Starting Strong: Nutrition Support Initiation & Optimization

by Bridget Storm MA, RD, LDN, CNSC

In clinical practice, the timing of nutrition support initiation is crucial for optimizing patient outcomes, particularly in critically ill patients or those with malnutrition. Both enteral nutrition (EN) and parenteral nutrition (PN) have specific guidelines regarding their initiation, which can significantly impact recovery and overall health. This blog explores the optimal timing for both nutrition modalities, supported by current research and clinical guidelines.

ENTERAL NUTRITION (EN)

Enteral nutrition is generally preferred over parenteral nutrition for patients who can tolerate it. The American Society for Parenteral and Enteral Nutrition (ASPEN) recommends initiating enteral nutrition within 24 to 48 hours of hospital admission for critically ill patients, assuming there are no contraindications. Early initiation of EN can reduce the risk of complications associated with malnutrition, such as infection and prolonged recovery times.

Benefits of Early EN

Preservation of Gut Integrity: Early EN helps maintain the gut mucosal barrier, which can prevent translocation of bacteria and reduce the risk of infections.

Reduced Length of Stay: Studies have shown that early EN can lead to a shorter hospital stay and decreased healthcare costs.

Improved Outcomes: Early initiation is associated with better clinical outcomes, including reduced mortality rates in critically ill patients.

PARENTERAL NUTRITION (PN)

Parenteral nutrition is typically reserved for patients who cannot meet their nutritional needs enterally, either due to gastrointestinal dysfunction or inability to access the GI tract. ASPEN guidelines suggest that PN should be considered if a patient is unable to achieve adequate nutrition via the enteral route for more than 7 days. 

ASPEN guidelines advocate for earlier PN initiation in patients who are malnourished or high risk, but this timeline had not been clearly defined. Newer research supports a timeframe of 3-5 days for these populations. Timely initiation of PN can prevent malnutrition and its associated complications, especially in patients with high nutritional needs, such as those undergoing major surgeries or suffering from severe burns.

The Case for Early PN Support

Since the 2016 Adult Critical Care Guidelines, strategies to prevent catheter-related bloodstream infections (CRBSIs) have evolved, including proper line care, infection control practices, pharmacy compounding practices, and appropriate nutrient provision.  Additionally, use of 70% ethanol-impregnated caps (lock) has been found to reduce the incidence of CRBSIs by >40%, decrease length of stay, and lower hospital costs.

The European Society for Parenteral and Enteral Nutrition (ESPEN) guidelines published in 2023 recommend early EN & progressive PN over withholding nutrition support in critical illness and severe malnutrition. Two hallmark randomized-controlled studies comparing early EN and early PN – the CALORIES & NUTRIREA-2 studies – demonstrated greater caloric deficit among EN-only patients with no difference in mortality or infectious complications.

Supplemental PN Support

Recent studies suggest that supplemental parenteral nutrition (SPN) in critically ill patients may provide benefits when added to enteral nutrition (EN), especially when EN alone is insufficient to meet nutritional needs. SPN may enhance outcomes by increasing calorie intake, reducing infections, and potentially lowering mortality in high-risk groups. SPN appears most beneficial when started after day 4 to support enteral nutrition (EN) progression or as early as day 3 post-surgery for infection reduction. 

Conclusion

Optimal timing of nutrition support initiation is critical for improving patient outcomes in various clinical settings, and individual patient circumstances and clinical judgment should guide the decision-making process.  The infographic below can serve as a guide for appropriately timing the initiation of nutrition support. 

Visit me at https://nutritionstudysupport.com for more blogs, resources, and valuable insights!

Interested in increasing your proficiency in nutrition support? Check out our CNSC Study Guide and our training guide: Feeding the Critically Ill & GI Compromised.

References

1. Kreymborg K, et al. Nutritional management in critically ill patients: A review of the literature. Crit Care Med. 2020;48(5):737-746.
2. Compher C, Bingham AL, McCall M, et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: The American Society for Parenteral and Enteral Nutrition. JPEN. 2022; 1-30. 
3. McClave SA, et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient. JPEN J Parenter Enteral Nutr. 2016;40(2):159-211.
4. Marik PE, et al. The role of early enteral nutrition in critically ill patients: A systematic review. Nutr Ther Metab. 2017;35(2):112-119.
5. Weimann A, et al. ESPEN Guidelines on Parenteral Nutrition: Intensive care. Clin Nutr. 2017;36(3):481-488.
6. Bechtold ML, Brown PM, Escuro A, et al. When is enteral nutrition indicated? J Parenter Enteral Nutr. 2022; 46: 1470-1496.
7. Cogle SV, Hallum M, Mulherin DW. Applying the 2022 ASPEN adult nutrition support guidelines in a 2024 ICU. Nutr Clin Pract. 2024; 39 (5): 1055-1068. doi:10.1002/ncp.11188
8. Kumar S, et al. Timing of parenteral nutrition in critically ill patients. Br J Nutr. 2018;119(5):453-460.
9. Reignier J, Boisramé-Helms J, Brisard L, et al. Enteral versus parenteral early nutrition in ventilated adults with shock: a randomised, controlled, multicentre, open-label, parallel-group study (NUTRIREA-2). Lancet. 2018; 391(10116): 133-143.
10. Russell, Mary K, and Paul E Wischmeyer. “Supplemental Parenteral Nutrition: Review of the Literature and Current Nutrition Guidelines.” Nutr Clin Pract. 2018; 33(3): 359-369.
11. Alsharif, D. J., Alsharif, F. J., Aljuraiban, G. S., & Abulmeaty, M. M. A. (2020). Effect of Supplemental Parenteral Nutrition Versus Enteral Nutrition Alone on Clinical Outcomes in Critically Ill Adult Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients, 12(10), 2968.
12. Gao X, Liu Y, Zhang L, et al. Effect of Early vs Late Supplemental Parenteral Nutrition in Patients Undergoing Abdominal Surgery: A Randomized Clinical Trial. JAMA Surg. 2022;157(5):384–393.
13. Berger, M.M., Burgos, R., Casaer, M.P. et al. Clinical nutrition issues in 2022: What is missing to trust supplemental parenteral nutrition (SPN) in ICU patients?. Crit Care 26, 271 (2022).