R. Speakman ◽  
K. S. Nair ◽  
M. I. Goran
Keyword(s):  
Fixed Ratio ◽  
Interindividual Variation ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Analytical Uncertainty ◽  
Accuracy And Precision ◽  
Modified Equations ◽  
Biological Sources

The Schoeller model for calculating rate of CO2 production (rCO2) from doubly labeled water (DLW) relies on the assumption that deuterium and oxygen-18 overestimate body water by 4 and 1%, respectively. However, the deuterium-to-oxygen-18 dilution space ratio (DSR) varies considerably, and it is unknown whether this is due to analytical or biological sources. From 161 published values in adult humans, we derived a mean DSR of 1.0427 +/- 0.0218. Propagation of error suggests that analytical uncertainty accounts for 20-50% of the observed variation in the DSR, whereas reliability testing in vivo and in vitro demonstrate that 70-100% of observed interindividual variation in the DSR can be attributed to analytical uncertainty. The discrepancy between propagated error and experimental reliability suggest that it is unwise to rely on propagation of error when evaluating sources of error in DLW. The new constant of 1.0427 was used to revise existing equations for calculating rCO2 from DLW. Compared with the existing equation, the revised equation improved the accuracy (-0.38 vs. +10.3%) and the precision (9.3 vs 10.7%) of rCO2 calculations in previously published validation studies. We conclude that 1) variation in the oxygen-18-to-deuterium DSR is primarily influenced by analytical noise and warrants use of a fixed ratio, 2) existing equations should be revised because the original DSR may have been underestimated, and 3) the modified equations improve the accuracy and precision of rCO2 calculated from DLW.

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