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| Sometimes individuals are not able to consume foods by mouth, or consume enough food to maintain their health. In these cases, health care professionals must find alternative ways to provide the nutrients necessary. Enteral nutrition (tube feeding) is one method often chosen to nourish individuals who cannot eat (or eat enough) because enteral nutrition uses the digestive tract. The following module will discuss the method of enteral nutrition including who requires them, the types of formula available, the route of the feeding, administration of the feeding, and complications that may arise. |
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| Who needs a tube feeding? |
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Definition
Not Consuming Enough Nutrients: Illnesses and their treatments can be very taxing on the body. People often become very lethargic and unable to consume enough food to maintain their bodies. Many illnesses also increase the metabolic rate so high, that consuming enough kcalories from food is too difficult. In cases where an individual cannot eat enough food, a tube feeding can be used.
Dysphagiatext annotation indicator: swallowing difficulties can be moderate to severe. The biggest complication of swallowing dysfunction is aspiration and risk of infection. Once an individual is identified as having dysphagia, swallowing studies are generally done to identify the types of foods tolerated (not aspirated). Occasionally, the level of dysfunction is so severe the patient may not be able to tolerate any solids or liquids. In this case, tube feeding is the likely choice. However, if the individual is able to consume some consistencies, but is not consuming enough, a tube feeding may still be necessary.
Some gastrointestinal problems can interfere with a person's ability to eat as well. Depending on the location and severity of the problem, tube feeding can sometimes be used with partial obstructions, fistulas, and impaired motility.
Confusion or dementia can also interfere with a person's ability to eat enough. The individual may not understand or refuse to eat food in a confused or altered state. If the individual is not able to maintain his/her nutritional status, tube feeding may be indicated.
Ventilator support: individuals who are not able to breathe on their own and require mechanical respiration will be sedated and require alternative nutrition than orally. Tube feedings are generally used unless the GI tract is unable to be used. |
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There are literally hundreds of formulas on the market for use in tube feedings. Many of them you have probably seen in the grocery store, although most are obtained through the pharmacy. Tube feed formulas are made by major pharmaceutical companies in separate nutrition-related divisions. Of all the formulas available, we can classify them into four major categories.
Standard Formulas are designed for individuals who can digest and absorb foods normally. The formulas contain whole protein, fat, and modified starches and sugars. Some blenderized formulas are made from whole foods, pureed and liquefied.
Elemental of hydrolyzed formulas are designed for individuals who cannot digest and absorb foods normally. These formulas contain carbohydrates and proteins that are partially or fully broken down. Fat is generally very low in these formulas to ease digestion and they often contain more MCTtext annotation indicator.
Specialized or Disease Specific formulas are, as the name implies, designed to meet the individual nutrient demand of specific disease states. Instead of adjusting standard formulas, manufacturers have produced formulas designed for the unique needs of each disease. Products exist for renal failure, respiratory failure, diabetes, liver disease, etc.
Modular Formulas are made from single nutrients. Sometimes they contain vitamin and mineral mixtures to meet the individual's needs. |
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Macronutrient Composition: the percentage of carbohydrate, fat and protein varies with each formula. Depending on the type of formula and/or disease the nutrient content will vary. For instance, protein is normally provided at 12-20% of total kcalories. But, in metabolic stress, the protein needs are higher and may require a formula with more protein. On the other hand, in kidney failure before dialysis is initiated, the protein need is lower and may require a formula with less protein.
Energy Density: The amount of energy/kcalories in a formula varies. Formulas range from 0.5-2.0 kcals/mL. Standard formulas provide 1.0-1.2 kcals/mL and are designed for individuals with normal fluid and calorie requirements. However, sometimes individuals cannot handle large amounts of fluid. Providing a higher density formula with 1.3 -2.0 kcals/mL allows the patient to receive the amount of energy and nutrients needed with a smaller amount of fluid/volume. The low density formulas (<1.0 kcals/mL) are used less often. Simply diluting a standard formula serves the same purpose.
Osmolality: When the nutrient density changes in a formula, the osmolality changes as well. Osmolality is simply explained as the amount of particles in a solution. If the formula is high nutrient density, it will have more nutrients/particles in the solution. If a formula is low nutrient density, it will have less nutrients/particles in the solution. Standard formulas providing 1.0-1.2 kcals/mL are considered isotonictext annotation indicator. The osmolality of isotonic solutions are similar to that of the blood stream (~300 milliosmoles/kg). The high density formulas providing 1.3-2.0 kcals/mL are called hypertonictext annotation indicator because they have a higher osmolality than the blood stream. Lower density formulas (or diluted) are hypotonic because they have lower osmolality than the blood stream. The osmolality can make a difference in how well an individual tolerates the feeding. Recall from module 6 that fluid is attracted to areas of higher concentration. If we put a hypertonic solution with osmolality higher than the blood stream into the gut, fluid from the circulating blood stream may diffuse into the gut. The extra fluid can lead to diarrhea, and hyperperistalsis. Most individuals tolerate any form of tube feeding, even the hypertonic formulas. Occasionally, when an individual is extremely ill or receiving a feeding directly into the small intestine, the osmolality may make a difference. If a standard formula is not an option, simply infusing at a slow rate, and advancing slowly can help the tolerance of the tube feeding.
Fiber content: some formulas contain fiber, and others do not. It is important to determine if the patient should or should not have fiber, and choose accordingly. Some individuals requiring large bowel rest would require formulas without fiber. However, fiber can be beneficial in maintaining blood sugars or treating constipation.
