Introduction to Enteral Nutrition

Question 1

What is the maximum hang time for closed-system enteral formulas?

1: 24 hours
2: 36 hours
3: 48 hours
4: 72 hours

Answer 1

3: 48 hours

Research concludes that closed-system enteral formulas can hang for a maximum of 48 hours based on manufacturer guidelines.

Question 2

A 74 year old male patient with history of Alzheimer’s dementia and dysphagia requiring enteral nutrition as sole source of nutrition presents to hospital with fever, hypotension, poor skin turgor and dry mucus membranes. His height is 5’9” and weight is 67 kg. He is receiving 1200mL free water per day from enteral nutrition formula and 400mL from free water flush. His estimated calorie needs are 1800 kcal/day. How should his fluid needs be estimated?

1: 20 mL per kg
2: 1 mL per calorie intake
3: Minimum of 1500mL/day
4: 30 mL per kg

Answer 2

4: 30 mL per kg

The typical formulas utilized to estimate water requirements are energy based (e.g. 1 mL/kcal required) or a weight based per kg body weight (e.g. 25-35 mL/kg). For individuals over the age of 65, some experts discourage the use of energy-based formulas and instead recommend 30mL/kg with a minimum of 1500mL per day, 1500-2000mL/day or use of the Holliday-Segar formula (1500mL for the first 20kg body weight plus 15mL/kg for remaining body weight. Weight based formulas may lead to fluid overload in patients with severe cardiac issues or kidney disease. Additional fluid should be provided for individuals with severe diarrhea or emesis, large draining wounds, paracentesis loses, drains, high gastric, fistula, and ostomy outputs and persistent fevers. Any formula to estimate water requirement is only an estimate; fluid balance and hydration status should be closely monitored.

Question 3

A 56 year old female with dysphagia who is afebrile and weighs 60 kg is on a standard 1.0 kcal/mL enteral formula at 180 mL/hr over 10 hours nightly. Which of the following volumes of water flushes would best meet her daily estimated fluid requirements?

1: 100 mL
2: 300 mL
3: 600 mL
4: 1000 mL

Answer 3

2: 300 mL

Daily fluid requirements in an afebrile enterally fed patient can be estimated using 30-40 mL/kg or 1 kcal/mL. For this patient, an initial estimate of her daily water requirement would be 1800 mL which corresponds to 30 mL/kg and 1 kcal/mL. Standard enteral formulas are ~84% free water so she would receive ~1.5 L of water from the formula. The remainder (300 mLs) can be given as flushes and/or boluses. Any formula to estimate water requirement is only an estimate; fluid balance and hydration status should be closely monitored.

Question 4

Which of the following is NOT a perceived benefit of early enteral feeding in critically ill patients?

1: Decreases translocation of gut bacteria
2: Reduces atrophy of intestinal villae
3: Reduces risk for infectious complications
4: Increases intestinal permeability

Answer 4

4: Increases intestinal permeability

Early appropriate enteral tube feeding may prevent the occurrence of bacterial translocation (the passage of bacteria across the intestinal wall), and preserve gut mucosal immunity. Lack of feeding via the gut during critical illness may lead to atrophy of intestinal villi which could predispose the patient to translocation, increase in gut permeability, and potentially increase the risk of infection.

Question 5

A patient is receiving enteral nutrition during her second trimester of pregnancy. Nutritional assessment data reflect an average maternal weight gain of 0.42 lbs per week, normal fetal growth, an albumin of 2.0 gm/dL, and a nitrogen balance of +2 gm/day. Based on the data provided, which of the following parameters is not useful in assessing the efficacy of enteral nutrition in pregnancy?

1: Maternal weight gain
2: Fetal growth
3: Serum Albumin
4: Nitrogen balance

Answer 5

3: Serum Albumin

Maternal weight gain and fetal growth are the most important factors in assessing the adequacy and efficacy of enteral tube feedings in pregnancy. There is a strong correlation between infant birth weight and maternal weight. Positive nitrogen balance is important in assessing provision of adequate protein. Use of serum albumin is not recommended due to dilutional effects associated with normal plasma expansion and alterations in plasma protein production.

