Chapter 10 Blenderized Diets for Dogs and Cats *Predicted as fed energy density of blended mixture. From Hand M: Small animal clinical nutrition, ed 5, 2010, Mark Morris Associates. Commercially Available Diets and Their Composition* *These figures should be used for the energy requirement calculations in Figure 10-1. Polymeric enteral diets contain complex large-molecular-weight proteins, carbohydrates, and fats. These diets approach isotonic osmolality, require normal gastrointestinal digestive processes, supply about 1 kcal/ml, and are more economical than monomeric diets. Polymeric diets include blenderized diets, commercially available partially hydrolyzed diets, and commercially available liquid diets (see Tables 10-1 and 10-2). Commercial polymeric diets are available in a variety of osmolalities, caloric densities, and compositions. Examples of commonly used commercial polymeric diets and their compositions are listed in Table 10-2. These diet formulas are indicated for malnourished patients with intact digestive and absorptive function and those suspected of having food allergies. These diets also should be used for patients that must be fed through small-diameter tubes, such as nasoesophageal, gastroduodenostomy, or enterostomy tubes. Polymeric liquid enteral diets have been shown to be effective in providing for nutritional support in critically ill and injured animals. PPN can be administered through a peripheral catheter because partial parenteral solutions are not as hypertonic as TPN solutions. Although a dedicated catheter is ideal, it is not as critical with PPN as it is with TPN. PPN is generally administered on a short-term basis to nondebilitated patients that are unable to tolerate full enteral feeding. Calculations for formulating PPN diets are listed in Box 10-3. The median duration of feeding in dogs and cats receiving PPN is reported to be 3 days (Chan et al, 2002). Patients receiving PPN initially are monitored once a day in the same way as patients receiving TPN. Complications (e.g., sepsis, phlebitis, hyperglycemia, other metabolic derangements) are less common with PPN than with TPN. Nasoesophageal intubation is easy, effective, and efficient. The availability of small-bore, soft rubber (polyvinyl chloride), and Silastic feeding tubes (i.e., 5 Fr) and of low-viscosity, nutritionally complete liquid diet formulations (see Table 10-2), in addition to patient tolerance of tube placement, have made nasoesophageal feeding popular. Advantages of nasoesophageal tubes include ease of placement, acceptance by patients, ease of tube care and feeding, patients’ ability to eat and drink around the tube, and flexibility that allows tube removal at any time after placement. Major disadvantages of nasoesophageal tubes include the small size of the tube, inadvertent tracheal placement, and premature removal by the patient. Occasionally, a patient may vomit out or regurgitate the tube. Light general anesthesia may be necessary to place a nasoesophageal tube, but a topical anesthetic or light sedation is usually sufficient. Instill proparacaine hydrochloride (0.5 to 1 ml; 0.5%) into the nasal cavity and elevate the head to encourage the anesthetic to coat the nasal mucosa. Repeat the application to ensure adequate anesthesia of nasal mucous membranes. If the patient will not tolerate nasal intubation, consider topical lidocaine (e.g., 1 to 2 ml of 2% lidocaine), heavy sedation, or light general anesthesia. Select an appropriate-size feeding tube (see Box 10-4). Estimate the length of tube to be placed in the esophagus by measuring the tube from the nasal planum, along the patient’s side, to the seventh or eighth intercostal space. Place a tape marker on the tube once the appropriate measurement has been taken. Do not allow the feeding tube to pass through the lower esophageal sphincter because this may result in sphincter incompetence, esophageal reflux of hydrochloric acid, esophagitis, and vomiting. Before passing the tip of the tube, lubricate it with 5% viscous lidocaine and hold the patient’s head in a normal functional position (i.e., avoid hyperflexion or hyperextension). Identify the prominent alar fold and direct the tube from a ventrolateral location in the external nares to a caudoventral and medial direction as it enters the nasal cavity (Fig. 10-2). When the tube has been introduced 2 to 3 cm into the nostril, contact with the median septum at the floor of the nasal cavity can be felt. Push the external nares dorsally to facilitate opening of the ventral meatus. Elevate the proximal end of the tube and advance it into the oropharynx and esophagus. It will generally “drop” into the oropharynx, stimulating a swallowing reflex. Several methods can be used to confirm esophageal placement: (1) check for negative pressure, (2) inject 3 to 5 ml of sterile saline through the tube and see if a cough is elicited, (3) inject 6 to 12 ml of air and auscultate for borborygmus at the xiphoid, (4) connect the tube to a capnograph, or (5) visualize tube placement using a thoracic radiograph. If the patient requires general anesthesia, correct tube placement can be visually confirmed. Once satisfied that the tube has been placed properly, suture it to the nose and head to prevent removal by the patient. In cats, it is important that the tube is not in contact with the whiskers; position it directly over the dorsal aspect of the nose and forehead (Fig. 10-3), and secure it with a Chinese finger-trap friction suture (see Fig. 31-10 on p. 999). In dogs, secure the tube to the lateral aspect of the nose and the dorsal nasal midline with a Chinese finger-trap friction suture or cyanoacrylate glue. Place a column of water in the tube before capping it to prevent air intake, reflux of esophageal contents, or occlusion of the tube by diet.
Nutritional Management of the Surgical Patient
Diets for enteral use
TABLE 10-1
TABLE 10-2
Methods of Providing Hyperalimentation
Partial Parenteral Nutrition
Nasoesophageal Intubation
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Nutritional Management of the Surgical Patient
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