Religious Consideration: Most pharmaceutical companies have enteral formulas that are Kosher. However, this should be verified before choosing a formula for someone requiring a Kosher diet. |
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| The route chosen to provide nutrients largely depends on the medical condition and length of time tube feeding is required. We can divide the routes into two categories, trans nasal and enterostomies. |
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| The Transnasal routes are designed for short term use (less than four weeks). The tube enters the nasal passages and ends in either the stomach or small intestine. |
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| Nasogastric (NG feeding) enters the nasal passage and ends in the stomach. This route is most commonly used. With contents entering the large holding tank of the stomach, larger amounts can be tolerated. The stomach also controls the rate at which the nutrients enter the small intestine. The biggest complication of NG feeding is reflux and aspirationtext annotation indicator of the stomach contents. Although research is not consistent, it is believed that NG feedings are associated with higher risk of aspiration. Because the NG tube holds the LES (lower esophageal sphincter) open, contents of the stomach can go around the tube and into the esophagus, with potential for aspiration into the lungs. |
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| Nasoduodenal and nasojejunal |
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Definition
| Nasoduodenal and nasojejunal routes both enter the nose and end in the small intestine, one in the duodenum (first section of the small intestine) and the other in the jejunum (the second portion of the small intestine). The nasoduodenal and jejunal feedings offer lower risk aspiration. But, these routes are more difficult to place and verification of the correct placement of the tip in the intestinal tract is required by X-ray before feedings can begin. These feedings also require a pump. Bolus and intermittent feeds are not possible with this type of placement. Feedings may require a slower advancement to the goal rate as well, and sometimes the osmolality may not be tolerated as well. |
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The enterostomies are preferred for longer term use (more than four weeks) or if part of the GI tract must be bypassed. These routes allow direct access through an opening into the stomach or jejunum through a surgical procedure.
The most common enterostomy used is the gastrostomy, a placement directly into the stomach. It is also referred to as a PEG tube (percutaneous endoscopic gastrostomy) or a G-tube. For long term use, this route is preferred because the stomach offers the ability to use large volumes (like with bolus feedings) and it controls the rate at which the nutrients enter the small intestine. Aspiration is less in the gastrostomy than the nasogastric because the tube is not holding the LES open. However, it does present a moderate aspiration risk and may be contraindicated in someone with extremely high aspiration risk.
Used less often is the jejunostomy with placement directly into the jejunum (the second portion of the small intestine). Just like with the nasojejunal route, a pump is required for this feeding. Bolus and intermittent feeds are not possible with this type of placement because large volumes are not tolerated. Feedings may require a slower advancement to the goal rate as well, and sometimes the osmolality may not be tolerated as well. Depending on the type of tip used in the jejunostomy, sometimes only hydrolyzed (elemental) formulas can be used. |
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| Feeding Route comparisons |
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Definition
Insertion
Method or
Feeding Site Advantages Disadvantages
Nasogastric Easiest to insert and confirm placement; least expensive method; feedings can often be given intermittently and without an infusion pump. Highest risk of aspiration in compromised patients; risk of tube migration to small intestine.
Nasoduodenal
and nasojejunal Lower risk of aspiration in compromised patients; allows for earlier tube feedings than gastric feedings during severe stress; may allow enteral feedings even when obstructions, fistulas, or other medical conditions prevent gastric feedings. More difficult to insert and confirm placement; risk of tube migration to stomach; tube feedings require an infusion pump for administration; may take longer to reach nutrition goals.
Gastrostomy Feedings can often be given intermittently and without a pump; easier insertion procedure than a jejunostomy. Moderate risk of aspiration in high-risk patients.
Jejunostomy Lowest risk of aspiration; allows for earlier tube feedings than gastrostomy during severe stress; may allow enteral feedings even when obstructions, fistulas, or medical conditions prevent gastric feedings. Most difficult insertion procedure; most costly method; feedings require an infusion pump for administration; may take longer to reach nutrition goals. |
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| Depending on the individual fluid needs, additional water may be necessary to provide in flushes. The tubes always require some amount of water flushes (approximately 30-40 mL every four hours) to keep the tube from clogging, and additional flushes if medications are being administered by the tube. If the patient is receiving an IV for hydration, additional flushes may not be required beyond that. However, if the patient is not receiving an IV, water flushes should be calculated based on fluid needs of the individual and what is being provided in the formula. If a patient is on a fluid restriction, careful monitoring of the total amount of fluid administered through IV, tube feeding and flushes is required. |
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| Formulas are available in closed and open feeding systems. With a closed feeding systemtext annotation indicator, the formula is prepackaged in bottles that connect directly to the tube. This type of system provides the least contamination risk, the least nursing time to administer, and can hang for longer periods of time. However, they do cost more initially and may have more waste when not tolerated or as the feeding is weaned. Open feeding systemstext annotation indicator are usually in smaller containers that need to be transferred to a feeding container such as a bag or syringe. This type of system allows more flexibility for bolus feeds, and making adjustments (mixing or diluting formulas). However, it requires more nursing time to administer these feedings and is more likely to be contaminated. |
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Continuous Feedings: infused via a pump over a 8-24 hour period, the continuous feeding is ideal for most health care facilities such as hospitals and long term care. Infusing smaller amounts over a long period of time, increases the patients tolerance of the feeding. A rate of 80cc/hr over 24 hours would be equivalent to sipping 1/3 cup of formula over one hour every hour of the day. This delivery can be used with any route of feeding whether into the stomach or small intestine. The disadvantage is that the patient is tied to a pump for long periods of time. Individuals at home or in therapies may not enjoy have the pole and pump to carry along with them.
