- Email: [email protected]
Enteral Nutrition
CHAPTER 129 ENTERAL NUTRITION Laura Eirmann,
DVM, DACVN • Kathryn
E. Michel,
KEY POINTS • 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 (RER). 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.
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 (see later). Hospitalized patients often have decreased caloric intake for many reasons, including patient factors such as nausea, pain, and anxiety and nonpatient factors such as poorly written feeding orders. 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-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 GI tract integrity, and intermediary drug metabolism.2 Malnutrition in humans is associated with increased complication rates, duration of hospitalization, and cost.3 Extensive studies have not been conducted in veterinary medicine, but in one prospective study, puppies with parvoviral enteritis receiving early enteral nutrition showed earlier clinical improvement and significant weight gain compared with puppies who remained NPO until vomiting ceased for 12 hours.4 Two retrospective studies also provide evidence for nutritional support in veterinary medicine. One study demonstrated a positive association between energy intake and hospital discharge.5 The second retrospective made a positive association between dogs with septic peritonitis receiving early enteral or parenteral support and a shorter length of hospitalization.6
DVM, MS, DACVN
DETERMINING THE ROUTE OF NUTRITIONAL SUPPORT Enteral Versus Parenteral Nutritional support can be delivered via the GI tract (enteral route), intravenously (parenteral route), or using a combination of the two. Hypotensive or hypothermic patients likely have poor gut motility and perfusion and so should first be stabilized before initiating enteral feeding. 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 more physiologic, less costly, and safer.7 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 129-1 outlines the decision process for selecting an appropriate enteral feeding route.
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 often 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. Appetite stimulants such as cyproheptadine or mirtazapine may be considered after careful patient assessment. The effectiveness of the treatment must be closely monitored by recording daily caloric intake and any possible side effects. Pharmacologic stimulation of appetite does not replace the need for daily nutritional assessment nor negate consideration of enteral feeding devices. If adequate intake is not achieved or side 681
682
PART XIV • NUTRITION No
Is patient hemodynamically and metabolically stable?
Stabilize patient
Yes
Can patient protect airway and is GI tract functional?
No
Consider parenteral nutrition
Yes
Will patient voluntarily eat?
Yes
Write feeding orders, monitor intake and reassess
Yes
No
Does patient have facial trauma or respiratory disease?
No
Can patient undergo general anesthesia?
No
No
Yes Consider NE/NG tube
Can patient tolerate feeding above the pylorus?
Can patient tolerate feeding distal to duodenum?
No
Yes
Yes Does patient have a functional esophagus? Yes
No
Does patient have normal gastric function?
Consider J-tube
Yes
Consider E-tube
Consider G-tube FIGURE 129-1 Decision tree for selecting enteral feeding route. CRI, Constant rate infusion; GI, gastrointestinal; NE, nasoesophageal; NG, nasogastric; E, esophagostomy; G, gastrostomy; J, jejunostomy..
effects occur, the plan must be revised to meet the patient’s nutritional needs. 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 and, when anticipated, can be placed while the patient is sedated or anesthetized for a diagnostic or therapeutic procedure. A retrospective
owner survey concluded that owners were comfortable managing their cats at home with esophagostomy and percutaneous endoscopic gastrostomy tubes.8 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 129-1 outlines advantages and disadvantages of the various forms of enteral access used in veterinary patients.
CHAPTER 129 • Enteral Nutrition
Table 129-1 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 NG tube may create incompetence of lower esophageal sphincter
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
Able to feed distal to pylorus and pancreatic duct
Requires general anesthesia Limited to liquid diets 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.
FIGURE 129-2 Placement of a nasoesophageal tube in a dog. Note that the nose is being pushed upward to facilitate passage of the tube into the ventral meatus.
ENTERAL FEEDING TUBES Nasoesophageal or Nasogastric Tubes A 3.5 to 8 Fr silicone or polyurethane feeding tube may be placed through the nares into the distal esophagus (nasoesophageal [NE]) or into the stomach (nasogastric [NG]) (Figure 129-2). NE tubes have historically been recommended because the risk of gastric reflux increases if the tube passes through the lower esophageal sphincter, compromising sphincter competence. However, one small retrospective study failed to demonstrate a difference in recorded complication rates between a group of dogs fed via NE versus NG tubes.9 NG tubes
allow for gastric decompression and measurement of gastric residual volume. Radiographic confirmation of correct placement for all tube types is recommended. An advantage of NE and NG tubes is that they can be placed easily using a local anesthetic or light sedation.10 This is a good option for patients that are poor candidates for general anesthesia. Facial trauma or coagulopathy may preclude placement of this type of tube, and it should not be used in patients with respiratory disease because it may exacerbate respiratory compromise by occluding a nares. Any patient that receives enteral nutrition must have a functional GI tract and the ability to guard the airway if vomiting or regurgitation occurs. Because only small-bore tubes are used, diet selection is limited to liquids. NE and NG tubes are best for short-term (7 to 14 days) feeding because they can be irritating. An Elizabethan collar (E-collar) and close monitoring are required because the pet may attempt to dislodge the tube. In addition, sneezing or vomiting may dislodge the tube, requiring reassessment for correct placement. Complications associated with NE or NG tubes include epistaxis, rhinitis, sinusitis, dacryocystitis, inadvertent placement or dislodgement of the tube into the airway, esophageal irritation, reflux, or clogging of the tube. One prospective11 and two retrospective12,13 studies evaluating nasoenteric feeding tubes compared bolus versus constant rate infusion and reported differing results with respect to time required to achieve targeted caloric intake. However, all three studies concluded that the nasoenteral feeding was well tolerated.
Esophagostomy Tube A larger feeding tube (usually a 12 to 14 Fr tube for cats and up to a 22 Fr for larger dogs) can be placed in the proximal esophagus at the mid-cervical level, with the tip positioned in the distal esophagus (Figure 129-3). The esophagostomy tube (E-tube) has several
683
684
PART XIV • NUTRITION
to 14 days or longer in more severely compromised or malnourished patients. Major complications associated with G-tubes include abdominal visceral injury during percutaneous placement or peritonitis if stomach contents leak into the abdominal cavity secondary to tube displacement or dehiscence. As with any surgically placed feeding device, cellulitis or infection at the stoma site is possible. Pressure necrosis can occur if the external flange places too much pressure on the stoma site. Improperly placed G-tubes may cause a pyloric outflow obstruction. A G-tube requires closer monitoring and is more costly than techniques previously described.
