Nutritional support for ill patients: Specialty feeding tubes (Proceedings)

The primary goal of nutritional assessment is to identify which patient is at risk for malnutrition. As altered nutritional status is associated with adverse clinical outcomes, it becomes paramount to address the nutritional needs early in the critically ill patient. Although clinical status alone may dictate the need for nutritional intervention, a thorough nutritional assessment consists of evaluating both clinical and biochemical data, including patient history, and a thorough physical exam including body weight and body condition scoring. A baseline nutritional assessment should be followed by serial assessments throughout the course of hospitalization. The veterinary technician is in a crucial position to identify baseline data and ongoing changes in nutritional status, as it is the technician that spends most the time with the patient. Nutritional intervention is crucial to recovery and survival, particularly with the critical patient, and appropriate consideration as to the type and route of nutrition should be given based on the underlying disease process or diagnosis.

Patients at risk for malnutrition

Any patient that is anorexic or NPO for three days or longer is a candidate for malnutrition. However, of particular concern for nutritional insufficiencies include patients with increased metabolic stress levels, including surgical patients, sepsis patients, burn victims, trauma patients, head injuries, and patients with respiratory difficulties. The hypermetabolic state these types of patients exhibit results from increased catecholamine releases in order to increase their fuel production. Unfortunately, the increased metabolic rate and subsequent catabolism rapidly exacerbates weakness in patients without nutritional support. Even more serious is the loss of visceral proteins such as serum proteins, immunoglobulins, and leukocytes needed to maintain immunocompetence to fight infection.

Undernourished patients are three times as likely as well nourished patients to have major surgical complications. Wound dehiscence, decubital ulcers, sepsis, and pulmonary complications such as pneumonia, are secondary to poor nutritional status. Pediatric patients are especially susceptible to malnutrition and often present with dangerously low blood glucose levels.

Signs and symptoms of nutritional deficiency

Critical illness is associated with increases in metabolism to provide energy for immune responses and healing. Again, this hypermetabolic process is an effort by the body to mobilize its supply of circulating nutrient substrates such as glucose and amino acids. Unfortunately, this mobilization occurs at the expense of body tissue and function at a time when protein synthesis demands are also high. The body becomes reliant on its protein stores to provide gluconeogenesis, as glucose is desperately needed as a fuel source. Consequent loss of protein results in weight loss and alternations in protein homeostasis. Loss of lean body mass is associated with patient morbidity and mortality, and it critical to be able to recognize symptoms of nutritional insufficiency. In the critically ill or injured patient, the hypermetabolic state continues as the body attempts to heal itself. Thus, as a result of the hypermetabolic state, a patient's resting energy expenditure and oxygen demands are increased. Clinical signs of such metabolic events include tachycardia, tachypnea, hyperglycemia, and the eventual net breakdown of skeletal muscle protein and the mobilization of body fat.

Generalized weakness and exercise intolerance are generally the first signs of malnutrition to surface. This weakness reflects the loss skeletal muscle mass from altered protein homeostasis. Again, keep in mind that such a patient may have normal to high blood glucose as it is using its protein for fuel as a normal stress response. Protein from all body organs is utilized, which can result in eventual organ dysfunction without nutritional support. It is important to note that the obese or overweight patient can also develop malnutrition in spite of excessive amounts of fat. The overweight patient's nutritional needs may also be overlooked as the signs of muscle weakness and muscle wasting become less obvious. Note that all critically ill patients, regardless of body weight, need the same degree of nutritional assessment and monitoring.

Respiratory function deteriorates as intercostals and diaphragmatic muscles waste, resulting in poor ventilation and consequent hypoxia. Chronic hypoxia results in pneumonia and atelectasis. Increased respiratory efforts and increased respiratory rates require a tremendous amount of energy. Recumbent patients are at the greatest risk of respiratory insufficiency as nutritional uptake is generally poor, with muscle fatigue and muscle wasting further complicating patient recovery. In addition, recumbent patients with muscle wasting are prone to megaesophagus and aspiration pneumonia. Renal function can also deteriorate as a result of poor nutrition as decreased urea concentration in the renal medulla results in a loss of the kidney's concentrating ability. Poor nutrition can cause decreased muscle function leading to decreased motility and malabsorption in the gastrointestinal tract. Sadly, even cardiac muscle can become weak by the increased demand for oxygen consumption due to the hypermetabolic state from injury or illness.

