The Importance of Nutrition as an Integral Part of Disease Management

R. F. Meier, B. R. Reddy, P. B. Soeters

• Editore: S. Karger
• Anno: 2015
• ISBN:
  9783318054996
• Argomento: Medicine
• Categoria: Nutrition, Dietics & Bariatrics

Although of vital importance, nutrition is still a neglected issue in medical curricula - a fact that this book is aiming to remedy by addressing topics ranging from basic physiology to the implementation of nutritional practices in the hospital as well as in the home setting. Papers discuss the morbidity and mortality caused by malnutrition, the nutritional requirements as well as beneficial effects on the gut of enteral nutrition, the noncaloric benefits of fibers or nutritional support during cancer treatment. Also considered are nutritional therapy for critically ill patients, perioperative nutritional intervention, management of the metabolic syndrome, the biological value of protein, the benefits and hazards of parenteral nutrition in patients with intestinal failure, and the role of nutrition in frailty of aged people.

Meier RF, Reddy BR, Soeters PB (eds): The Importance of Nutrition as an Integral Part of Disease
Management. Nestlé Nutr Inst Workshop Ser, vol 82, pp 103-116, (DOI: 10.1159/000382007)
Nestec Ltd., Vevey/S. Karger AG., Basel, © 2015

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Nutritional Therapy for Critically Ill Patients

Robert G. Martindale^a · Malissa Warren^a · Sarah Diamond^b · Laszlo Kiraly^a

Departments of ^aSurgery and ^bGastroenterology, Oregon Health and Science University, Portland, OR, USA

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Abstract

Nutrition therapy provided early in the critical care setting has been shown to improve outcome. Appropriate and early nutrition interventions can attenuate the hyperdynamic systemic response and depressed immune reaction to injury, serious illness and major surgery. Controversies limit the uniform application and potential benefits of nutrition, including failure to accurately predict who will ‘need’ nutritional intervention, lack of consensus on what the optimal enteral formulation is, overreliance on parenteral nutrition, failure to maximize the use of early enteral nutrition (EN), and how much and how best to feed the morbidly obese population. Despite challenges and inconsistencies in today's critical care setting, specialized nutrition has evolved from metabolic ‘support’ during critical illness to a primary therapeutic intervention designed, individualized and focused to achieve metabolic optimization and mitigation of stress-induced immune and hyperdynamic systemic responses. Nutrition should be considered early and commenced after initial resuscitation has taken place. This is most effectively accomplished with the use of protocols that aggressively promote early EN, and will result in lower mortality and a reduction in major complications. Though the complexity of the heterogeneous critically ill population will always be challenging, we are developing a better understanding of immunity, metabolic needs and catabolism associated with intensive care unit admissions.

© 2015 Nestec Ltd., Vevey/S. Karger AG, Basel

Introduction

Nutrition therapy provided early in the critical care setting has been shown to improve outcome [1, 2]. Appropriate intervention can attenuate the hyperdynamic systemic response and depressed immune reaction to injury, serious illness and major surgery. Not all intensive care unit (ICU) patients will derive similar benefits, nor tolerate prolonged periods of starvation or underfeeding. One of the main criticisms of aggressive nutritional interventions in the ICU is that not all ICU patients need it. In fact, previously well-nourished patients with a mild degree of critical illness and a relatively short stay in the ICU may derive little or no benefit from nutritional intervention. Most patients admitted at moderate-to-severe nutritional risk, however, should realize benefits from early enteral nutrition (EN) and could be harmed by ongoing prolonged iatrogenic underfeeding [3].

Controversies limit the uniform application of nutritional interventions, including failure to accurately predict who will ‘need’ it, lack of consensus of the optimal enteral formulation, overreliance on parenteral nutrition (PN), failure to maximize use of early enteral feeding, and how much and how best to feed the morbidly obese population. Recent studies on trophic feeding have been misinterpreted to imply that nutrition therapy is not important in the first week of hospitalization following ICU admission [4-6]. Across the globe, most ICUs fail to take steps to identify degrees of nutrition risk, determine the need for nutrition therapy or implement protocols to optimize delivery of the nutrition regimen. There are a number of modifiable factors that will determine whether or not benefits are realized, including the route of delivery, dosing, timing, content of nutrient substrate, interruptions in delivery and efforts to promote patient mobility [3]. Nonmodifiable factors include age, gender and genetics.

Despite challenges and inconsistencies in today's critical care setting, specialized nutrition has evolved from metabolic ‘support’ during critical illness to a primary therapeutic intervention designed, individualized and focused to achieve metabolic optimization and mitigation of stress-induced immune and hyperdynamic systemic responses.

