Dietitian Blog, Nutrition Support | Aug 9 2022

Part 3: Nutrition recommendations for your critically ill patients | ICU series

ICU patient room

You’ve assessed your critically ill patient, and now it’s time to develop your nutrition intervention. In this blog, we’ll review recommendations from the latest version of the Critical Care Guidelines, as outlined by the American Society for Parenteral and Enteral Nutrition (ASPEN) and the Society of Critical Care Medicine (SCCM).

Calculating nutritional needs

Most likely, your critically ill patient will need nutrition support. First, you need a ballpark estimation of their calorie and protein needs as a guidepost for your nutrition support calculations. Indirect calorimetry is the most accurate method to estimate nutritional needs. In the absence of this technology, ASPEN and SCCM recommend weight-based equations. See below for the specifics.


  • For BMIs up to 29.9 kg/m2: 25 to 30 kcal/kg
  • For BMIs between 30 to 50 kg/m2: 11 to 14 kcal/kg actual weight
  • For BMIs >50 kg/m2: 22 to 25 kcal/kg ideal weight


  • For BMIs between 30 to 39.9 kg/m2: 2 g/kg ideal weight
  • For BMIs 40 kg/m2 or higher: 2.5 g/kg ideal weight

Keep in mind, these recommendations are a starting point and should be adjusted based on other medical conditions or treatments that may impact energy needs.

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Enteral nutrition

Start early. ASPEN and SCCM continue to recommend early enteral nutrition for ICU patients. How early? Ideally, patients should receive enteral feeding within 24 to 48 hours of ICU admission, as long as they are stable. 

Volume matters (sort of). Not all ICU patients respond or receive the same benefit from enteral nutrition. Research now suggests that nutritionally at-risk or malnourished patients benefit more from an enteral nutrition regimen that meets their energy needs than well-nourished patients do. So, make every effort to meet at least 80% of energy needs for malnourished patients. On the other hand, trickle/trophic tube feeding can be an appropriate option for well-nourished patients.

Back to basics. ASPEN and SCCM now recommend using standard, polymeric formulas for most patients. Evidence to support using specialized, disease-specific formulas is just not there. However, patients who need specific formulas to manage their acute condition (i.e., a kidney-specific formula to manage hyperkalemia or hyperphosphatemia) should certainly receive those formulas.

Parenteral nutrition

Timing is everything. Just as with enteral nutrition, recommendations for using parenteral nutrition depend on the nutrition status of the patient. Low nutrition risk patients can safely wait seven days to receive parenteral nutrition. However, parenteral nutrition should be initiated right away for high nutrition risk patients who cannot meet their nutritional needs with oral or enteral nutrition alone.

Permissive underfeeding is A-okay. When crafting custom parenteral nutrition regimens, it’s perfectly fine to aim to meet approximately 80% of calorie needs. However, do your best to meet 100% of the patient’s protein needs. Once the patient transfers out of the ICU, adjust the regimen to meet 100% of calorie needs. This strategy may help to reduce hyperglycemia, infection, and length of stay.

Consider withholding lipids. Most facilities are still using soy-based lipid emulsions. These products have a pro-inflammatory profile. Thus, current recommendations are to withhold IV lipids from your parenteral nutrition order for seven days or limit the dosage to 100 g/week. Alternative lipid emulsions are available now, and they are safe. However, more data are needed to understand the impact they may have on clinical outcomes.

We have more information on assessing your ventilator-dependent or prone patient. And check out our Critical Care Toolkit to round out your knowledge.

This the third and final installment of our ICU blog series. Catch up on parts one and two.

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McClave SA, Taylor BE, Martindale RG, et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.). J Parenter Enteral Nutr. 2016;40(2):159-211.
Sara Glanz, registered dietitian

About Sara Glanz

Sara Glanz, MS, RD, LD, CNSC worked as a traveling dietitian for Dietitians On Demand for two years before joining the corporate team. In her current role as Director of Clinical Education, she has championed the continuing education program to empower dietitians everywhere to achieve their professional goals.

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