COPD: Effectiveness of Therapies (2007-2008)


Akrabawi SS, Mobarhan S, Stoltz RR, Ferguson PW.  Gastric emptying, pulmonary function, gas exchange, and respiratory quotient after feeding a moderate versus high fat enteral formula meal in chronic obstructive pulmonary disease patients.  Nutrition 1996;12(4):260-5.

PubMed ID: 8862532
Study Design:
Randomized Crossover Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To compare the effects of a moderate versus a high fat meal on gastric emptying time, pulmonary function, respiratory quotient and gas exchange parameters in patients with COPD.
Inclusion Criteria:
  • Male or female COPD patients of any race, between ages 40 - 75 years
  • FEV1 <60% predicted
  • Patients were not excluded if they used bronchodilators or steroids or if they were on maintenance cardiovascular medications
  • Patients were screened prior to study for height, weight, mid-arm circumferences, blood chemistries, CBC, platelet counts, prothrombin time, and pulmonary function tests
Exclusion Criteria:
  • Severe diabetes
  • History of significant renal or hepatic dysfunction
  • Unable to tolerate study formulas
Description of Study Protocol:


Recruitment methods not described.

Design:  Randomized Crossover Trial

Blinding used (if applicable):  Double blind

Intervention (if applicable)

  • 55 ml (530 kcal) with either 41% fat calories or 55% fat calories

Statistical Analysis

The inclusion of 36 study participants would permit the detection of a difference of 35 minutes in gastric empytying time and 0.05 difference in RQ between groups at 80% power.  All statistical tests were two-sided.  ANOVA was used for gastric emptying and pulmonary function data.  The statistical model took into account the crossover design and included terms for estimated effects of sequence, patients with sequence, formulation and period.

Data Collection Summary:

Timing of Measurements

After overnight fast, patients reported to outpatient clinic.  After 30-minute rest, subjects consumed the formula within 30 minutes.  Measurements made at 0, 30, 60, 90 and 150 minutes postprandial.  Patients returned after 4 day washout period.

Dependent Variables

  • Gastric emptying half time measured using the 99M-Tc-radionuclide technique
  • CO2 production, O2 consumption, RQ, FEV1, FVC, tidal volume and other pulmonary functions were measured using the canopy mode of the Deltatrac Metabolic Monitor and the Renaissance spirometry system

Independent Variables

  • 355 ml (530 kcal) with either 41% fat calories or 55% fat calories

Control Variables

  • Effects of sequence, patients with sequence, formulation and period
Description of Actual Data Sample:

Initial N: 36 COPD outpatients, gender not specified

Attrition (final N):  36

Age:  mean age 60.47 +/- 7.22 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  crossover study

Location:  Indiana


Summary of Results:

Other Findings

There was a significantly longer gastic emptying half-time of the high fat meal compared to the moderate fat meal (134.1 +/- 24 vs 108.6 +/- 24 minutes, P = 0.0001).

At all postprandial times tested, there were no significant differences observed in tidal volume, FEV1, forced vital capacity or respiratory rate between formulas.

At 30 and 90 minutes, but not 150 minutes postprandial, the carbon dioxide production and oxygen consumption for patients fed the moderate fat formula were significantly higher (p = 0.05) than for those fed the high fat formula, no differences were observed for the other pulmonary functions.

Although RQ increased significantly after both meals (p = 0.01), no differences between formulas were observed at all postprandial times tested. 

Compared to the high fat meal, the moderate fat meal significantly enhanced gastric emptying.

The earlier rise in carbon dioxide production and oxygen consumption after the moderate fat meal did not impact pulmonary function and reflected the earlier utilization of the moderate fat meal.

The fact that RQ was not different between the 2 meals at all postprandial times tested suggest that the higher rise in VCO2 and VO2 after the moderate fat meal was most likely due to earlier gastric emptying of the moderate fat meal rather than the difference of the fat-to-carbohydrate ratio between the 2 meals.

Author Conclusion:
In conclusion, our study indicates that in COPD patients, feeding a meal with high fat content resulted in a significant delay in gastric emptying compared to feeding a meal with a moderate fat content.  The higher carbon dioxide production and oxygen consumption noted at 30 and 90 minutes after feeding the moderate fat meal was likely due to earlier gastric emptying and earlier absorption and utilization of its calories.  There was no difference noted in pulmonary function or RQ between the 2 meals at all postprandial times tested.  Long-term studies are needed to see whether these findings can be demonstrated to impact the long-term management and clinical outcome of COPD patients.
Funding Source:
Reviewer Comments:
Recruitment methods and subjects not well described.  150 minutes may not be sufficient time to capture all data, especially with delayed gastric emptying.  Study supported by Mead Johnson.
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? ???
  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? No
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
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) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  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")? 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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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.) Yes
  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? ???
  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? ???
  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? 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? ???
  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? ???
  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? 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? Yes
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? No
10. Is bias due to study's funding or sponsorship unlikely? No
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? No