Therapeutics Iii Exam 4 - Lectures 9-10 (Enteral Nutrition)

Front 1

1. Identify the indications for enteral nutrition support.

Back 1

Remember, if the gut works, use it. Indications for enteral support include inadequate oral intake, inability to eat (anorexia, dysphagia, esophageal obstruction, head/neck surgery, chemotherapy), increased requirements (burns, trauma, cancer), GI disorders (IBD, SBS, malabsorption, entero-cutaneous fistula, pancreatic insufficiency, radiation enteritis), and neurologic concerns (CVA, demyelinating diseases, trauma).
The only absolute contraindications to enteral nutrition are mechanical obstruction and necrotizing enterocolitis (rot-gut).

Front 2

2. Describe the role of the gastrointestinal tract (GIT) in host immune defense and the influence of feeding on GIT barrier function.

Back 2

Besides digesting and absorbing nutrients to maintain nutritional health, the GI tract is actively involved in defending the host from toxins and antigens by means of nonimmunologic and immunologic mechanisms. These gut host defense mechanisms are also collectively referred to as the gut barrier function. The gut barrier acts to prevent the spread of intraluminal bacteria and endotoxin to systemic organs and tissues. Hydrochloric acid secreted by the stomach kills the majority of the bacteria ingested with food. Under normal circumstances, a mucus gel layer coats the intestinal epithelium and thereby alters the adherence of bacteria to the cells of the GI tract and provides a favorable environment for anaerobic bacteria. Anaerobic bacteria, which normally colonize the mucus layer, aid in preventing tissue colonization by potential pathogens. Small-bowel peristalsis further prevents bacterial stasis and overgrowth. The gut barrier function is also maintained by the intestinal immune system, known as the gut-associated lymphoid tissue. This gut-associated lymphoid tissue regulates the local immune response to antigens within the GI tract. Specific immunoglobulins are secreted to kill remaining organisms and neutralize any toxins they produce. The hepatic Kupffer cells help to maintain gut barrier function by clearing the portal blood of gut-derived bacteria and endotoxins. The integrity of gut barrier function may be affected by numerous pathogenic insults such as physiologic stress and ischemia, and a variety of drugs, including chemotherapeutic agents.

Front 3

3. Discuss the administration routes and methods used in the delivery of enteral nutrition support.

Back 3

Oral (PO) route requires no surgery and consists of physiologic consumption. But, it cannot ensure adequate intake and requires cooperative, alert patients.

Nasogastric (NG) tubes do not require surgery and are not permanent. They can be used in patients in whom eating is not desirable. They have a risk of aspiration. The use of large bore tubes can cause nasopharyngeal irritation and/or ulceration. The tubes can be easily malpositioned.

Esophagostomy requires surgery and is permanent. It does not require laparotomy. The tube can be replaced easily as needed. The patient may feed without loosening clothing. It cannot be hidden by clothing though. It is uncomfortable and there is risk for aspiration.

Nasoduodenal (ND) or nasojejunal (NJ) do not require surgery and are not permanent. They have a decreased risk for aspiration. Transpyloric passage can be difficult. Tubes are easily clogged and malpositioned.

Gastrostomy (abdomen to stomach) requires surgery and is permanent. It is conducive to bolus feeding. It can be concealed by clothing. There is a risk for aspiration. There is also a risk of leakage of gastric contents.

Jejunostomy requires surgery and is permanent. There is low aspiration risk. It requires meticulous rate control and is easily dislodged. Fistula formation is common as is intestinal obstruction. It requires laparotomy.

Front 4

4. Compare and contrast various enteral nutrition formulas with regard to macronutrient substrates.

Back 4

Blenderized formulas contain intact protein, complex and simple carbohydrates, fiber, and long chain fatty acids. They are indicated for function GI tracts if the patient will not or cannot eat by mouth. They provide complete nutrition. On the other hand, they have high viscosity and osmolality, may contain lactose, are not palatable, and are expensive.
Milk-based formulas contain intact protein, primarily long chain fatty acids, disaccharides and corn syrup solids. They are indicated for functional GI tracts and are usually supplemental. They tend to be palatable, but they do have lactose and a high osmolality.
Lactose-free formulas contain largely intact protein, oligosaccharides, long chain fatty acids and some medium chain triglycerides. Indications include functional GI tract. They are used as supplemental or total nutrition via a tube or orally. They are lactose free, palatable, inexpensive, and have a low viscosity. On the other hand, protein quality is lower than milk-based and blenderized formulas.
Peptide based formulas contain peptide chains that are easily absorbed. They are indicated for altered GI tracts. They have a moderate osmolality, increased palatability, and low viscosity. They are also expensive and cause diarrhea.
Elemental formulas have selected nutrients supplied in partially digested form. They are indicated for limited GI function and metabolic abnormalities. They are expensive and unpalatable.
Disease-specific formulas are designed for a specific organ or metabolic failure (liver, kidney). They may require supplementation. They are unpalatable and expensive.

