patients. Inadequate fluid intake and lack of fiber may be factors

associated with constipation. Diabetic EN formulas contain fiber.

However, if the decision is to use a very-high-protein formula for

J.K., a fiber-containing formula would be reasonable to use based

on his known history.

MEDICATIONS AND ENTERAL

NUTRITION BY TUBE

CASE 37-4, QUESTION 3: J.K. has been receiving EN for

4 days and has been at goal rate for 2 days. Laboratory

evaluation today shows the following:

Sodium, 135 mEq/L

Potassium, 2.7 mEq/L (decreased from 3.5 mEq/L yesterday, 3.9 mEq/L the previous day, and 4.6 mEq/L when

tube feeding started)

Chloride, 95 mEq/L

Calcium, 7.9 mg/dL

Magnesium, 1.4 mEq/L (decreased from 2.5 mEq/L

2 days ago)

Phosphorus, 2.8 mg/dL (decreased from 4.4 mg/dL

2 days ago)

Albumin, 2.4 g/dL

Micro-K (8 mEq KCl/capsule) has been ordered as six

capsules via feeding tube along with calcium carbonate

(260 mg elemental calcium/tablet) as two tablets twice daily

via feeding tube. Orders were also placed in the chart for

J.K. to begin warfarin. He was placed on a heparin drip yesterday for a newly diagnosed deep vein thrombosis (DVT)

in his left leg, despite prophylactic heparin therapy since

admission. Home medications are to be restarted, including enteric-coated aspirin, 81 mg daily; famotidine tablet,

20 mg twice daily; simvastatin tablet, 20 mg daily; metoprolol succinate tablet, 95 mg daily; and verapamil capsule,

240 mg daily. How should J.K.’s medications be administered when he is receiving EN?

Patients receiving EN often receive medications through the

same tube. Feeding tube occlusion, adverse effects caused by

changes in pharmaceutical dosage forms, and alteration of medication pharmacokinetics and pharmacodynamics are among the

potential problems.76–79 Interactions related to pharmacologic or

physiologic effects of medications or enteral nutrients also may

occur. For this reason, oral medication administration should be

considered unless a strict NPO status is required. J.K. has severe

gastroparesis, a diagnosis not requiring a strict NPO status; however, the medical team is concerned that medications administered by mouth may have erratic absorption and poor efficacy

due to delayed gastric emptying. Medications are ordered to be

administered through J.K.’s feeding tube.

903Adult Enteral Nutrition Chapter 37

Medication Selection

Solid dosage forms are a challenge to administer by feeding tube.

Crushing a medication and mixing the powder in water results

in an altered pharmaceutical dosage form, and this may affect its

efficacy or patient tolerance. Liquid dosage forms are generally

recommended for administration through a feeding tube, but

they are not without problems, and a liquid dosage form may

not always be the best choice. Liquids should be diluted at a

minimum of 1:1 with water before administration to avoid coating the tube interior. High viscosity liquids, such as suspensions,

should be diluted 3:1 with water. Pharmaceutical syrups with a

pH of 4 or less must be used with caution because immediate

clumping and tackiness of formulas mixed with the syrups have

been reported.76,77 For medications not available in liquid form,

a therapeutically equivalent medication in a liquid form can be

considered. Extemporaneous preparation of a liquid also may be

considered, but can increase cost significantly. Medications in a

soft gelatin capsule are best avoided for administration through a

feeding tube. If there is no alternative, the capsule can be dissolved

in warm water. Undissolved gelatin should not be administered,

because this may occlude the tube. The safety and efficacy of simple compressed tablets are not affected by crushing and dissolving in water immediately before use. Simple compressed tablets

can be crushed to a fine powder, then dissolved or suspended

in water for administration. Powder in hard gelatin capsules can

be poured into water and mixed thoroughly before administration through a feeding tube. Failure to adequately suspend or

thoroughly dissolve any of these dosage forms in water before

administration through the tube can result in occlusion. Some

medications appear to be particularly troublesome for administration through a feeding tube. Calcium salts, iron salts, lansoprazole, omeprazole, multivitamins, pentoxifylline, potassium

chloride, phenytoin, protein supplements, sucralfate, and zinc

salts were identified by nurses as the products most frequently

contributing to feeding tube occlusion.74,78 J.K. has both calcium

and potassium ordered today.

