EE: Application of RQ (2005)


Kan MN, Chang HH, Sheu WF, Cheng CH, Lee BJ, Huang YC. Estimation of energy requirements for mechanically ventilated, critically ill patients using nutritional status. Crit Care. 2003;7(5): R108

Study Design:
Retrospective Cohort Study
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To determine the energy requirement for mechanically ventilated, critically ill patients using the nutritional status.


  1. Steady state
  2. Measured energy expenditure (MEE): a single 40-min measure taken on day 1
  3. Total energy requirement (TER): “MEE” plus 5% activity factor plus 15% day-to-day variability
  4. UF: subject’s actual average intake <90% of TEE
  5. AF: subject’s actual average intake within±10% of TEE
  6. OF: subject’s actual average intake >110% of TEE.
Inclusion Criteria:
  1. Understand and give written consent
  2. Patients that were hemodynamically stable, not comatose, and requiring at least 7 days of mechanical ventilation.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. If they received a fraction of inspired oxygen >60% at the time of IC measure
  4. Oliguric patients
Description of Study Protocol:


  • Ht measured? yes
  • Wt measured? yes
  • Fat-free mass measured? Yes; TSK and mid-arm circumference


  • Monitored heart rate? Likely
  • Body temperature? Likely
  • Medications administered? Not reported

Resting energy expenditure

  • IC type: Deltatrac II MBM-200
  • Equipment of Calibration: Yes
  • Coefficient of variation using std gases: Not specified
  • Rest before measure (state length of time rested if available): Bedridden
  • Measurement length: 40 min
  • Steady state: Not specified
  • Fasting length: were without intermittent caloric intake for at least 4 hrs prior to IC; Continuous enteral or parenteral were not stopped
  • Exercise restrictions XX hr prior to test? not applicable
  • Room temp: ICU Taichung Veterans hospital
  • No. of measures within the measurement period: 1
  • Were some measures eliminated? Not specified
  • Were a set of measurements averaged? No
  • Coefficient of variation in subjects measures? Not specified
  • Training of measurer? Yes
  • Subject training of measuring process? Not applicable


Three types: enteral nutrition, TPN, or combined enteral nutrition plus TPN. RNs and dietitians routinely recorded infusion nutrient intake.

2 nutritional indices used:

  • Maastricht Index (MI):
    MI=20.68- [0.24 X albumin (g/l)] – [19.21 X prealbumin (gram/l)] – [1.86 X lymphocytes (109/Liter)] –(0.04 X % ideal body weight).
    MI >0 were considered malnourished
  • Nutritional Risk Index (NRI)=
    [15.9 X plasma albumin (gram/deciliter) + 41.7 X (present weight/usual weight).


  • >100 indicates not malnourished
  • 97.5-100 indicates mildly malnourished
  • 83.5 to <97.5 indicates moderately malnourished.
  • <83.5 indicates severely malnourished
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. Nutrition outcomes: Fdg route, energy expenditure, Nutrient intake (kcal), CHO, (grams/d and % of total energy) , Protein (grams/d and % total energy), and Fat (grams/d and % total energy)
  3. Clinical outcomes: APAHCE II score, hospital stay length, ICU stay length, ventilator dependence length
  4. Biochemical measures: albumin, prealbumin, TLC, CHI, and N-balance
  5. Urinalysis: urine urea nitrogen (UUN), creatinine
  6. Independent variables of weight, height, age, BMI, MAC, and fat-free mass, fat mass.

Blinding used: No

Description of Actual Data Sample:
  • N=118 patients entered study;
  • 54 completed (40 men, 14 women)
  • (46% of patients entering)
  • Age range, yr: 23-89

Most common diagnoses: GI disorders, malignant neoplasm, and pneumonia.

Statistical tests

1-way ANOVA; Student t test to compare difference between day 1 and day 7 within a group; Pearson correlation coefficient; P <0.05 significant; Means ±SD.

Summary of Results:


  • UF (n=15; 14 M; 1 F)

Day 1

Age, y 61.9±14.6

Wt, kg



TSK, mm 11.6±5.8
MAC, mm 282.3±33.4

MAMC, mm

  • AF (n=20; 17 M; 3 F)

Day 1

Age, y            68.0±14.1
Wt, kg           63.1±13.0
BMI               23.8±4.2
TSK, mm         11.5±5.1
MAC, mm        271.5±38.0

MAMC, mm

  • OF (n=20; 17 M; 3 F)
Day 1 Mean±SD
Age, y            72.2±2.1
Wt, kg           52.7±7.9
BMI               21.1±4.0
TSK, mm         10.8±5.4
MAC, mm        245.9±37.9

MAMC, mm     


There were no statistically significant age, ht wt differences at admission.


