Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  1. Is the REE measurement reproducible in stable COPD pt?
  2. What is the influence of physical activity on the REE measurement?
  3. Is there a difference in REE measurements using a ventilated hood or a mouthpiece?


"Steady state”

“Resting or basal energy expenditure (REE or BEE)” – The minimum rate of energy expenditure in an awake, relaxed person, lying on a bed after an overnight fast.

Inclusion Criteria:
  1. COPD pts in stable condition admitted to a pulmonary rehab center
  2. Maintenance medications were allowed
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
Description of Study Protocol:


  • Ht measured? Unknown if measured or requested
  • Wt measured? Unknown if measured or requested
  • Fat-free mass measured? No


  • Monitored heart rate? Unknown
  • Body temperature? Unknown
  • Medications administered? Mention of broncho-dialators and theophylline

Resting energy expenditure

  • IC type: computerized open circuit ventilated hood
  • Equipment of Calibration: Extensive description; Completed at the beginning and at the end of each test
  • Coefficient of variation using std gases:  Yes
  • Rest before measure (state length of time rested if available): Lying in semi-recumbent position; Taken at 8:30 – 9:30 a.m.
  • For study 1: after initiating the measurements, ±7 mins was allowed to adjust to the hood and to stabilize energy expenditure.
  • For study 2:  In 12 COPD patients, 20 minutes was allowed for rest before measure BEFORE measure started.
  • Measurement length:  Measurements of different duration were compared: 5, 10, 15, 20, 25 and 30 minutes.
  • Steady state: Investigators ensured that the subjects did not move or sleep; after initiating the measurements, time was allowed (+7 min) to adjust to the hood and to stabilize energy expenditure.
  • Fasting length: Yes, 10 hrs; 2 hr after maintenance medications
  • Exercise restrictions XX hr prior to test? As part of study question, activities of daily living were evaluated in Study 2.
  • Room temp:  Not specified
  • No. of measures within the measurement period: Was part of Study 4
  • Were some measures eliminated?
  • Were a set of measurements averaged?  No
  • IF avg, identify length of each measure & no. of measurements?
  • Coefficient of variation in subjects measures? Not specified
  • Training of measurer? Given the equipment specifications, yes.
  • Subject training of measuring process? Subjects allowed initial time to acclimatize to IC

Activities of Daily Living

One day 1, pts were allowed to dress, wash, and walk to the metabolic ward.  After lying down for 20 mins, energy expenditure was measured over a 30-min period.  On next day, the pt stayed in their beds until the investigator took them in a wheelchair to the metabolic ward.  Both measurements completed in the same position.

Intervening factors

As discussed by the researchers, “the precise influence of B2 agonists and theophylline was not measured bcause withdrawing treatment might exacerbate the condition.  [In contrast], bronchodilating treatment itself may reduce the work of breathing.

Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2, l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
  2. Inspiratory vital capacity; Forced expiratory volume in 1 second (FEV1); arterial oxygen (carbon dioxide) tension (i.e., PaO2 (kPa) and PaCO2 (kPa)
  3. Independent variables of weight, height, age
Blinding used:  No blinding used
Description of Actual Data Sample:

N=12 COPD pt in stable clinical condition admitted to a pulmonary rehabilitation center; Healthy volunteers consisted of the study groups for the difference experiments.

Summary of Results:

Statistical tests

Bland and Altman used to calculate the overall mean bias (mean difference) between the two methods, the associated limits of agreement Schols AMWJ, Schoffelen PFM, et al 1992 (1g, rest periods) ±2SD), and the extent to which the mean bias changes with an increase in the mean of two measurements.

Study 1: Variability and Accuracy of the method

Variability and Method Accuracy: Ethanol combustion tests revealed that the gain during the calibration was slight to high (2.2%) and that the deviation of measurements was 2.7% for O2, 2.1% for CO2, and 1.7% for RQ

Study 1, after 12 patients (mean age 66±6 y) were awakened and lying in a semi-recumbent position, a 7-minute acclimatization period to the hood was allowed to stabilize energy expenditure.

[Analyst note: Measurement length was not stated but due to association with Study 2, most likely 30 minutes; 1 drop-out due to claustrophobia].

Study 2: Effect of Activities of Daily Living

The same 11 patients from Study 1 were allowed to awaken, dress, wash and walk to the metabolic ward.  Once they arrived, they were asked to lie down and had a rest period for 20 minutes; then, a 30-minute RMR was taken.  On a separate day, the patients did not get out of bed and were wheeled down to the metabolic ward for a RMR measure.  No significant group mean RMR differences were established between measurements performed after awakening, being wheeled down to the measurement lab and allowing a 7-minute acclimatization period compared to a RMR measure taken after light physical activities and allowing a 20-minute rest (1406±238 kcal vs. 1431±259 kcal/d).