Front 5

5. Select the appropriate enteral formula category when given patient-specific information.

Back 5

There are many things to consider when selecting a formula. Does the patient need complete or incomplete nutrition? What is the GI function? What additional substrates are needed (calories, protein)? Is the substance palatable? How is the formula packaged? What is the route of administration? What is the disease state of the patient (hepatic or renal failure)? What is the osmolality of the formula?

Front 6

6. Recommend an appropriate regimen for initiating and titrating enteral nutrition including route (gastric, small bowel) and method of administration (continuous, cyclic, bolus).

Back 6

Continuous infusion typically runs all day and has a max of 125 mL/hour. Continuous cyclic infusion runs for 10-14 hours/day. Intermittent feeding is the administration of 240 to 500 mL of formula infused over 20 to 60 minutes 4-6 times/day (bolus feeding must go into stomach). Bolus feeding is the administration of 240 to 500 mL of formula over less than 10 minutes 4-6 times daily (also into stomach). If rate of infusion is very important, use a pump. If rate is not important, use a controller.
Feeding must be adequate to meet nutritional needs. 240-500 mL bolus is usually adequate and tolerated. If gastric “meal” (intermittent bolus) is not feasible, use continuous gastric, jejunal or duodenal infusions. Administer feeding at room temperature or cool from refrigerator. Warming of food is not required but cold feeding may not be tolerated. For continuous feeding begin at full strength, 20-50 mL/hour. Advance by 10-25 mL/hr every 4-8 hours as tolerated to desired level. For intermittent feeding, begin with 120 mL every 4 hours and advance by 30-60 mL every 8-12 hours as tolerated to the desired volume.

Front 7

7. Design a monitoring plan for administration of enteral nutrition.

Back 7

Monitor for aspirate gastric residual (is food moving through tube?) every 4 hours
Irrigate NG tube with water every 4 hours
Refill feeding bag to prevent bacterial overgrowth at room temp every 4-8 hours
Check tube position every 4-8 hours
Change feeding bag and tubing daily
Keep head of bed elevated 30-45 degrees always
Check vital signs every 4-6 hours
Check weight and fluid input/output daily

Front 8

8. Recommend strategies to minimize the risk of complications due to provision of enteral nutrition.

Back 8

Metabolic complications associated with EN are similar to those associated with PN, but the incidence tends to be lower. EN is frequently administered at lower rates than PN, resulting in less risk of metabolic complications associated with overfeeding. In addition, EN is associated with the achievement of lower blood glucose concentrations than PN. Complications related to hydration and electrolyte imbalance and altered glucose control are observed more frequently in critically ill patients, especially those with underlying organ dysfunction. The micronutrient and water content within enteral feeding formulations are in fixed amounts intended to meet recommended dietary allowances for the average patient. Consequently, the frequency of clinical and laboratory assessment to monitor hydration, electrolyte, organ function, and glucose control adequately for a patient who is critically ill is greater than for a stable patient residing in a rehabilitation unit or at home. Patients receiving long-term EN at home may only require laboratory monitoring every 2 to 3 months, depending on their clinical status. In addition to macronutrient content, it is important to evaluate the actual content of water and micronutrients provided by the enteral formulations, especially in critically ill patients at high risk for metabolic complications. Supplemental fluid and electrolytes may be required in some patients. Conversely, for patients who have fluid retention or increased serum electrolytes, the enteral formulation may need to be changed to one that is more concentrated or provides less of a particular nutrient.