Calcium carbonate is a simple compressed tablet that can be

crushed, suspended in 30 mL of water, and administered through

the feeding tube. Risk of tube occlusion from an inadequately

crushed tablet may be decreased by use of calcium carbonate suspension (500 mg calcium/5 mL), if available. Administration of

either crushed and suspended tablets or commercial suspension

requires flushing the tube with 15 mL of water before and after

medication administration.37 Diluting the suspension at least 1:1

with water, preferably 3:1, and flushing with 75 to 100 mL may

be advisable because suspensions may otherwise coat the tube.

The appropriateness of calcium supplementation should be questioned, however, because J.K.’s serum calcium concentration is

within normal limits after correction for his low serum albumin concentration, and the ionized calcium concentration would

likely be within normal limits. Administering any medication via

the feeding tube may occlude the tube; therefore, administering

an unneeded medication through the feeding tube is an unwarranted risk. Alternative dosage forms for electrolytes are limited

to IV forms so the easiest and most cost effective route is via

feeding tube if J.K. cannot take oral medications.

Potassium supplementation is ordered today for J.K.’s low

serum potassium. Potassium should have been considered yesterday because the serum level has been decreasing since tube

feeding began. The selected potassium supplement is inappropriate for administration by tube because Micro-K is a slowrelease product. Crushing any type of slow-release or sustainedrelease product destroys slow-release mechanisms, resulting in

the immediate release of several hours worth of the medication

at one time. An exaggerated therapeutic response may be seen

initially, followed by a loss of response part way through the

dosing interval. Deaths have occurred when sustained-release or

long-acting products are crushed before administrations; therefore, these dosage forms should not be crushed.80 Instead, an

immediate-release dosage form should be used, with appropriate

adjustment of dose and dosing interval, or an alternate administration route (e.g., intravenous, suppository, transdermal patch)

may be available. Potassium chloride powder for solution (three

packets with 15 mEq KCl/packet) or liquid (10% KCl 35 mL, 15%

KCl 25 mL, or 20% KCl 15–20 mL) should be ordered rather than

the slow-release product. Dividing the potassium dose into two

or three smaller doses and diluting each dose with 60 mL of water

may be better tolerated. Giving 45 to 50 mEq of potassium as a

single dose may cause nausea, vomiting, abdominal discomfort,

or diarrhea. These symptoms might be mistaken as intolerance

to EN, resulting in the tube feeding being stopped temporarily.

The larger fluid volume for administration also may help reduce

the GI irritation associated with potassium doses.

Potassium supplementation could also be partially accomplished by changing part of the potassium ordered to potassium

phosphate, which is available as a 250 mg capsule that provides

8.1 mmol of phosphate and 14.2 mEq of potassium. J.K. appears

to have a mild refeeding syndrome, with phosphorus and magnesium slightly less than the normal range and having decreased

significantly during the past 2 days.25 Supplements should be

started today so that smaller daily quantities can be used before

electrolytes are critically low. This may decrease the risk of diarrhea and GI upset caused by the administration of oral phosphate

or magnesium. Contents of each potassium phosphate capsule

are designed to be dissolved in 75 mL of water for administration, so dissolution is not a concern. One potassium phosphate

capsule twice a day plus KCl liquid to provide 20 mEq potassium

is the same potassium dose as is ordered currently. The liquid

KCl dose should be separated from the potassium phosphate to

minimize GI effects.

Magnesium supplementation could be accomplished with a

magnesium oxide tablet (400 or 500 mg) administered two to

four times daily. These are simple compressed tablets that can

be crushed and suspended for administration via feeding tube.

