Enteral Nutrition

Chapter 13 Enteral Nutrition

Laura Eirmann, DVM, Kathryn E. Michel, DVM, MS, DACVN

• The goal of enteral nutrition is to provide the patient with adequate caloric and nutrient intake to prevent the adverse consequences of malnutrition.

• Every critically ill patient must have an assessment performed to determine an appropriate nutrition plan. Patient reevaluation and nutrition plan reassessment need to occur throughout the hospitalization.

• As a general guideline, enteral feeding as far proximal as possible in the gastrointestinal (GI) tract is the preferred route of delivering nutritional support.

• Feasibility of enteral nutrition is based on patient factors such as GI function and ability to protect the airway, as well as nonpatient factors such as cost, predicted length of hospitalization, technical expertise, and level of patient monitoring.

• The daily caloric goal for most critically ill patients will be the resting energy requirement. Evaluating whether a patient achieves this level of intake requires detailed feeding orders and documentation of patient intake.

• Potential complications of enteral nutrition include patient factors such as inadequate intake, GI side effects, metabolic derangements, and infectious complications, as well as nonpatient factors such as mechanical complications related to the feeding device.

INTRODUCTION

The goal of enteral nutrition is to provide the patient with adequate caloric and nutrient intake via the gastrointestinal (GI) tract in order to prevent the adverse consequences of malnutrition. Hospitalized patients frequently have decreased voluntary food intake for many reasons, including nausea, pain, and anxiety. At the same time, critically ill patients have metabolic alterations mediated by catecholamines, corticosteroids, and inflammatory mediators such as interleukin-1 and tumor necrosis factor (TNF)-α, which alter metabolism resulting in a catabolic state.¹ Decreased voluntary intake coupled with a catabolic state places critically ill patients at high risk for malnutrition, necessitating nutritional support. Malnutrition in the critically ill patient leads to depletion of endogenous proteins, which may have serious adverse effects on tissue synthesis, immunocompetence, maintenance of gut integrity, and intermediary drug metabolism.² Malnutrition in humans is associated with increased complication rates, duration of hospitalization, and cost.³ While analogous studies have not been conducted in veterinary medicine to date, it seems reasonable to assume that comparable outcomes would be expected in malnourished veterinary patients.

NUTRITIONAL ASSESSMENT

Intervention begins with a nutritional assessment of the individual patient. The goal is to determine whether the patient is at low, moderate, or high risk for malnutrition. The process begins with a review of the history and medical record. The clinician obtains a comprehensive, detailed dietary history regarding all foods ingested before and during the current illness, including pet foods, table foods, and nutritional supplements. Both a subjective assessment of appetite and an objective determination of the amount of food consumed are recorded. The logistics of feeding management, such as number of meals per day, are noted. The clinician must assess nutritional adequacy because clients frequently feed their pets unbalanced diets during periods of illness to encourage intake. Past or current GI signs should be noted because these may affect the nutritional plan. A thorough medication history is required because some medications affect appetite or nutrient metabolism.

Veterinary patients who have not consumed or are not anticipated to consume their resting energy requirement (RER) for 3 to 5 days or who have lost 10% of usual or optimal body weight (5% for pediatric patients) are at high risk of malnutrition and require nutritional support once their immediate hydration, hemodynamic, acid-base, blood glucose, and electrolyte abnormalities are stabilized.²

A physical examination is performed to assess body weight, body condition, and muscle mass. The clinician should be aware that a patient might have excessive fat stores but low muscle (lean body) mass.⁴ The metabolic derangements of critical illness often lead to a precipitous loss of lean body mass, placing the patient at high risk for protein calorie malnutrition. Careful physical examination may also detect signs of malnutrition such as poor skin or coat quality. Physical examination may reveal abnormalities that preclude certain feeding modalities. For example, facial trauma necessitates enteral feeding that bypasses the oral cavity.

Routinely measured laboratory parameters such as complete blood count, serum biochemistry, and urinalysis are poor indicators of overall nutritional status. However, hypoalbuminemia, anemia, or low blood urea nitrogen (BUN) levels may occur secondary to malnutrition. The underlying disease factors into risk assessment for malnutrition and often dictates several components of the nutrition plan, including route of delivery and the nutrient composition of the diet. Some diseases such as protein-losing enteropathy, protein-losing nephropathy, chylothorax, burns, and draining wounds cause excessive loss of body protein, requiring an aggressive nutrition plan to meet caloric and protein needs. Conversely, a patient with protein intolerance such as hepatic encephalopathy might need a plan to meet the patient’s caloric needs without further elevating nitrogenous wastes in the bloodstream.

History, physical examination, and diagnostic findings determine the patient’s risk for malnutrition. As a general guideline, higher risk patients require a more aggressive nutritional intervention plan and closer monitoring for both positive response and complications of dietary intervention. However, the risk of malnutrition may change over time. Patient reevaluation and nutrition plan reassessment must occur throughout hospitalization.

