EE: Respiratory Quotient (RQ) (2013)

Citation:

Ireton-Jones CS, Turner WW. The use of respiratory quotient to determine the efficacy of nutrition support regimes. J Am Diet Assoc. 1987 (2): 180-183.

PubMed ID: 3102586
 
Study Design:
Retrospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To examine the RQs of patients administered IV and enteral nutrition containing varying amounts of carbohydrate and fat to determine the effect of the various formulas, as assessed by the resulting RQ.

Definitions/Abbreviations

  • GAPPN: glucose and amino acid parenteral nutrition
  • GFAAPN: glucose, fat, and amino acid parenteral nutrition
  • GFPEN: carbohydrate, fat, and protein enteral nutrition
  • CI/BSA: caloric intake adjusted for body surface area
  • CI/MEE: caloric intake adjusted for measured energy expenditure
Inclusion Criteria:
  • Understand and give written consent
  • There is no specific inclusion criteria given in the article
Exclusion Criteria:
  1. Refusal to consent
Description of Study Protocol:

112 RQs and MEEs were determined on 102 patients over 28-month period. Measurements were made on both spontaneously breathing and ventilation-dependent patients using a portable IC

ANTHROPOMETRIC

  • Not specified

CLINICAL

  • Not specified

Resting energy expenditure

  • IC type: Portable indirect calorimetry
  • Equipment of Calibration: not specified
  • Coefficient of variation using std gases: not specified
  • Rest before measure (state length of time rested if available): not specified
  • Measurement length:
  • Steady state:
  • Fasting length: not specified
  • Exercise restrictions XX hr prior to test? Don’t know
  • Room temp: data not available
  • No. of measures within the measurement period: not specified
  • Were some measures eliminated?
  • Were a set of measurements averaged? Not specified
  • IF avg, identify length of each measure & no. of measurements?
  • Coefficient of variation in subjects measures? Not known
  • Training of measurer? Not specified
  • Subject training of measuring process? Not specified

DIETARY

  • Caloric intakes were prescribed on the basis of estimates of energy expenditure, calculated from the Harris-Benedict equation and multiplied by a factor of 1.5
  • Actual caloric intake were recorded for the 24 h prior to the days on which RQ and MEEs were measured.
  • Intervening factor:
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. Predicted RMR using: HB? WHO/FAO?
  3. Independent variables of weight, height, age, BMI,and fat-free mass, fat mass

Blinding used: no

Description of Actual Data Sample:
  • N=102 (64 men, 38 women)
  • Statistical tests:
  • Kruskal-Wallis
  • Mann-Whitney U
  • Chi-square
Summary of Results:

ANTHROPOMETRIC: not assessed  

Caloric distribution (* significant)

 GAPPN

GFAAPN CFPEN

CHO

83.1±0.4* 44.6±5.4 42.8±4.4

Fat 

0 40.4±3.1 42.7±3.7

Pro

16.9±0.4 15.2±2.3 14.5±1.2

RQ and other measurements GAPPN GFAAPN CFPEN

RQ

1.02±0.1* 0.8±0.13 0.86±0.07

CI

2275±689* 2173±1001 1940±963

CI/BSA

1393±429* 1288±601 1085±503

MEE

1486±348* 2031±639 1684±487

CI/MEE

1.58±0.54* 1.09±0.38 1.20±0.56

CHO intake (mg/kg/min)

6.9±2.4* 3.3±2.0 2.6±1.1

RQ

Over a 28-month period, 102 consecutively hospitalized patient (64 men; 38 women) were studied and 112 RQs were measured on spontaneously breathing and ventilator-dependent patients. With the exception of one patient, 53 mechanically ventilated or spontaneously breathing patients who received glucose, fat and amino acid parenteral nutrition or oral/nasoenteral carbohydrate fat, and protein diets (with a group mean caloric intake to measured energy expenditure of 1.09±0.38 and 1.20±0.56, respectively) had RQs <1.

The mean RQ of the glucose and amino acid parenteral nutrition was significantly higher than the glucose, fat, and amino acid parenteral nutrition and the oral or nasoenteral carbohydrate, fat, protein diets (RQ 1.02±0.10, 0.8±0.13, and 0.86±0.07, respectively). RQs were greater than 1.0 in 35 (64%) of the measurements on glucose amino acid parenteral patients, none on the glucose, fat, amino acids parenteral nutrition patients, and 1 (3%) measurement on a carbohydrate fat, and protein oral or nasoenteral diets. Twenty-five patients in the glucose, amino acid parenteral nutrition group had infusion rates in excess of 7 mg/kg/minute and 19 (76%) had RQs >1.0. Only one person in the glucose, fat, amino acid parenteral group had a glucose infusion rate in excess of 7 mg/kg/minute. Among the patients with RQs >1.0, the mean glucose infusion rate was 7.5 mg/kg/minute. Among the patients with RQs less than or equal to 1.0, the mean glucose infusion rate was 6.0 mg/kg/minute (P=0.21).

The mean RQ of the GAPPN patients was significantly higher than those of both the GFAAPN and the CFPEN patients.

The mean total caloric intake was significantly higher in the CAAPN than in the CFPEN patients (P=0.012). There was a similar finding when total caloric intakes were adjusted for body surface area (p=0.002).

25 pts in the GAAPN group had glucose infusion rates in excess of 7 mg/kg/min. Of those pts, 19 (76%) had RQs greater than 1.0.

The mean MEE of the GAAPN was significantly lower than that of the other two groups.

Author Conclusion:

“RQ greater than 1.0 were noted more frequently in pts who received GAAPN. Pts who received GFAAPN or CFPEN had, with one exception, RQs less than 1.0. Glucose intake in CAAPN pts were as much as twice those of the GFAAPN or CFPEN pts.”

“In pts with RQ >1.0, the mean rate of glucose infusion was 7.5 mg/kg/min. Our finding of RQs >1.0 in a large number of the CAAPN pts suggests that excess glucose begin administered to those pts was synthesized into fat.”

“This study suggests that fat added to nutritional regimen containing CHO and Pro optimized substrate utilization.”

“The route of nutrient intake did not influence energy nutrition untilzation as determined by RQ measurements. Patients who received fat in addition to CHO and Pro, whether administered parenterally or enterally, had similar RQ.”

Funding Source:
Industry:
Coram Healthcare, Preferred Nutrition Therapists
Other:
Reviewer Comments:

Strengths

  • Appropriate statistical tests.
  • Large sample size
  • Conclusions consistent with data.

Generalizability/Weaknesses

  • Anthropometric data was not available. Comparability of anthropometric variables between groups was not assessed.
  • Patients were not randomized into treatment groups, may systematically biased the results.
  • Inclusion/exclusion criteria were not defined in details.
  • Generalizability difficult due to reporting data on ventilator dependent and spontaneously breathing patients; group means not defined.
  • RMR variation within each nutrient feeding type group associated with diagnoses variation between groups, kcals provided (i.e., diet-induced thermogenesis) and fat-free mass differences are confounding factors that limit interpretations.
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
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
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? 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. 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.3. 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
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  3. Were study groups comparable? No
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
  3.1. 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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.4. 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
  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. 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
  5.1. 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
  5.2. 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
  5.3. 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
  5.4. 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
  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. 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
  6.1. 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
  6.2. 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
  6.3. 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments 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
  6.7. 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
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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
  8.5. 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
  8.6. 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
  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. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  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
  10.2. Was the study free from apparent conflict of interest? N/A