All tube feedings begin as continuous feedings to ensure the patient tolerates the feeding. If mobility becomes an issue (as when the individual is sent home on a tube feeding or to rehabilitation), the feeding can be changed to one of the next two feedings once tolerance has been established. |
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| Intermittent Feedings: providing large amounts (250 -500 mL) through intermittent feeds can be done through a gravity drip so no pump is needed. A pump can be used, but is generally done over a short period of time (20-40 minutes). This delivery is ideal for individuals with more mobility, who do not want to be tied to pump/pole all day. It also mimics mealtimes more effectively. |
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| Bolus Feedings: with a more rapid delivery, a bolus feeding infuses large volumes (250-500 mL) over a shorter period of time (10-20 minutes) with a syringe. Patients may not tolerate this feeding as well. If you can imagine guzzling 2 cans of Ensure in 10-20 minutes, you will get the idea of what that delivery is like. On the other hand, it works well with individuals wanting more mobility like in rehabilitation or at home. |
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Tube feedings are usually started at low rates and advanced slowly over a period of time. If continuous feedings are used the common protocol is to start at 20-30 mL/hr. If intermittent feeding is used, an amount of 60-120mL may be initiated to start. Once tube feedings begin, the nurse generally checks to make sure the feeding is well tolerated. Signs of nausea, vomiting, or diarrhea may be indications that the patient is not tolerating the feeding. Other factors such as medications may cause these symptoms as well, so careful monitoring and assessing is needed. Checking residuals is another means of determining if the tube feed is tolerated. The nurse routinely measures the amount of formula left in the stomach by withdrawing stomach contents with a syringe. Large volumes of formula (compared to the amount infusing) may indicate the stomach is not emptying properly. The physician will set what residuals are considered adequate for each individual. When residual volume is higher than accepted, the physician will set a protocol such as shutting off the tube feed temporarily and/or starting medication to boost gastric motility.
If the tube feeding is tolerated, the rate of administering it will be increased gradually to goal ratetext annotation indicator. In continuous feedings, the rate is increased 10-25 mL every 4-6 hours. With intermittent, the rate is increased 30-60 mL at each feeding. The goal rate is ordered by the physician, but is usually determined by the dietitian. In the hospital and long term care facilities, a dietitian will assess all patients on tube feedings to verify the correct formula, route and rate of delivery is being used. Incorrect use of tube feedings can impair an individuals health including problems with organ systems (such as lungs and kidneys), and ability to heal or fight infection. Especially in critically ill individuals, the dietitian is crucial in the assessment and ongoing evaluation of tube feedings.
When/if the individual is ready to transition to table foods, we must do so gradually. We cannot discontinue the feedings just because they are ready to eat. With the tube feed continuing, oral diet is initiated. If on a continuous delivery, the pump will often be turned off during meal times. As the patient eats more with each meal, the rate of the pump can be tapered down. If receiving intermittent or bolus feedings, the patient may receive less formula separate from meal times or after a meal if the oral intake is low (<50%). Once the patient is tolerating 2/3 of his/her nutrient needs from the oral diet, the tube feeding can be discontinued and tube removed. |
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| As mentioned already, tube feedings that are not tolerated well may cause nausea, vomiting, and diarrhea. Clogged tubes are another common problem, but normally avoided with adequate water flushes. Metabolic complications can also occur such as fluid/electrolyte or glucose imbalances. Careful monitoring of symptoms, weight, and labs can help prevent most complications. Aspiration of contents into the lungs is one of the most serious consequences of tube feedings. It can lead to infections such as pneumonia and possible death. The route of administration should be carefully considered in persons who have aspiration risk. The following is a summary of some common complications and actions. |
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Aspiration precaution patients
physician may request blue food dye to determine if aspiration occurs
Keep HOB (head of bed) elevated
Clogged tube
Flush with water
Enzymes to unclog
Diarrhea
Look at meds and possible bacterial contamination
May need to change osmolality
Sometimes fiber helps
Constipation
Add fluids and fiber
Hyperglycemia
Often caused by stress
Can decrease volume or change to diabetic formula
Use fiber containing formula
Nausea and Vomiting
Probably not tolerating
Stop or change formulas (esp. if hypertonic) |
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Definition
| The first part of this module discussed how we use tube feedings to nourish individuals who cannot consume enough nutrients through food. But, sometimes tube feedings are not an option. In many cases, the gastrointestinal tract is compromised, and using it for nutrition can be detrimental. An alternative route of providing nutrition is via the circulatory system (directly into the veins). The golden rule for determining nutrition support is "If the gut works, use it!" If a person cannot eat orally but their GI tract is functioning (bowel sounds present), enteral nutrition should be used. If the GI tract is not functioning, such as is the case with shock, gastrointestinal bleeding, and GI surgery, then you should use parenteral nutrition delivered directly into the veins. The next module will go over many of the upper and lower gastrointestinal problems that may lead to the necessity of parenteral nutrition. The following decision tree is useful in determining the type of nutrition support necessary for a patient. |
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| There are two routes of delivery for parenteral nutrition. The first is PPN or peripheral parenteral nutrition, and the other is TPN or total parenteral nutrition. Each route has its intended uses, indications and contraindications. Choosing the correct delivery is important to success of patients who are typically quite ill. |
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| Peripheral Parenteral Nutrition (PPN) |
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| PPN is a route of delivery directly into one of the peripheral veins. These solutions normally enter the smaller veins carrying blood from the arms and legs. PPN carries several risks with it. Veins must be strong to handle the more concentrated solution (2-3 times more concentrated than the blood stream). This type of parenteral nutrition is designed for short term use only (should not exceed 7-10 days), and veins are often rotated to prevent inflammation and other complications. The smaller peripheral veins can be damaged by highly concentrated solutions. The osmolarity of the solutions must be maintained between 600 and 900 milliosmoles per liter. Since nutrients increase the concentration and osmolality of solutions, high calories and protein are usually not possible. This route is not indicated for individuals who are malnourished or have high energy demands because nutrient density cannot be met. The main source of kcalories is lipid. Individuals being considered for PPN should be able to tolerate large amounts of lipid since half the kcalories are normally supplied by fat. The concentration limitations also present questions about fluid demands as well. To receive PPN, the individual must be able to handle large amounts of fluid (to keep the osmolarity at 600-900 milliosmoles per liter). In the later modules of this course, we will discuss several conditions that cannot handle large amounts of fluid such as Congestive Heart Failure, Renal Failure and Liver Failure. |
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| Total Parenteral Nutrition (TPN) |
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Definition
By far, the most widely used route of parenteral nutrition is TPN. This route uses the larger central veins entering directly into the heart. Using this route allows much more flexibility with concentration. With the large volume of blood entering the heart here, it quickly dilutes the TPN solution. With few limitations, the solution can be made more concentrated for individuals requiring high kcalorie or protein demand or for individuals not able to tolerate large volumes of fluid. Because most individuals are able to meet more of their nutrient requirements through the large central veins, it is referred to as total parenteral nutrition. This route is also preferred for long-term nutrition support lasting more than 10 days. Infection, however, is our biggest concern.
