March 2022 Issue

MNT for Critically Ill COVID-19 Patients
By Jennifer Doley, MBA, RD, CNSC, FAND
Today’s Dietitian
Vol. 24, No. 3, P. 32

Research is limited, but RDs can follow established guidelines used to treat the critically ill without COVID-19.

By the end of 2021, COVID-19 had taken the lives of more than 832,000 Americans and 5.5 million people worldwide. In the United States, since March 2020, the average hospitalization rate for adults with COVID-19 is approximately 4.7%. Hospitalization rates are disproportionately higher in African Americans and other people of color compared with non-Hispanic whites, and risk of severe illness from COVID-19 also significantly rises with age. Individuals with a greater number of underlying medical conditions also are at increased risk of severe illness; these conditions include chronic diseases of the lungs, kidneys, liver, and cardiovascular system, as well as cancer, diabetes, and obesity.1

COVID-19 in hospitalized critically ill patients poses significant and unique challenges in achieving and maintaining optimal nutrition status. As COVID-19 is a new disease, research on MNT in this population is limited, thus nutrition recommendations are based on expert opinion and guided by evidence-based requirements for critically ill patients who don’t have COVID-19.2,3

This article reviews the impact of COVID-19 on the nutrition status of hospitalized patients and provides MNT strategies for RDs to help meet nutrition needs in this vulnerable population.

COVID-19 and Nutrition Status
Although malnutrition rates in hospitalized COVID-19 patients haven’t yet been reported, risk of malnutrition is high. Poor appetite, shortness of breath, loss of taste and smell, and gastrointestinal (GI) symptoms such as nausea and diarrhea can significantly impair oral intake even before hospital admission. Furthermore, severe COVID-19 results in significant systemic inflammation, which increases energy and protein needs and is a risk factor for malnutrition. For these reasons, most patients admitted to the hospital already are nutritionally compromised.3

Nutrition Screening
As with all hospitalized patients, those with COVID-19 should be screened for malnutrition within 24 hours of admission with the use of a validated screening tool.2,3 The Academy of Nutrition and Dietetics (the Academy) recommends using the Malnutrition Screening Tool (MST) for all hospitalized adult patients.4 Although this tool hasn’t been validated for COVID-19 patients, it appears reasonable to use the MST in this population, as the two-question tool is simple and quick to administer.2

The MST does have a significant limitation, though. It can’t be used with patients who can’t answer questions due to altered mental status or mechanical ventilation. Use of the NUTRIC (Nutrition Risk in the Critically Ill) Score can be considered, as this screening tool was developed and validated for critically ill patients who can’t provide information on weight and oral intake history.5

Nutrient Needs
Because data are lacking on critically ill COVID-19 patients, recommendations for assessing energy and protein needs are derived from evidence-based guidelines for the general critically ill population.2,3 Some experts have recommended micronutrient supplementation due to the inflammatory nature of the condition.6 Research on macro- and micronutrient needs for critically ill COVID-19 patients is needed to ensure nutrition status is accurately assessed and appropriate MNT is implemented.

Energy and Protein
Indirect calorimetry is considered the gold standard for assessing energy needs; however, some experts have discouraged its use in COVID-19 patients. Time needed to conduct the measurements is a significant consideration for busy clinicians. Furthermore, as an aerosol-generating procedure, indirect calorimetry measurements may increase risk of viral transmission.2,3,7

If indirect calorimetry isn’t available or feasible, or is considered unsafe, predictive equations should be used to estimate energy needs. The American Society for Parenteral and Enteral Nutrition (ASPEN) recommends the use of calories per kilogram of body weight,8 while the Academy’s Evidence Analysis Library states that the Penn State equations are most accurate in critically ill intubated patients.9 Protein recommendations are 1.2 to 2 g/kg.2,3 (See table below for a summary of energy and protein need estimations.)

Click to enlarge

Regardless, predictive equations are far from perfect and may not accurately estimate energy needs because of wide variations in patients’ age, degree of illness, other medical conditions, weight, and body composition. Furthermore, accuracy of predictive equations hasn’t been studied in COVID-19 patients.2,3