Jejunal Tubes
FIGURE 129-3 A cat with an esophagostomy tube in place.
advantages. Veterinary patients appear to tolerate them quite well. They can be used for fairly long periods (weeks to months) in both the hospital and outpatient settings. The larger tube allows for a wider selection of diets, including blenderized canned pet foods. The tube can be used in patients with facial or oral disease that precludes NE tube placement. As with the NE tube, the patient must have normal GI function, including normal esophageal function and the ability to protect the airway. Placement of this tube requires general anesthesia and technical skill, although the procedure is relatively simple and well described.14-18 E-tubes can be used for feeding as soon as the patient recovers from anesthesia and can be removed by the clinician when the patient has resumed adequate voluntary intake. Risks associated with E-tubes include placement in the airway or mediastinum, pneumomediastinum, pneumothorax, and damage to cervical vascular structures or nerves. As with the NE tube, a lateral radiograph should be taken to verify placement. Complications after placement include cellulitis or infection at the tube site, patient dislodgement, esophageal irritation and reflux, displacement during vomiting or regurgitation, and clogging of the tube.
Gastrostomy Tube Larger (usually 16 to 22 Fr mushroom-tipped) feeding tubes can be placed directly in the stomach via surgical placement,2,19 endoscopic guidance,2,20 or blind technique using a gastrostomy tube placement device.2,21 All techniques require longer time under anesthesia and more technical skill than is needed for E-tube placement. The percutaneous endoscopic gastrostomy and blind technique avoid doing a laparotomy, but if the patient is undergoing abdominal surgery, surgical placement is preferable because the surgeon can visualize placement and “-pexy” the stomach to the abdominal wall. Endoscopic placement is preferred over a blind technique because it allows visualization of the gastric placement site and decreases the risk of iatrogenic injury to abdominal viscera during placement.18 The gastrostomy tube (G-tube) provides nutrients distal to the esophagus, providing enteral feeding to patients with esophageal disease. The G-tube is well tolerated, permits bolus meal feedings, and is appropriate for long-term at-home feeding.8,22 As with the E-tube, the option of blenderized pet foods allows a wider diet selection. The patient must tolerate feeding above the pylorus without vomiting. The tube cannot be used for the first 24 hours after placement to allow return of gastric motility and formation of a fibrin seal at the stoma. The tube should not be removed until the stomach has adhered to the body wall to prevent stomach content leakage and secondary peritonitis. The tube is typically left in place for at least 10
A small-bore feeding tube (usually 5 to 8 Fr) can be placed directly in the proximal jejunum (J-tube). Nasojejunal, gastrojejunal, and jejunostomy tubes permit enteral feeding distal to the pylorus for patients unable to tolerate gastric feedings. Indications include gastroparesis, uncontrolled vomiting, proximal GI obstruction (i.e., secondary to neoplasia), massive proximal GI resection, and inability to protect the airway. Jejunal feeding is often recommended for the treatment of acute canine pancreatitis to decrease stimulation of pancreatic secretion, although early enteral feeding proximal to the pylorus may be well tolerated in these patients.23 A J-tube can be placed surgically during laparotomy or laparascopy,24-27 and transpyloric placement techniques via nasojejunal or gastrojejunal feeding tubes using surgical, endoscopic, or fluoroscopic techniques have been described.27-33 Surgical placement allows visualization of tube position and a pexy of the bowel to the abdominal wall. Transpyloric techniques are less invasive, with nasojejunal tubes eliminating the risk of bowel content leakage into the peritoneum. However, transpyloric placement requires advanced technical skill and either endoscopic or fluoroscopic guidance. J-tubes can be used for a moderately short period (days to weeks). Surgically placed J-tubes placed using the purse string, inverted serosal, or simple jejunopexy techniques or endoscopically placed gastrojejunal tubes cannot be removed for a minimum of 5 to 7 days, until a fibrin seal has formed at the body wall, to avoid the risk of peritonitis. The small diameter of J-tubes limits diet selection to liquids. To minimize the risk of abdominal cramping and vomiting, constant infusion is preferred over bolus feeding. This requires more diligent patient monitoring and does not allow for at-home feeding under most circumstances. Complications associated with J-tubes include peristomal cellulitis or infection, peritonitis secondary to leakage, retrograde migration of the J-tube, intestinal obstruction secondary to tube migration, and clogging of the tube.
DETERMINING THE AMOUNT TO BE FED Hospitalized patients should initially be fed to meet the RER, defined as the amount of energy (calories) needed to maintain homeostasis in the fed state in a thermoneutral environment.2 “Illness factors” are no longer widely used in critical care nutrition.34 Calorimetry is not used in the clinical veterinary setting, so estimates of RER can be calculated by allometric formulas such as 70(BWkg)0.75. Calculations for obese patients should be based on optimal body weight to prevent overfeeding. Calculations for growing puppies and kittens start with an initial caloric goal of RER to ensure tolerance. However, as with any patient, the pediatric patient must have frequent assessments. Caloric intake may need to be increased, especially if hospitalization is prolonged, provided the patient is tolerating the prescribed feeding amount. All patients must be reassessed to see if the initial caloric estimate is appropriate. The goal during hospitalization is to maintain body weight (excluding fluctuations as a result of hydration status) and lean body mass. Overfeeding is associated with GI and
CHAPTER 129 • Enteral Nutrition
metabolic complications. Certain disease conditions such as sepsis, head trauma, increased muscle activity (e.g., tremors, seizures) or burns may require increased caloric intake if the previously stated goals are not met by RER. In patients with prolonged anorexia, gastrointestinal compromise, or metabolic derangements, the caloric goal should be achieved over several days. Typical feeding protocols might provide 25% to 50% RER on day 1, with the goal of reaching full RER over the next 1 to 3 days.
