Personalized nutrition therapy in critical care: 10 expert recommendations.

Personalization of ICU nutrition is essential to future of critical care. Recommendations from American/European guidelines and practice suggestions incorporating recent literature are presented. Low-dose enteral nutrition (EN) or parenteral nutrition (PN) can be started within 48 h of admission. While EN is preferred route of delivery, new data highlight PN can be given safely without increased risk; thus, when early EN is not feasible, provision of isocaloric PN is effective and results in similar outcomes. Indirect calorimetry (IC) measurement of energy expenditure (EE) is recommended by both European/American guidelines after stabilization post-ICU admission. Below-measured EE (~ 70%) targets should be used during early phase and increased to match EE later in stay. Low-dose protein delivery can be used early (~ D1-2) (< 0.8 g/kg/d) and progressed to ≥ 1.2 g/kg/d as patients stabilize, with consideration of avoiding higher protein in unstable patients and in acute kidney injury not on CRRT. Intermittent-feeding schedules hold promise for further research. Clinicians must be aware of delivered energy/protein and what percentage of targets delivered nutrition represents. Computerized nutrition monitoring systems/platforms have become widely available. In patients at risk of micronutrient/vitamin losses (i.e., CRRT), evaluation of micronutrient levels should be considered post-ICU days 5-7 with repletion of deficiencies where indicated. In future, we hope use of muscle monitors such as ultrasound, CT scan, and/or BIA will be utilized to assess nutrition risk and monitor response to nutrition. Use of specialized anabolic nutrients such as HMB, creatine, and leucine to improve strength/muscle mass is promising in other populations and deserves future study. In post-ICU setting, continued use of IC measurement and other muscle measures should be considered to guide nutrition. Research on using rehabilitation interventions such as cardiopulmonary exercise testing (CPET) to guide post-ICU exercise/rehabilitation prescription and using anabolic agents such as testosterone/oxandrolone to promote post-ICU recovery is needed.

Optimizing the nutrition support care model: Analysis of survey data.

BACKGROUND: Malnutrition is underrecognized and underdiagnosed, despite high prevalence rates and associated poor clinical outcomes. The involvement of clinical nutrition experts, especially physicians, in the care of high-risk patients with malnutrition remains low despite evidence demonstrating lower complication rates with nutrition support team (NST) management. To facilitate solutions, a survey was designed to elucidate the nature of NSTs and physician involvement and identify needs for novel nutrition support care models. METHODS: This survey assessed demographics of NSTs, factors contributing to the success of NSTs, elements of nutrition education, and other barriers to professional growth. RESULTS: Of 255 respondents, 235 complete surveys were analyzed. The geographic distribution of respondents correlated with population concentrations of the United States (r = 90.8%, p < .0001). Most responding physicians (46/57; 80.7%) reported being a member of NSTs, compared with 56.5% (88/156) of dietitians. Of those not practicing in NSTs (N = 81/235, 34.4%), 12.3% (10/81) reported an NST was previously present at their institution but had been disbanded. Regarding NSTs, financial concerns were common (115/235; 48.9%), followed by leadership (72/235; 30.6%), and healthcare professional (HCP) interest (55/235; 23.4%). A majority (173/235; 73.6%) of all respondents wanted additional training in nutrition but reported insufficient protected time, ability to travel, or support from administrators or other HCPs. CONCLUSION: Core actions resulting from this survey focused on formalizing physician roles, increasing interdisciplinary nutrition support expertise, utilizing cost-effective screening for malnutrition, and implementing intervention protocols. Additional actions included increasing funding for clinical practice, education, and research, all within an expanded portfolio of pragmatic nutrition support care models.

