CI: Enteral Nutrition vs. Parenteral Nutrition (2012)

Hadfield RJ, et al. Effects of enteral and parenteral nutrition on gut mucosal permeability in the critically ill. Am J Respir Crit Care Med. 1995;152:1545-1548. PubMed ID: 7582291
Study Design:
Randomized Controlled Trial
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Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. Directly measure gastrointestinal tract (GIT) permeability in normal individuals and the critically ill.
  2. Assess effects of EN and TPN on this parameter over a period in randomized trial.
Inclusion Criteria:
 ICU patients (>18 years old) requiring nutrition support for greater than 3 days.
Exclusion Criteria:
< 72 hours in ICU, history of malabsorption, bowel surgery, or renal failure
Description of Study Protocol:

GIT mucosal absorption and permeability were measured in the subjects by administering four saccharides; 3-O-methyl-G-glucose (3OMG), D-xylose, L-rhamnose, and lactulose. All urine passed in 5 hours was collected and analyzed.   The analyst was blinded to which type of nutritional support patients received.  Baseline measurements of GIT mucosal absorption and permeability were performed and patients were randomized to one of two study groups; Enteral nutrition (EN) or total parenteral nutrition (TPN)

Patients nutritional needs were assessed by Harris Benedict Equation.  Patients in EN group received Alitraq according to a formal EN protocol.  Patients in TPN group received a standard regimen.  On each subsequent third day GIT absorption and permeability were measured again.

10 normal volunteers had GIT mucosal absorption and permeability measured following the same 4 saccharide administration

Data Collection Summary:
Measured saccharides recovered in the urine.
Description of Actual Data Sample:

24 pts, 17 male, aged 54 – 79 years old. All patients were intubated. 13 patients were randomized to the EN group – all tolerated enteral nutrition. There were no treatment failures. 11 patients were randomized to the TPN group. No significant differences were found between the groups APACHE II scores or ages.

  • 2 EEN pts died
  • 6 TPN pts died
Summary of Results:

Baseline recovery of D-xylose and 3OMG in both treatment groups were significantly lower than for the controls (p <0.05).

Baseline lactulose (L)/rhamnose (R) increased in both study groups compared with controls.  There were no significant differences between the two patient groups for the baseline measurements.

2 EN pts died and 6 TPN pts died – however the difference in mortality rates between the two groups was not significant (p<0.08).

D-xylose absorption became higher in both study groups however this was only significant in EN patients.   In the EN group, the L/R ration displayed significant fall towards control values.  The TPN group had no significant change in L/R ratio throughout the study. 

Author Conclusion:

In the critically ill population GIT dysfunction is seen in terms of reduced absorption and increased permeability.

The authors noted  changes in the L/R permeability index is explained by mucosal integrity only. They concluded that “the results indicated early institution of EN results in a progressive restoration of internal mucosal integrity, whereas the use of TPN is associated with a continued increase in GI tract. permeability.”

Route of nutrition support is important in preventing bacterial over-growth and translocation of bacteria in limiting the risk of sepsis but it’s only one key factor among others.

They also concluded that there was a trend toward increased mortality in TPN patients compared with the EN group even though this was not significant.

Funding Source:
Abbott Laboratories
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:

Sample size was small. Authors blinded analysts studying urine collections and measuring saccharides.

The study showed decrease in GIT permeability and increase in absorption in enterally fed patient population demonstrating strong evidence for using the GI tract in critically ill patients when appropriate.

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? 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.) 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? 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? Yes
  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? No
  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