In essence, no organ is spared during malnutrition. It is important to note that the interrelationships between organ function and nutrition are complex and delicate. Wherein no single parameter or observation can define the degree of nutritional insufficiency, being conscious of the nutritional need for mere patient maintenance is an important step in providing good patient care.

Development of malnutrition can be hospital related and not just a reflection at time of admission. Frequent diagnostics testing, stress from being apart from owners, lack of sleep, or unregulated pain can cause a patient to quit eating. Good communication between nursing staff should include a patient's behavior and eating habits during patient rounds. Other practices known to adversely affect the nutritional status of hospitalized patients include the failure to record a daily body weight, lack of nutritional intervention after surgical procedures, (particularly if the patient is kept sedated on heaving infusions of analgesia), medications causing inappetence or nausea, and improper diet types.

Physical exam findings

During the physical exam of the critical patient, it is important to first start with patient mentation. Does the patient appear lethargic, listless, or disoriented? Are the eyes sunken, dull, or the sclera icteric or injected? Are the mucus membranes of normal color and moist? Does the hair coat appear lackluster and is alopecia present? Any abnormal findings can be attributed to poor nutritional uptake. In addition, it is important to note any decreased subcutaneous fat stores, muscle wasting or loss of lean body mass. Note respiratory patterns and the presence of limb edema that may suggest hypoproteinemia. Stool analysis can also be helpful and be an important diagnostic indication of hydration status. Body condition scoring should be compiled and ideal body weight calculated with the weight of admission. Again, physical exam findings should be combined with a good patient history to determine the nutritional needs of the patient.

Routine laboratory tests can also provide additional evidence of nutritional insufficiency. Tests of immune function such as lymphocyte count are important, as well as the hematocrit and reticulocyte count if anemia is present. In addition, serum albumin is important to measure in nutritionally challenged patients. It is important to note that any abnormal lab findings can also be from several underlying disease processes simply complicated by poor nutrition.

Routes of feeding and tube selection

The enteral route is the preferred method of feeding whenever possible, as this is the safest and least expensive route to provide nutrition. Oral supplementation is recommended to the patient who can eat and has both normal digestion and absorption, but simply cannot consume enough calories and protein required. Examples include the orthopedic patient or burn victim, patients with mild anorexia, geriatric patients, and patients simply stressed from hospitalization. Enteral tube feedings are generally reserved for the patient who has digestive or absorptive capabilities but is unwilling or cannot be feed by mouth. Patient examples include those patients with mandibular or maxillary fractures, oral tumors, patients with megaesophagus, laryngeal or pharyngeal weakness, or the patient who becomes too stressed to force-feed. In addition, those patients that have profound cachexia or weakness may benefit from tube feeding until strong enough to consume their daily requirements without assistance.

Enteral feeding tubes used in veterinary medicine include nasogastric, esophageal, nasoesophageal, gastronomy, and jejunal. Nursing responsibilities usually include insertion of the tube, daily bandage changes to inspect insertion site for infection or dislocation, and frequent feeding and flushing of the tube to prevent clogging. It is important to monitor for delayed gastric emptying of the feeding tube by aspirating the stomach contents prior to subsequent feedings.

The enteral route is accessed in the small animal to meet the nutritional demands in the sick or injured patient. The enteral route is preferred whenever possible, as this route is safer and much less expensive than parental feeding. There are a variety of enteral tubes utilized for patients who have at least some digestive and absorptive capability but are unwilling or unable to consume food by mouth. The location and type of feeding tube depends on both the length of time feedings are anticipated, as well as determined by patient injury or illness. Sites of intubation include nasogastric, nasojejunal, esophageal, pharyngeal, jejunal, or gastrointestinal. Nursing responsibilities usually includes tube insertion (if a temporary tube is required), maintenance of the tube, and administration of the feedings. Prevention of complications associated with each particular tube, including assessment of the patient during feeding, is vital to patient recovery.