SELECTING THE DIET Patient Variables Highly digestible nutrients from high-quality sources should be selected for critical care patients. A patient with a poor appetite may benefit from a more calorie-dense diet because a smaller volume of food will meet the caloric goal. A more calorie-dense slurry may also be indicated for patients who are volume intolerant such as those at risk of congestive heart failure. The clinician must determine if any macronutrients or micronutrients should be altered because of the patient’s disease condition. For example, enteral protein intake should be 4 to 6 g of protein per 100 kcal (15% to 25% of total energy) for dogs and 6 g or more of protein per 100 kcal (25% to 35% of total energy) for cats.34 Certain disease conditions, such as hepatic encephalopathy, may require the clinician to select diets closer to the minimum protein requirement to help prevent worsening of the clinical signs of encephalopathy. However, when a lower protein diet is fed, adequate calorie and protein intake is essential in order to minimize the risk of protein malnutrition. Conversely, disease conditions associated with a high degree of protein loss may require a diet replete with protein. Other examples of nutrient modulation include sodium in patients with congestive heart failure and fat in patients with hyperlipidemia, canine pancreatitis, and GI diseases leading to fat malassimilation. Certain patients with known dietary hypersensitivities may need to avoid products containing certain ingredients. In addition to veterinary enteral products, there is a vast array of enteral products formulated for humans. However, these formulas typically are not balanced for veterinary patients and often require modification such as additional protein, arginine, taurine, and B vitamins for cats.
Nonpatient Variables Nonpatient variables contribute to diet selection. Small-diameter NE, NG, or J-tubes require liquid diets. Financial constraints and cost of diets may factor into the selection process. Choices are limited by availability (i.e., the hospital inventory) and the clinician’s knowledge of various products.
MONITORING THERAPY Nutritional assessment should occur at least daily. The clinician reviews past feeding orders to determine if the appropriate diet plan was instituted and if the patient achieved the set goals. If the patient did not meet the dietary goal, the clinician must determine whether the cause was related to patient issues (e.g., nausea, unpalatable diet) or nonpatient issues (e.g., improperly written orders, orders not followed, feeding withheld for procedures). The clinician then updates the plan. Patients unable to meet desired nutritional goals enterally may benefit from supplemental parenteral nutrition (see Chapter 130).35 Monitoring of body weight (at least every 12 to 24 hours), hydration status, and laboratory values such as blood glucose, total solids, triglycerides, serum lipemia, blood urea nitrogen, and electrolytes must be done to assess the response to, or complications from, dietary intervention. The frequency and specifics of monitoring depend on the patient’s disease condition, the mode of dietary
intervention, and financial constraints. Patients that are critically ill and those receiving aggressive dietary intervention require the closest monitoring.
PREVENTING AND MANAGING COMPLICATIONS Patient-Related Complications Many feeding complications can be prevented by proper patient evaluation, selection of the appropriate route and amount of nutrient delivery, an understanding of the risks associated with the specific feeding plan, and close patient monitoring. Most enteral feeding complications are minor, but aspiration, premature dislodgement of a gastrostomy or enterostomy tube, and certain metabolic abnormalities can be life threatening.36 GI intolerance may manifest as vomiting, diarrhea, or ileus. This complication can compromise the ability to continue enteral feeding. The clinician should assess the feeding plan to confirm that daily intake does not exceed the patient’s energy requirements (approximately RER in most cases) and that the day’s feeding is divided into multiple small meals. Food should be warmed to body temperature for tube feeding. The patient’s disease condition or medications may contribute to nausea, vomiting, ileus, or diarrhea. Altering medications or providing antiemetics or prokinetic agents may allow for continued enteral feeding. Metabolic complications can arise if a patient is unable to assimilate certain nutrients. For example, a patient with glucose intolerance may need a dietary formulation low in simple carbohydrates to modulate hyperglycemic episodes. Anticipating specific intolerances during nutritional assessment and setting conservative caloric goals will minimize the risk.36 Refeeding syndrome is a life-threatening metabolic complication that may occur in patients after prolonged anorexia or in certain catabolic states, such as hepatic lipidosis. In this syndrome, upon reintroduction of feeding, there is a rapid shift of key intracellular electrolytes from the vascular to the intracellular space causing life-threatening hypokalemia, hypophosphatemia, or hypomagnesemia. This electrolyte abnormality can occur within days of resuming enteral (or parenteral) feeding.37 At-risk patients should be fed conservative amounts initially with close monitoring and correction of any electrolyte abnormalities via parenteral or enteral replacement. Aspiration is a potentially life-threatening complication that can be minimized by careful patient selection and close monitoring. Infections may occur at the peristomal site, along fascial planes, or within the peritoneum. Infectious complications can be minimized with proper tube placement, careful monitoring of tube sites, and basic hygiene during the preparation and delivery of food.
Non–Patient-Related Complications Mechanical complications include obstructed tubes or tube migration. Clogging can be prevented by proper management such as flushing with warm water before and after every use. One should avoid using the feeding tube to administer medications. If the tube becomes obstructed, flushing with warm water under alternating pressure and suction may dislodge the debris.38 Assessment of various solutions to dissolve in vitro feeding tube clogs caused by a veterinary critical care diet revealed that the injection of a solution of 1 4 tsp pancreatic enzyme and 325 mg sodium bicarbonate in 5 ml warm water was most effective.38 Proper technique in placing and suturing tubes will minimize the risk of tube migration and dislodgement. E-collars, bandages, and patient monitoring help prevent the patient from removing a tube. The tube should be marked with indelible ink where it exits the body so that migration can be detected. Radiographs should be performed to confirm placement of NE, NG, and E-tubes, especially if tube migration is suspected. If leakage of enteral contents into the peritoneum is suspected, a water-soluble contrast
685
686
PART XIV • NUTRITION
study can also be performed. Dislodged or migrated tubes should never be used for feeding without verifying placement.
