Finding the Evidence: Enteral Nutrition in Critical Care

Amy Lichtfuss

Finding the Evidence: Enteral Nutrition in Critical Care

Rush University

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Finding the Evidence: Enteral Nutrition in Critical Care

Nutritional support in the intensive care unit (ICU), by way of enteral nutrition (EN), is an essential component in treating critically ill patients. We, as humans, rely on nutrition to keep our body functioning efficiently at the cellular level and this becomes even more essential in critically ill patients as the body repairs itself from sickness or injury. While malnutrition is known to be associated with poor outcomes, increased mortality, morbidity, and increased length of stays (LOS) (Schub, 2013), many researchers are beginning to realize the importance of initiating EN as early as possible in the treatment process. According to Mikhailov et al. (2014), animal studies show that without nutrition there are detrimental effects to the antioxidant system in the body seen as early as 12 hours after an injury. Furthermore, early enteral nutrition (EEN) protects vital organs from shutting down, maintains gut function, and improves protein synthesis, amongst other things, all of which are crucial components for recovering from illness. With that said, the American Society of Parenteral and Enteral Nutrition/Society of Critical Care Medicine (ASPEN/SCCM) recommends a guideline of starting enteral feeding within 24-48 hours of ICU admission.

Numerous studies (see Appendix A) support this guideline proving the initiation of EN in ICU patients within 48 hours of admission is associated with improved clinical outcomes, lower infection rates, and a reduced LOS (Schub, 2013). Three research studies were found for this exercise by using key search terms such as enteral nutrition guidelines, early enteral nutrition, and critical care, and databases included PubMed, Google Scholar, and Nursing Reference Center (NRC) though EBSCOhost. Careful attention was paid to focus on enteral nutrition rather than parenteral nutrition.  

Ultimately, all three articles found the initiation of EEN within 24-48 hours of admission to benefit the patients regardless of the severity of their illness. The research article by Khalid et al. (2010), addressed a controversial issue of EEN in hemodynamically unstable patients (those with mechanical ventilation (MV) and vasopressor drugs). Generally, EEN is not initiated in these patients because of two main outcomes: possible increase in gut ischemia with feedings and the “steal” phenomenon suggesting increased splanchnic blood flow without increased cardiac output, which leads to further complications (Kahlid et al., 2010). However, the authors also mentioned that these clinical outcomes are questionable and unclear, and in their study the patients who received EEN (defined as within 48 hours) all had better outcomes. The patients who received EEN had reduced LOS and reduced mortality than those who received late enteral nutriton (after 48 hours). Furthermore, there was no evidence of any harm in these EEN patients regardless of the severity of their illness, possibly indicating the current concerns of gut ischemia and “steal” phenomenon need further exploration. 

            Mosier et al. (2011), discussed the current nutrition support guidelines for burn patients in the ICU and researched associated complications and outcomes of EEN, as well as clinican barriers to following the guideline. EEN in this study is defined as feeding within 24 hours of admission. Results showed decreased mortality, morbidity, LOS, and less wound infections for those with EEN, although days on MV were not affected. There was also high clinican compliance as 80% of patients began EN by 24 hours and 95% of patients had EN by 48 hours.  One barrier to initiating EEN were patients who were hemodynamically unstable (on vasopressors, etc.) did not receive EN within the expected time frame. At the time of this study it was unclear whether this was due to provider preference or a medical contraindication.  However, according to Kahlid et al. study, hemodynamically unstable patients can safely receive EEN and will have better outcomes (2010). 

            In January of 2014, Mikhailov et al. researched the initiation of EEN in the PICU and, in line with the other two studies, found favorable patient outcomes. EEN was defined as within 48 hours of admission. While LOS and duration of MV were not significantly impacted by EEN, mortality rates declined, which is significant. An interesting factor noted by the researchers, is the patients who did receive EEN were younger, MV or had some respiratory illness, and were less of a risk of mortality than the patients who did not receive EEN (those who were postop, trauma, or on CPB). Again, it needs to be determined whether this was provider preference for not feeding critically ill patients, or if there is some other contraindication.

Further research should be done to study the effects of EEN on thermodynamically unstable patients, as the current practice is ambiguous at this time. With that, studies should be done to determine if specific caloric/protein guidelines alter outcomes in critically ill patients of different severities. A definitive causality for how EEN improves patient outcomes should be researched, possibly by studying patient outcomes in parenteral vs. enteral feedings. Also, with much data supporting the practice of EEN, the guideline should be established further by defining the term “early” as either 24 hours or 48 hours. This can be accomplished by studying patient outcomes in a 24-hour group versus a 48-hour group. While these studies differed in their recommendations, Lewis, Dirksen, Heitkemper, Bucher, & Camera (2011) suggest 24 hours is ideal. Finally, once the evidence has been consolidated, a formal policy should be established and disseminated amongst stakeholders.    

 References

Khalid, I., Doshi, P., & DiGiovine, B. (2010). Early enteral nutrition and outcomes of critically

            ill patients treated with vasopressors and mechanical ventilation. American Journal of

            Critical Care, 19(3), 261-268.  Retrieved from

            ajcc.aacnjournals.org/content/19/3/261.full.pdf

Lewis, S., Dirksen, S., Heitkemper, M., Bucher, L., & Camera, I. (2011). I. Lewis (Ed.),

            Medical-Surgical Nursing: Assessment and Management of Clinical Problems (8th ed.,

            Vol. 2, p. 1733). St. Louis, Missouri: Mosby.

Mikhailov, T. A., Kuhn, E. M., Manzi, J., Christensen, M., Collins, M., Brown, A. M., ... &

            Goday, P. S. (2014). Early Enteral Nutrition Is Associated With Lower Mortality in

            Critically Ill Children. Journal of Parenteral and Enteral Nutrition, 0148607113517903.

            Retrieved from

            http://pen.sagepub.com.ezproxy.rush.edu/content/early/2014/01/08/0148607113517903.l ong

Mosier, M. J., Pham, T. N., Klein, M. B., Gibran, N. S., Arnoldo, B. D., Gamelli, R. L., ... &

            Herndon, D. N. (2011). Early enteral nutrition in burns: compliance with guidelines and

            associated outcomes in a multicenter study. Journal of Burn Care & Research, 32(1),

            104-109.

Schub, T. (2013). Feeding practices: Critically ill patients. In D. Pravikoff (Ed.), CINAHL

            Nursing Guide. Ipswich, Massachusetts: EBSCO. Retrieved from

            http://search.ebscohost.com.ezproxy.rush.edu/login.aspx?direct=true&db=nrc&AN=T70

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