Nasogastric, nasojejunal, and jejunostomy tubes are most often used when there is danger of pulmonary aspiration, because the pyloric sphincter provides a barrier, which appears to lessen the risk of regurgitation and aspiration. Jejunostomy tubes also have the added advantage of being able to bypass an upper gastrointestinal obstruction. Advantages of these particular feeding tubes include ease of insertion, low cost, variability in size and length of the tubes, radio-opaque insertion stylets, and fenestrated ends to facilitate ease of nutritional delivery. Nursing responsibilities often include tube insertion (nasogastric and nasojejunal) in which proper techniques are critical. It is often required to ensure patency post- placement by radiographic techniques, although prior to food administration, the tube should be always be aspirated for negative pressure and proper gastric emptying to avoid gastric distention. Suturing techniques are recommended in lieu of tissue glue, as nasal and skin erosion can occur.

Other types of enteral devices include pharyngeal, esophagostomy, and gastrointestinal tubes. Usually intended for the patient needing long term nutritional support, general disadvantages of these types of feeding tubes include the need for local anesthesia. Relatively inexpensive, these specialty tubes generally require the same type of nursing care as other enteral feeding tubes. Regardless of tube type, careful attention to both maintenance and administration of feeding solutions can prevent many complications. Maintenance of the tubes requires regular irrigation to maintain patency, particularly after feedings. Diets should be blenderized and strained, particularly with smaller diameter tubes. Very clean techniques in the handling during both tube placement and diet delivery can help prevent many complications. The skin around the tube should be cleaned at least daily, inspected for fluid leaks, and the tape or bandage around the tube changed daily. The tube should be marked with permanent marker where it enters the skin, in order to monitor correct placement. A light bandage or dressing is recommended for most feeding tubes to keep entry site clean. If constant rate infusions are required, the administration bag should contain only a few hours of solution at a time to avoid curdling.

Patient response to feedings is important during administration. Patients that show signs of discomfort during feeding, such as restlessness, salivation, or vomiting, can be signs of improper tube position. Other common but serious complications of tube feedings include pulmonary aspiration, diarrhea, constipation, tube occlusion, peritonitis from improper tube position, and delayed gastric emptying. Such complications can be avoided by checking tube placement prior to feeding, measuring gastric residue before each feeding, monitoring gastric tubes for migration during daily bandage changes, and evaluating both diet type and concurrent medications to determine the cause of the diarrhea or constipation.

Bacterial contamination can also occur during enteral tube use. It is important to use clean techniques during tube placement and handling, and to keep opened containers of formula refrigerated and discarded after 48hours, and to routinely change enteral bags and administration lines every 24 hours.

Parental nutrition refers to the delivery of nutrients intravenously. Candidates for parental nutrition include patients who are unable to digest or absorb nutrients via the GI tract, or have uncontrolled vomiting. Examples include patients with severe pancreatitis, inflammatory bowel disease, peritonitis, or post-op intestinal surgery patients needing bowel rest. Parental nutrition is expensive and requires strict antiseptic technique in catheter placement.

The nurse's role in maintenance of the parental IV catheter is critical. Responsibilities include catheter placement with sterile technique, daily bandage changes, insertion site inspection and cleansing, sterile IV injections, and routine sterile changes of IV bags and administration lines.

Summary

Nutritional support to critically ill animals is essential for recovery. Providing nutrition prevents loss of functional body tissue, as there is no true reserve of protein in the body. Catabolism of these proteins represents a loss of function to the animal and impedes even simple metabolic processes. Systems such as the immune, liver, heart, and kidney become compromised from lack of fuel substrates. Being able to identify which patients are at risk for nutritional insufficiency, and to intervene early on in their course of therapy, is critical to patient outcome. Obtaining a baseline nutritional profile and monitoring nutritional parameters are important throughout the hospital stay. Frequent physical examination of the patient and reassessing patient status should be implemented as part of patient protocol. Good communication between doctors and nurses regarding body weight, hydration status, and nutritional intake is paramount to patient survival.