An Assignment on

Nutritional Support to

Veterinary Surgical Patients

Submitted to Dr. Manoj Kumar Shah

Lecturer Department of surgery and pharmacology

IAAS, Rampur campus, Chitwan

Submitted by Suraj Subedi

B.V.Sc & A.H 7th semester Roll no 29

IAAS, Rampur campus, Chitwan

September, 2010

Nutritional Support to Veterinary Surgical Patients

IntroductIon Nutrition is the process by which an organism assimilates materials and uses them for normal growth and maintenance of life. Nutrition provides the substrates essential for living creatures to use for protein synthesis, cellular function, and metabolic processes.

When an animal is ill or injured and is recommended for surgical intervention, it faces a substantial decrease in the normal intake of protein and energy at a time when more energy is being utilized for metabolic fuel and cell turnover. A negative energy and protein balance exists, and providing adequate nutrition is essential to avoid malnutrition. Extensive research and clinical studies have shown a close relationship between morbidity and mortality rates and nutrition in the animal having critical conditions. Consequences of malnutrition include increased susceptibility to infection, shock, delayed wound and fracture healing, muscle weakness, impaired immunity, major organ failure and death.

Tissue synthesis and wound healing depend on local and whole body nutrition. Amino acids and carbohydrates are needed for collagen and ground substance synthesis while fibroblasts require energy to synthesize RNA, DNA and ATP necessary for proteins. The liver and bone marrow require energy and protein for glucose, complement, platelet, and leukocyte and monocyte production. Studies show that post operative patients that are fed demonstrate a much higher rate of protein synthesis versus protein degradation while those that are not fed demonstrate higher protein degradation.

The immune system is particularly susceptible to the effects of poor nutrition and post surgical patients depend on a healthy immune system to ward off infection. In animals, decreased protein-calorie intake is the most common cause of secondary immunodeficiency.

There are other factors that make adequate nutrition following surgery even more critical and these are in response to the injury itself. Following trauma, metabolic and physiologic changes occur in response to the release of catecholamines, adrenocorticoids, glucagons, and a number of other hormones associated with the "fight or flight(emergency)" response. The result of this hormonal surge is:

Suppression of insulin secretion

Hyperglycemia

Increased proteolysis

Increased cardiac output

This metabolic alteration must be met with a supply of adequate nutrition that meets the requirements of the body.

In summary, the benefits of nutritional support are

• Preservation of nutritional status • Prevention of complications of protein malnutrition • Decreased post-operative complications

Role of Nutrition in Peri-operative Patients

Enhances wound healing Enhances immunocompetance Speeds onset of therapeutic effects from other treatments Serves to meet the metabolic demands of the patient Improves survival rate of critical care patients

Goals of Nutritional Management and Support

Provide enough calories to aid the body in healing from surgery and underlying disease. Prevent atrophy of the gut, which predisposes the patient to ulceration, bacterial

translocation, and potential for sepsis. Ensure adequate glucose levels and avoid large fluctuations. Maintain neutral PH. Provide organs with nutritional support to prevent organ failure as a result of

malnutrition.

HOW MUCH TO FEED

The basal energy requirement (BER) is the energy needed for a healthy resting animal in a postabsorptive (unfed) state in a thermoneutral environment. Resting energy requirement (RER) is BER plus the energy needed for assimilation of food and recovery from physical activity. In humans, RER is estimated to be about 10 per cent greater than BER, but this difference is unlikely to have any clinical significance. The RER is the same as resting energy expenditure (REE). The most widely used allometric formula for RER in cats and dogs of any weight is:

RER (kcal) 70 x (Current bodyweight in kg)0·75 Alternatively, for animals weighing between 2 and 30 kg, a linear formula may be used:

RER (kcal) = (30 x Current bodyweight in kg) + 70 Maintenance energy requirement (MER) is the energy required by an animal with a moderately active life. It is usually estimated to be a multiple of RER; for example, 1·6 to 1·8 x RER for dogs and 1·2 to 1·4 x RER for cats. It does not include energy needed for growth, gestation, lactation or work. A dog (or less likely a cat) with a very active lifestyle may need more energy than is supplied by the estimated MER.

Methods of assessment of nutritional status

Accumulation of lean body mass is the principal objective of nutritional support; thus determination of lean body mass is the most appropriate means of nutritional assessment. The methods used are:

History and physical examination

Weight loss, anorexia or a disease process that interferes with intake (such as esophageal carcinoma) should alert the examiner to the possibility of malnutrition. On physical examination, muscle wasting; loss of thenar eminence muscles; loose flabby skin; edema of hypoproteinemia; weakness; loss of body fat and pallor are the key signs that confirm the malnutrition.

Nitrogen balance Indirect calorimetry Functional studies of muscle function Displacement of water volume

Neuron activation analysis Magnetic resonance imaging Delayed cutaneous hypersensitivity or

allergy

Some indications of surgical nutrition:

Paralytic ileus more than 4 days. Surgical sepsis. Intestinal fistula. Massive intestinal resection. Pancreatitis.