An alternative would be magnesium hydroxide suspension 5 mL

two to four times daily. Magnesium doses are distributed through

the day to reduce the risk of diarrhea. The feeding tube must

be flushed adequately before and after each dose of electrolyte

replacement. The flush volume should be a minimum of 15 mL,

although 75 to 100 mL after the magnesium dose may be better to ensure the electrolyte preparation is out of the tube. The

volume of other tube flushes can be adjusted to limit the total

fluid intake to the estimated requirements. It can be difficult

to provide large quantities of potassium, phosphate, and magnesium via feeding tube secondary to the GI intolerance they

cause. Therefore, IV electrolyte replacement may be necessary

if intracellular depletion is extensive and J.K. does not tolerate

oral electrolyte replacement.

Famotidine is a simple compressed tablet that can be crushed.

However, both the verapamil and metoprolol dosage forms

ordered for J.K. contain multiple doses intended to be slowly

released. The once-daily dosing schedule helps identify these

two medications as slow-release products and, for metoprolol,

the succinate salt is also a clue as this is different than other dosage

forms of metoprolol. Both verapamil and metoprolol should be

changed to immediate-release dosage forms if J.K. cannot take

them by mouth. The dose and frequency of dosing will need to

be adjusted to reflect the immediate release dosage form.

Enteric-coated tablets are designed to release medication in

the small bowel because the medication is either acid labile or

irritates the stomach. Protection for the medication or stomach

904 Section 7 Nutrition Issues

is lost when enteric-coated tablets are crushed and delivered via

feeding tube into the stomach, resulting in decreased efficacy of

the medication or increased gastric irritation. When an irritating medication must be given by tube into the stomach, diluting

the medication in at least 60 mL of water is recommended.76

J.K. has enteric-coated aspirin ordered for administration into

a jejunal feeding tube. The enteric coating is designed to dissolve in the small bowel and could be dissolved with bicarbonate

solution before administration into the small bowel. However,

it would be better to use a noncoated tablet for his aspirin dose.

If enteric-coated beads, such as those found in several proton

pump inhibitor dosage forms, are to be administered through

a feeding tube, use of an acidic liquid (e.g., fruit juice) helps

prevent the enteric coating from becoming sticky and adhering

to the inside of the feeding tube. This should only be considered for a large-bore feeding tube, such as a gastrostomy, or

the beads will occlude the tube. Film-coated tablets also cause

problems when crushed because the coating does not crush well

and becomes sticky in water. J.K.’s simvastatin has a film coating and may be a problem to crush and administer through the

feeding tube.

Administering buccal or sublingual dosage forms via feeding tube may result in altered absorption or destruction of the

medication by stomach acid. Therefore, therapeutically equivalent medications (e.g., isosorbide dinitrate rather than sublingual nitroglycerin) or an alternate route of administration

(e.g., nitroglycerin ointment or transdermal system rather than

sublingual nitroglycerin) should be used. A listing of medications that should not be crushed is available at http://www.

ismp.org/Tools/DoNotCrush.pdf.81 Carcinogens, teratogens,

or cytotoxic agents that should not be crushed are included in

the list.

Pharmacokinetic parameters can be altered when medications are administered by feeding tube. J.K. has a jejunal tube

and delivering medication into the jejunum could affect bioavailability, although few studies address this issue. Medications taken

orally are delivered to the stomach, where dissolution occurs for

most dosage forms and hydrolysis of some medications may

occur. Delivery into the small bowel may alter these processes,

thereby affecting bioavailability. For instance, recovery of digoxin

from intrajejunal dosing is higher than with oral administration, primarily because of reduced intragastric hydrolysis.28,76