Barriers to nutrition therapy in the critically ill patient with COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has created challenges for intensivists, as high ventilatory demands and prolonged hypermetabolism make it difficult to sustain nutrition status. The purpose of this survey was to determine current practices in nutrition therapy and identify barriers to its delivery. METHODS: A survey about delivering nutrition therapy to critically ill patients with COVID-19 was sent to clinicians at academic and community hospitals from September to December 2020. RESULTS: Of 440 who viewed the survey, 199 (45%) completed the questionnaire. Respondents were composed of 30%, physicians and 70% registered dietitians, with 51% representing community programs, 43% academic institutions, and 6% Veterans Affairs centers. Half (49%) had protocols for managing critically ill patients with COVID-19, and 21% had a protocol for nutrition therapy. Although most respondents (83%) attempted to feed by the intragastric route, only 9% indicated that energy/protein needs were met. The biggest barriers to delivery of enteral nutrition (EN) involved the patients unpredictable clinical course and fear of aspiration given the lack of respiratory reserve. Intensivists were reluctant to add supplemental parenteral nutrition (PN) because of perceived lack of benefit. CONCLUSION: The survey results would suggest that strategies for nutrition therapy based on the intragastric infusion of EN are unsuccessful in meeting the energy/protein needs of critically ill patients with COVID-19. It is likely these barriers exist in providing nutrition to non-Covid-19 critically ill patients. Intensivists need protocols that optimally deliver intragastric EN, consider early postpyloric infusion, and address adding supplemental PN in a deteriorating nutrition status.

Point-Counterpoint: Indirect Calorimetry Is not Necessary for Optimal Nutrition Therapy in Critical Illness.

Clinicians have widely recognized that indirect calorimetry (IC) is the "gold standard" for measuring energy expenditure (EE) and thus would intuitively anticipate that its use would be needed to provide optimal nutrition support in critical illness. Recent studies in the literature as well as dramatic changes in clinical practice over the past decade, though, would suggest that such a precise measure by IC to set energy goals is not required to maximize clinical benefit from early feeding in the intensive care unit (ICU). Results from randomized controlled trials evaluating permissive underfeeding, use of supplemental parenteral nutrition to achieve tight calorie control, and caloric density of formulas to increase energy delivery have provided an important perspective on 3 pertinent issues. First, a simple weight-based predictive equation (25 kcal/kg/day) provides a clinically useful approximation of EE. Second, a precise measure of EE by IC does not appear to improve outcomes compared with use of this less accurate estimation of energy requirements. And third, providing some percentage of requirements (50%-80%), achieves similar clinical benefit to full feeding (100%) in the early phases of critical illness. The value from IC use lies in the determination of caloric requirements in conditions for which weight-based equations are rendered inaccurate (anasarca, amputation, severe obesity) or the clinical state is markedly altered (such as the prolonged hyperinflammatory state of coronavirus disease 2019 [COVID-19]). In most other circumstances, routine use of IC would not be expected to change clinical outcomes from early nutrition therapy in the ICU.

How to Increase Muscle Mass in Critically Ill Patients: Lessons Learned from Athletes and Bodybuilders.

PURPOSE OF REVIEW: Decades of research on nutrition and exercise on athletes and bodybuilders has yielded various strategies to promote anabolism and improve muscle health and growth. We reviewed these interventions in the context of muscle loss in critically ill patients. RECENT FINDINGS: For critically ill patients, ensuring optimum protein intake is important, potentially using a whey-containing source and supplemented with vitamin D and leucine. Agents like hydroxyl ß-methylbutyrate and creatine can be used to promote muscle synthesis. Polyunsaturated fatty acids stimulate muscle production as well as have anti-inflammatory properties that may be useful in critical illness. Adjuncts like oxandralone promote anabolism. Resistance training has shown mixed results in the ICU setting but needs to be explored further with specific outcomes. Critically ill patients suffer from severe proteolysis during hospitalization as well as persistent inflammation, immunosuppression, and catabolism syndrome after discharge. High protein supplementation, ergogenic aids, anti-inflammatories, and anabolic adjuncts have shown potential in alleviating muscle loss and should be used in intensive care units to optimize patient recovery.

Relevant Nutrition Therapy in COVID-19 and the Constraints on Its Delivery by a Unique Disease Process.

Worldwide, as of July 2020, >13.2 million people have been infected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The spectrum of coronavirus disease 2019 (COVID-19) ranges from mild illness to critical illness in 5% of cases. The population infected with SARS-CoV-2 requiring an intensive care unit admission often requires nutrition therapy as part of supportive care. Although the various societal guidelines for critical care nutrition meet most needs for the patient with COVID-19, numerous factors, which impact the application of those guideline recommendations, need to be considered. Since the SARS-CoV-2 virus is highly contagious, several key principles should be considered when caring for all patients with COVID-19 to ensure the safety of all healthcare personnel involved. Management strategies should cluster care, making all attempts to bundle patient care to limit exposure. Healthcare providers should be protected, and the spread of SARS-CoV-2 should be limited by minimizing procedures and other interventions that lead to aerosolization, avoiding droplet exposure through hand hygiene and use of personal protective equipment (PPE). PPE should be preserved by decreasing the number of individuals providing direct patient care and by limiting the number of patient interactions. Enteral nutrition (EN) is tolerated by the majority of patients with COVID-19, but a relatively low threshold for conversion to parenteral nutrition should be maintained if increased exposure to the virus is required to continue EN. This article offers relevant and practical recommendations on how to optimize nutrition therapy in critically ill patients with COVID-19.

