Major clinical approaches to macro and micronutrients in enteral therapy according to international guidelines and clinical studies: a systematic review

Introduction: In the context of Nutritional Therapy (NT), critically ill patients are associated with a state of catabolic stress and a systemic inflammatory response. Patients admitted to intensive care units (ICU) have a prevalence of malnutrition greater than 35%. The main objective of parenteral nutrition (PN) is to provide a nutrient mix closely related to requirements safely and avoid complications. However, PN poses a considerable risk of overfeeding, which can be just as harmful as underfeeding. Long-term survival data (expressed as 6-month survival) will also be considered a relevant outcome measure. Objective: It was performed a systematic review to evaluate the main clinical approaches of macro and micronutrients in enteral therapy according to international guidelines and clinical studies. Methods: The present study followed a concise systematic review model, following the systematic review rules (PRISMA). The literary search process was carried out from August to October 2022 and was developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, using scientific articles from 2011 to 2022. The low quality of evidence was attributed to case reports, editorials, and brief communications, according to the GRADE instrument. The risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: It was found 118 studies that underwent eligibility analysis, and then 20 of the 22 total studies were selected for this systematic review. According to the GRADE instrument, most studies showed homogeneity in their results, with I2 =97.7% >50%. Standard crystalline amino acid solutions, while devoid of side effects, remain incomplete regarding their composition (eg glutamine). Lipid emulsions have come a long way and are now included in bi- and tri-compartment feeding bags, allowing for true total PN as long as daily micronutrients are prescribed. The issue of exact individual needs for energy, macro, and micronutrients has not yet been resolved. Many complications attributed to total PN are the consequence of under or overfeeding. Total PN indications have evolved towards its use alone or in combination with enteral nutrition. The start time varies by country between admission (Australia and Israel), day 4 (Swiss), and day 7 (Belgium, USA). The most important issue may be an individualized and time-dependent prescription of the feeding pathway, energy, and substrates.