Bioavailability of medications also can be affected by the presence of enteral formula in the GI tract. Medications affected

by the presence of food are expected to be affected in a similar

manner by the presence of formula.77,79 For example, administration of tetracycline with formula present is expected to reduce

tetracycline bioavailability because of interactions with divalent

cations. A similar interaction is expected between ciprofloxacin

and enteral formula, although some evidence suggests a mechanism other than binding with divalent cations is responsible for

reduced ciprofloxacin concentrations with enteral feeding.28

Phenytoin is particularly troublesome to manage in patients

receiving EN, with reduced phenytoin concentrations reported

in numerous case reports and small studies. Methods suggested

for management include using a meat-based formula, administering phenytoin capsules rather than the suspension, and stopping

formula delivery for 1 to 2 hours before and after the phenytoin dose.76,82 Holding formula administration before and after

phenytoin dosing is often recommended, although others claim

that adequate dilution will reduce loss of the medication. None

of these methods, however, clearly prevents low phenytoin concentrations; thus, monitoring of serum concentrations is important whenever EN is started or altered. Large-scale, controlled

trials are needed to determine the most appropriate method for

managing the phenytoin–EN interaction.

Warfarin can also be troublesome to manage in patients with

a feeding tube, and J.K. is to start warfarin for a newly diagnosed

DVT. Reversal of warfarin anticoagulation by vitamin K included

in enteral formulas is an important pharmacologic interaction.28

The vitamin K content of most enteral formulas today is about

the same as found in a mixed diet and is unlikely to interfere with

anticoagulation, but should be evaluated if adequate anticoagulation is difficult to achieve. In addition, binding of warfarin to a

component of enteral formulas, likely protein, has been proposed

to explain warfarin resistance with formulas containing low vitamin K content.28 Stopping formula administration for an hour

before and after warfarin administration appears to prevent this

type of interaction. Unfortunately, rigorous, randomized studies

to provide evidenced based guidance for the management of this

potential interaction are lacking.

Liquid dosage forms are often hypertonic. Diarrhea is a potential problem related to physiologic effects of hypertonic medications. Diluting hypertonic medications (e.g., potassium chloride)

with 30 to 60 mL of water before administration is suggested.

Dividing the medication dose and separating doses by about

2 hours also decrease GI effects of hypertonic medications. In

addition, selection of brands and dosage forms with minimal

sorbitol can reduce the risk of diarrhea. Sorbitol is a nonabsorbed

sugar alcohol found in many liquid dosage forms. Cumulative

sorbitol doses greater than 5 g can cause bloating and flatulence,

whereas larger doses may act as a cathartic.37,76,77

Tube Occlusion

CASE 37-4, QUESTION 4: J.K.’s feeding tube has occluded

(clogged). What are the causes of feeding tube occlusion

and how can occlusions be managed? What can be done to

avoid occluding J.K.’s tube in the future?

The incidence of feeding tube occlusion is 1.6% to

66%.9,35,37,78 Pump malfunction, lack of periodic tube flushing, formula characteristics, and tube characteristics are non–

medication-related factors affecting tube occlusion. Important

tube characteristics include the inner diameter (bore size), tube

material, and the arrangement and number of delivery holes

(ports) at the distal end. The most important formula characteristic appears to be the protein source. In vitro studies suggest

formulas with intact protein, particularly caseinates or soy, coagulate and clump when exposed to an acidic pH, whereas formulas

with hydrolyzed protein do not.28,76

Medication-related factors influencing feeding tube occlusion

include the administration method, dosage form, pH, and viscosity. Medications must be crushed to a fine powder, mixed

with water to form a smooth slurry, and adequately diluted

before administration. Medications admixed with formula have

the greatest potential for occluding tubes owing to alteration

of the texture, viscosity, or physical form of the medication or

formula. Therefore, medications should not be admixed directly

with formula. The enteral formula infusion should be stopped,

the tube flushed with a minimum of 15 mL water before and

after medication administration, and with 15 mL between each

medication.35,37,38,42,76 Contact between medications and formula within the tube lumen should be limited to decrease the risk

of occlusion. Each medication should be administered separately

to reduce the risk of interactions.

When a feeding tube occludes, it must be replaced unless

patency can be restored. Frequent tube replacement disrupts

nutrient delivery and increases patient discomfort as well as the

cost of care. The initial treatment for tube occlusion is to flush

the tube with warm water using a large syringe, at least 20 mL

905Adult Enteral Nutrition Chapter 37

but preferably 50 mL, to avoid generation of excessive pressure

that could rupture the tube. When a specific cause for occlusion

can be identified (e.g., a specific medication) and physiochemical characteristics of the responsible product are known (e.g.,

solubility, pH), it may be possible to select a more appropriate

flush preparation than water. In most cases, however, use of an

acidic or basic flush preparation could worsen the occlusion.