Enteral Nutrition Therapy

Historically, multiple reports have shown the significant physiologic value of EN over PN delivery (table 1) [7]. EN should be started as soon as possible, i.e. following admission to the ICU, to establish its nonnutritional, immunologic benefits and minimize the protein-calorie debt that frequently occurs during the 1st week of critical illness [8]. Nonnutritional benefits are described as the physiologic mechanisms that maintain structural and functional gut epithelial integrity [9], attenuate oxidative stress, maintain humoral immunity and modulate the metabolic response [10-12]. By modulating the metabolic response, EN supports optimal carbohydrate utilization thereby decreasing insulin resistance [3].

Table 1. Advantages of EN over PN

Gastrointestinal benefits of EN

Maintains gut integrity

Reduced gut/lung axis of inflammation

Enhances motility/contractility

Improves absorptive capacity

Maintains gut-associated lymphoid tissue

Supports and maintains commensal bacteria

Reduces virulence of endogenous pathogenic organisms

Promotes the production of secretory IgA

Promotes trophic effects on epithelial cells

Immune benefits of EN

Modulates key regulatory cells to enhance systemic immune function

Promotes dominance of anti-inflammatory Th-2 over proinflammatory Th-1 responses

Influences anti-inflammatory nutrient receptors in the gastrointestinal tract (duodenal, vagal and colonic butyrate)

Maintains mucosa-associated lymphoid tissue at all epithelial surfaces (lung, liver, lacrimal, genitourinary and pulmonary)

Modulates adhesion molecules to attenuate transendothelial migration of macrophages and neutrophils

Metabolic benefits of EN

Promotes insulin sensitivity through stimulation of incretins

Reduces hyperglycemia (advanced glycation end products), and muscle and tissue glycosylation

Attenuates stress metabolism to enhance more physiologic fuel utilization

More obvious nutritional benefits are obtained from the delivery of exogenous nutrients that provide sufficient protein and energy substrates and deliver micronutrients and antioxidants, and other specialized nutrients that aid in the attenuation of metabolic responses to stress. Overarchingly, maintaining lean body mass is the primary goal of successful nutrition intervention (table 1).

Patients receiving early EN versus PN consistently suffer fewer infections and have fewer hospital and ICU days. In some studies, a decrease in mortality has also been reported [13-16]. Randomized controlled trials of early versus delayed EN (e.g. feeding after 72 h) have shown that EN started within the first 24-48 h reduces infection, hospital length of stay (LOS) and mortality [1, 17]. When comparing early EN to ‘standard therapy’ (i.e. no supplemental nutrition) in elective surgical and surgical ICU populations, patients receiving EN initiated the day after surgery experienced similar results [13-15]. In observational cohort studies, early initiation of feeding prevents an caloric deficit, and improves outcomes in ICU [8, 18]. When a caloric deficit exceeds 4,000-10,000 calories, a rise in complications, including organ failure and infection occur. Other outcomes, including hospital LOS and ICU LOS, also worsen [18-21]. Studies that include protocols to increase the delivery of nutrient and energy to the ICU population improve clinical outcomes, with decreases in infection, shorter hospital LOS and decreased mortality compared to those without an EN protocol [22-26].

Determining patient candidacy for early EN is challenging; not all critically ill patients are appropriate candidates. Patients with minimal metabolic or traumatic stress should not be fed enterally. For example, aggressive, early EN would be inappropriate in patients expected to regain adequate, volitional oral intake within 48-72 h. Additionally, patients with absolute contraindications to EN (e.g. complete bowel obstruction or bowel discontinuity) should not be fed enterally. Nutritionally high-risk patient populations benefit most from early enteral feeds, including those malnourished prior to ICU admission, patients with sepsis, systemic inflammatory response syndrome, persistent inflammatory catabolism syndrome, immunosuppression and catabolism syndrome, and those expected to have a prolonged ICU stay [27-30]. This population should begin enteral feeding as soon as possible after admission. On rare occasions, they may need supplemental PN [31, 32]. If necessary, small bowel feeding should be considered, as well as the use of prokinetic agents to improve tolerance.

While little controversy surrounds the importance of supplemental nutrition for the nutritionally high-risk patient, assessment remains challenging. Nutritional assessment in the ICU population is often inappropriately judged by the use of visceral protein levels, such as albumin and prealbumin [10]. These serum tests are at best surrogate markers and seldom, if ever, of any clinical use in the ICU setting. A...