Nutrition Therapy in Critically Ill Patients With Coronavirus Disease 2019.

In the midst of a coronavirus disease 2019 (COVID-19) pandemic, a paucity of data precludes derivation of COVID-19-specific recommendations for nutrition therapy. Until more data are available, focus must be centered on principles of critical care nutrition modified for the constraints of this disease process, ie, COVID-19-relevant recommendations. Delivery of nutrition therapy must include strategies to reduce exposure and spread of disease by providing clustered care, adequate protection of healthcare providers, and preservation of personal protective equipment. Enteral nutrition (EN) should be initiated early after admission to the intensive care unit (ICU) using a standard isosmolar polymeric formula, starting at trophic doses and advancing as tolerated, while monitoring for gastrointestinal intolerance, hemodynamic instability, and metabolic derangements. Intragastric EN may be provided safely, even with use of prone-positioning and extracorporeal membrane oxygenation. Clinicians should have a lower threshold for switching to parenteral nutrition in cases of intolerance, high risk of aspiration, or escalating vasopressor support. Although data extrapolated from experience in acute respiratory distress syndrome warrants use of fiber additives and probiotic organisms, the lack of benefit precludes a recommendation for micronutrient supplementation. Practices that increase exposure or contamination of equipment, such as monitoring gastric residual volumes, indirect calorimetry to calculate requirements, endoscopy or fluoroscopy to achieve enteral access, or transport out of the ICU for additional imaging, should be avoided. At all times, strategies for nutrition therapy need to be assessed on a risk/benefit basis, paying attention to risk for both the patient and the healthcare provider.

Clinical nutrition for the gastroenterologist: the physiologic rationale for providing early nutritional therapy to the hospitalized patient.

PURPOSE OF REVIEW: Conflicting reports in the literature have been misinterpreted by clinicians, who conclude that nutritional therapy for the hospitalized patient is of marginal value. The true benefit of such therapy is derived from the provision of early enteral nutrition. This article describes the physiologic response to enteral feeding, which accounts for the outcome benefits, and illustrates how use of the gut alters immune responses and the intestinal microbiota. RECENT FINDINGS: The provision of early enteral nutrition has been shown to reduce infection and mortality in high-risk hospitalized patients (compared with not providing such therapy). Early feeding maintains gut integrity, reduces permeability, promotes tolerance and appropriate immune responses, and supports commensalism of the intestinal microbiota. Early enteral nutrition influences cross-talk signaling between luminal bacteria and the intestinal epithelium. Failure to utilize the gut in acute illness can amplify the systemic inflammatory response syndrome and worsen disease severity, while at the same time promoting antibiotic resistance and increased septic morbidity. SUMMARY: Appropriate nutritional therapy does change outcomes in the hospitalized patient, especially for those who are at risk on the basis of disease severity and/or poor nutritional status. Greatest benefit is seen from those therapeutic regimens that specifically target gut defenses and the intestinal microbiome.

Mitochondrial Dysfunction in Critical Illness: Implications for Nutritional Therapy.

PURPOSE OF THE REVIEW: This paper will review the evidence for mitochondrial dysfunction in critical illness, describe the mechanisms which lead to multiple organ failure, and detail the implications of this pathophysiologic process on nutritional therapy. RECENT FINDINGS: Mitochondria are particularly sensitive to increased oxidative stress in critical illness. The functional and structural abnormalities which occur in this organelle contribute further to the excessive production of reactive oxygen species and the reduction in generation of adenosine triphosphate (ATP). To reduce metabolic demand, mitochondrial dysfunction develops (a process likened to hibernation), which helps sustain the life of the cell at a cost of organ system failure. Aggressive feeding in the early phases of critical illness might inappropriately increase demand at a time when ATP production is limited, further jeopardizing cell survival and potentiating the processes leading to multiple organ failure. Several potential therapies exist which would promote mitochondrial function in the intensive care setting through support of autophagy, antioxidant defense systems, and the biogenesis and recovery of the organelle itself. Nutritional therapy should supplement micronutrients required in the mitochondrial metabolic pathways and provide reduced delivery of macronutrients through slower advancement of feeding in the early phases of critical illness. A better understanding of mitochondrial dysfunction in the critically ill patient should lead to more innovative therapies in the future.