Question 6

A diabetic patient presents with early satiety, bloating, occasional vomiting, and extensive weight loss. After a thorough GI workup, the patient is diagnosed with gastroparesis. Which type of enteral formula would be more efficacious in this patient?

1: Concentrated, standard, polymeric
2: High fiber
3: Concentrated, high protein, elemental
4: High fat

Answer 6

1: Concentrated, standard, polymeric

Most patients with gastroparesis will tolerate a standard, polymeric formula. A concentrated formula may be used for those patients sensitive to volume. High fat and high fiber enteral formulas may decrease or delay gastric emptying exacerbating gastroparesis symptoms. Elemental formulas are typically indicated for patients with malabsorptive syndromes and/or pancreatic insufficiency. High protein formulas may be used for wound healing and in critical care formulations.

Question 7

Lactose is a common ingredient in which type of enteral formula?

1: Semi-elemental formula
2: Standard adult formula
3: Standard infant formula
4: Elemental formula

Answer 7

3: Standard infant formula

Lactose is routinely used in standard infant formula to mimic the carbohydrate found in human milk. Most adult medical nutritional products are lactose-free due to the prevalence of lactose intolerance in many populations and because lactase production may be decreased during illness.

Question 8

Which of the following patient populations would most likely have difficulty tolerating a polymeric enteral formula?

1: Crohn’s disease
2: Chyle leak
3: Gastroparesis
4: Celiac disease

Answer 8

2: Chyle leak

Elemental enteral formulas, which contain individual amino acids and contain <2-3% of total calories from long-chain fatty acids, are ideal for patients with chyle leaks. The goal of nutritional management of patients with chylous effusions is to reduce the quantity and duration of chyle loss. Nutrition management should be started as soon as the chyle leak is suspected. Some controversy exists as to whether patients should be placed directly on parenteral nutrition. However, most investigators recommend determining the patient’s response to an elemental low fat diet before initiating parenteral nutrition. Patients with Crohn’s or celiac disease most often tolerate formulas with intact macronutrients. In severe cases refractory to medical management, trial of an elemental diet may be necessary. Patients with gastroparesis most often tolerate polymeric enteral formula fed into the jejunum.

Question 9

In patients with pancreatitis, which of the following parameters would be LEAST important in predicting tolerance of enteral feedings?

1: APACHE II score
2: Duration of NPO
3: Abdominal pain
4: Triglyceride level

Answer 9

4: Triglyceride level

The most influential factor in determining tolerance of enteral nutrition in pancreatitis is disease severity as measured by APACHE II scores. Duration of NPO is also important as studies have shown poor tolerance in patients NPO for greater than or equal to 6 days prior to initiation of enteral feeding. Increasing abdominal pain is a clinical indication of enteral feeding intolerance in pancreatitis. Serum triglyceride levels are routinely used to measure tolerance of parenteral rather than enteral nutrition.

Question 10

Which of the following best describes the rationale for initiating enteral nutrition (EN)?

1: It may be implemented in patients who cannot or will not eat adequately.
2: It is reserved for malnourished patients with an intact gastrointestinal tract.
3: It should be implemented regardless of a patient’s hemodynamics.
4: It is commonly used to treat specific disease manifestations.

Answer 10

1: It may be implemented in patients who cannot or will not eat adequately.

Enteral nutrition may be implemented in patients who cannot or will not eat adequately. Prior to initiating EN, important factors such as ethical issues, the patient and/or family’s wishes, quality of life, risks and benefits of therapy, the patient’s clinical status, diagnosis, and prognosis should be considered. EN should be initiated when patients are expected to (or have) not received adequate oral intake for 7 to 14 days. Duration of EN therapy should not be less than 5 to 7 days in the malnourished adult patients or 7 to 9 days in the adequately nourished adult patients. The initiation of EN is not an emergency and should only be started when patients are fully resuscitated and/or stable.