  • UF (n=15; 14 M; 1 F)



RQ, 98%


MEE, kcal/d


TEE, kcal/d


TEE (kcal/kg/day)

  • AF (n=20; 17 M; 3 F)



RQ, 98%


MEE, kcal/d


TER, kcal/d


TER (kcal/kg/day)

  • OF (n=20; 17 M; 3 F)



RQ, 98%


MEE, kcal/d


TER, kcal/d


TER (kcal/kg/day)  


OF pt had a mean RQ value >1

[Analyst note: assuming normality, 98% of pt had RQ from 0.52-1.80 in the OF group].


  • UF patients were more likely to be receiving combined nutrition (n=8), while AF and OF pt were more likely to be receiving enteral and combined nutrition (n=7 each). UF pt had the highest MEE and total energy requirement.
  • UF patients received, on average, only 68.3% of energy requirements, while OF pt received up to 136.5% of their estimated total energy requirements.
  • OF pt had a higher enrgy intake attributed to CHO and fat, but not protein; No significant difference in % energy intake from CHO, protein, and fat.
  • OF pt had a significantly higher CHO intake than other 2 group when expressed per kg body wt; but no significant different in total CHO intake among 3 groups.
  • UF pt had a CHO intake >60% of total calories.
  • NO significant difference in group mean protein intake among 3 groups.
  • 5 UF pt, 6 AF pt, and 2 OF pt had a protein intake <0.8 g/kg/day. The % of calories from fat for all 3 groups <30%.


  • Mean current weight did not significantly change between Day 1 and Day 7.
  • UF pt showed a significant reduction in MAC, MAMC, and arm muscle areas when compared with day 1.
  • AF and OF pt showed slight increases (statistically insignificant) in weight, BMI and TSF.
  • Pts in all 3 gropus showed no significant changes in albumin, prealbumin, and TLC by day 7.
  • Mean % CHI was <90% with no significant changes compared to day 7.
  • All 3 groups were in negative N-balance on admission and only AF pt showed a positive N-balance on day 7.
  • All 3 group patients were malnourished when admitted using MI and there were no significant differenced among groups on day 7.
  • All 3 group patients were considered severely malnourished using NRI and only AF pt had a significantly higher NRI value at day 7 than at day 1.


  • Severity of disease (APACHEII score) was not significantly different among the 3 groups at admission and 7 days after.
  • No statistically significant differences among groups for length of ventilator dependency, ICU stay and hospital stay.
  • Length of ventilator dependency was significantly positively correlated (r=0.494, P=-0.3) on in the AF group.
  • Length of ICU stay was significantly positively (r=0.525, P=0.02) correlated with CHO intake in AF group.
Author Conclusion:

As stated by the author in body of report

Using single and multiple parameters to assess nutritional status results showed our critically ill patients were in a severely malnourished state.” [and] “Driver & LeBrun, 1980 found that nutritional support was inadequate in 3 out of 26 pt ”

“Mean RQ value in present AF and OF pt was close to or >1 [and] OF group received significantly higher CHO amouts and correlated with ICU stay length. Thus, when there is a need for increasing energy intake, the enrgy source should be carefully chosen to avoid giving excess CHO calories.”

“Patients had a mean protein intake of ~1.1 g/kg per day, obviously inadequate for critically ill population to achieve a positive N-balance . . . [However,] the severity, duration and influence of N-balance on patients’ clinical outcome still cannot be assessed from the data we collected. Pt in UF group showed decreases in MAC, MAMC, and arm muscle area at day 7, indicating pt in a catabolic state and losing LBM.

“Limitations of our study are sample size and 7-day length of observation [and] slight wt increases could be due to pt with mechanical ventilation having greater fluid retention, not breathing spontaneously.

“Providing at least 120% of RMR seemed adequate to meet caloric energy needs of hemodynamically stable, mechanically ventilated, critically ill patients.”
Funding Source:
University/Hospital: Taichung Veterans General Hospital (Tiawon)
Reviewer Comments:


“Study protocol completely described, and included nutrition parameters.”

“Used two validated nutrition risk tools”


Generalizability to critically ill patients with respiratory, GI, malignant neoplasms, infection, and trauma.” Unable to generalize for burn patients as only one patient in the underfed group was diagnosed as “burn patient”

Study biases include 54% drop-out rate and patient characteristics of drop-outs not reported.”

Limitations as per researcher: sample size unable to detect a beta-error and length of observation may not be long enough to assess some biochemical and clinical nutrition markers.

Intervening variables not discussed were medication usage (i.e., sedation, chemical paralysis), and fever which may affect IC measure technique and nutrition outcome interpretations; Also note that the UF group did NOT include any pt with infection (i.e., groups may not be comparable due to intervening variable)

Analyst note: Interesting that the “overfed” group had the lowest BMI range of 17.1-25.1] which would be interesting if they had used Harris-Benedict and stress factor if this would have occurred?]
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? 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? 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? 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? No
  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? No
  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? 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? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? No
  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? Yes
  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