Factors That Worsen Disease Severity in Acute Pancreatitis: Implications for More Innovative Nutrition Therapy.

The pathophysiologic process of severe acute pancreatitis involves a vicious cycle of inflammation and increasing oxidative stress. Secretory defects trap activated pancreatic enzymes within the gland leading to autodigestion while circulatory abnormalities add the insult of ischemia/reperfusion injury. What may have the greatest impact in amplifying the systemic inflammatory response, though, is intestinal failure with breakdown of gut barrier defenses, subversion of submucosal immune responses, and emergence of a virulent pathobiome. Understanding the intricacies of these changes has broad-reaching implications for nutrition therapy, which should no longer be limited to the provision of early enteral feeding alone. Emerging strategies should attempt to maintain commensalism, bind potential pathogens, refaunate the microbiome, actively turn off inflammation, reset cross-talk signaling with epithelial receptors, and deliver nutrients further down the gastrointestinal tract to the level of greatest microbial burden. Innovative nutrition therapy for the patient with severe acute pancreatitis should be designed to address and include all of these strategies in order to shift the course of clinical outcome toward a pattern of recovery and homeostasis.

Why do current strategies for optimal nutritional therapy neglect the microbiome?

Strategies for providing optimal nutritional therapy have evolved over time, with the emphasis on specific directives (such as route, use of immunonutrition, high protein, organ-specific formulas, etc.), achieving variable degrees of success for improving outcomes in the intensive care unit. As the largest immune organ in the body comprising the largest interface between the host and the external environment, the gut can have an amplifying effect on a pattern of dysbiosis, immune dysregulation, and multiple organ failure seen in the critically ill patient. Conversely, maintenance of gut integrity can serve to restore a pattern of homeostasis, appropriate immune responses, symbiosis, and clinical recovery. Simply providing refined polymeric formulas as enteral nutrition may not take full advantage of the potential for optimal outcome that could be derived by giving therapy designed to directly stimulate gut defenses and support the intestinal microbiota. This article describes a series of strategies (such as use of intact whole food formulas, soluble fiber, fecal microbial transplantation, serum bovine immunoglobulin, or agents to promote commensal behavior) that should modulate the gut microbiome and shift the critically ill patient toward a pattern of health and recovery.

Technical Aspects of Fecal Microbial Transplantation (FMT).

PURPOSE OF REVIEW: Fecal microbial transplantation (FMT) has become established as an effective therapeutic modality in the treatment of antibiotic-refractory recurrent Clostridium difficile colitis. A number of formulations and methods of delivery of FMT are currently available, each with distinct advantages. This review aims to review donor and patient selection for FMT as well as procedural aspects of FMT to help guide clinical practice. RECENT FINDINGS: FMT can be obtained in fresh, frozen, lyophilized, and capsule-based formulations for delivery by oral ingestion, nasoenteric tube, colonoscopy, or enema (depending on the formulation used). Choosing the optimal method relies heavily on patient-related factors, including underlying pathology and severity of illness. As potential applications for FMT expand, careful donor screening and patient selection are critical to minimizing risk to patients and physicians. FMT represents an excellent therapeutic option for treatment of recurrent Clostridium difficile colitis and holds promise as a possible treatment modality in a variety of other conditions. The wide array of delivery methods allows for its application in various disease states in both the inpatient and outpatient setting.

Controversies Surrounding Critical Care Nutrition: An Appraisal of Permissive Underfeeding, Protein, and Outcomes.

Over the past few years, numerous studies have called into question the optimal dose, timing, composition, and advancement rate of nutrition during the early acute phase of critical illness. These studies suggest permissive underfeeding with slow advancement may be more beneficial than aggressive full feeding. These counterintuitive results were possibly explained by enhanced autophagy, less hyperglycemia, or prevention of refeeding syndrome. This review underscores the controversies surrounding permissive underfeeding, aims to answer whether permissive underfeeding is appropriate for all critically ill patients, describes the impact of optimal protein delivery on critical care outcomes, discusses nutrition risk, and cogitates on the impact of nutrition on critical care outcomes.