REFERENCES 1. Thatcher CD: Nutritional needs of critically ill patients, Compend Contin Educ Vet Pract 18:1303, 1996. 2. Saker KE, Remillard RL: Critical care nutrition and enteral-assisted feeding. In Hand MS, Thatcher CD, Remillard RL, et al, editors: Small animal clinical nutrition, ed 5, Topeka, KS, 2010, Mark Morris Institute. 3. Giner M, Laviano A, Meguid MM, Gleason JR: In 1995 a correlation between malnutrition and poor outcome in critically ill patients still exists, Nutrition 12:23, 1996. 4. Mohr AJ, Leisewitz AL, Jacobson LS, et al: Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoenteritis, J Vet Intern Med 17:791, 2003. 5. Brunetto MA, Gomes MOS, Andre MR, et al: Effects of nutritional support on hospital outcome in dogs and cats, J Vet Emerg Crit Care 20:224, 2010. 6. Liu DT, Brown DC, Silverstein DC: Early nutritional support is associated with decreased length of hospitalization in dogs with septic peritonitis: a retrospective study in 45 cases (2000-2009), J Vet Emerg Crit Care 22:453, 2012. 7. Prittie J, Barton L: Route of nutrient delivery, Clin Tech Small Anim Pract 1:6, 2004. 8. Ireland LM, Hohenhaus AE, Broussard JD, Weissman BL: A comparison of owner treatment and complications in 67 cats with esophagostomy and percutaneous endoscopic gastrostomy feeding tubes, J Am Anim Hosp Assoc 39:241, 2003. 9. Freeman L: Personal communication, 2012. 10. Abood SK, Buffington CA: Improved nasogastric intubation technique for administration of nutritional support in dogs, J Am Vet Med Assoc 199:577, 1991. 11. Holahan M, Abood S, Hauptman J, et al: Intermittent and continuous enteral nutrition in critically ill dogs: a prospective randomized trial, J Vet Emerg Crit Care 24:520, 2010. 12. Klaus JA, Rudloff E, Kirby R: Nasogastric tube feeding in cats with suspected acute pancreatitis: 55 cases (2001-2006), J Vet Emerg Crit Care 19:337, 2009. 13. Campbell JA, Jutkowitz LA, Santoro KA, et al: Continuous versus intermittent delivery of nutrition via nasoenteric feeding tubes in hospitalized canine and feline patients: 91 patients (2002-2007), J Vet Emerg Crit Care 20:232, 2010. 14. von Werthern CJ, Wess G: A new technique for insertion of esophagostomy tubes in cats, J Am Anim Hosp Assoc 37:140, 2001. 15. Devitt CM, Seim HB: Clinical evaluation of tube esophagostomy in small animals, J Am Anim Hosp Assoc 33:55, 1997. 16. Rawlings CA: Percutaneous placement of a midcervical esophagostomy tube: new technique and representative cases, J Am Anim Hosp Assoc 29:526, 1993. 17. Rawlings CA, Bartges JW: Esophagostomy tube placement: alternative technique. In Borjab MJ, editor: Current techniques in small animal surgery, Baltimore, 1998, Williams & Wilkins.
18. Han E: Esophageal and gastric feeding tubes in ICU patients, Clin Tech Small Anim Pract 1:22, 2004. 19. Seim HB, Willard MD: Postoperative care of the surgical patient. In Fossum TW, editor: Small animal surgery, ed 2, St Louis, 2002, Mosby. 20. Mauterer JV: Endoscopic and nonendoscopic percutaneous gastrostomy tube placement. In Bonagura JD, editor: Kirk’s current veterinary therapy XIII, St Louis, 2000, Saunders. 21. Fulton RB, Dennis JS: Blind percutaneous placement of a gastrostomy tube for nutritional support in dogs and cats, J Am Vet Med Assoc 201:697, 1992. 22. Elliot DA, Riel DL, Rodgers QR: Complications and outcomes associated with the use of gastrostomy tubes for nutritional treatment of dogs with renal failure, J Am Vet Med Assoc 217:1337, 2000. 23. Mansfield CS, James FE, Steiner JM, et al: A pilot study to assess tolerability of early enteral nutrition via esophagostomy tube feeding in dogs with severe acute pancreatitis, J Vet Intern Med 25:419, 2011. 24. Crowe DT, Devey JJ: Clinical experience with jejunostomy feeding tubes in 47 small animal patients, J Vet Emerg Crit Care 7:7, 1997. 25. Daye RM, Huber ML, Henderson RA: Interlocking box jejunostomy: a new technique for enteral feeding, J Am Anim Hosp Assoc 35:129, 1999. 26. Hewitt SA, Brisson BA, Sinclair MD, et al: Evaluation of laparoscopicassisted placement of jejunostomy feeding tubes in dogs, J Am Vet Med Assoc 225:65, 2004. 27. Heuter K: Placement of jejunal feeding tubes for postgastric feeding, Clin Tech Small Anim Pract 1:32, 2004. 28. Cavanaugh RP, Kovak JR, Fischetti AJ, et al: Evaluation of surgically placed gastrojejunostomy feeding tubes in critically ill dogs, J Am Vet Med Assoc 232:380, 2008. 29. Jergens AE, Morrison JA, Miles KG, et al: Percutaneous endoscopic gastrojejunostomy tube placement in healthy dogs and cats, J Vet Intern Med 21:18, 2007. 30. Jennings M, Center SA, Barr SC, et al: Successful treatment of feline pancreatitis using an endoscopically placed gastrojejunostomy tube, J Am Anim Hosp Assoc 37:145, 2001. 31. Papa K, Psader R, Sterczer A, et al: Endoscopically guided nasojejunal tube placement in dogs for short-term postduodenal feeding, J Vet Emerg Crit Care 19:554, 2009. 32. Wohl JS: Nasojejunal feeding tube placement using fluoroscopic guidance: technique and clinical experience in dogs, J Vet Emerg Crit Care 16:S27, 2006. 33. Beal MW, Brown AJ: Clinical experience utilizing a novel fluoroscopic technique for wire-guided nasojejunal tube placement in the dog: 26 cases (2006-2010), J Vet Emerg Crit Care 21:151, 2011. 34. Chan DL: Nutritional requirements of the critically ill patient, Clin Tech Small Anim Pract 1:1, 2004. 35. Chan DL, Freeman LM, Labato MA, et al: Retrospective evaluation of partial parenteral nutrition in dogs and cats, J Vet Intern Med 16:440, 2002. 36. Michel KE: Preventing and managing complications of enteral nutritional support, Clin Tech Small Anim Pract 1:49, 2004. 37. Justin RB, Hohenhaus AE: Hypophosphatemia associated with enteral alimentation in cats, J Vet Intern Med 9:228, 1995. 38. Parker VJ, Freeman LM: Comparison of various solutions to dissolve critical care diet clots, J Vet Emerg Crit Care 23(3):344, 2013.
