VETTECH U 2024 / HOUSTON, TX
WHAT SHOULD THE PATIENT BE FED? Nutritionists debate the exact formula for determining daily energy requirements in critically ill patients. A good starting point is to calculate the resting energy requirements for the patient’s current weight. If a patient’s ideal weight is used, underweight animals may be at greater risk for complications from overfeeding. Resting energy requirements can be calculated using the following equation: RER = 70 x (current body weight in kg)0.75. Another equation that may be used is RER = (kg x kg x kg, √ , √ ) x 70. It is imperative that the nutritional status of the patient be monitored vigilantly as caloric intake may need to be adjusted to prevent weight loss or unintended weight gain. Food selection depends on tube size and location within the GI tract, the availability and cost of products and the experience of the clinician. Commercial foods available for enteral use in veterinary patients can be divided into two major types: 1) liquid or modular products and 2) blended pet foods. Nasal and jejunostomy tubes usually have a small diameter (<8 Fr.), which requires use of liquid foods. Orogastric, pharyngostomy, esophagostomy, and gastrostomy tubes have large diameters (>8 Fr.) and are suitable for blended pet foods.3,5 Human liquid foods cost more than veterinary liquid products. Most human liquid foods are adequate for adult dogs but are too low in protein for cats, puppies, and adult dogs with increased protein losses (e.g., protein-losing enteropathies, drains). 3,9 Human liquid enteral products may not contain adequate concentrations of protein, taurine, arginine, and arachidonic acid for long-term feeding of cats, but are satisfactory for fewer than seven days. It is recommended that veterinary liquid products be used when managing veterinary patients. (See the comparison chart at the end for additional information.) Liquid foods are of two basic types: 1) elemental or monomeric and 2) polymeric. Foods said to be "elemental" are not truly elemental; rather they are ‘semi-elemental’ and contain nutrients in small hydrolyzed absorbable forms and are best described as monomeric. The proteins are usually present as free amino acids, small dipeptides or tripeptides or larger hydrolyzed protein fractions. The fat source is often an oil of mixed (medium- and long-chain) fatty acids and the carbohydrate sources are mono-, di- and trisaccharides. Semi-elemental nutrition provides easier digestion and rapid absorption of nutrients, designed to support the critical systems of the body.
The gastrointestinal tract is lined with cells called enterocytes, which aid in digestion, absorption, and transportation of nutrients into the body. Vital nutrients absorbed by enterocytes include amino acids and peptides, carbohydrate (complex and simple saccharides), lipids, water, vitamins, and ions (or minerals). Enteral nutrition is preferred whenever possible because enterocytes undergo atrophy without luminal nutrient stimulation. By focusing on the nutritional needs of the enterocyte, semi-elemental diets provide the maximum amount of nutrition that can be absorbed with the least energy expenditure. In critically ill patients, the body’s main goal is to support key organs like the heart, brain, liver, and lungs. Blood flow to the gastrointestinal tract is reduced thus slowing gastrointestinal motility. As enterocytes form a tight seal to protect the body from harmful bacteria or toxins, digestion and absorption of nutrients are similarly altered. Unfortunately, these physiologic changes make it difficult for nutrients to be absorbed when the body needs nutrition the most. Thus, weakened, and debilitated patients benefit from a predigested or a semi-elemental diet. Semi-elemental diets contain ingredients that are purified and hydrolyzed and are usually combined with a small amount of complex highly digestible ingredients. Semi-elemental diets that are nourishing the enterocytes of the GI tract help to maintain an osmotic balance which minimizes the risk of diarrhea by preventing the loss of water and other vital nutrients from the gastrointestinal tract.10 There is a company that produces species specific semi- elemental diets, which have been shown to be beneficial to the GI tract and to the management of the critical and/or recovering patient. (EmerAidvet.com) There are several liquid foods on the human medical market that are positioned as monomeric or hydrolyzed diets and are suitable when initially refeeding dogs and cats. These monomeric products are homogenized liquids that can be fed through any feeding tube including a J-tube. Monomeric foods are indicated in disease conditions such as inflammatory bowel disease, lymphangiectasia, refeeding parvoviral enteritis and pancreatitis cases and any other condition in which a patient's digestive capabilities are questionable. Polymeric products contain mixtures of more complex nutrients. Protein is supplied in the form of large peptides (e.g., casein or whey). Carbohydrates are usually supplied as corn starch or syrup,
SEPTEMBER 20-22, 2024 | PROCEEDINGS | VETGIRLONTHERUN.COM
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