Chapter 073. Enteral and Parenteral Nutrition (Part 3)

Efficacy of SNS in Different Disease StatesEfficacy studies have shown that malnourished patients undergoing major thoracoabdominal surgery benefit from SNS. Critical illness requiring ICU care including major burns, major trauma, severe sepsis, closed head injury, and severe pancreatitis [positive CT scan and Acute Physiology and Chronic Health Evaluation II (APACHE II) 10] all benefit by early SNS, as indicated by reduced mortality and morbidity. In critical illness, initiation of SNS within 24 h of injury or ICU admission is associated with a ~50% reduction in mortality. Patients with nitrogen accumulation disorders of renal and hepatic failure have a...
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Chapter 073. Enteral and Parenteral Nutrition (Part 3) Chapter 073. Enteral and Parenteral Nutrition (Part 3) Efficacy of SNS in Different Disease States Efficacy studies have shown that malnourished patients undergoing majorthoracoabdominal surgery benefit from SNS. Critical illness requiring ICU careincluding major burns, major trauma, severe sepsis, closed head injury, and severepancreatitis [positive CT scan and Acute Physiology and Chronic HealthEvaluation II (APACHE II) > 10] all benefit by early SNS, as indicated byreduced mortality and morbidity. In critical illness, initiation of SNS within 24 hof injury or ICU admission is associated with a ~50% reduction in mortality.Patients with nitrogen accumulation disorders of renal and hepatic failure have alikelihood of PCM of >50% and at least a moderate SRI. Improvements inmorbidity, including infection rates, encephalopathy, liver or renal function, andlength of hospital stay have been found with SNS. Inflammatory bowel disease—including Crohns disease particularly, and, to a lesser degree, ulcerative colitis—often produce PCM. In the outpatient setting, SNS in Crohns disease can improvenutritional status, quality of life, and the likelihood of remission. With pulmonarydisease in the critically ill, SNS improves ventilatory status, and in acute lunginjury the use of omega 3 fats as a component of SNS improves gas exchange andrespiratory dynamics and reduces the need for mechanical ventilation. Low bodyweight in chronic obstructive pulmonary disease is associated with diminishedpulmonary status and exercise capacity and higher mortality rates. However, thereis little convincing evidence that SNS as caloric supplementation improvesnutrition or pulmonary function. PCM is also common in the course of cancer andHIV disease, although less so in the latter with the advent of highly activeantiretroviral therapy. When PCM develops as a consequence of SRI in theseconditions, there is limited likelihood of substantial efficacy or benefit from SNS.However, when PCM develops as a consequence of gastrointestinal dysfunction,SNS can be effective. Although no randomized trials have been performed forSNS provided for hyperemesis gravidarum, there is considerable clinical evidencethat it improves pregnancy outcomes. Risks and Benefits of Specialized Nutrition Support The risks are determined primarily by patient factors such as state ofalertness, swallowing competence, the route of delivery, underlying conditions,and the experience of the supervising clinical team. The safest and least costlyapproach is to avoid SNS by close attention to oral food intake, by adding an oralliquid supplement, or in certain chronic conditions by using medications tostimulate appetite. Nutrient intake monitoring by frequent calorie counts or oralformula selection is best performed by a nutritionist. Enteral tube feeding is often required in patients with anorexia, impairedswallowing, or bowel disease. The bowel and its associated digestive organsderive 70% of their required nutrients directly from food in the lumen. Arginine,glutamine, short-chain fatty acids, long-chain omega 3 fatty acids, and nucleotidesavailable in some specialty enteral formulas are particularly important formaintaining immunity. Enteral feeding also supports gut function by stimulatingsplanchnic blood flow, neuronal activity, IgA antibody release, and secretion ofgastrointestinal hormones that stimulate gut trophic activity. These factors supportthe gut as an immunologic barrier against enteric pathogens. For these reasons,some luminal nutrition should be provided, even when PN is required to providemost of the nutritional support. The combination of some enteral feeding either bymouth or by enteral tube with parenteral feeding often shortens the transition tofull enteral feeding, which can generally be used when >50% of requirements canbe met enterally. Substantial nutritional benefit can be achieved by providing~50% of energy needs for periods of up to 10 days, if protein and other essentialnutrient requirements are met. For longer periods of time, it may be preferable toprovide 75–80% of energy needs, rather than full feeding, if this improvesgastrointestinal tolerance, glycemic control, and avoidance of excess fluidadministration. In the past, bowel rest through PN was the cornerstone of treatment formany severe gastrointestinal disorders. However, the value of providing evenminimal amounts of EN is now widely accepted. The development of protocols tofacilitate more widespread use of EN include initiation within 24 h of ICUadmission; aggressive use of the head-upright position; postpyloric andnasojejunal feeding tubes; prokinetic age ...