Deficiency or inadequate intake of vitamins A and D are associated with increased severity of illness and poorer clinical outcomes in some viral diseases. Vitamin A deficiency in particular has been associated with higher morbidity and mortality in viral illnesses such as HIV, measles, and malaria.6 Researchers have proposed that these and other micronutrients that play a role in immunity or function as antioxidants, such as vitamin C, B vitamins, selenium, zinc, and iron, should be assessed and perhaps supplemented in hospitalized COVID-19 patients due to the highly inflammatory nature of the disease.6,10,11 However, the Academy’s guidelines for nutrition care in COVID-19 patients doesn’t recommend routine micronutrient supplementation in this population, and the ASPEN COVID-19 guidelines don’t specifically address micronutrient needs or supplementation.2,3 The European Society for Parenteral and Enteral Nutrition’s COVID-19 guidelines suggest these patients receive the recommended allowances for vitamin and trace elements, specifically focusing on maximizing anti-infection nutrient defenses.12 It should be emphasized that there’s no evidence suggesting that routine micronutrient supplementation in COVID-19–related critical illness can improve outcomes.6,10,11

MNT: Enteral Nutrition
To improve nutrition status in critically ill COVID-19 patients who can’t tolerate oral intake, enteral nutrition (EN) should be initiated. Data are lacking on outcomes related to timing, administration, and choice of EN formula for COVID-19 patients. However, early EN has been shown to reduce mortality and infection rates in the overall critically ill population and is preferred over parenteral nutrition, as it helps maintain gut integrity and supports immune function.8 Expert opinion suggests these tenets hold true for critically ill COVID-19 patients; thus, EN recommendations are based on the general critical care population.2,3

EN should be initiated within 24 to 36 hours of admission to the ICU in patients who can’t meet adequate oral intake, and within 12 hours of intubation.3 EN should be delayed in the event of unexplained GI symptoms such as abdominal pain, distention, or emesis. EN also shouldn’t be initiated in cases of shock, as gut ischemia has been reported in enterally fed hypotensive patients.8 Although this complication appears to be rare, experts recommend holding EN when mean arterial pressure is less than or equal to 65 mm Hg, the number or dose of vasopressors is increasing, or lactate levels are rising.2,3

In patients with tenuous hemodynamic stability, start EN at trophic rates, generally defined as 10 to 20 mL/hr.8 These patients should be monitored closely for signs of intolerance.

Administration: Gastric vs Enteric
Gastric feeding, as opposed to enteric feeding (ie, postpyloric), is recommended in COVID-19 patients. Use of an enteric feeding tube requires time for the tube tip to migrate past the stomach and radiological confirmation of placement, which can delay the start of EN. Moreover, enteric feeding tube placement is considered an aerosol-generating procedure, as patients may cough during the process, which can increase the risk of viral transmission. Postpyloric feeding tubes have a smaller bore than gastric tubes, thus are more prone to clogging. This may further reduce the amount of EN patients receive, and it’s a significant time burden for nurses. For these reasons, gastric feeding is preferred; however, enteric feeding should be considered in patients with gastric intolerance despite the use of prokinetic medications or in those at high risk of aspiration.2,3

Administration: Continuous vs Bolus
To help reduce the risk of aspiration and GI intolerance in COVID-19 patients, continuous EN administration is recommended. Nursing time and safety are also benefits of continuous feeding; with long tubes, the EN pump can be kept outside the patient’s room, potentially reducing the number of times the nurse must enter the room. Bolus feeding requires more frequent close contact with patients, increasing the risk of viral exposure.2,3

Administration: Prone Positioning
Proning, or laying the patient face down in bed, has been used for years to treat patients on mechanical ventilation due to severe acute respiratory distress syndrome. Proning can help the lungs ventilate more evenly and improve arterial oxygenation and clinical outcomes.13,14 However, proning isn’t without risks. Pressure injuries, facial edema, IV line or endotracheal tube displacement, and cardiovascular instability have been reported in proned patients. Research has shown proning for 16 or more hours has the most benefit; a commonly employed schedule is 16 hours in the prone position and eight hours supine.15

Proning has become a common treatment for critically ill COVID-19 patients on mechanical ventilation. Early research has yielded promising results indicating lower mortality rates in those who are proned, but further research is needed to validate these results.16,17 Despite its apparent benefits, proning poses challenges in the adequate administration of EN. The feeding tube must be placed while the patient is in the supine position. To reduce the risk of aspiration, the bed should be placed in the reverse Trendelenburg position with the head of the bed elevated 10 to 25 degrees. Prokinetic medication, such as metoclopramide, may be administered to ensure adequate gastric emptying.14