Acidic liquids (e.g., cranberry juice, diet soda, regular soda) may

perpetuate or extend the occlusion, especially when coagulated

proteins are the cause.76,77 When water fails to restore patency,

activated pancreatic enzymes may be effective. Previously, one

crushed pancrelipase tablet and one sodium bicarbonate tablet

(324 mg) were dissolved in 5 mL of warm water just before instillation into the occluded tube.38,76 A commercial product containing multiple enzymes, buffers, and antibacterial agents in a

powder form (Clog Zapper) is now available. Adherence to flush

protocols and proper medication administration techniques are

essential to maintain patency once tube patency is restored.

Transfer to Home on Enteral Nutrition

CASE 37-5

QUESTION 1: B.A., a 78-year-old man, was admitted 2 days

ago from an SNF for evaluation of a hematoma on his left

lower extremity and possible bone fracture due to a fall.

He receives intermittent feedings through his PEG. The volume is 1,680 mL (seven cans) daily. B.A.’s history indicates

he was hospitalized approximately 5 weeks ago with an

ischemic stroke and was discharged to an SNF (see Case

37-2). B.A.’s tube-feeding volume has increased from 1,440

mL on discharge, but the formula remains the same (1.06

kcal/mL, 0.044 g protein/mL, 15 g fiber/1,000 kcal polymeric formula). His weight has increased 2 kg since hospital

discharge and his overall status has improved. Bone fracture

is ruled out and B.A. is able to participate in physical therapy

(PT). The PT consult indicates B.A. can ambulate safely with

a walker and is able to transfer from bed to chair and to the

bedside commode with minimal assistance. He is deemed

appropriate for outpatient PT after hospital discharge. The

swallow study performed this morning indicates B.A. must

continue NPO for at least another 6 months when the swallow study will be repeated again. B.A.’s daughter has made

arrangements for him to move in with her family. She is concerned about insurance coverage for the EN therapy and

states B.A. has Medicare insurance, including a Part D prescription plan. Will Medicare cover EN?

Before addressing the coverage of EN therapy in the home, it

should be determined whether B.A. is an appropriate candidate

for home versus return to the SNF. Based on the PT assessment,

it is likely B.A. is appropriate for discharge home, providing he

will have some supervision and assistance available. Typically, a

case manager or social worker is involved in arranging appropriate discharge facilities; however, the health care professional

managing nutrition support in the hospital setting should facilitate the nutrition support portion of discharge, as necessary. The

pharmacist should review the medication regimen to assure it is

appropriate for administration through the feeding tube.

Strict guidelines exist for home EN coverage. Medicare Part B

(not Part D) will cover 80% of the cost if criteria are met.83–85 EN

must be medically necessary to “maintain weight and strength

commensurate with overall health status” and there must be a

functional disability of the GI tract (e.g., dysphagia, swallowing

disorder) that is expected to be “permanent.”86,87 The formula

must be delivered by feeding tube (i.e., not oral supplements) and

must provide most of the patient’s nutritional requirements (i.e.,

not supplemental nutrition). Approval is on an individual basis,

requires a physician’s written order, and sufficient documentation

must be available to support the need for EN. Calories less than

20 kcal/kg/day or greater than 35 kcal/kg/day require additional

documentation. The duration of therapy must be 90 days or more

to meet the test of permanence. B.A.’s therapy falls within these

guidelines. In addition, the formula B.A. receives is in a category

that does not require him to meet additional eligibility criteria

related to the formula itself. Additional documentation would

be needed to justify a pump if B.A. was receiving EN via pump.