DVM, DACVN • Kathryn
E. Michel,
KEY POINTS • 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 (RER). 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.
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 (see later). Hospitalized patients often have decreased caloric intake for many reasons, including patient factors such as nausea, pain, and anxiety and nonpatient factors such as poorly written feeding orders. 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-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 GI tract integrity, and intermediary drug metabolism.2 Malnutrition in humans is associated with increased complication rates, duration of hospitalization, and cost.3 Extensive studies have not been conducted in veterinary medicine, but in one prospective study, puppies with parvoviral enteritis receiving early enteral nutrition showed earlier clinical improvement and significant weight gain compared with puppies who remained NPO until vomiting ceased for 12 hours.4 Two retrospective studies also provide evidence for nutritional support in veterinary medicine. One study demonstrated a positive association between energy intake and hospital discharge.5 The second retrospective made a positive association between dogs with septic peritonitis receiving early enteral or parenteral support and a shorter length of hospitalization.6
DVM, MS, DACVN
DETERMINING THE ROUTE OF NUTRITIONAL SUPPORT Enteral Versus Parenteral Nutritional support can be delivered via the GI tract (enteral route), intravenously (parenteral route), or using a combination of the two. Hypotensive or hypothermic patients likely have poor gut motility and perfusion and so should first be stabilized before initiating enteral feeding. 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 more physiologic, less costly, and safer.7 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 129-1 outlines the decision process for selecting an appropriate enteral feeding route.
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 often 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. Appetite stimulants such as cyproheptadine or mirtazapine may be considered after careful patient assessment. The effectiveness of the treatment must be closely monitored by recording daily caloric intake and any possible side effects. Pharmacologic stimulation of appetite does not replace the need for daily nutritional assessment nor negate consideration of enteral feeding devices. If adequate intake is not achieved or side 681
682
PART XIV • NUTRITION No
Is patient hemodynamically and metabolically stable?
Stabilize patient
Yes
Can patient protect airway and is GI tract functional?
No
Consider parenteral nutrition
Yes
Will patient voluntarily eat?
Yes
Write feeding orders, monitor intake and reassess
Yes
No
Does patient have facial trauma or respiratory disease?
No
Can patient undergo general anesthesia?
No
No
Yes Consider NE/NG tube
Can patient tolerate feeding above the pylorus?
Can patient tolerate feeding distal to duodenum?
No
Yes
Yes Does patient have a functional esophagus? Yes
No
Does patient have normal gastric function?
Consider J-tube
Yes
Consider E-tube
Consider G-tube FIGURE 129-1 Decision tree for selecting enteral feeding route. CRI, Constant rate infusion; GI, gastrointestinal; NE, nasoesophageal; NG, nasogastric; E, esophagostomy; G, gastrostomy; J, jejunostomy..
effects occur, the plan must be revised to meet the patient’s nutritional needs. 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 and, when anticipated, can be placed while the patient is sedated or anesthetized for a diagnostic or therapeutic procedure. A retrospective
owner survey concluded that owners were comfortable managing their cats at home with esophagostomy and percutaneous endoscopic gastrostomy tubes.8 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 129-1 outlines advantages and disadvantages of the various forms of enteral access used in veterinary patients.
CHAPTER 129 • Enteral Nutrition
Table 129-1 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 NG tube may create incompetence of lower esophageal sphincter
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
Able to feed distal to pylorus and pancreatic duct
Requires general anesthesia Limited to liquid diets 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.
FIGURE 129-2 Placement of a nasoesophageal tube in a dog. Note that the nose is being pushed upward to facilitate passage of the tube into the ventral meatus.
ENTERAL FEEDING TUBES Nasoesophageal or Nasogastric Tubes A 3.5 to 8 Fr silicone or polyurethane feeding tube may be placed through the nares into the distal esophagus (nasoesophageal [NE]) or into the stomach (nasogastric [NG]) (Figure 129-2). NE tubes have historically been recommended because the risk of gastric reflux increases if the tube passes through the lower esophageal sphincter, compromising sphincter competence. However, one small retrospective study failed to demonstrate a difference in recorded complication rates between a group of dogs fed via NE versus NG tubes.9 NG tubes
allow for gastric decompression and measurement of gastric residual volume. Radiographic confirmation of correct placement for all tube types is recommended. An advantage of NE and NG tubes is that they can be placed easily using a local anesthetic or light sedation.10 This is a good option for patients that are poor candidates for general anesthesia. Facial trauma or coagulopathy may preclude placement of this type of tube, and it should not be used in patients with respiratory disease because it may exacerbate respiratory compromise by occluding a nares. Any patient that receives enteral nutrition must have a functional GI tract and the ability to guard the airway if vomiting or regurgitation occurs. Because only small-bore tubes are used, diet selection is limited to liquids. NE and NG tubes are best for short-term (7 to 14 days) feeding because they can be irritating. An Elizabethan collar (E-collar) and close monitoring are required because the pet may attempt to dislodge the tube. In addition, sneezing or vomiting may dislodge the tube, requiring reassessment for correct placement. Complications associated with NE or NG tubes include epistaxis, rhinitis, sinusitis, dacryocystitis, inadvertent placement or dislodgement of the tube into the airway, esophageal irritation, reflux, or clogging of the tube. One prospective11 and two retrospective12,13 studies evaluating nasoenteric feeding tubes compared bolus versus constant rate infusion and reported differing results with respect to time required to achieve targeted caloric intake. However, all three studies concluded that the nasoenteral feeding was well tolerated.
Esophagostomy Tube A larger feeding tube (usually a 12 to 14 Fr tube for cats and up to a 22 Fr for larger dogs) can be placed in the proximal esophagus at the mid-cervical level, with the tip positioned in the distal esophagus (Figure 129-3). The esophagostomy tube (E-tube) has several
683
684
PART XIV • NUTRITION
to 14 days or longer in more severely compromised or malnourished patients. Major complications associated with G-tubes include abdominal visceral injury during percutaneous placement or peritonitis if stomach contents leak into the abdominal cavity secondary to tube displacement or dehiscence. As with any surgically placed feeding device, cellulitis or infection at the stoma site is possible. Pressure necrosis can occur if the external flange places too much pressure on the stoma site. Improperly placed G-tubes may cause a pyloric outflow obstruction. A G-tube requires closer monitoring and is more costly than techniques previously described.