The insertion of the central catheters can be done one of two ways. Infusion through the right subclavian vein offers direct access to the heart. PICC lines or peripherally inserted central catheters may also be used. A catheter is inserted into a peripheral line and then advanced to a central vein. These are sometimes used instead of central lines because of the lower cost and lower infection rates. The person needs to have strong peripheral veins with this method of feeding as well. |
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| Simple IV's are not considered parenteral nutrition because it does not provide all of the nutrients necessary. Simple IV's are for hydration (fluid and electrolytes) only and should not be confused with providing nutrition support. Providing only simple IV's for longer than 3-5 days can result in protein breakdown, affecting lean tissue, immune system, fluid balance, etc. |
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| Since the parenteral solutions enter directly into the circulatory system, the GI tract (and all digestion/absorption) is bypassed. The nutrients used in parenteral solutions must be in the smallest form (that would normally be absorbed into the blood stream). |
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| The form carbohydrates used in IV solutions is dextrose monohydrate. It is a form of glucose that contains a molecule of water and is stable in intravenous solutions, and it provides 3.4 kcal/g, whereas pure glucose provides 4 cal/gram. Concentrations of dextrose vary from 2.5% to 70%. The higher concentrations (>12%) are normally only used in TPN solutions. Orders for dextrose in the IV solution is usually written as D followed by the percent dextrose and the solution used (water or normal saline). With an order of D20W we are providing 20% dextrose in a solution of water. D20NS would indicate 20% dextrose in a solution of normal saline. |
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| The form of protein necessary for the circulatory system is amino acids. Parenteral nutrition solutions provide all of the essential amino acids plus a mixture of the nonessential amino acids. Amino acids in a solution range from 3.5 to 15%. Just like with carbohydrate, the higher concentrations are normally only used in TPN. Amino Acids provide 4 kcalories per gram, however, many clinicians prefer not to calculate protein as part of the kcalories provided. Protein is essential for many life-necessary functions such as healing, immune function, acid base balance, fluid balance, etc. In very sick individuals who may be in a catabolic state and negative nitrogen balance, protein needs are difficult to meet when it is being used as an energy source. Providing 70% of kcals from carbohydrate and 30% from lipid spares the protein from being used as a kcalorie source so it can serve the vital functions of the body and prevent catabolism. Clinicians will often calculate the non protein kcals from carbohydrate and fat while providing the protein in addition to those non protein kcals (based on weight). Disease specific formulas of amino acids are available for use with renal failure and encephalopathy in liver failure. |
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| Lipid emulsions provide the essential fatty acids and are a significant source of kcalories. Lipids can be provided either daily or periodically (i.e. 3 times per week). When provided daily it serves as a source of energy, and when provided periodically it is used to prevent an essential fatty acid deficiency. Just like in foods, lipids provide 9 calories per gram. Using fat daily helps reduce the amount of dextrose needed to meet energy demand, and decreases complications such as hyperglycemia. Lipid solutions are available in 10, 20 and 30% solutions. They can be mixed with the parenteral nutrition bag or administered separately with a Y-connector, often called 'piggyback'. Typically, fat is utilized in a concentration to provide 20-30% of total kcalories. However, if triglycerides are too high, lipid reduction may be necessary. |
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Fluid is generally needed at 30-40 milliliters per kilogram. Amounts are adjusted based on disease states and fluid output. Calculating a person's fluid needs in addition to nutrient needs will determine the concentration and rate at which the solution will be infused. Electrolytes are a precarious component of the solution. Administered incorrectly, the electrolytes can be lethal. Only experienced professionals should determine the amount of sodium, potassium and chloride necessary in a solution. Careful evaluation with serum levels daily is necessary.
Electrolytes are ordered in millequivalents, which are units indicating the electrical charge provided by each electrolyte. Since the body's fluids are neutral (with equal numbers of positive and negative electrical charges), it is essential to calculate the electrolytes in this manner. |
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| Vitamins and Trace Minerals |
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| Commercial preparations of vitamins and minerals are usually added to parenteral solutions daily. All of the vitamins are normally provided, but vitamin K may be eliminated for patients received blood thinning medications such as Coumadin (Warfarin). Minerals provided normally include zinc, copper, chromium, selenium and manganese. Since iron affects the stability of the solution, injections are given separately. |
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| As mentioned before, the osmolarity depends largely on the route of delivery, the energy demand of the patient and the fluid load allowed. PPN must limit osmolarity to below 900 milliosmoles per liter. Because lipid does not alter the concentration of a solution, larger amounts of lipid are used in PPN solutions to provide the kcalories necessary. |
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| Some medications can be mixed in a parenteral bag, but most are not. To prevent drug-nutrient interactions, medications are often infused through the same line with a Y-connector. |
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| Solutions that provide all three energy nutrients mixed in the bag are called total nutrient admixture (TNA) or a 3-in-1 solution. A 2-in-1 solution does not include lipids. The fat is provided separately. The TNA solutions are easier because only 1 pump is necessary, but the addition of lipid to the solution reduces the stability. |
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| Administration of Parenteral Nutrition |
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Definition
| The nutrition support team must determine the best administration method before starting parenteral nutrition. Determining how slowly to start and advance the solution is largely determined by the condition of the patient. Solutions can be administered continuously over a 24 hour period or during 10-16 hour periods, known as cyclic parenteral nutrition. Continuous parenteral nutrition is often used for critically ill patients who cannot meet their nutrient needs in shorter 10-16 hour periods of time. Cyclic parenteral nutrition administration is more successful with individuals who will require nutrition support for longer term, and are likely to be sent home with it. |
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| Discontinuing Parenteral Nutrition |
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Definition
| Once the GI tract can be used, it should be. Check for bowel sounds, bowel movements, and flatus. A patient may start with enteral feedings or liquids depending on their swallowing status. The diet can then progress. Parenteral nutrition is weaned as diet tolerance is achieved (once 2/3rd- 3/4th of estimated nutritional needs are met orally, IV feedings can be discontinued). If the patient is not eating well (50% of needs not met orally) the patient may need supplemental tube feedings. A patient may go from TPN to tube feeding to oral diet, or TPN to oral diet, or never advance to oral diet or tube feeding at all. After being on nutrition support for a long time period, some people may be very happy to eat again and eat very well, while others maybe very scared and not want to eat. Some people may complain of lack of appetite. They need to be encouraged to eat, and a possible appetite stimulant may be necessary. |
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| Several metabolic complications must be monitored. Since we are dealing with infusion directly into the circulatory system, some of the complications can be life threatening. |