Front 9

9. Identify risk factors for diarrhea associated with enteral nutrition.

Back 9

Diarrhea in patients receiving tube feeding may be caused by a number of factors and management should be directed at identifying and correcting the most likely cause(s). Tube feeding-related factors that may contribute to diarrhea include too rapid delivery or advancement of formula, intolerance to the formula composition, administering large volumes of feeding into the small bowel, and formula contamination.
A common cause of diarrhea that is unrelated to the tube feeding is drug therapy, particularly the use of broad-spectrum antibiotics. Another drug-related cause is the sorbitol contained in many liquid medication formulations. Sorbitol is used as a sweetening agent to enhance palatability, but acts as an osmotic laxative. In addition, many drugs available in a liquid form are hyperosmolar, which may also contribute to diarrhea. Infectious causes of diarrhea, such as antibiotic-induced bacterial overgrowth by Clostridium difficile or other intestinal flora, need to be considered when diarrhea develops. Diarrhea also may occur as a result of malabsorption, secondary to the underlying disease state or condition.

Front 10

10. Recommend strategies to prevent and manage diarrhea associated with enteral nutrition.

Back 10

Measures to prevent or manage the development of diarrhea related directly to the tube feeding should address these potential causes. If diarrhea occurs when using a fiber-free formulation, consider switching to a fiber-containing formulation. If using a high-fat formulation, it may be beneficial to switch to a formulation lower in fat or having a proportion of the fat supplied as MCTs. If protein malabsorption is suspected, switching from an intact protein to a peptide-based source may be beneficial. Avoid lactose-containing enteral formulations, although the majority of products designed for tube feeding are lactose-free. Finally, assess the risk of bacterial contamination of the formula and take steps to minimize any potential risk factors. Once infectious etiologies have been excluded, pharmacologic intervention may be required to control severe diarrhea, including the use of opiates, diphenoxylate, and loperamide.

Front 11

11. Identify and address drug-nutrient interactions and considerations of pharmacokinetic alterations of drugs with enteral nutrition.

Back 11

Physical incompatibility with medications and enteral feeds is more common with formulas containing intact proteins than those with hydrolyzed proteins and those with acidic pharmaceutical syrups. Dosage form and site of drug delivery must be altered.
Specific drugs to watch include anticonvulsants (phenytoin, carbamazepine), antimicrobials (ciprofloxacin, ofloxacin, itraconazole, norfloxacin), gastrointestinals (sucralfate, omeprazole, lansoprazole), immunosuppressives (cyclosporine, tacrolimus), and others (digoxin, theophylline, warfarin).

Front 12

12. Describe appropriate procedures for administration of medications via an enteral feeding tube.

Back 12

1. Administer medications by mouth when feasible; consider enteral feeding tube as an alternative route.
2. Determine location of feeding tube tip, because pre- or post-pyloric drug instillation can alter effectiveness.
3. Liquid dosage forms should be used if available. Dosage and frequency adjustment are required if changing from a sustained release drug to administer a non-sustained release liquid form.
4. Hyperosmolar medications require dilution.
5. The contents of hard or soft gelatin capsules reconstituted with 10-15 ml of water and crushed compressed tablets reconstituted with 15-30 ml of water can be administered when a liquid form is unavailable.
6. Do not crush and administer sustained release or enteric coated medications.
7. Flush the feeding tube with water prior to administering a medication. Do not mix medications. Administer each medication separately, flushing with water between medications. Flush with water after medication administration completed.
8. In general, do not add medications to the enteral formula. Exceptions exist for the adding of hypertonic electrolyte injection to enteral formulas. Be aware of specific drug-enteral product incompatibilities.

Front 13

What are the only absolute contraindications to enteral nutrition?

Back 13

1. Mechanical obstruction
2. Necrotizing enterocolitis

Front 14

Which forms of enteral nutrition have aspiration risks and which don't?

Back 14

Aspiration risk: nasogastric, esophagostomy, gastrostomy
Low or no aspiration risk: nasoduodenal, nasojejunal, jejunostomy

Front 15

Which formula is indicated for altered GI function?

Back 15

Peptide-based formula

Front 16

Which formula is indicated for limited GI function?

Back 16

Elemental formulas

Front 17

What is hyperosmolarity and what is it associated with?

Back 17

It is >300 mOsm/kg and has been associated with gastric retention, N/V/D, and abdominal distension

Front 18

What is the max rate for a continuous enteral infusion?

Back 18

125 mL/hour

Front 19

What is the typical dose of intermittent or bolus enteral feeding?

Back 19

240-500 mL

Front 20

What are some techiniques to unclog feeding tubes?

Back 20

1. Water irrigation
2. Cranberry juice or carbonated diet cola
3. Introduction of pancreatic enzymes plus sodium bicarbonate