Will We Ever Agree on Protein Requirements in the Intensive Care Unit?

The precise value of the normal adult protein requirement has long been debated. For many reasons-one of them being the difficulty of carrying out long-term nutrition experiments in free-living people-uncertainty is likely to persist indefinitely. By contrast, the controlled environment of the intensive care unit and relatively short trajectory of many critical illnesses make it feasible to use hard clinical outcome trials to determine protein requirements for critically ill patients in well-defined clinical situations. This article suggests how the physiological principles that underlie our understanding of normal protein requirements can be incorporated into the design of such clinical trials. The main focus is on 3 principles: (1) the rate of body nitrogen loss roughly predicts an individual's minimum protein requirement and is thus essential to measure to identify individual patients and clinical situations in which the minimum protein requirement is importantly increased, (2) existing muscle mass sets an upper limit on the rate at which amino acids can be mobilized from muscle for transfer to central proteins and sites of injury and is thus important to monitor to identify patients who are at greatest risk of protein deficiency-related adverse outcomes, and (3) negative energy balance increases the dietary protein requirement, so calorie-deprived patients-whether obese or not-should be enrolled in hard clinical outcome trials that compare the current practice of "permissive underfeeding" (underprovision of all nutrients, including protein) with hypocaloric nutrition supplemented by a suitably generous amount of protein.

Protein Kinetics and Metabolic Effects Related to Disease States in the Intensive Care Unit.

Evaluating protein kinetics in the critically ill population remains a very difficult task. Heterogeneity in the intensive care unit (ICU) population and wide spectrum of disease processes creates complexity in assessing protein kinetics. Traditionally, protein has been delivered in the context of total energy. Focus on energy delivery has recently come into question, as the importance of supplemental protein in patient outcomes has been shown in several recent trials. The ICU patient is prone to catabolism, immobilization, and impaired immunity, which is a perfect storm for massive loss of lean body tissue with a unidirectional flow of amino acids from muscle to immune tissue for immunoglobulin production, as well as liver for gluconeogenesis and acute phase protein synthesis. The understanding of protein metabolism in the ICU has been recently expanded with the discovery of how the mammalian target of rapamycin complex 1 is regulated. The concept of "anabolic resistance" and identifying the quantity of protein required to overcome this resistance is gaining support among critical care nutrition circles. It appears that a minimum of at least 1.2 g/kg/d with levels up to 2.0 g/kg/d of protein or amino acids appears safe for delivery in the ICU setting and may yield a better clinical outcome.

Critical Care Nutrition: Where's the Evidence?

The surgical critically ill patient is subject to a variable and complex metabolic response, which has detrimental effects on immunity, wound healing, and preservation of lean body muscle. The concept of nutrition support has evolved into nutrition therapy, whereby the primary objectives are to prevent oxidative cell injury, modulate the immune response, and attenuate the metabolic response. This review outlines the metabolic response to critical illness, describes nutritional risk; reviews the evidence for the role, dose, and timing of enteral and parenteral nutrition, and reviews the evidence for immunonutrition in the surgical intensive care unit.

Evidence-Based Support for Nutrition Therapy in Head and Neck Cancer.

PURPOSE OF REVIEW: Patients diagnosed with head and neck (H&N) cancer often present in a malnourished state for varied reasons; nutritional optimization is therefore critical to the success of treatment for these complex patients. This article aims to review the current nutrition literature pertaining to H&N cancer patients and to present evidence-based strategies for nutritional support specific to this population. RECENT FINDINGS: Aggressive nutritional intervention is frequently required in the H&N cancer patient population. Rehabilitating nutrition during operative and nonoperative treatment improves compliance with treatment, quality of life, and clinical outcomes. When and whether to establishing alternative enteral access are points of controversy, although recent evidence suggests prophylactic enteral feeding tube placement should not be universally applied. Perioperative nutritional optimization including preoperative carbohydrate loading and provision of arginine-supplemented immunonutrition has been shown to benefit at-risk H&N cancer patients. SUMMARY: With multidisciplinary collaboration, H&N cancer patients can receive individualized nutritional support to withstand difficult cancer treatment regimens and return to acceptable states of nutritional health.