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| Hyper- and hypo- glycemia |
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Definition
| Hyper- and hypo- glycemia: Maintenance of blood sugars can be very difficult, especially with critically ill patients. Hyperglycemia (raised levels of blood sugars) is much more likely to occur than low blood sugars. However, if the parenteral nutrition is interrupted or not weaned correctly, hypoglycemia may develop. |
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| Hypertriglyercidemia: High levels of triglycerides in the blood stream is more likely to develop in critically ill patients, especially those with severe infection, liver disease, kidney failure and hyperglycemia. If triglycerides levels exceed 500 milligrams per deciliter, infusion should be stopped. |
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| Refeeding Syndrome: Refeeding syndrome can occur anytime a malnourished individual is fed too quickly. It is more likely with parenteral nutrition, however. Refeeding syndrome is characterized by fluid and electrolyte imbalances and hyperglycemia, resulting in the possibility of life-threatening complications including respiratory and cardiac failure. The key to preventing refeeding syndrome is carefully assessing a patient for malnutrition and advancing nutrition support very slowly, allowing the body to adjust to the nutrient intervention. |
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| Liver Failure: Parenteral nutrition can result in excessive fatty acid deposited in the liver, causing fatty liver. Most of the time the fatty liver is reversed when parenteral nutrition is stopped. In the case of long term parenteral nutrition, the fatty liver can progress to permanent damage and possible liver failure. Triglycerides and liver enzymes are monitored carefully to prevent this from happening. The amount of fat storage in the liver is related to the constant high levels of insulin. Therefore, cyclic feedings (having less amount of time with hyperinsulinemia) seem to prevent some of the fatty liver complications long term. |
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| Gall Bladder disease: Long periods of time (>4 weeks) not using the GI tract causes the bile in the gall bladder to thicken. This increases the risk of stones from developing. If a patient requires long term parenteral nutrition, medication injections can be given to force the gall bladder to release the bile. |
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| Metabolic Bone Disease: Long term parenteral nutrition has been associated with decreased bone density and mineralization. It is likely due to alterations in calcium, phosphorus, magnesium, sodium, vitamin K and vitamin D metabolism. When long term parenteral nutrition is required, dietary adjustments to the solution, supplements, medications and physical activity must be evaluated. |
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It may be necessary to send a patient home with nutrition support. Due to the cost and time it takes to train a patient and/or their family members, nutrition support is only appropriate for people who need long term care. Tube feeding is most often performed at home, although parenteral nutrition can be done too. In some cases, the person may need supplemental nutrition support to add to a regular oral diet. For example, a child with cystic fibrosis often needs supplemental home tube feeds in addition to regular oral meals in order to get the required amount of calories to sustain normal growth and development.
The patient and/or caretakers must be capable to learn, able to rationally deal with possible problems at home with their nutrition therapy, must be compliant with recommendations, must have good emotional support, professional support and financial support for supplies and equipment. Home nutrition support is very different than oral intake, therefore the patient needs to make many adjustments. Disadvantages of home nutrition support may include embarrassment, inconvenience, inability to eat at social gatherings, limited freedom of movement, difficulty traveling, need to go to the bathroom more frequently, sleep pattern changes, and the time involved in learning how to do it.
Home nutrition support can be very expensive. Insurance and Medicare may pay for some of it, but the rest of the financial responsibility falls on the patient and his/her family. Home health programs must be aware of federal and state regulations, reimbursement, and the patient's medical and nutrition needs. The home environment must be assessed for safety and cleanliness. The physician directs the patient's care, while the RN's do most of the training for the patient or their family members. The RD monitors the patient's nutrition status, and the pharmacist may coordinate delivery of formulas, medications and supplies.
The following video is an example of home management. Mom administrators tube feeding through child's PEG tube.
embedded media indicator |
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| Nutrition in Severe Stress |
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Definition
| The following section of this module covers the imbalances and body responses that occur due to stress. Effects from both metabolic and respiratory stressors will be discussed. Stress is defined as the state in which the body's internal balance is upset by a threat to a person's physical well being. Stressors to the body include infection, illness/disease, and injury. Metabolic and Respiratory stresses lead to hypermetabolismtext annotation indicator, protein catabolismtext annotation indicator, fluid imbalancetext annotation indicator, and negative nitrogen balance.text annotation indicator |
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| The Body's Response to Stress |
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| The way a body responds to acute stressors is dictated by hormones, nervous system and immune responses. The most life-saving processes become heightened and more protected, while functions of lesser consequences are delayed. With hypermetabolism as a primary body response, energy intake becomes a crucial component. Without adequate kcalories lean tissue breakdown increases and whole body processes are affecting, leading to potentially lethal complications. |
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Definition
| The hormone responses to stress are geared at mobilizing nutrients. With the necessity of immune and healing factors, mobilizing all nutrients to the blood stream is essential for fast response to the areas of the body affected. The body wants carbohydrates, fats and amino acids ready for immediate release to the cells needing energy, or healing as well as to feed the immune system. In order to mobilize the nutrients, tissue must be broken down. Although a life-saving response to mobilize these nutrients, the complications associated with the hypermetabolism and protein catabolism can have catastrophic effects. Without adequate kcalories provided in nutrition support, the catabolism can lead to whole body processes being affected, including the immune response. The following table identifies the hormones and what effect they have on the body. |
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Increase in metabolic rate
Glycogen breakdown in liver and muscle
Glucose production from amino acids
Release of fatty acids from adipose tissue
Glucagon secretion from pancreas |
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Protein degradation
Enhancement of Glucagon's action on liver glycogen
Glucose production from amino acids
Release of fatty acids from adipose tissue |
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| Sodium reabsorption in kidneys |
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| Water reabsorption in kidneys |
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The immune system responds to stress with an inflammatory process designed to prevent invading organisms from entering and spreading throughout the body and to prevent further tissue damage. The inflammatory response causes dilation of the vessels going to site of injury (allowing more blood flow, immune factors, and nutrients to enter), and constriction of the smaller vessels going away from the site of injury (to prevent spread of invading organisms). While the change in blood flow is necessary for immediate post injury needs, long term changes in response to stress can result in severe problems with organ systems.
