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Systematic review of early enteral feeding in acutely ill patients.

Citation/s: Marik PE, Zaloga GP. Early enteral nutrition in acutely ill patients: A systematic review. Critical Care Medicine 2001 Vol. 29 No.12. 2264-2270
 

Lead author's name and fax: Paul E Marik

Three-part Clinical Question: Does early enteral feeding improve infectious and non-infectious morbidity, length of stay and mortality in critically ill and seriously injured patients?
 

Search Terms: PubMed Search: early enteral nutrition, critically ill, intensive care

The Review:
Data Sources: Medline, Citation Index, own files, contact with expert informants.
 

Study Selection: 27 RCTs comparing early with delayed enteral nutrition in adult post-operative, trauma, head-injured, burn or medical ICU patients. 12 were excluded, 15 included; none of these included medical ICU patients. Exclusions were studies including children, those using TPN in either arm or those in which enteral feeding was delayed for more than 36 hours.
 

Data Extraction: 15 studies containing 753 patients were analyzed with descriptive and outcome data being extracted independently by 2 reviewers. Outcome measures infections, non-infectious complications, length of hospital stay and mortality. Meta-analysis performed with random effects model.
 

The studies were multiple independent reviews of individual reports. They were tested for heterogeneity. Early feeding was defined as feeding occurring within 36 hours of surgery or admission to hospital. 

The Evidence:

Comments:
1.  Do the methods allow accurate testing of the hypothesis? There was significant heterogeneity amongst the trials due to difficulty in blinding, small trial size, differences in populations, study design and in types of feed used. Heterogeneity only just reached significance for infectious complications but was highly significant for LOS, indicating that many other factors may determine LOS. Of the trials looking at post-surgical patients, 5/7 dealt with patients after elective gastrointestinal or liver transplant surgery who may not be fulfill our criteria for critical illness or require ICU admission. No definition of “acutely ill” is given by the authors. The authors admit that in the presence of significant heterogeneity between the trials, the meta-analysis should be interpreted with some caution. There may be bias as positive studies are more likely to be published than negative ones.

2.  Do the statistical tests correctly test the results to allow differentiation of statistically significant results? The statistical tests were appropriate. 

3.  Are conclusions valid in light of the results?   In terms of validity of the conclusions, the authors point out that the results are supported by many small studies carried out over the last two decades and the physiological rationale behind early feeding is supported by animal studies looking at intestinal and hormonal changes during starvation.

4. Did results get omitted, and why?  Twelve RCTs were not included in the final analysis for various reasons: These included paediatric patients, enteral nutrition was delayed beyond 36 hours or the administration of combined enteral and parenteral nutrition. 

5.  Did they suggest areas of further research?  They suggest that a large double-blind RCT would provide more definitive evaluation of the benefits of early enteral feeding.

6.  Did they make any recommendations based on the results and were they appropriate? The study supports the use of early enteral feeding in ‘critically ill’ (mainly high dependency) surgical and intensive care trauma patients, but does not give data on medical patients. It does not address the issue of early enteral feeding in patients after emergency abdominal surgery- only one of the studies looked at these patients and it is not a strong study methodologically; it also includes a population that differs to the UK population.  

7.  Is the study relevant to my clinical practice?  Many of the post-surgical patients in the studies were not ones we would consider critically ill and would not enter ICU in the UK.  Other trials involved burns, trauma and head injury patients.  We do treat these categories of patients and therefore the study is relevant to these categories of patient. Most of the trials involved using jejunal or small bowel tubes rather than naso-gastric tubes to deliver enteral feed which is not yet routine practice in Scottish hospitals.

8.  What level of evidence does this study represent? The level of evidence is 1^-, as the meta-analysis was of a small number of heterogeneous RCTs. 

9.  What grade of recommendation can be made on this study alone?  N/A.

10.  What grade of recommendation can I make when this study is considered along with the other available evidence?  The grade of recommendation which can be made in conjunction with looking at other evidence is B as the other available evidence consists of small heterogeneous trials and one meta-analysis (Lewis- see CAT). 

11. Should I change my practice because of these results?   We should bear in mind that although there is not a large RCT supporting the practice of early enteral feeding, what evidence there is suggests that it is beneficial in certain identified groups and therefore we should attempt to start early feeding in these groups.  In trauma, burns and head injured patients we already do this but in surgical high dependency patients intensivists do not always have control of when feeding is commenced- this may be determined by the surgical team.

12.  Should I audit my current practice because of these results?  If there is a doubt that early feeding is being practiced, it is worth auditing the timing of feeding so that the maximum benefit may be obtained.

Appraised by: Marcia McDougall; 28^th March 2005. Email: marcia@dsl.pipex.com

Kill or Update By: 30/05/06

Edited by BC & GI

Citation: EBM Critical Appraisals. Scottish Intensive Care Society EBM Group. McDougal M. 2005. Marik PE, Zaloga GP. Early enteral nutrition in acutely ill patients: A systematic review. Critical Care Medicine 2001 Vol. 29 No.12. 2264-2270.

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