[Analyst note:  results section for this study reference Figure2 that reports data for 11 individuals and discussed in text as one patient being claustrophobic in Study 1.  In Figure 2, individual RMR kcal/d difference expressed relative to the mean RMR (RMR rest plus RMR activity/2) ranges from resting RMR being ~30-70 kcal greater to activity RMR (after a 20-minute rest) being 5-70 kcals greater].

Study 3: Length of measurement

N= 12 patients aged mean 66 y ± 6 yr
Gender unknown

Patients         Controls
n=12 n=14
Mean±SD Mean±SD
Age 66±6 31±8
Weight 65.7±11.0


Height                  170.0±7.


IVC, %                


FEV1, %              


PaO2 (kPa)%       


PaCO2 (kPa), %  


Measured REE did not differ significantly between measurements of 5, 10, 15, 20, 25, and 30 minutes’ duration.  (No p-value given)


Time, min Patients Control


1420±242 1510±227


1410±226 1505±224


1410±237 1514±225


1414±239 1521±229
25 1428±243 1531±229


1436±245 1535±231

In Study 3, the same group of patients and an additional 14 healthy controls (mean age 31±8 y), group mean RMR not differ between a 5-, 10-, 15-, 20-, 25-, and 30 minute measurement duration.

[Analyst note:  there is no rest time described for Study 3; therefore healthy adults either slept overnight in facility and were wheeled down and given a 7-minute acclimatization period after awakening or allowed to complete daily living activities and given a 20-minute rest period]. 

Group mean RMR in healthy adults ranged from the lowest at 1505±224 kcal/day after a 10-minute measurement interval (plus rest time) to 1535±231 kcal/day at a 30 minute measurement interval (plus rest time).

Group mean RMR in patients ranged from the lowest at 140±267 kcal/day after a 10-minute measurement interval (plus rest time) to 1436±245 kcal/day at a 30 minute measurement interval (plus rest time).

Study 4:Reproducibility of the method

N= 12 patients aged mean 66 y ± 6 yr
Gender unknown

Age 65±9
Weight 64.7±14.3
Height 168.0±7.8
IVC, % 70±20

FEV1, %

PaO2 (kPa), %


PaCO2 (kPa), % 5.8±0.9

Average REE in the 12 weight-stable patients after 2 months was not significantly different from the baseline value at admission to the center (198±138 kcal/day)

Study 5:Ventilated hood or Mouthpiece

N= 12 patients aged mean 66 y ± 6 yr
Gender unknown

Patients Controls
n=12 n=6
Mean±SD Mean±SD


63±7                31±16


61.7±8.8          73.0±10.4


170.0±7.0        177.3±8.2

IVC, %

FEV1, % 29±10
PaO2 (kPa), % 8.2±1.5

PaCO2 (kPa), %


The difference between measurements with mouthpiece and ventilated hood was larger in patients than in control subjects, but no systematic difference could be established between both devices in either group. The difference between measured REE (using only O2) or VO2 and VCO2 measurements amounted to 16 kcal/day, or -1.9% (Range, -3% to 0.3%).

Author Conclusion:

As stated by the author in body of report:

  • The ethanol combustion tests revealed that when properly maintained, calibrated, and interfaced to the patient, the device is very accurate. ”
  • “A considerable number of patients were dyspneic at rest or suffered from severe exercise impairment. . . in agreement with finding in patients not suffering from COPD, we found that limited physical activity had no measurable effect on REE when a short rest was taken before the assessment.”
  • “Based on the experiments and to obtain an optimum between sample frequency and acceptability of the measurements, we changed the duration of our standard REE experiments from 30 mins to 15 mins.  Reproducibility of two measurements with the ventilated hood performed under the same standard conditions with an interval of 2 months was excellent and comparable with findings in healthy subjects.   .”
  • “Although in some patients measurements with a mouthpiece and a ventilated hood indeed varied substantially, no systematic difference was established in patients or control subjects.
  • “The following implications for the clinical measurement of REE can be drawn from these results:  REE measurements using a ventilated hood are highly reproducible, suggesting that one measurement will suffice to characterize resting metabolic rate at a certain time point in patients with stable COPD.. . . REE in patients with severe COPD can be measured on an outpatient basis providing a rest is taken before the measurement.”
Funding Source:
University/Hospital: University of Limbourg
Reviewer Comments:
  • Comprehensive, and detailed description of the indirect calorimeter used, with attention to gas pressure and flow, humidity, and calibration.”
  • “Use of the Bland-Altman technique to establish limits of agreement between 2 measurements 2 months apart and in comparing differences between measurement type.”
  • Did a nice job describing the medication intervening possibilities of increasing and/or decreasing REE.”


  • Generalizability to pulmonary rehab settings and due to small sample size, unable to apply to general outpatient clinic settings.”
  • Very small convenience patient samples”; Not many specifics about inclusion/exclusion criteria
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? No
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
2. Was the selection of study subjects/patients free from bias? No
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? No
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? No
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A