At the site of injury the mast cells of the immune system release histamine to attack invading bacteria. Blood vessels dilate to the injury and constrict going away from the injury. The excess fluid accumulating in the area leaks out of the blood stream resulting in edematext annotation indicator. The inflammatory response is largely controlled by cytokines, proteins that direct the changes in body responses. Other components involved in the inflammatory response include eicosanoids (derived from fatty acids). Changes in dietary fat can have some effect on the inflammatory process. The omega 6 fatty acids are the primary precursors for the inflammatory mediators. Omega 3 fatty acids, on the other hand, decrease the inflammatory process.
System effects from the cytokines response has immediate effects as evidenced by the swelling and redness observed within a short period of time after injury. Other effects are not as visible. These acute-phase responsestext annotation indicator include :
Increased C-Reactive Proteintext annotation indicator in the blood stream
Increased blood clotting factors (such as fibrinogen and prothrombin)
Serum levels of albumin, iron and zinc fall (albumin is our indicator for protein status and may not be accurate after severe stressors; iron carries oxygen to tissues and zinc assists in the healing process)
Hyperglycemia
Negative nitrogen balance
Fluid shift
If the stressor continues long term, the effects of the inflammatory response can lead to multiple organ failure or multiple organ dysfunction syndrome (MODS). The changes in blood flow have serious effects on the organ systems. Over time, those systems fail, and recovering from MODS is very difficult. When the stressor is caused by injury or illness, the long term effects is called Systemic Inflammatory Response Syndrome (SIRS). In response to infection, the result is called Sepsis. Both disorders of SIRS and Sepsis have the same response leading to multiple organ failure and potential for death. |
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| Gastrointestinal Response |
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Definition
| The gastrointestinal system is also affected by stressors. Largely due to the changes in blood flow from the inflammatory response, the GI system is not a top-priority and its function is often delayed. Gastric motility is decreased, making the feeding process very difficult. Ulcers are more more likely to develop, and absorption is often impaired. Trying to use oral nutrition or enteral feeding may not be tolerated well. Also of importance to note, is that 70-80% of the immune system is secreted from intestinal cells. With decreased blood flow and function of the GI cells, immune response may be affected. |
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| The following graphic identifies the process of a stressor affecting the body. During the initial phase after an acute stress, the hypermetabolism and lean tissue breakdown send the patient downhill in what is typically a 7-10 day acute response. By day 3 or 4, the patient reaches resistance. If adequate nutrition is initiated by this point, the patient's body will likely recover and be into recovery within 7-10 days. However, if adequate nutrition is not initiated and the patient does not have adéquate nutrient stores, the patient will spiral into exhaustion. Recovery from this state is difficult and a long process. Often you will hear clinical dietitians use that 3-4 day period as the marker for initiating nutrition support. Dietitians understand the importance of nutrition to the body's hormone and immune response. Without adequate nutrition, the hypermetabolism will cause worsened lean tissue catabolism, affecting all of the organ systems, and interfering with adequate healing and fighting off infections. |
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| Each stressor will affect the body a little different and careful observation of fluid balance is essential. Clinicians want to ensure enough fluid is provided to restore circulation, and make sure nutrients, oxygen and meds can reach the tissues throughout the body. However, we cannot provide too much that it stresses the heart. Excess fluid in the blood stream will increase the workload of the heart trying to pump all the extra volume. |
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As mentioned before, provide adequate energy (kcalories) is crucial. In a hypermetabolic state, not providing enough kcalories will result in further protein catabolism affecting the body's ability to heal, and the immune system's ability to fight off infection. But, more is not always better. When excess kcalories are provided, it increases the demand on the respiratory system. As carbohydrates, fats and proteins are metabolized in the cells, one of the bi-products is CO2 (carbon dioxide). Providing more kcalories than the body needs leads to increased CO2 production and more work on the heart and lungs.
Calculating energy needs in severe stress is not always the easiest process. In module 1 we discussed the most accurate way to determine caloric needs (especially in severe stress) is through indirect calorimetry. Also called metabolic cart studies, indirect calorimetry is an indirect estimate of resting energy needs made by measuring the amount of carbon dioxide produced and the amount of oxygen consumed. The Acadmey of Nutrition and Dietetics states "indirect calorimetry is the standard for determination of Resting Metabolic Rate in critically ill patients, since Resting Metabolic Rate based on measurement is more accurate than estimation using predictive equations". The results help the health care team better assess actual energy and protein needs.
If predictive equations are needed in critically ill patients, dietitians will often consider using one of the following, as they have the best prediction accuracy of equations studied: Ireton-Jones, the Harris-Benedict (with or without activity and stress factors), and the Fick equation. The Mifflin-St. Jeor equation should not be considered for use in critically ill patients, as it was developed for healthy people and has not been well researched in the critically ill population. The following formulas are often used by dietitians in calculating energy needs for critically ill patients. While you are not required to memorize these formulas, it is good to understand the process registered dietitians use.
