Foundations of Nutritional Support in Critical Care

 Foundations of Nutritional Support in Critical Care

By Baylee Rogge and edited by Bridget Storm, MA, RD, LDN, CNSC

What Does It Mean to Require Critical Care?

Those who have severe metabolic stress and life-threatening injuries are treated in a critical care setting. ICU admission can be due to many reasons such as progression of a chronic disease, major infections, traumatic accident, surgery, etc. There are different intensive care units that specialize in specific areas. For example, a medical ICU takes care of patients who have severe COPD or sepsis while a surgical ICU deals with trauma and major surgeries. Some other critical care units include neurovascular, cardiac, and even burns.

The Critical Role of Nutrition in Recovery  

People who are in critical care are highly catabolic, using all available energy stores to heal the body. It can be easy for someone in a state of stress to develop acute malnutrition. This is why nutrition support in a critical care setting is crucial for restoring one’s health. Nutrition support will not look the same for every patient and needs to be personalized for each individual. Since these patients are catabolic there is an increase in the breakdown of their lean muscle mass. A loss of 40% of lean muscle mass is generally fatal. Taking action by monitoring nitrogen balance and providing optimal protein is crucial.

Powering Recovery: Optimizing Nutrtitonal Goals in the ICU

Since patients are in a high metabolic stress situation, the goal of nutrition support is delivering sufficient calories, while being careful to avoid overfeeding. Overfeeding of total calories can increase CO2 output and complicate ventilator weaning. In many critical care populations, especially among those with obesity, the recommendation in the first two weeks may be hypocaloric nutrition. It can be challenging to navigate the balance between minimizing losses while also avoiding overfeeding. Hypocaloric feeding should always be higher in protein, as preventing muscle wasting and maintaining lean muscle mass is crucial for recovery. Typically, protein will be significantly increased, up to 2.0-2.5g/kg daily in some cases.

Balancing Fluid Status

 To ensure that patients are properly hydrated their fluid needs are calculated based on their weight and age. Depending on the patients’ needs, fluids can be increased or restricted. This can be determined by looking at multiple factors such as someone’s past medical history and electrolyte levels. Patients that are on dialysis with renal disease are more likely to be restricted since their kidneys are unable to filter their fluids properly. Electrolytes like sodium can be a huge indicator for determining someone’s hydration status. Having sodium levels less than 135 mEq/L can be a sign of overhydration and having sodium levels greater than 145 mEq/L can be a sign of dehydration. In a chronic situation, for those with hyponatremia the target rate of correction to prevent osmotic demyelination is not to exceed 6-8 mEq/L/d. For those with hypernatremia the target rate of correction to prevent neurologic impairment and cerebral edema is not to exceed 10 mEq/L/d.

Enteral flushes can be provided to help maintain hydration status once the patient is through the initial resuscitation period. It is common for critical care patients to receive substantial fluid resuscitation early in the ICU stay, further complicating fluid needs assessment. Patients can become quickly fluid overloaded, while also intravascularly dehydrated due to diuretic needs. When in doubt, fluid requirements can be deferred to the intensivist or nephrologist.

Nutritional Roadblocks

While the need to provide optimal nutrition to minimize losses is foundational to all ICU patients, in critical care there are many possible challenges that may arise in patients with diverse and evolving conditions. Gastrointestinal issues, variability in facility resources, and patient cultural diversity and family needs can significantly impact nutritional plan of care. Check out our next blog to see how we break down challenges in critical care.

 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.      Mueller CM, et al (Eds). The ASPEN Adult Nutrition Support Core Curriculum, 3rd Edition. ASPEN 2017.

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. https://doi.org/10.1002/jpen.2267

3.      McClave, SA 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.). JPEN. 2016; 40 (2): 159-211. 

4.      Dresen E, Notz Q, Menger J, et al. What the clinician needs to know about medical nutrition therapy in critically ill patients in 2023: a narrative review. Nutr Clin Pract. 2023; 38: 479-498. doi:10.1002/ncp.10984

5.      Singer, P, et al. ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit. Clinical Nutrition, 2023; 42 (9):1671 – 1689.

6.      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