Enteral formulas are divided into five categories for reimbursement purposes by Medicare Part B (Table 37-6). Formula

manufacturers typically list the Medicare category on the product

label. Medicare intermediaries may also list formula categories.88

Most polymeric formulas containing intact (whole) protein and

1 to 1.2 kcal/mL are in category I. These products have the lowest reimbursement rate and do not require documentation of

medical necessity for the specific formula itself, but still require

documentation of the need for EN. Clear documentation of medical need for formulas in specific categories (e.g., categories III

and IV) is required for their higher reimbursement rates. Appropriate forms available from the Centers for Medicare and Medicaid must be completed for Medicare reimbursement of any EN

therapy.89

Evaluation of Tube Feeding Intolerance

CASE 37-6

QUESTION 1: S.D., a 29-year-old woman, was admitted to

the hospital 65 days ago after a motor vehicle crash. She

sustained multiple traumatic injuries and exhibited multiple complications. S.D. has undergone several exploratory

laparotomies and has been treated for multiple infections,

including pneumonia, sepsis, and wound infection. She has

been treated for Clostridium difficile diarrhea but has not

had diarrhea since therapy was completed 3 weeks ago.

Lysis of adhesions, closure of an enterocutaneous fistula,

and placement of a feeding jejunostomy tube (J tube) were

done during the last laparotomy 8 days ago. Enteral feedings were started through her J tube 3 days ago and

advanced to the goal rate of 80 mL/hour within 36 hours.

The EN provides 35 kcal/kg/day and 1.75 g protein/kg/day,

which is less than her protein requirement based on nitrogen balance. She has received PN for nutrition support

during most of her hospitalization and the PN rate was

decreased as EN increased. S.D. now has diarrhea, which

started approximately 18 hours after her EN was increased

to goal rate. What is the likely cause of the diarrhea? What

other information related to the EN regimen would be helpful to determine if the EN should be stopped and the parenteral nutrition formulation restarted?

Diarrhea affects 15% to 30% of patients in the ICU.90 In

patients receiving EN, diarrhea is multifactorial. Factors associated with diarrhea, but not related to EN, include medications,

partial small bowel obstruction or fecal impaction, bile salt malabsorption, intestinal atrophy, hypoalbuminemia, malnutrition,

infections such as C. difficile, and underlying conditions affecting

the GI tract.38,39,42,75–77,90 Tube feeding-related causes of diarrhea

include high fat content, lactose content, and bacterial contamination. Formula temperature, caloric density, osmolality, formula strength, lack of fiber content, and method of delivery also

have been associated with diarrhea, although a cause-and-effect

relationship is not clear.

906 Section 7 Nutrition Issues

TABLE 37-6

Medicare Categories for Enteral Formulas

Category and Codea Description Examples (Partial Listing)

Category I

B4150

Semisynthetic intact protein or protein isolates

(general purpose formulas)

Boost, EnsurePowder, Isosource HN, Jevity 1.0 Cal, Nutren1.0 Fiber,

Osmolite 1.2 Cal

Disease-specific formulas: Glytrol

Category II

B4152

Intact protein or protein isolates; calorically

dense

Boost Plus, Carnation Instant Breakfast Lactose Free VHC, Ensure Plus,

Ensure Plus HN, Isosource 1.5 Cal, Jevity 1.5 Cal, Nutren 1.5, Nutren

2.0, Resource 2.0

Category IIIb

B4153

Hydrolyzed protein or amino acids Optimental, Peptamen 1.5, Peptamen AF, Perative, Vital HN

Documentation that may provide justification for use: dumping

syndrome, uncontrolled diarrhea, evidence of malabsorption on

appropriate semisynthetic formulas (e.g., isotonic, low long-chain fat

content, lactosefree) that resolves with an oligomeric formula or

documentation of the disease process causing malabsorption

Category IVb

B4154

Defined formula for special metabolic need

(i.e., disease-specific formulas)