Extra information on these Equations:
1. Harris-Benedict equation:
BEE(kcal/day):Males = 66.5 + (13.7 X W) + (5.0 X H) - (6.8 X A)
Females = 655 + (9.6 X W ) + (1.7 X H) - (4.7 X A) where:
W = usual or adjusted weight in kilograms H = height in centimeters A = age in years
Calculate Basal Energy Expenditure (BEE).
BEE refers to the metabolic activity necessary to sustain life (i.e., respiration, pulse, body temperature) and can be estimated using the following equation:
Calculate Total Energy Expenditure (TEE)
TEE can be estimated by multiplying the BEE by a factor that accounts for physical activity and stress factors (see below). Only one factor should be used (i.e. do not add multiple factors). Select the factor that corresponds to the patient's dominant situation. Most patients will require 1.3 - 1.7 times the BEE in total caloric intake or between 30 and 35 kcal/kg. Only rarely do calorie requirements exceed 2.0 x BEE or 40 kcal/kg in any patient. The TEE is adjusted as illness progresses and recovery proceeds to avoid complications of under or over feeding.
BEE Correction Factors for Physical Activity and Clinical Stress*
2. Fick Equation
The Fick equation can be used to calculate energy expenditure in ICU patients who have a pulmonary artery/Swan catheter. Twenty-four hour energy expenditure is approximately seven times the VO2 in mL/min. VO2 is calculated from cardiac output (CO) in L/min, content of venous O2 (CvO2) in mL/dL, and content of arterial O2 (CaO2) in mL/dL according to the following formula:
Where:
CaO2 - CvO2 = 1.39 X Hb(g/dL) X (SaO2 - SvO2)
SaO2 and SvO2 are respectively arterial and mixed venous oxygen saturation as a fraction
VO2 = [(CaO2 - CvO2)] x 10 x CO
VO2 (in mL/min) x 7 = 24 hour energy expenditure in kcal/day units
Venous blood gases must be determined at approximately the same time as cardiac output. Repeated measurements performed over several days are helpful in increasing the accuracy of the estimate and in determining trends in energy expenditure.
3. Mifflin St. Jeor Equation:
MEN: kcal/day = 5 + 10(wt) + 6.25 (ht) – 5 (age)
WOMEN: kcal/day = -161 + 10 (wt) + 6.25 (ht) – 5 (age) 0
4. Ireton-Jones Formula
Ventilator-dependent (EEVv) or breathing spontaneously (EEVsp)
EEVv = 1925 – 10A + 5W + 218S + 292T + 851B
EEVsp = 629 – 11A + 25W – 609O
W=weight in kg; A=age in years; S is score for sex (male 1, female 0); T, B, and O are scores for trauma, burns, and obesity (each score 1 if present, 0 if absent) |
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Stressed individuals with normal kidney function need between 1.0-2.0g/kg of protein per day. People with severe burns may need even more. In severe stress and normal kidney function require between 2.0-3.0 g/kg
Glutamine is a non-essential amino acid, which becomes an essential amino acid during stress because the body cannot synthesize enough to meet demands. It provides fuel for the intestinal cells, maintains immune function, and promotes wound healing. Arginine, also a non-essential amino acid, has been shown to provide beneficial immune system effects in the stressed patient. Supplementation of these amino acids has been shown to reduce infection in stressed people. |
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In stressed patients you want to provide a sufficient amount of carbohydrates and lipids to allow protein sparing. Carbohydrate is used for energy, while fat is also used for energy and to supply essential fatty acids. Excess carbohydrates can cause hyperglycemia. Excess fat can affect metabolic functions. The amount needed is individualized per patient status.
70% carbohydrates
30% lipids
Not to exceed total calorie needs
Omega 3 fatty acids can be beneficial in decreasing the inflammatory response. |
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| The need for vitamins and minerals increases with stress. The amount depends on the disease and/or illness. With hypermetabolism, a patient may need increased amounts of the B vitamins necessary for increased energy metabolism. Nutrients such as Vitamins A, C and zinc are involved in the immune system and healing process. Although exact amounts necessary have not been established, supplementing with these nutrients can speed recovery. |
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Patients are provided with oral diets when possible. Patients with severe malnutrition or are not expected to eat within 24-48 hours and should start with either a tube feeding or parenteral nutrition to meet needs. Refeeding syndrome is highly possible with individuals who are malnourished, so advancing nutrition slowly is recommended.
Early initiation of a feeding tube within 48 hours will prevent bacteria translocation due to the GI tract being used. There are many tube feeding formulas that are specifically made for the stressed patient, which are higher in calories and protein per milliliter and contain extra vitamins and minerals. They are very expensive, and sometimes are not beneficial for every stressed patient. Providing nutrients is easy, but absorption of the nutrients can be difficult in these patients. Blood flow to the GI tract decreases during stress. Therefore, stomach ulcers may form due to the stomach being less protected from gastric acid. The cells of the GI tract also shrink and become less absorptive, so malabsorption may occur. During stress, protein stores may be used for energy and nutrients cannot be absorbed or transported in the body due to the lack of protein bound transporters. |
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People who have suffered a burn are severely stressed. Our skin is our largest organ and our major protection against infection. Burns are classified by how deeply they penetrate the skin and underlying tissues.
Burns are also classified by the amount of the body the burns cover. Calculating the body surface area affected by burns is often done by the Rule of Nines. The body is divided into 11 parts, each covering 9% of the body. This gives a quick estimate of how much of the Total Body Surface Area (TBSA)text annotation indicator is covered by burns. Medical and nutrition treatment will be affected by the amount of TBSA affected and the classification of the burns.
The immediate response of burns once an individual is admitted to the hospital is to clean the wounds, stabilize breathing, minimize fluid losses with IV's and prevent infections. Once the patient is stable (often not for 2-3 days depending on the severity and amount of burns), nutrition support can begin. Burns cause some of the most severe metabolic stress to the body. As discussed earlier in this module, these patients will suffer hypermetabolism, protein catabolism, nutrient losses, and inflammatory responses with blood flow changes. In addition, the loss of skin (protective barrier) causes tremendous loss of fluid and nitrogen and increases risk of infections. Second and third degree burns have substantial losses of protein and micronutrients. Gastrointestinal function may be disrupted with burns covering 40-50% TBSA. |
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The goal of nutrition support in burns is much like any other metabolic stressor, minimize nutrient losses and promote nitrogen balance. The energy demand largely depends on the severity and amount of TBSA affected.
