Nutrition Support in Critically Ill Patients


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Nutrition Support in Critically Ill Patients


Ida Molavi, MD1 and Jorge Con, MD2


1 Department of Trauma and Acute Care Surgery, Louisiana State University Health, Shreveport, LA, USA


2 Division of Trauma and Acute Care Surgery, New York Medical College, Westchester Medical Center, Valhalla, NY, USA



  1. Based on current guidelines and recommendations, what should the glycemic control target be in the critically ill patient?

    1. ≤ 200 mg/dL
    2. ≤ 160 mg/dL
    3. ≤ 180 mg/dL
    4. ≤ 80–120 mg/dL
    5. ≤ 80–160 mg/dL

    Hyperglycemia in the critically ill patient is multifactorial and can be attributed to the activation of the sympatho‐adrenal system and the stress response triggering catecholamine and glucocorticoid production. These hormones in turn trigger glucagon release, which subsequently causes an increase in gluconeogenesis and glycogenolysis, leading to insulin resistance and decreased insulin production. Although a result of the body’s compensatory mechanism, this can lead to an array of complications including a suppressed immune system and increased risk of infection. A large, single‐center landmark trial revealed that tight glycemic control (80–110 mg/dL) with insulin infusion in the postoperative period was associated with reduced mortality, ICU length of stay, and sepsis. Tight glycemic control, however, does carry the risk of severe hypoglycemia, negating the benefits. Based off the results of the NICE‐SUGAR study, the Society of Critical Care Medicine (SCCM) and the American Society for Parenteral and Enteral Nutrition (ASPEN) nutritional guidelines recommend a glycemic range of 150–180 mg/dL and 140–180 mg/dL, respectively.


    Answer: C


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


    NICE‐SUGAR Study Investigators, Finfer, S., Chittock, D. R., Su, S. Y., et al. (2009). Intensive versus conventional glucose control in critically ill patients. The New England Journal of Medicine , 360(13), 1283–1297.


    Van den Berghe, G., Wouters, P., Weekers, F., et al. (2001). Intensive insulin therapy in critically ill patients. The New England Journal of Medicine , 345(19), 1359–1367.


  2. Prealbumin, retinol‐binding protein, and transferrin may be useful as nutritional markers. Which of the following is true regarding these proteins?

    1. The half‐life of prealbumin is longer than that of transferrin.
    2. They are positive acute phase proteins.
    3. Albumin has a half‐life of 120 days.
    4. Prealbumin and retinol‐binding protein are positive acute phase proteins, while transferrin is a negative acute phase protein.
    5. They do not accurately represent nutrition status in the critical care setting.

    Acute phase reactants (APR) are proteins whose plasma concentrations either increase or decrease by at least 25% percent during inflammatory states. Such proteins are termed either positive or negative acute phase reactants, accordingly. This is guided by the hepatic reprioritization of protein synthesis away from negative APRs and toward positive APRs. The negative acute phase proteins are albumin, prealbumin, retinol‐binding protein, and transferrin. Their serum concentrations fall immediately after injury, and in proportion to injury severity. Albumin has a half‐life of 20 days, transferrin 8 days, and prealbumin <2 days. Continued and prolonged production of acute phase proteins in critically ill patients may be an indicator of ongoing sepsis and tissue damage, and is associated with higher mortality rates. Recent studies have revealed that these acute phase reactants characterize an underlying inflammatory response and do not accurately represent nutritional status in the critical care setting.


    Answer: E


    Evans, D. C., Corkins, M. R., Malone, A., et al. & ASPEN Malnutrition Committee (2020). The use of visceral proteins as nutrition markers: an ASPEN position paper. Nutrition in Clinical Practice , doi:10.1002/ncp.10588.


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


    Raguso, C. A., Dupertuis, Y. M., & Pichard, C. (2003). The role of visceral proteins in the nutritional assessment of intensive care unit patients. Current Opinion in Clinical Nutrition and Metabolic Care , 6(2), 211–216.


  3. Which of the following statements is true regarding antioxidants?

    1. Antioxidants are not recommended in critically ill patients.
    2. Only vitamin C is an antioxidant.
    3. Antioxidants should be used only in burn patients.
    4. Selenium supplementation does not affect the mortality of critically ill patients.
    5. Selenium is the most effective antioxidant.

    Antioxidant vitamins (including vitamins A, E, and C) and trace minerals (including selenium, zinc, and copper) may improve patient outcome, especially in burns, trauma, and critically ill patients. It has been demonstrated that antioxidant and trace element supplementation is associated with a significant reduction in overall mortality. Infectious complications, length of stay, and duration of mechanical ventilation were not significantly different between patients placed on such antioxidant supplements and controls receiving placebo. Selenium is one of the micronutrients with antioxidant capabilities. Plasma concentration of selenium is decreased in septic patients, and it is believed to be one of the most potent antioxidant agents in clinical setting. The current recommendation is to provide a combination of antioxidant vitamins and trace minerals, especially including selenium, to all critically ill patients receiving specialized nutrition therapy.


    Answer: E


    Crimi, E., Liguori, A., Condorelli, M., et al. (2004). The beneficial effects of antioxidant supplementation in enteral feeding in critically ill patients: a prospective, randomized, double‐blind, placebo‐controlled trial. Anesthesia and Analgesia , 99(3).


    Huang, T. S., Shyu, Y. C., Chen, H. Y., Lin, L. M., Lo, C. Y., Yuan, S. S., Chen, P. J., et al. (2013). Effect of parenteral selenium supplementation in critically ill patients: a systematic review and meta‐analysis. PLoS One , 8(1), e54431.


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


  4. A severely injured 70‐year‐old man is admitted to the ICU for severe necrotizing pancreatitis. The following nutritional strategies are correct:

    1. Probiotics are of no benefit to pancreatitis patients receiving enteral nutrition.
    2. Patients with moderate‐to‐severe acute pancreatitis benefit from parenteral nutrition over enteral nutrition.
    3. Jejunal feeding is superior to gastric feeding regarding tolerance and clinical outcomes.
    4. Strategies to improve tolerance to enteral nutrition include: early start of enteral nutrition, feeding distally, and near fat‐free elemental diets.
    5. Parenteral nutrition should be started when enteral nutrition has not been feasible after 72 hours from onset of pancreatitis.

    In patients with mild acute pancreatitis, initiation and advancement of an oral diet is recommended over specialized enteral or parenteral nutrition. In patients with moderate‐to‐severe acute pancreatitis, enteral nutrition should be initiated within the first 24–48 hours of admission, at a trophic rate, and advanced to goal as fluid volume resuscitation is completed. Measures to improve tolerance to enteral nutrition should be initiated if necessary.


    Use of enteral nutrition is preferred to parenteral nutrition because of decreased infectious morbidity, hospital LOS, need for surgical intervention, and mortality. Several randomized controlled trials comparing gastric with jejunal feeding in severe acute pancreatitis showed no significant differences between the two. Measures to improve tolerance to enteral nutrition in patients with moderate‐to‐severe acute pancreatitis include starting enteral nutrition as soon as possible and within the first 48 hours of admission, feeding more distally in the gastrointestinal tract, changing from a standard polymeric formula to one that contains small peptides and medium chain triglycerides or to one that is a nearly a fat‐free elemental formulation, and switching from bolus to continuous infusion.


    Current guidelines suggest use of probiotics be considered in patients with severe acute pancreatitis who are receiving early enteral nutrition based on evidence that it may decrease sepsis and multi‐organ dysfunction in this population.


    If the patient is well nourished, supplemental parenteral nutrition (PN) should be considered after 7 days if unable to meet >50–60% of energy and protein requirements by the enteral route. If the patient is nutritionally at‐risk and unlikely to achieve desired EN goal, PN should be considered within 3–5 days of admission. PN should be initiated as soon as feasible for patients with baseline moderate‐to‐severe malnutrition in whom oral intake or enteral nutrition is not possible or sufficient; therefore, answer E is wrong.


    Answer: D


    Cao, Y., Xu, Y., Lu, T., Gao, F., et al. (2008). Meta‐analysis of enteral nutrition versus total parenteral nutrition in patients with severe acute pancreatitis. Annals of Nutrition & Metabolism , 53(3–4), 268–275.


    Chang, Y. S., Fu, H. Q., Xiao, Y. M., et al. (2013). Nasogastric or nasojejunal feeding in predicted severe acute pancreatitis: a meta‐analysis. Critical Care (London, England), 17(3), R118.


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


    Wang, G., Wen, J., Xu, L., et al. (2013). Effect of enteral nutrition and ecoimmunonutrition on bacterial translocation and cytokine production in patients with severe acute pancreatitis. The Journal of Surgical Research , 183(2), 592–597.


    Worthington, P., Balint, J., Bechtold, M., et al. (2017). When is parenteral nutrition appropriate? Journal of Parenteral and Enteral Nutrition , 41(3), 324–377.


  5. A 68‐year‐old woman with a history of hypertension, diabetes, and body mass index of 45 is admitted to the intensive care unit after a traumatic brain injury. She is intubated and is expected to remain intubated for the next few days. Which of the following statements is true?

    1. The optimal protein requirement for this patient is 1 g/kg/day.
    2. The caloric intake should not exceed 60–70% of her target energy requirement.
    3. Feeds should be advanced to 100% of target energy requirement within 24–48 hours of admission.
    4. Enteral nutrition should be held until post‐admission day 7.
    5. The caloric intake should be 45 kcal/kg actual body weight/day.

    Initiating early enteral nutrition within 24–48 hours of admission is essential in the critically ill patients who cannot sustain volitional intake, regardless of BMI. Current guidelines recommend high‐protein hypocaloric feeding in obese critically ill patients. Hypocaloric feeding in this patient population may decrease ventilator days and length of stay in the unit while improving insulin sensitivity. The goal of enteral nutrition should not exceed 60–70% of target energy requirement as measured by indirect calorimetry in the obese critically ill patient (answer C is therefore wrong). If indirect calorimetry is not available, 11–14 kcal/kg actual body weight per day should be the goal in order to minimize the metabolic complications of overfeeding. A critically ill patient with a BMI of 30–40 should receive 2 g of protein/kg/day, while patients with a BMI of greater than 40 should receive 2.5 g protein/kg/day as part of an overall hypocaloric feeding regime.


    Answer: B


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


    Jiang, H., Sun, M. W., Hefright, B., et al. (2011). Efficacy of hypocaloric parenteral nutrition for surgical patients: a systematic review and meta‐analysis. Clinical Nutrition (Edinburgh, Scotland) , 30(6), 730–737.


  6. The response to stress and injury consist of three phases: the ebb phase, the catabolic flow phase, and the anabolic flow phase. Which of the following is true:

    1. The anabolic flow phase is driven by cytokine mediators released by lymphocytes and macrophages in the cellular immune reaction, dominated by interleukin‐6 (IL‐6).
    2. The ebb phase is dominated by catabolism, typically lasts 3–10 days, but may last longer.
    3. The catabolic flow phase is dominated by circulatory changes that require resuscitation (with fluid, blood, and blood products) over a period of 8–24 hours.
    4. The ebb phase should be treated with fluid, blood, and blood products.
    5. The catabolic phase emerges as the patient’s metabolism shifts to synthetic activities and reparative processes.

    The response to stress and injury consists of three phases, the ebb phase, the catabolic flow phase, and the anabolic flow phase. Each of these phases has distinct changes that require specific interventions in order to eliminate or minimize the consequences of illness and/or injury. The ebb phase is dominated by circulatory changes that require resuscitation (with fluid, blood, and blood products) over a period of 8–24 hours. The catabolic flow phase, dominated by catabolism, typically lasts 3–10 days, but may last longer. The anabolic flow phase emerges as the patient’s metabolism shifts to synthetic activities and reparative processes. The catabolic flow phase is driven by cytokine mediators released from lymphocytes and macrophages in the cellular immune reaction, dominated by interleukin‐6 (IL‐6). The release of these mediators is proportional to the intensity of the injury, but the release of cytokines themselves is upregulated by hormonal and humoral events. The early nonspecific response to systemic tissue injury that is responsible for the reprioritization of protein synthesis in the liver is termed the acute phase response (APR). Depending on the magnitude and the severity of the injury, APR is characterized by an exponential increase in positive acute phase proteins and a decrease in negative acute phase proteins. The regulation of APR, a complex process, depends on many factors. Tissue injury or infection leads to a local inflammatory response, which in turn leads to the release of many cytokines at the site of inflammation; the cytokines are eventually carried to the liver, where they act on the hepatocytes. Crystalloids, blood, and blood products may be required for the initial resuscitation based on the severity and the magnitude of the injury.


    Answer: D


    Latifi, R . (2011). Nutritional therapy in critically ill and injured patients. Surgical Clinics , 91(3), 579–593.


    Şimşek, T., Şimşek, H. U., & Cantürk, N. Z. (2014). Response to trauma and metabolic changes: posttraumatic metabolism. Ulusal Cerrahi Dergisi , 30(3), 153–159.


    Varela, M. L., Mogildea, M., Moreno, I., & Lopes, A. (2018). Acute inflammation and metabolism. Inflammation , 41(4), 1115–1127.


  7. A 68‐year‐old man presents with perforated cancer of the ascending colon and is in septic shock. He is taken to the operating room for a right hemicolectomy and end‐ileostomy. His NUTRIC score is 3. He remains intubated in the intensive care unit, requiring minimal vasopressor for hemodynamic support. Which of the following statements is true?

    1. Withhold enteral nutrition, initiate parenteral nutrition within the first 7 days of ICU admission
    2. Withhold enteral nutrition, initiate parenteral nutrition after 7 days of ICU admission
    3. Initiate trophic enteral feeds and advance as tolerated
    4. Initiate trophic enteral feeds, supplemented with parenteral nutrition within the first 7 days of admission
    5. Withhold enteral feeds while the patient is on vasopressors

    In the critically ill septic patient, splanchnic perfusion to the bowel is reduced. Patients are therefore at risk for subclinical bowel ischemia, reperfusion injuries, and bowel perforation. This may steer clinicians away from initiating enteral feeds in the septic patient. A recent single‐center retrospective trial of mechanically ventilated patents with septic shock revealed that trophic enteral feeds, while on low‐dose vasopressors, was associated with decreased mortality, duration of mechanical ventilation, and ICU stay. Guidelines recommend considering early enteral nutrition in those undergoing withdrawal of vasopressor support, while monitoring for signs of intolerance (e.g. increasing base deficit or lactate, abdominal distention, decreased passage of flatus, and stool). Enteral nutrition, however, should be avoided in the hemodynamically unstable patient requiring high doses of vasopressors.


    Proper nutrition is essential in the management of trauma and surgical critical care patients. One way to assess the nutritional risk in this patient population is the Nutrition Risk in the Critically Ill (NUTRIC) score. This scoring system is capable of determining nutritional status and disease severity, while linking starvation, inflammation, nutritional status, and outcomes. The system utilizes 6 variables to formulate which patients will benefit more from aggressive protein‐energy provisions, and include age, APACHE II score, SOFA score, number of comorbidities, IL‐6 levels, and days from hospital to ICU admission. Patients with a score of greater than 5 out of a maximum of 10 are most likely to benefit from aggressive nutritional therapy.


    The above patient has a low NUTRIC score and low nutrition risk while on minimal vasopressor support, therefore trophic enteral feeds should be initiated. Supplemental parenteral nutrition should be considered after 7–10 days if unable to achieve >60% of energy and protein requirements by the enteral route alone. If the scenario was different in that the patient was determined to be at high nutrition risk while on high vasopressor support where enteral nutrition was not feasible, then parenteral nutrition should be initiated within 7–10 days of admission.


    Answer: C


    Mancl, E. E., & Muzevich, K. M. (2013). Tolerability and safety of enteral nutrition in critically ill patients receiving intravenous vasopressor therapy. Journal of Parenteral and Enteral Nutrition , 37(5), 641–651.


    McClave, S. A., Taylor, B. E., Martindale, R. G., et al. (2016). 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 (ASPEN). Journal of Parenteral and Enteral Nutrition , 40(2), 159–211.


    Patel, J. J., Kozeniecki, M., Biesboer, A., et al. (2016). Early trophic enteral nutrition is associated with improved outcomes in mechanically ventilated patients with septic shock: a retrospective review. Journal of Intensive Care Medicine , 31(7), 471–477.


  8. A patient with a traumatic brain injury has been receiving enteral nutrition in the ICU for the past week. You are being called because of a gastric residual of 400 mL. Which of the following statements is correct?

    1. Bundled interventions including chlorhexidine mouthwash has been shown to decrease nosocomial respiratory infections.
    2. Head of bed elevated 30–45 degrees, although routine, has not been shown to decrease the incidence of pneumonia.
    3. A gastric residual volume of 350 mL should always prompt cessation of feeds and further evaluation.
    4. Gastric residual volumes correlate well with gastric emptying.
    5. Scheduled monitoring of gastric residual volumes (GRV) should be part of routine care.

    Gastric residual volumes (GRVs) do not correlate well with the incidence of pneumonia, regurgitation, or aspiration. In a trial using a highly sensitive and specific marker for aspiration, GRVs (over a range of 150–400 mL) were shown to be a poor predictor of aspiration. Results from four randomized controlled trials indicate that raising the threshold to stop feeds for GRVs from 50–150 mL to 250–500 mL did not increase the incidence of regurgitation, aspiration, or pneumonia. Current recommendations do not support checking GRVs, and to use a threshold of > 500 mL GRVs to stop enteral nutrition if compelled to do so. Studies in which chlorhexidine oral care was included in bundled interventions showed significant reductions in nosocomial respiratory infections. Elevating the head of the bed 30°–45° was shown in to reduce the incidence of pneumonia from 23 to 5%.


    Answer: A


    Drakulovic, M. B., Torres, A., Bauer, T. T., et al. (1999). Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial. The Lancet , 354(9193), 1851–1858.

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Dec 15, 2022 | Posted by in CRITICAL CARE | Comments Off on Nutrition Support in Critically Ill Patients

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