DETERMINING THE ROUTE OF NUTRITIONAL SUPPORT

Enteral Versus Parenteral

Nutritional support can be delivered via the GI tract (enteral route), via the vasculature (parenteral route), or using a combination of the two. Both routes require a hemodynamically stable patient with no major acid-base or electrolyte abnormalities. The route of nutrient delivery is determined by patient factors such as GI function and ability to protect the airway, and nonpatient factors such as cost, predicted length of hospitalization, technical expertise, and level of patient monitoring. Enteral feeding is preferable to parenteral feeding because it is physiologically sound, less costly, and safer.⁵ The physiologic benefits of enteral feeding include prevention of intestinal villous atrophy, maintenance of intestinal mucosal integrity, which decreases the risk of bacterial translocation, and preservation of GI immunologic function. Contraindications for enteral feeding are uncontrolled vomiting, GI obstruction, ileus, malabsorption or maldigestion, or inability to protect the airway. However, if the patient is unable to protect the airway, the clinician may select a route of nutrient delivery distal to the pharynx or esophagus if the concern is aspiration during swallowing, or distal to the pylorus if the concern is aspiration during vomiting or regurgitation. Figure 13-1 outlines the decision process for selecting an appropriate enteral feeding route.

Figure 13-1 Decision tree for selecting enteral feeding route. GI, Gastrointestinal.

Oral Intake Versus Enteral Feeding Device

When enteral feeding is appropriate, the clinician selects the mode of nutrient delivery, sets a caloric goal, and chooses an appropriate diet. Enteral feeding as far proximal in the GI tract as the patient can tolerate is preferred. Voluntary oral intake has distinct advantages. It requires no special equipment or techniques and allows the owner to participate in patient care. If the oral route is selected, the clinician must write specific feeding orders. The technical staff offers the amount written on the feeding orders and records the amount consumed. The clinician then determines if the nutrition goal was met. If intake does not meet the goal, the clinician reassesses the patient, diet, and environment. The clinician may change the diet (e.g., more palatable diet, warming the food) or change the environment (e.g., quieter ward, owner feeding the pet). Syringe feeding a liquid or blenderized pet food may be attempted for 1 to 2 days but frequently becomes too stressful and time consuming. If the patient shows any signs of nausea, oral feeding should be discontinued immediately, because this can lead to a learned food aversion. Medication to ameliorate nausea and an alternative feeding method should be considered.

An enteral feeding tube removes the variable of voluntary intake. The technical staff delivers a prescribed amount of a specific diet via the feeding tube according to orders written by the veterinarian. These tubes are well tolerated by veterinary patients. A retrospective owner survey concluded that owners were comfortable managing their cats at home with esophagostomy and percutaneous endoscopic gastrostomy tubes.⁶ However, enteral feeding device placement usually requires sedation or anesthesia and technical skill. Technicians and owners must be taught how to use feeding devices and monitor for complications. Table 13-1 outlines advantages and disadvantages of the various forms of enteral access used in veterinary patients.

Table 13-1 Advantages and Disadvantages of Enteral Feeding Devices

Enteral Feeding Device	Advantages	Disadvantages
NE or NG tube	Ease of placement No general anesthesia NG tube allows for gastric decompression	Limited to liquid diets Short term (<14 days) Can be irritating; requires E-collar Can dislodge if patient sneezes or vomits Contradicted in facial trauma or respiratory disease Increased risk of vomiting with NG vs NE tube
Esophagostomy tube	Blenderized pet foods or liquid diets can be used Well tolerated by patient Ease of placement Can feed as soon as patient awakens from anesthesia Can be removed at any time Good long-term option	Requires general anesthesia Risk of cellulitis or infection at site Can dislodge if patient vomits Can cause esophageal irritation or reflux if malpositioned
Gastrostomy tubes	Blenderized pet foods or liquid diets can be used Well tolerated by patient Good long-term option	Requires general anesthesia Risk of cellulitis or infection at site Risk of peritonitis Must wait 24 hours after placement before feeding Must wait 10 to 14 days before removing
Jejunostomy tube	Requires liquid diet Able to feed distal to pylorus and pancreatic duct	Requires general anesthesia Technically more difficult to place Risk of cellulitis or infection at site Risk of peritonitis Risk of tube migration with secondary GI obstruction Must wait 24 hours after placement before feeding Requires CRI feeding Requires very close monitoring Short-term option

CRI, Constant rate infusion; GI, gastrointestinal; NE, nasoesophageal; NG, nasogastric.

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Tags: Small Animal Critical Care Medicine

Sep 10, 2016 | Posted by admin in SMALL ANIMAL | Comments Off

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