Advera, Alitraq, Glucena 1.0, Glucerna 1.5, Glucerna Shake, NutriHep,

Nepro with Carb Steady, Nutren Renal, Oxepa, Peptamen, Peptamen

VHP, Pulmocare, Renalcal, Suplena with Carb Steady

Documentation that may provide justification for use: evidence of

inability to meet nutritional goals with category I or II products

without compromising patient safety and documentation of the

specific diagnosis for which a formula is intended

Category Vb

B4155

Modular components for protein, fat, and

carbohydrate

Protein: Complete amino acid mix, ProMod Liquid Protein

Carbohydrate: Moducal, Polycal, Polycose

Fat: MCT oil

Documentation that may provide justification for use: inability to meet

specific nutrient requirements (i.e., protein, carbohydrate, or fat)

with a commercially available formula

aCode refers to the Health Care Procedure Code System (HCPCS) billing code used by providers billing the Center for Medicare and Medicaid.

b Failure to provide adequate documentation of medical necessity for the specific formula will likely result in denial of claim or payment at the lower category I rate for

Medicare Part B insurance coverage.

MCT, medium-chain triglyceride.

S.D.’s hospitalization has been unusually long and complicated. Many factors could contribute to her diarrhea; however, the diarrhea coincides relatively closely with initiation and

advancement of tube feeding. She may have intestinal atrophy and impaired absorptive function because of her prolonged

period without GI tract stimulation. She has had multiple surgeries, including GI surgeries, and may have reduced absorptive

capacity, bile salt malabsorption, dumping syndrome, or reduced

pancreatic enzyme availability related to her complications and

surgeries. At least theoretically, an oligomeric formula would be

better absorbed if any of these conditions exist. Some practicebased publications suggest consideration of an oligomeric formula for patients whose GI tract has not been used for more

than 7 days.1,91,92 The CCP guidelines recommend initiation of

EN with a polymeric formula.18,19 The SACC guidelines recommend a standard formulation for those not meeting guidelines for

an immune-modulating product.4 Only four studies comparing

oligomeric with polymeric formulas in critically ill patients were

found for the CCP guidelines, and none met the criteria for the

highest level of study. Available data did not indicate a clinically

important benefit for oligomeric formulas; however, these studies did not evaluate patients without use of the GI tract for weeks

before EN initiation. Formula selection is often determined by

physician preference and the calorie, protein, and fat content of

formulas on the institution’s formulary. Because S.D. had been

more than 2 months without significant use of the GI tract, she

was started on an oligomeric formula which is lactosefree and

fiberfree.

The EN formula selected for S.D. is only slightly more than

isotonic at 460 mOsm/kg. Risk of diarrhea from fat malabsorption should be minimal because the formula contains only 15% of

calories from a 50% MCT–50% long-chain triglycerides fat mix.

Increasing EN to goal rate within 36 hours may have contributed

to diarrhea. Initiation at 10 to 20 mL/hour and advancement by 10

mL every 8 to 12 hours to reach goal in 48 to 72 hours would have

been appropriate for S.D. because she had not used her GI tract

for about 2 months.34–40 The jejunum adapts slowly to changes

in volume or concentration, and formula volume was increased

less than 24 hours before diarrhea started. Also, an enteral infusion pump should be used to maintain consistent flow. Changing

back to the previous volume or slightly less should decrease stool

output within 24 hours if the volume change was responsible. If

S.D. does not respond to decreasing formula volume, the formula

may be held for 24 hours to assess whether diarrhea decreases or

stops. Diarrhea related directly to EN usually is an osmotic diarrhea that stops within 24 hours of stopping the formula.42 A more

objective approach than stopping the formula is to measure stool

osmolality. Enteral-formula–induced diarrhea is associated with

a large osmotic gap, whereas secretory diarrhea (e.g., infectious

diarrhea) is associated with a low or negative osmotic gap.42

The selected oligomeric formula is ready-to-use; therefore,

bacterial contamination from mixing technique is not of concern. Cleanliness during formula transfer to the delivery bag, the

period of time formula is in the bag, and methods of cleaning

the delivery bag may contribute to bacterial contamination of

formula. S.D. is receiving her formula from a closed enteral system (i.e., ready-to-hang formula-filled containers), and this virtually eliminates transfer-related contamination when proper technique is used. Any addition (e.g., medication, carbohydrate, fat or