Jejunal Tubes
FIGURE 129-3 A cat with an esophagostomy tube in place.
advantages. Veterinary patients appear to tolerate them quite well. They can be used for fairly long periods (weeks to months) in both the hospital and outpatient settings. The larger tube allows for a wider selection of diets, including blenderized canned pet foods. The tube can be used in patients with facial or oral disease that precludes NE tube placement. As with the NE tube, the patient must have normal GI function, including normal esophageal function and the ability to protect the airway. Placement of this tube requires general anesthesia and technical skill, although the procedure is relatively simple and well described.14-18 E-tubes can be used for feeding as soon as the patient recovers from anesthesia and can be removed by the clinician when the patient has resumed adequate voluntary intake. Risks associated with E-tubes include placement in the airway or mediastinum, pneumomediastinum, pneumothorax, and damage to cervical vascular structures or nerves. As with the NE tube, a lateral radiograph should be taken to verify placement. Complications after placement include cellulitis or infection at the tube site, patient dislodgement, esophageal irritation and reflux, displacement during vomiting or regurgitation, and clogging of the tube.
Gastrostomy Tube Larger (usually 16 to 22 Fr mushroom-tipped) feeding tubes can be placed directly in the stomach via surgical placement,2,19 endoscopic guidance,2,20 or blind technique using a gastrostomy tube placement device.2,21 All techniques require longer time under anesthesia and more technical skill than is needed for E-tube placement. The percutaneous endoscopic gastrostomy and blind technique avoid doing a laparotomy, but if the patient is undergoing abdominal surgery, surgical placement is preferable because the surgeon can visualize placement and “-pexy” the stomach to the abdominal wall. Endoscopic placement is preferred over a blind technique because it allows visualization of the gastric placement site and decreases the risk of iatrogenic injury to abdominal viscera during placement.18 The gastrostomy tube (G-tube) provides nutrients distal to the esophagus, providing enteral feeding to patients with esophageal disease. The G-tube is well tolerated, permits bolus meal feedings, and is appropriate for long-term at-home feeding.8,22 As with the E-tube, the option of blenderized pet foods allows a wider diet selection. The patient must tolerate feeding above the pylorus without vomiting. The tube cannot be used for the first 24 hours after placement to allow return of gastric motility and formation of a fibrin seal at the stoma. The tube should not be removed until the stomach has adhered to the body wall to prevent stomach content leakage and secondary peritonitis. The tube is typically left in place for at least 10
A small-bore feeding tube (usually 5 to 8 Fr) can be placed directly in the proximal jejunum (J-tube). Nasojejunal, gastrojejunal, and jejunostomy tubes permit enteral feeding distal to the pylorus for patients unable to tolerate gastric feedings. Indications include gastroparesis, uncontrolled vomiting, proximal GI obstruction (i.e., secondary to neoplasia), massive proximal GI resection, and inability to protect the airway. Jejunal feeding is often recommended for the treatment of acute canine pancreatitis to decrease stimulation of pancreatic secretion, although early enteral feeding proximal to the pylorus may be well tolerated in these patients.23 A J-tube can be placed surgically during laparotomy or laparascopy,24-27 and transpyloric placement techniques via nasojejunal or gastrojejunal feeding tubes using surgical, endoscopic, or fluoroscopic techniques have been described.27-33 Surgical placement allows visualization of tube position and a pexy of the bowel to the abdominal wall. Transpyloric techniques are less invasive, with nasojejunal tubes eliminating the risk of bowel content leakage into the peritoneum. However, transpyloric placement requires advanced technical skill and either endoscopic or fluoroscopic guidance. J-tubes can be used for a moderately short period (days to weeks). Surgically placed J-tubes placed using the purse string, inverted serosal, or simple jejunopexy techniques or endoscopically placed gastrojejunal tubes cannot be removed for a minimum of 5 to 7 days, until a fibrin seal has formed at the body wall, to avoid the risk of peritonitis. The small diameter of J-tubes limits diet selection to liquids. To minimize the risk of abdominal cramping and vomiting, constant infusion is preferred over bolus feeding. This requires more diligent patient monitoring and does not allow for at-home feeding under most circumstances. Complications associated with J-tubes include peristomal cellulitis or infection, peritonitis secondary to leakage, retrograde migration of the J-tube, intestinal obstruction secondary to tube migration, and clogging of the tube.
DETERMINING THE AMOUNT TO BE FED Hospitalized patients should initially be fed to meet the RER, defined as the amount of energy (calories) needed to maintain homeostasis in the fed state in a thermoneutral environment.2 “Illness factors” are no longer widely used in critical care nutrition.34 Calorimetry is not used in the clinical veterinary setting, so estimates of RER can be calculated by allometric formulas such as 70(BWkg)0.75. Calculations for obese patients should be based on optimal body weight to prevent overfeeding. Calculations for growing puppies and kittens start with an initial caloric goal of RER to ensure tolerance. However, as with any patient, the pediatric patient must have frequent assessments. Caloric intake may need to be increased, especially if hospitalization is prolonged, provided the patient is tolerating the prescribed feeding amount. All patients must be reassessed to see if the initial caloric estimate is appropriate. The goal during hospitalization is to maintain body weight (excluding fluctuations as a result of hydration status) and lean body mass. Overfeeding is associated with GI and
CHAPTER 129 • Enteral Nutrition
metabolic complications. Certain disease conditions such as sepsis, head trauma, increased muscle activity (e.g., tremors, seizures) or burns may require increased caloric intake if the previously stated goals are not met by RER. In patients with prolonged anorexia, gastrointestinal compromise, or metabolic derangements, the caloric goal should be achieved over several days. Typical feeding protocols might provide 25% to 50% RER on day 1, with the goal of reaching full RER over the next 1 to 3 days.