Research in non–COVID-19 patients suggests that EN can be safely administered at goal rate into the stomach even while a patient is in the prone position.13,14 However, some clinicians may not be comfortable with this practice for fear of aspiration. In this case, EN can be administered at a trophic rate of 20 mL per hour during proning and increased during the remaining eight hours when the patient is supine to make up for the lost volume while prone. Although not specifically recommended by most professional organizations, some facilities may hold EN before turning the patient, which further reduces the time available to feed at a higher rate. These practices make it challenging or impossible to meet the nutrition needs of patients who require a high volume of EN, as clinicians also may be uncomfortable administering EN at much higher rates than is usual. In these cases, clinicians can use a more concentrated EN formula, although this may result in inadequate protein administration, as calorie-dense formulas have a lower proportion of protein compared with very high-protein formulas. When EN isn’t tolerated at goal volumes, parenteral nutrition can be initiated to supplement or replace nutrient intake from EN.13,18

Feeding Goals
Clinicians also must determine whether to choose hypocaloric or full feedings in critically ill COVID-19 patients. Guidelines for nutrition support in critical illness from ASPEN and the Academy state that the evidence suggests there’s no difference in clinical outcomes between hypocaloric and full feedings within the first week of intubation for critically ill non–COVID-19 patients.8 However, expert opinion for critically ill COVID-19 patients suggests initiating hypocaloric EN and advancing it to goal volume over the ensuing week (see table above).2,3 These feeding recommendations may change as more research is conducted on nutrition support in COVID-19–related critical illness.

Moreover, clinicians should consider the risk of refeeding when establishing EN administration parameters. In refeeding syndrome, patients with recent poor energy intake and/or malnutrition may experience significant cellular uptake of potassium, phosphorus, and magnesium when they ingest carbohydrate, resulting in low serum levels of these electrolytes. In severe cases, this can be life threatening. Experts recommend replacing electrolytes before starting EN, initiating EN at a rate that provides 25% of energy goals, and frequent monitoring of phosphorus, magnesium, and potassium.3 Thiamin also may decrease, as it’s needed in carbohydrate metabolism, so supplemental thiamin may be advisable.20 Although reaching energy goals is important, clinicians should focus on more aggressive provisions of protein, which they can do by using very high-protein formulas.3,19

Formula Selection
High-protein formulas often are necessary since estimated protein needs are high in critically ill COVID-19 patients. Moreover, extra sources of energy such as dextrose or lipid emulsions (eg, propofol and clevidipine) necessitate lower EN goal rates to avoid overfeeding. However, this usually results in insufficient protein intake. Protein modulars may be necessary to meet needs even when high-protein formulas are infused. Yet, modular use should be limited if possible, as administration is cumbersome for nurses and may require more frequent patient contact. If protein modulars are prescribed, doses should be consolidated when possible to mitigate this risk.2,3

Intact nutrient (whole protein) formulas with or without fiber are sufficient for most COVID-19 patients. Acutely ill patients with some hemodynamic instability shouldn’t receive EN formulas with fiber; however, when stable, clinicians can use fiber-containing formulas. Nevertheless, standard intact nutrient formulas typically are lower in protein than peptide-based formulas, thus the use of standard formulas may inhibit adequate protein provision.3

It’s also important to note that critically ill COVID-19 patients frequently develop hyperglycemia and renal failure. And while EN formulas have been designed for patients with these conditions, there’s insufficient evidence demonstrating benefit of these specialty formulas, and therefore their use generally isn’t indicated. An exception may be use of a renal formula when elevated electrolytes can’t be controlled by medical or pharmaceutical means.8

Monitoring Tolerance
As is formula selection, monitoring tolerance of EN is important in critically ill patients and those with COVID-19. Although some clinicians still monitor tolerance by checking gastric residual volumes, this no longer is recommended, as research has shown that this metric doesn’t correlate with outcomes such as aspiration and pneumonia.8 Instead, clinicians should monitor EN tolerance through physical examination of the abdomen to assess for distention or firmness and check bowel function. Indication of intolerance includes emesis, in which case EN should be held. However, EN shouldn’t be held for diarrhea. Several factors may cause diarrhea, including GI infection, altered gut microbiota, and medications, including overuse of drugs prescribed to promote bowel motility, medications delivered in hypertonic solutions, and those containing sorbitol or other poorly digested sugar alcohols. Critically ill COVID-19 patients may have more GI symptoms, including diarrhea, than other critically ill patients, as GI dysfunction is a known symptom of the disease, especially in severe cases.3,8 If a patient has diarrhea, clinicians should investigate all potential causes and use pharmacological interventions to address it. Holding EN isn’t recommended because it can cause or worsen malnutrition.8

Recommendations for RDs
Caring for hospitalized critically ill COVID-19 patients is complex, as research is ongoing. Because these patients are at high risk of nutrient deficiencies, they should be screened for malnutrition upon hospital admission with the use of a validated screening tool. Clinicians should initiate MNT interventions within 24 to 36 hours of ICU admission or within 12 hours of intubation. Much is unknown about the nutrient needs of critically ill COVID-19 patients as well as ideal EN interventions, such as feeding goals and administration parameters. Therefore, most recommendations are based on evidence regarding the general critically ill population. However, studies are underway and clinicians should keep abreast of current research as MNT recommendations for this population continue to evolve.