protein module, MCT oil) to the prefilled container before hanging can contaminate the system, and guidelines (e.g., hang-time,

set changes) for an open enteral system then apply. Even when

907Adult Enteral Nutrition Chapter 37

administered separately from the formula, modular components

are a potential contributor to diarrhea due to their osmolarity

and potential contamination during preparation and administration. The selected formula does not meet S.D.’s protein requirement; therefore, a modular protein is needed to supplement the

enteral formula. In addition, the SACC guidelines recommend

consideration of enteral glutamine administration in two or three

divided doses to 0.3 to 0.5 g/kg/day.4 The nutrition plan includes

both enteral glutamine and addition of a modular protein component; however, on review of the medication administration

record, neither of these has been started.

Medications are a major contributor to diarrhea in tube-fed

patients.38 S.D. currently receives antibiotics and has for some

time. However, study results implicating antibiotic therapy in

diarrhea have been questioned because of failure to report stool

frequency and consistency as well as lack of a clear definition

of diarrhea.93 C. difficile may have relapsed after her previous

treatment. Stool specimens should be sent for culture and/or

C. difficile toxin. Evaluation of S.D.’s medications may reveal

medications associated with diarrhea (e.g., sorbitol-containing

products, antacids, oral magnesium, potassium chloride, phosphate supplements, H2 receptor antagonists) for which therapeutic alternatives or different routes of administration could

be considered.38 High osmolality liquid medications should be

diluted before administration to reduce GI side effects.35,37,76,77

S.D.’s GI tract should continue to be used to the extent possible. EN appears to be better than PN for maintaining the GI tract

barrier and host immunologic function.1,4,18,19,58,59,64,91,92,94

Both the CCP and SACC guidelines strongly recommend use of

EN over PN in critically ill patients.4,18,18 Both guidelines also recognize the need for PN at some point when EN cannot meet the

patient’s nutritional requirements; however, neither guideline

addresses patients with long-term, chronic critical illness such as

S.D. The risk of sepsis increases without enteral stimulation of

the GI tract. Whether this occurs through bacterial translocation, an unproved process in humans in which enteric bacteria

or endotoxin cross the GI mucosa into mesenteric lymph nodes

and portal circulation, or through another mechanism is unclear.

In addition, the GI tract serves an immune function, especially

with respect to IgA secretion. Respiratory tract infections, such

as pneumonia, may increase without proper stimulation of the

GI tract, owing to less-effective protection from IgA. Compared

with PN, EN attenuates catabolism in highly stressed patients,

although initiation of feedings soon after the stressing event may

be required to obtain this response. Before a decision is made to

stop S.D.’s EN, all possible causes of diarrhea should be investigated. Possible benefits of improved fluid and electrolyte balance

from stopping EN should be weighed against the potential benefits of reduced infections from continued use of the GI tract.

Combined EN plus PN can also be considered, especially if S.D.

tolerates partial EN but cannot advance to goal rate. Full PN

should be provided if EN is stopped for more than 1 or 2 days.

KEY REFERENCES AND WEBSITES

A full list of references for this chapter can be found at

http://thepoint.lww.com/AT10e. Below are the key references

and websites for this chapter, with the corresponding reference

number in this chapter found in parentheses after the reference.

Key References

Bankhead R et al. Enteral nutrition practice recommendations.

JPEN J Parenter Enteral Nutr. 2009;33:122. (37)

Gottschlich MM et al, eds. A.S.P.E.N. Nutrition Support Core Curriculum: A Case-Based Approach—The Adult Patient. Silver Spring,

MD: American Society for Parenteral and Enteral Nutrition;

2007. (2, 3, 7)

Marik PE, Zaloga GP. Immunonutrition in critically ill patients:

a systematic review and analysis of the literature. Intensive Care

Med. 2008;34:1980. (63)

Marik PE, Zaloga GP. Immunonutrition in high-risk surgical

patients: a systematic review and analysis of the literature. JPEN

J Parenter Enteral Nutr. 2010;34:378. (56)

Merritt R et al, eds. A.S.P.E.N. Nutrition Support Practice Manual.