The Cureri Equation is a formula for calculating the specific needs of a burn patient.
Ages 16-59: [25 kcal X preburn weight (kg)] + (40kcal X % TBSA)
Ages 60 and up: [20 kcal X preburn weight (kg)] + (65 kcal X %TBSA)
Protein demand is very high due to excessive protein catabolism and nitrogen losses. Depending on the severity and amount of TBSA affected, protein may be as high as 2.0 - 3.0 g/kg.
Additional nutrients necessary to burn patients include Vitamins C, A, and zinc to support immune function and promote healing.
If oral nutrition can be provided, that is the best source to maintain blood flow to the gut and support the good bacteria. However, the high kcalorie and protein demand may be very difficult to achieve with oral diet alone. Tube feeding may be necessary. If the burns are affecting a large amount of TBSA, the gut motility may be affected. Choosing an enteral route going to the small intestine may help. If the patient is not able to tolerate the tube feeding, parenteral nutrition would the likely choice. With the high energy and protein demand, TPN would be indicated over PPN.
Hydration status is another difficult component of burns. Careful management of fluid status is crucial. With the inflammatory response and blood flow changes, fluid tends to pool in the areas of injury (as discussed earlier in this module). However, with loss of skin, fluid losses can be quite high. Providing too much fluid would likely cause worsened problems with heart and lung function, but not enough fluid will limit transport of nutrients and oxygen to cells. |
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| Nutrition and Respiratory Stress |
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| Respiratory status is often compromised in illness or injury to the body. When breathing is affected, nutrition is also affected. The type of nutrition provided can improve or worsen a person's respiratory status. Therefore, careful attention is necessary. |
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| Chronic Obstructive Pulmonary Disease (COPD) |
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| COPD describes several disorders that persistently obstruct airflow through the lungs. Emphysema is a disease characterized by the progressive damage to alveoli (air sacs) in the lungs, causing difficulty with breathing. Chronic bronchitis is a persistent inflammation of the mucous membranes lining the main airway of the lungs. This leads to a narrow airway and difficulty breathing. Smoking and exposure to respiratory irritants are the main causes of COPD. The disease leads to frequent episodes of decrease oxygen to the blood, increased respiration, infection, respiratory failure and heart failure. Treatment for COPD includes smoking cessation, close monitoring of respiratory status, and use of medication to help improve breathing and/or airflow. |
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| Medical Nutrition Therapy |
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Definition
The main goal of medical nutrition therapy is to correct the malnutrition that affects up to 60% of those with COPD, and prevent lean tissue losses. Patients with COPD have many nutritional concerns due to their high nutritional risk for weight loss, protein energy malnutrition, and infection. Typically, they experience lack of appetite and weight loss due to difficulty chewing. Eating foods when on an air mask also presents problems.
Early on in the diagnosis, if a patient is overweight, weight loss can be beneficial (help with breathing). With weight loss, the focus is on moderate kcalorie restriction and exercise to promote lean tissue development. However, as the disease progresses, and consuming enough kcalories becomes very difficult, weight loss is prevented. The difficulty in breathing puts increased energy demand (15% higher resting energy rate than normal) on the patient. As the disease worsens, consuming the extra kcalories necessary can become very difficult. Recommending small frequent meals is often very helpful. Patients with low weights or malnutrition often benefit from pulmonary formula supplements between meals to help maintain their nutrition status. However, too many kcalories will produce more CO2, making breathing more difficult. The disease-specific pulmonary formulas have a higher fat content. Fat produces less CO2 than Carbohydrate, and is preferred. Weight in the end stages is a predictor of survival. Low weights and malnutrition increase mortality. Appropriate nutrition support is crucial. Helping to maintain lean tissue and correct malnutrition can help lengthen a patient's life and quality of life. |
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| Respiratory failure can occur from chronic deterioration of the lungs, as in COPD, or from acute sudden onset. One of the most common forms of acute respiratory failure is Acute Respiratory Distress Syndrome (ARDS). The sudden onset typically follows acute lung injury due to conditions such as sepsis, trauma, severe pneumonia, inhalation of smoke or toxic chemicals, aspiration of gastric contents. The permeability of the lungs increases allowing fluid to accumulate in the lungs, interfering with the exchange of gasses. Respiratory failure generally requires mechanical ventilation. Later stages cause fibrosis and disrupt lung structure with possible progression to multiple organ failure . |
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| Medical Nutrition Therapy |
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| Individuals with respiratory failure are often on a ventilator and sedated. In most cases tube feedings will be necessary. Unless another condition exists, tube feedings are generally tolerated well. In choosing the correct nutrition support, several factors need to be considered. The first is energy balance. With an increased energy demand from the overworked respiratory system, kcalories need to be higher. Dietitians will generally use one of the predictive equations such as Harris Benedict to determine resting metabolic rate, and adjust with a stress factor of 1.2 -1.5. Providing too many kcalories will increase CO2 production, making breathing more difficult. Protein is also typically higher to boost immune function. Other nutrients that are beneficial to ARDS include omega 3 fatty acids (decrease inflammation) and vitamins A, C and E. With fluid accumulation, diuretics are often used to mobilize the fluids. Monitoring the electrolytes and fluid balance is crucial. Often a fluid restriction is necessary. Disease specific formulas for ARDS are available. They are typically high nutrient density (1.5 to 2.0 kcals/mL) to prevent fluid overload and to provide the extra kcalories. Choosing the correct rate to infuse the tube feeding is very important. Often medical care professionals will forget they are working with a nutrient dense formula and infuse it a higher rate. The increased CO2 production from the increased kcalories puts more work on the heart and lungs. It can impair the person's ability to wean from the vent. Careful observation of nutrition is crucial to the entire medical treatment. |
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