CI: Best Method to Estimate RMR (2010)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine whether patients at an ICU are adequately fed.
Inclusion Criteria:
Surgical and medical mechanically ventilated patients who were at least 2 days on the ICU, with no leakage of air through tubes.  Amount and composition of nutrition had to be known.  Diuresis of at least 500 ml for nitrogen balance evaluation.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:


Patients at the surgical and medical ICU of a community hospital.


Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Energy expenditure measured by indirect calorimetry and estimated using Harris-Benedict equation.

Statistical Analysis

The differences in the administered, measured and calculated amounts of energy, carbohydrates, fats and proteins were calculated.  Pearson correlations between the administered, measured and calculated amounts of energy were calculated.  The association between determinants and a negative energy balance was estimated by logistic regression.

Data Collection Summary:

Timing of Measurements

Energy needs calculated based on clinical information obtained on the day prior to the day the indirect calorimetry measurements performed.

Dependent Variables

  • Energy expenditure measured by indirect calorimetry using a DeltaTrac II metabolic monitor over 18 hours, procedures not described
  • Urinary nitrogen loss measured over 24 hours
  • Energy needs calculated using Harris-Benedict formula and Long corrections for Activity (1.3 used for all as bedridden) and Injury factors varying from 1.0 to 1.7

Independent Variables

  • Exact amounts of macronutrients given over 24 hours by parenteral or enteral route was calculated
  • Age
  • Sex
  • Comorbidities
  • Body surface area
  • Cerebral condition
  • Respiratory condition
  • Infections
  • Body temperature
  • Medications

Control Variables


Description of Actual Data Sample:

Initial N: 39 patients, 15 female, 24 male

Attrition (final N):  39

Age:  mean 65 years (range 23 - 88)

Ethnicity:  not mentioned

Other relevant demographics: mean APACHE III score 70


Location:  The Netherlands


Summary of Results:


Calculated - Measured Energy Number of Patients %
> 1500 0 0
1000 - 1500 1 2.6
500 - 1000 5 12.8
0 - 500 22 56.4
-500 to 0 10 25.6
-1000 to -500 1 2.6

-1500 to -1000






Other Findings

In 10 patients (26%) the administered amount of energy was lower than the measured amount.

In 16 patients (41%) the protein balance was negative.

4 of the patients (10%) received more than 1500 kcal above the measured amount.

In 11 patients (28%) the calculated amount of energy was lower than the measured energy expenditure.

Coefficients of correlation between measured versus administered, calculated versus administered and measured versus calculated amounts of energy were 0.19 (p = 0.25), 0.03 (p = 0.87) and 0.57 (p = 0.0002), respectively. 

Author Conclusion:
In conclusion, our study demonstrated that a substantial part of patients at an ICU were underfed.  Although the use of the equations of Long et al could have improved the quality of feeding in those patients, a substantial part would still have been underfed.  The application of routine bedside short-term measurement of energy requirements by indirect calorimetry is an important development in this respect.
Funding Source:
Reviewer Comments:
IC protocol not described.
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? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? N/A
  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? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? ???
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? ???
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
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? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  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? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes