Nutrition Support in Critically Ill Adults in Intensive Care Units: An Evidence Analysis Center Scoping Review of Current Systematic Reviews and Guidelines

Background: Critically ill adults in intensive care unit settings are at high risk of malnutrition, which is linked to poor outcomes. Delivery of optimal nutrition support in this population is challenging due to patient complexity and inconsistent nutrition care recommendations. Objective: To provide a comprehensive overview of guidelines and systematic reviews relevant to clinicians managing enteral and parenteral nutrition in critically ill adults and determine whether or not an update to the Academy of Nutrition and Dietetics Nutrition Support Guideline is warranted. Methods: The Academy of Nutrition and Dietetics Evidence Analysis Center conducted a scoping review following methodologies adapted from Arksey and O'Malley, Levac and colleagues, and the Joanna Briggs Institute. A comprehensive search was performed on January 13, 2025, in MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Cochrane Database of Systematic Reviews, the Guidelines International Network, and the Guideline Central databases. Included sources were English-language guidelines published in 2015 or after, or systematic reviews published after 2020, on nutrition support for adults (aged 18 years or older) in intensive care units. Data were extracted using standardized templates. Guideline quality was assessed independently by 2 blinded reviewers using the Appraisal of Guidelines for Research & Evaluation II (AGREE II); systematic reviews were appraised using critical domains from A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR2). Results were summarized using charts and maps. Results: Eleven guidelines and 58 systematic reviews were included. Guideline topics included provision of enteral vs parenteral nutrition, timing of initiation, and energy/protein provision. Systematic reviews most often cover energy/protein amounts, delivery rates, and fiber/prebiotics. All guidelines had notable quality issues, often lacking patient input, peer review, or implementation strategies. More than half of the systematic reviews met key AMSTAR2 criteria, although many had methodological concerns. Conclusions: There are numerous guidelines and systematic reviews on nutrition support interventions for critically ill adults, with substantial variability in quality and scope. A comprehensive, high-quality guideline should be developed through the Grading of Recommendations Assessment, Development and Evaluation approach to Adoption, Adaption, and De novo development (GRADE-ADOLOPMENT) process to leverage current resources. Future systematic reviews of subpopulations are needed to address evidence gaps.