SELECTING THE DIET Patient Variables Highly digestible nutrients from high-quality sources should be selected for critical care patients. A patient with a poor appetite may benefit from a more calorie-dense diet because a smaller volume of food will meet the caloric goal. A more calorie-dense slurry may also be indicated for patients who are volume intolerant such as those at risk of congestive heart failure. The clinician must determine if any macronutrients or micronutrients should be altered because of the patient’s disease condition. For example, enteral protein intake should be 4 to 6 g of protein per 100 kcal (15% to 25% of total energy) for dogs and 6 g or more of protein per 100 kcal (25% to 35% of total energy) for cats.34 Certain disease conditions, such as hepatic encephalopathy, may require the clinician to select diets closer to the minimum protein requirement to help prevent worsening of the clinical signs of encephalopathy. However, when a lower protein diet is fed, adequate calorie and protein intake is essential in order to minimize the risk of protein malnutrition. Conversely, disease conditions associated with a high degree of protein loss may require a diet replete with protein. Other examples of nutrient modulation include sodium in patients with congestive heart failure and fat in patients with hyperlipidemia, canine pancreatitis, and GI diseases leading to fat malassimilation. Certain patients with known dietary hypersensitivities may need to avoid products containing certain ingredients. In addition to veterinary enteral products, there is a vast array of enteral products formulated for humans. However, these formulas typically are not balanced for veterinary patients and often require modification such as additional protein, arginine, taurine, and B vitamins for cats.
Nonpatient Variables Nonpatient variables contribute to diet selection. Small-diameter NE, NG, or J-tubes require liquid diets. Financial constraints and cost of diets may factor into the selection process. Choices are limited by availability (i.e., the hospital inventory) and the clinician’s knowledge of various products.
MONITORING THERAPY Nutritional assessment should occur at least daily. The clinician reviews past feeding orders to determine if the appropriate diet plan was instituted and if the patient achieved the set goals. If the patient did not meet the dietary goal, the clinician must determine whether the cause was related to patient issues (e.g., nausea, unpalatable diet) or nonpatient issues (e.g., improperly written orders, orders not followed, feeding withheld for procedures). The clinician then updates the plan. Patients unable to meet desired nutritional goals enterally may benefit from supplemental parenteral nutrition (see Chapter 130).35 Monitoring of body weight (at least every 12 to 24 hours), hydration status, and laboratory values such as blood glucose, total solids, triglycerides, serum lipemia, blood urea nitrogen, and electrolytes must be done to assess the response to, or complications from, dietary intervention. The frequency and specifics of monitoring depend on the patient’s disease condition, the mode of dietary
intervention, and financial constraints. Patients that are critically ill and those receiving aggressive dietary intervention require the closest monitoring.
PREVENTING AND MANAGING COMPLICATIONS Patient-Related Complications Many feeding complications can be prevented by proper patient evaluation, selection of the appropriate route and amount of nutrient delivery, an understanding of the risks associated with the specific feeding plan, and close patient monitoring. Most enteral feeding complications are minor, but aspiration, premature dislodgement of a gastrostomy or enterostomy tube, and certain metabolic abnormalities can be life threatening.36 GI intolerance may manifest as vomiting, diarrhea, or ileus. This complication can compromise the ability to continue enteral feeding. The clinician should assess the feeding plan to confirm that daily intake does not exceed the patient’s energy requirements (approximately RER in most cases) and that the day’s feeding is divided into multiple small meals. Food should be warmed to body temperature for tube feeding. The patient’s disease condition or medications may contribute to nausea, vomiting, ileus, or diarrhea. Altering medications or providing antiemetics or prokinetic agents may allow for continued enteral feeding. Metabolic complications can arise if a patient is unable to assimilate certain nutrients. For example, a patient with glucose intolerance may need a dietary formulation low in simple carbohydrates to modulate hyperglycemic episodes. Anticipating specific intolerances during nutritional assessment and setting conservative caloric goals will minimize the risk.36 Refeeding syndrome is a life-threatening metabolic complication that may occur in patients after prolonged anorexia or in certain catabolic states, such as hepatic lipidosis. In this syndrome, upon reintroduction of feeding, there is a rapid shift of key intracellular electrolytes from the vascular to the intracellular space causing life-threatening hypokalemia, hypophosphatemia, or hypomagnesemia. This electrolyte abnormality can occur within days of resuming enteral (or parenteral) feeding.37 At-risk patients should be fed conservative amounts initially with close monitoring and correction of any electrolyte abnormalities via parenteral or enteral replacement. Aspiration is a potentially life-threatening complication that can be minimized by careful patient selection and close monitoring. Infections may occur at the peristomal site, along fascial planes, or within the peritoneum. Infectious complications can be minimized with proper tube placement, careful monitoring of tube sites, and basic hygiene during the preparation and delivery of food.
Non–Patient-Related Complications Mechanical complications include obstructed tubes or tube migration. Clogging can be prevented by proper management such as flushing with warm water before and after every use. One should avoid using the feeding tube to administer medications. If the tube becomes obstructed, flushing with warm water under alternating pressure and suction may dislodge the debris.38 Assessment of various solutions to dissolve in vitro feeding tube clogs caused by a veterinary critical care diet revealed that the injection of a solution of 1 4 tsp pancreatic enzyme and 325 mg sodium bicarbonate in 5 ml warm water was most effective.38 Proper technique in placing and suturing tubes will minimize the risk of tube migration and dislodgement. E-collars, bandages, and patient monitoring help prevent the patient from removing a tube. The tube should be marked with indelible ink where it exits the body so that migration can be detected. Radiographs should be performed to confirm placement of NE, NG, and E-tubes, especially if tube migration is suspected. If leakage of enteral contents into the peritoneum is suspected, a water-soluble contrast
685
686
PART XIV • NUTRITION
study can also be performed. Dislodged or migrated tubes should never be used for feeding without verifying placement.