Trauma: • Mainly maxillofacial. • Multiple trauma. • Burns

Organ failure: renal, liver, cardiac.

Approaches to feeding the surgical patient

Enteral Force feeding/appetite stimulation Nasoesophageal tube Nasogastric tube Percutaneous endoscopic gastrostomy tube Esophagestomy tube Gastrostomy tube Jejunostomy tube

Parenteral Partial parenteral nutrition (PPN) Total parenteral nutrition (TPN)

Total parenteral nutrition (TPN) A mixture of dextrose, amino acids, and lipid solution providing 100% of the patient’s

nutritional requirements in a central vein.

Partial parenteral nutrition (PPN) • Dextrose solutions that provide minimal calories to the patient • Free amino acid solutions (FreeAmine, Aminosyn, Travasol) with balanced electrolytes added. • Amino acid and dextrose solutions (Clinimix, Quick Mix, ProcalAmine) • Dextrose, amino acids, and lipid mixtures that provide 50% of the patient’s caloric

requirements

Major complications in enteral and parenteral nutrition delivery

Mechanical: Blocked enteral tubes and kinked catheters can present physical difficulties

Metabolic: Alterations in electrolyte balances, hyperglycemia, acid-base disturbances, and hyperlipidemia occur. It is not uncommon to see diarrhea or soft stool from enteral nutrition.

Septic: Parenteral solutions are an ideal growth medium for bacteria (aseptic technique is essential when administering parenteral solutions).

Monitoring of Patients during nutritional support

Patients should be weighed daily. Temperature, pulse, and respiration can be monitored four times a day. A minimum database of packed cell volume, total protein, glucose, and blood urea nitrogen should be performed twice a day. Monitoring electrolyte imbalances, albumin, hypertriglyceridemia, hypercholesterolemia, hyperammonemia, and urine dipstick for glucosuria and ketones is recommended. The patient should be monitored for volume overload.

RER (Resting energy requirement) amount of calories to maintain minimal metabolism;

RER = 30× body weight (kg) + 70 = kcal/day (for patients weighing 2-35 kg)

IER (Illness energy requirement) amount of calories required to feed an ill patient;

IER = RER × illness factor (illness factors = cage rest [1.25], postsurgery [1.30], trauma [1.5])

PER (Partial energy requirement)

amount of calories required to supply 50% of the IER

Calculations of the nutrition 1. Calculation of protein requirement: • Dogs - Approximately 4-6 gram/100kcal • Cats - Approximately 6 + grams/100kcal But it should be kept in mind that increased protein is needed in animals with severe burns and restriction of protein for patients in renal failure. Protein requirement is typically provided by an 8.5% amino acid solution.

2. Calculation of the non protein requirement: Non-protein calories are typically provided as a 50/50 mixture of lipid and dextrose. Carbohydrate requirement is provided by 5% dextrose solution and lipid requirement is provided by 20% lipid solution. Calculation of the volumes of each nutrient solution:

• 5% dextrose solution = 0.17 kcal/ml • 8.5% amino acid solution = 0.085 g/ml = 0.34 kcal/ml • 20% lipid solution = 2 kcal/ml

What to Feed

As mentioned previously, a patient recovering from surgery requires protein and calories at a higher level than its normal resting energy requirement. This can be supplied in many forms but the easiest way is to use one of the many veterinary critical care diets available. A syringable diet high in fat, low in carbohydrate (to combat insulin resistance) and high in omega fatty acids, amino acids and glutamine are prescribed. The diet is very palatable and well received by many patients. There are several other veterinary diets available and homemade diets can also be formulated.

It is important to remember that some patients, especially cats, may develop food aversions. When forced to eat a food when in pain or unwell, the patient may refuse to eat the same food once forced feeding is discontinued. Always offer other alternatives so that the patient can resume eating on its own as soon as possible. It is important to remember that a successful surgical outcome depends heavily on post operative care and nutrition is one of the key components.

Types of diets

Polymeric diets (Clincare, Osmolite, Jevity) contain nutrients that require digestion before absorption can occur and are generally preferred over monomeric diets (Vivonex HN, Vital HN ), which are composed predominately of simple molecular substrates, including mono- and oligosaccharides and amino acids. Polymeric diets are less expensive and more physiologic than monomeric diets, however monomeric diets are used when polymeric diets are not tolerated such as short bowel syndromes, pancreatitis, parvovirus, pancreatic abscess, exocrine pancreatic insufficiency and extreme IBD.

Feeding pattern of animals

Many non-injured patients do not eat well in the hospital so those recovering from surgery may be even more challenging due to factors such as anesthetic effects and pain. Proper attention to analgesia and comfort will make your patients more likely to regain their appetite. Depending on the type of surgery, in most cases you will want to start feeding your patients as soon as the noticeable effects of anesthesia have worn off. It is best to select a food with high palatability and it may be necessary to warm the food above room temperature to increase its attractiveness. Hand feeding may be required in some cases combined with some tender loving care (TLC). This seems to be particularly important with cats who we all know can be extremely finicky when it comes to food.