— Jennifer Doley, MBA, RD, CNSC, FAND, is a regional clinical nutrition manager and dietetic internship director with Morrison Healthcare. She has been a dietitian for more than 26 years and certified as a nutrition support clinician for 25. She has extensive experience providing MNT to critically ill patients receiving enteral and parenteral nutrition, including patients with COVID-19.


1. Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET). Center for Disease Control and Prevention website. Updated December 3, 2021.

2. Handu D, Molony L, Rozga M, Cheng FW. Malnutrition care during the COVID-19 pandemic: considerations for the registered dietitian nutritionists. J Acad Nutr Diet. 2021;121(5):979-987.

3. Martindale R, Patel JJ, Taylor B, Warren M, McClave SA; Society of Critical Care Medicine; American Society for Parenteral and Enteral Nutrition. Nutrition therapy in the patient with COVID-19 disease requiring ICU care. Updated April 1, 2020.

4. Skipper A, Coltman A, Tomesko J, et al. Position of the Academy of Nutrition and Dietetics: malnutrition (undernutrition) screening tools for all adults. J Acad Nutr Diet. 2020;120(4):709-713.

5. Heyland DK, Dhaliwal R, Jiang X, Day AG. Identifying critically ill patients who benefit the most from nutrition therapy: the development and initial validation of a novel risk assessment tool. Crit Care. 2011;15(6):R268.

6. Zhang L, Liu Y. Potential interventions for novel coronavirus in China: a systematic review. J Med Virol. 2020;92(5):479-490.

7. Singer P, Pichard C, De Waele E. Practical guidance for the use of indirect calorimetry during COVID 19 pandemic. Clin Nutr Exp. 2020;33:18-23.

8. 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.

9. Academy of Nutrition and Dietetics, Evidence Analysis Library website. Accessed December 30, 2021.

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11. Gasmi A, Tippairote T, Mujawdiya PK, et al. Micronutrients as immunomodulatory tools for COVID-19 management. Clin Immunol. 2020;220:108545.

12. Barazzoni R, Bischoff SC, Breda J, et al. ESPEN expert statements and practical guidance for nutritional management of individuals with SARS-CoV2 infection. Clin Nutr. 2020;39(6):1631-1638.

13. Behrens S, Kozeniecki M, Knapp N, Martindale RG. Nutrition support during prone positioning: al old technique reawakened by COVID-19. Nutr Clin Pract. 2021;36(1):105-109.

14. de la Fuente IS, de la Fuente JS, Estelles MDQ, et al. Enteral nutrition in patients receiving mechanical ventilation in a prone position. JPEN J Parenter Enteral Nutr. 2016;40(2):250-255.

15. Intensive Care Society and Faculty of Intensive Care Medicine. Guidance for: prone positing in adult critical care. Published November 2019. Accessed November 26, 2021.

16. Shelhamer MC, Wesson PD, Solari IL, et al. Prone positioning in moderate to severe acute respiratory distress syndrome due to COVID-19: a cohort study and analysis of physiology. J Intensive Care Med. 2021;36(2):241-252.

17. Mathews KS, Soh H, Shaefi S, et al. Prone positioning and survival in mechanically ventilated patients with coronavirus disease 2019–related respiratory failure. Crit Care Med. 2021;49(7):1026-1037.

18. American Society for Parenteral and Enteral Nutrition. How to enterally feed the prone patient with COVID-19. Published 2020. Accessed November 26, 2021.

19. Ochoa JB, Cárdenas D, Goiburu ME, Bermúdez C, Carrasco F, Correia MITD. Lessons learned in nutrition therapy in patients with severe COVID-19. JPEN J Parenter Enteral Nutr. 2020;44(8):1369-1375.

20. da Silva JSV, Seres DS, Sabino K, et al. ASPEN consensus recommendations for refeeding syndrome. Nutr Clin Pract. 2020;35(2):178-195.

21. Barritta R, Adaglio J, Capelli O, Navarro P, Anfolisi M, Milkovic I. Critically ill COVID-19 patients: timing to reach energy and protein targets. J Acad Nutr Diet. 2021;121(10):A123.