REFERENCES 1. Thatcher CD: Nutritional needs of critically ill patients, Compend Contin Educ Vet Pract 18:1303, 1996. 2. Saker KE, Remillard RL: Critical care nutrition and enteral-assisted feeding. In Hand MS, Thatcher CD, Remillard RL, et al, editors: Small animal clinical nutrition, ed 5, Topeka, KS, 2010, Mark Morris Institute. 3. Giner M, Laviano A, Meguid MM, Gleason JR: In 1995 a correlation between malnutrition and poor outcome in critically ill patients still exists, Nutrition 12:23, 1996. 4. Mohr AJ, Leisewitz AL, Jacobson LS, et al: Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoenteritis, J Vet Intern Med 17:791, 2003. 5. Brunetto MA, Gomes MOS, Andre MR, et al: Effects of nutritional support on hospital outcome in dogs and cats, J Vet Emerg Crit Care 20:224, 2010. 6. Liu DT, Brown DC, Silverstein DC: Early nutritional support is associated with decreased length of hospitalization in dogs with septic peritonitis: a retrospective study in 45 cases (2000-2009), J Vet Emerg Crit Care 22:453, 2012. 7. Prittie J, Barton L: Route of nutrient delivery, Clin Tech Small Anim Pract 1:6, 2004. 8. Ireland LM, Hohenhaus AE, Broussard JD, Weissman BL: A comparison of owner treatment and complications in 67 cats with esophagostomy and percutaneous endoscopic gastrostomy feeding tubes, J Am Anim Hosp Assoc 39:241, 2003. 9. Freeman L: Personal communication, 2012. 10. Abood SK, Buffington CA: Improved nasogastric intubation technique for administration of nutritional support in dogs, J Am Vet Med Assoc 199:577, 1991. 11. Holahan M, Abood S, Hauptman J, et al: Intermittent and continuous enteral nutrition in critically ill dogs: a prospective randomized trial, J Vet Emerg Crit Care 24:520, 2010. 12. Klaus JA, Rudloff E, Kirby R: Nasogastric tube feeding in cats with suspected acute pancreatitis: 55 cases (2001-2006), J Vet Emerg Crit Care 19:337, 2009. 13. Campbell JA, Jutkowitz LA, Santoro KA, et al: Continuous versus intermittent delivery of nutrition via nasoenteric feeding tubes in hospitalized canine and feline patients: 91 patients (2002-2007), J Vet Emerg Crit Care 20:232, 2010. 14. von Werthern CJ, Wess G: A new technique for insertion of esophagostomy tubes in cats, J Am Anim Hosp Assoc 37:140, 2001. 15. Devitt CM, Seim HB: Clinical evaluation of tube esophagostomy in small animals, J Am Anim Hosp Assoc 33:55, 1997. 16. Rawlings CA: Percutaneous placement of a midcervical esophagostomy tube: new technique and representative cases, J Am Anim Hosp Assoc 29:526, 1993. 17. Rawlings CA, Bartges JW: Esophagostomy tube placement: alternative technique. In Borjab MJ, editor: Current techniques in small animal surgery, Baltimore, 1998, Williams & Wilkins.
18. Han E: Esophageal and gastric feeding tubes in ICU patients, Clin Tech Small Anim Pract 1:22, 2004. 19. Seim HB, Willard MD: Postoperative care of the surgical patient. In Fossum TW, editor: Small animal surgery, ed 2, St Louis, 2002, Mosby. 20. Mauterer JV: Endoscopic and nonendoscopic percutaneous gastrostomy tube placement. In Bonagura JD, editor: Kirk’s current veterinary therapy XIII, St Louis, 2000, Saunders. 21. Fulton RB, Dennis JS: Blind percutaneous placement of a gastrostomy tube for nutritional support in dogs and cats, J Am Vet Med Assoc 201:697, 1992. 22. Elliot DA, Riel DL, Rodgers QR: Complications and outcomes associated with the use of gastrostomy tubes for nutritional treatment of dogs with renal failure, J Am Vet Med Assoc 217:1337, 2000. 23. Mansfield CS, James FE, Steiner JM, et al: A pilot study to assess tolerability of early enteral nutrition via esophagostomy tube feeding in dogs with severe acute pancreatitis, J Vet Intern Med 25:419, 2011. 24. Crowe DT, Devey JJ: Clinical experience with jejunostomy feeding tubes in 47 small animal patients, J Vet Emerg Crit Care 7:7, 1997. 25. Daye RM, Huber ML, Henderson RA: Interlocking box jejunostomy: a new technique for enteral feeding, J Am Anim Hosp Assoc 35:129, 1999. 26. Hewitt SA, Brisson BA, Sinclair MD, et al: Evaluation of laparoscopicassisted placement of jejunostomy feeding tubes in dogs, J Am Vet Med Assoc 225:65, 2004. 27. Heuter K: Placement of jejunal feeding tubes for postgastric feeding, Clin Tech Small Anim Pract 1:32, 2004. 28. Cavanaugh RP, Kovak JR, Fischetti AJ, et al: Evaluation of surgically placed gastrojejunostomy feeding tubes in critically ill dogs, J Am Vet Med Assoc 232:380, 2008. 29. Jergens AE, Morrison JA, Miles KG, et al: Percutaneous endoscopic gastrojejunostomy tube placement in healthy dogs and cats, J Vet Intern Med 21:18, 2007. 30. Jennings M, Center SA, Barr SC, et al: Successful treatment of feline pancreatitis using an endoscopically placed gastrojejunostomy tube, J Am Anim Hosp Assoc 37:145, 2001. 31. Papa K, Psader R, Sterczer A, et al: Endoscopically guided nasojejunal tube placement in dogs for short-term postduodenal feeding, J Vet Emerg Crit Care 19:554, 2009. 32. Wohl JS: Nasojejunal feeding tube placement using fluoroscopic guidance: technique and clinical experience in dogs, J Vet Emerg Crit Care 16:S27, 2006. 33. Beal MW, Brown AJ: Clinical experience utilizing a novel fluoroscopic technique for wire-guided nasojejunal tube placement in the dog: 26 cases (2006-2010), J Vet Emerg Crit Care 21:151, 2011. 34. Chan DL: Nutritional requirements of the critically ill patient, Clin Tech Small Anim Pract 1:1, 2004. 35. Chan DL, Freeman LM, Labato MA, et al: Retrospective evaluation of partial parenteral nutrition in dogs and cats, J Vet Intern Med 16:440, 2002. 36. Michel KE: Preventing and managing complications of enteral nutritional support, Clin Tech Small Anim Pract 1:49, 2004. 37. Justin RB, Hohenhaus AE: Hypophosphatemia associated with enteral alimentation in cats, J Vet Intern Med 9:228, 1995. 38. Parker VJ, Freeman LM: Comparison of various solutions to dissolve critical care diet clots, J Vet Emerg Crit Care 23(3):344, 2013.