If the patient does not respond within 24 hours of surgery it is time to consider some assisted feeding techniques which can range from simple to quite complicated. Some pharmacological agents will increase appetite in cats and can be tried before physical intervention. These include cyproheptadine (2-4 mg per cat) and diazepam (dosage varies).

Forced feeding involves using a syringe to place a semi-solid food into the pharyngeal area to stimulate the swallowing reflex. This can be met with resistance and care must be taken to avoid injury to the patient or the nurse. In dogs, it is best to place the syringe between the cheek and the molars with the head held in a normal position. For cats the syringe is placed between the four canine teeth. Some animals will refuse to swallow a bolus of food and you must be careful not to be too aggressive or aspiration may result.

The next level of intervention is the use of an orogastric tube and should only be used on cooperative patients that require such feeding for 2-3 days. A lubricated soft rubber tube is pre-measured to the ninth rib and introduced gently with the head held in the normal position. Once the patient swallows, pass the tube to the pre-measured mark and instill some sterile water to ensure proper placement before feeding. There is some mouth gags designed to prevent the patient from chewing on the tube.

For patients that require assisted feeding for a prolonged period it is best to place a fixed feeding tube as this will reduce the stress on the patient and ensure proper delivery.

Naso-esophageal Tubes

Nasoesophageal tubes can be left in place for prolonged periods of time (usually 1-2 weeks) and are generally well tolerated if properly inserted. As noted by the term, these tubes are best placed in the distal esophagus rather than the stomach to prevent reflux. A number of different tube types can be used and vary in size from 5-Fr for cats to 8-Fr for most dogs. These tubes can be placed without anesthesia or sedation (in most cases) and are thus preferable for patients considered anesthetic risks. After some drops of local anesthesia, the tube is directed ventromedially to avoid the ethmoturbinate bones and advanced to the pre-measured mark once the swallowing reflex is initiated. Sterile water should be used to ensure proper placement and the tube can be fixed to the skin with a couple of sutures or tissue glue followed by a protective buster collar.

Pharyngostomy/Esophagostomy Tubes

For patients with oral trauma or for those that need a longer term of tube placement (weeks to months), pharyngostomy or esophagostomy tubes can be used. These procedures require anesthetic and complications include infection, hemorrhage and aspiration. Owners can maintain these tubes at home and due to their larger size (8-16 Fr) they can tolerate a wider range of food types than nasogastric tubes.

Gastrostomy Tubes

Gastrostomy tubes have become more popular for enteral feeding now that different placement techniques have been developed. The most common method employs an endoscope but there are blind methods that can be used and special kits that make this much easier. Food is placed directly into the stomach and as in the other tube techniques, the patient is able to eat on its own if it desires.

Fig: jejunostomy tube

Jejunal feeding and jejunostomy

This assisted-feeding method is indicated in animals that are unable to tolerate gastric feeding but have normal jejunal, ileal and colonoic function. Placement of jejunostomy tubes may be indicated in animals with gastric outflow or proximal small-intestine obstructions and severe pancreatitis. These tubes are most commonly placed surgically (jejunostomy), but newer percutaneous endoscopic gastrojejunal tube (J-G) and fluroscopically guided nasaljejunal tube techniques have been evaluated in dogs and cats and may play a role in the management of hospitalized animals in the future.

Jejunostomy tubes must be placed under general anesthesia and are again limited in diameter (5-8 Fr). Because nutrients delivered into the jejunum have bypassed the major steps in digestion that occur in the stomach and duodenum, liquid elemental diets are preferred with this feeding type and should be delivered as a constant rate infusion over 12 to 16 hours to prevent complications, such as abdominal cramping and diarrhea.

Surgical placement of jejunostomy tubes also carries the risks of tube displacement and subsequent peritonitis. Jejunal feeding through a J-G or nasaljejunal tube eliminates the risk of leakage through a jejunostomy site. These tubes can be removed or "backed out" once pancreatitis or the intestinal disease has resolved and still allow for further enteral nutrition without an additional procedure. These feeding tubes are best utilized in a veterinary hospital where continued monitoring and care can be provided.

Tube removal

Gastrostomy, gastroduodenostomy and jejunostomy tubes should remain in place for at least 5 days before being removed to ensure adequate adhesion formation to prevent gastrointestinal leakage

Complications of tube feeding

Complications of tube feeding can be divided into mechanical complications, gastrointestinal complications and metabolic complications. Mechanical complications include improper tube placement, GI perforation by the feeding tube, peritoneal leakage, subcutaneous leakage, leakage through osteotomy site, regurgitation or vomiting the tube, esophageal irritation, infection at tube exit site/focal cellulitis, tube occlusion, tube kinking, premature tube removal by the patient and tube migration. Gastrointestinal complications include vomiting, cramping, abdominal distension, diarrhoea, reflux esophagitis and aspiration pneumonia. Metabolic complications include hyperglycaemia and hypophosphataemia. Tube complications can generally resolved by slowing the feeding rate, replacing the tube, or placing a different type of feeding tube.