CI: Best Method to Estimate RMR (2010)

Savard JF. Faisy C. Lerolle N. Guerot E. Diehl JL. Fagon JY. Validation of a predictive method for an accurate assessment of resting energy expenditure in medical mechanically ventilated patients. Critical Care Medicine. 2008; 36(4): 1,175-1,183.
PubMed ID: 18379244
Study Design:
Diagnostic, Validity or Reliability Study
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

Compare Harris-Benedict, Swinamer and Ireton-Jones equations with Faisy equation and indirect calorimetry.

Inclusion Criteria:
  • Age 18 years or more
  • Intubated and mechanically ventilated for more than 24 hours
  • Informed consent by patient or family member.
Exclusion Criteria:
  • No exclusions based on prior length of stay in ICU
  • Potential sources of errors for indirect calorimetry:
    • Hemodynamic or respiratory instability
    • Variations in carbon dioxide pool
    • Intravenous carbohydrate load less than 15kcal per kg per day
    • Air leaks in respiratory system
    • Accumulation of intermediate metabolites
    • FIO2 more than 80%.
Description of Study Protocol:


Prospective study of sensitivity and specificity of a diagnostic test. 

Statistical Analysis

  • Descriptive statistics
  • Regression analysis and correlation coefficients.
Data Collection Summary:

Timing of Measurements

REE was measured by indirect calorimetry one time over 18 consecutive five-minute periods. All patients were fed, but EN was held four hours prior to indirect calorimetry.

Dependent Variable

The calculated difference between each predicted energy expenditure equation and the actual measured energy expenditure.

Independent Variables: 

REE equations used in the study included:

  • Harris Benedict (basic; no activity factor added):
    • Men: 66.47 + 13.75(wt in kg) + 5(ht in cm) - 6.8(age in years)
    • Women: 655.1 + 9.56 (wt in kg) + 1.85 (ht in cm) - 4.68 (age in years)
  • Harris Benedict (corrected for hypermetabolism):
  • Faisy8 (wt in kg) + 14 (ht in cm) + 32 (minute ventilation L per minute) + 94 (body temperature oC) - 4,834
  • Swinamer: 945 (body surface area  in m2) -  6.4 (age in years) + 108 (body temp in oC) + 24.2 (respiratory rate in cycles per minute) + 817 (minute ventilation L per minute) - 4,349
  • Fusco: - 983 - 4[age iBrandi: HBE(0.96) + HR(7) = Ve(48) - 702 years) + 32 (ht inches) + 11 (wt in kg)]
  • Ireton-Jones: 1925 - 10 (age in years) + 5 (body wt kg) + 281 (gender male = 1, female = 0).

Control Variables

Continuous enteral feeding stopped four hours prior to indirect calorimetry.

Description of Actual Data Sample:
  • Initial N: (45 with 58% males)
  • Attrition (final N): 45
  • Age: 62±14 years.

Other Relevant Demographics

  • Mean SAPS II score on day of monitoring 39±13
  • 22% of patients had documented infection.


France and Quebec, Canada.


Summary of Results:

With no stress or injury factor, R2=0.41 (P=0.001)  with Bland-Altman analysis showing mean bias of -279±346. When stress correction factors were used, correlation was less R2=0.18 (Bland-Altman analysis -357±750kcal per day).

Method Mean REE±SD

kcal per kg per Day

(mean ±SD)


R2 (P-value)

Bland-Altman Bias kcal per Day (95% CI)

Indirect calorimetry 1,779±450kcal 25±6 - -
Faisy equation 1,971±372kcal 28±5 0.62 (0.001) -192±277 (-355 to -29)
Harris-Benedict equation 1,500±292kcal 21±3 0.41 (0.001)

 279±346 (177 to 381)

Corrected Harris-Benedict 2,136±820kcal 29±9 0.18 (0.001)

357±750 (-578 to -137)

Swinamer equation 2,955±561kcal 42±11 0.41 (0.001)

-1,172±447 (-2,048 to -296)

Fusco equation 1,703±299kcal 24±3 0.38 (0.001)

76±359 (-628 to 780)

Ireton-Jones equation 2,118±258kcal 30±6 0.39 (0.001)

-339±356 (-1,037 to 359)


Author Conclusion:

The Faisy equation provided precise and unbiased REE for estimating REE in mechanically ventilated critically ill patients.

Funding Source:
Reviewer Comments:
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? N/A
  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? Yes
  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.) Yes
  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")? Yes
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? 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? Yes
5. Was blinding used to prevent introduction of bias? Yes
  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? Yes
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? 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? Yes
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? 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? Yes
  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? 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? 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