Question 11

Tube feedings can be effectively used in which of the following conditions?

1: Intractable obstipation and vomiting
2: High output mid-jejunal fistula
3: Open abdomen
4: Short bowel syndrome (<50cm) without colon

Answer 11

3: Open abdomen

In an open abdomen, the peritoneum is left open and the viscera are protected with a temporary dressing until the abdomen can be closed by performing skin grafting over the exposed peritoneal organs. Numerous studies have demonstrated safety and improved outcomes with administration of enteral nutrition in patients with open abdomen. In patients requiring open abdomen management after laparotomy, parenteral nutrition should be deferred until EN is not tolerated for a period of 7 or more days. Parenteral nutrition should be indicated in patients with high output mid-jejunal fistula, intractable obstipation and vomiting, and short bowel syndrome.

Question 12

Which of the following is an indication to place a gastrojejunostomy feeding tube?

1: Hyperemesis gravidarum
2: Dysphagia
3: Gastroesophageal reflux
4: Diabetic gastroparesis

Answer 12

4: Diabetic gastroparesis

Gastroparesis is an indication for placing a gastrojejunostomy feeding tube versus a gastrostomy tube. The jejunostomy tube bypasses the stomach thus preventing nausea and vomiting during feeding. The gastric portion can be used for decompression. Research has not supported the need for placement of a gastrojejunostomy tube in patients with hyperemesis gravidarum, gastroesophageal reflux, or dysphagia.

Question 13

Skin-level or low-profile enteral access devices have many desirable features including

1: can be capped when not in use.
2: can only be placed as an exchange tube.
3: are only used for gastric access.
4: are easily accessed for feedings or medications.

Answer 13

1: can be capped when not in use.

Skin level or low profile devices are often more comfortable and cosmetically more appealing for patients. These devices can be capped when not in use. Skin level or low profile devices require an access connector prior to the administration of medications or feedings which requires adequate manual dexterity. They can be placed as an exchange tube or at the time of initial tube insertion. Newer devices are available for both gastric decompression and/or jejunal feeding. These devices are held in place with an inflated internal balloon or a solid silicone internal retention bolster.

Question 14

What is the gold standard for determining proper position of a feeding tube placed at the bedside?

1: Radiographic confirmation
2: pH testing for acidity of aspirates
3: Aspiration of enteric contents
4: Air sufflation and auscultation over the gastric bubble

Answer 14

1: Radiographic confirmation

Radiographic confirmation after insertion of a nasoenteric feeding tube is the gold standard for determining proper placement of a nasogastric tube. Recent studies suggest that radiographic confirmation of placement may not be required when electromagnetic imaging technology is utilized for placement. Auscultation, pH testing, aspiration and capnography still require radiographic confirmation.

Question 15

Placement of a jejunostomy feeding tube would NOT be beneficial for which of the following conditions?

1: Gastroparesis
2: Pancreaticoduodenectomy (Whipple)
3: Short bowel syndrome
4: Chronic pancreatitis

Answer 15

3: Short bowel syndrome

Jejunal feeding would not be beneficial in a patient with short bowel syndrome. Infusion of enteral formula into the jejunum will result in increased stool output and decreased absorption. Slow continuous infusion into the stomach is recommended to maximize absorption and increase intestinal transit time. Jejunal feeding may be beneficial to patients with gastroparesis, post Whipple, and chronic pancreatitis.

Question 16

Compared to gastric feeding, small bowel feeding is associated with which of the following outcomes in critically ill patients?

1: Longer time to achieve target nutrition
2: Increased nutrient delivery
3: Increased gastroesophageal regurgitation
4: Decreased rate of ventilator-associated pneumonia

Answer 16

2: Increased nutrient delivery

Based on a systematic review of studies comparing gastric and small bowel feeding methods, small bowel feeding is associated with reduced gastric residual volume and reflux, but adequately powered trials are not available to support prevention of aspiration pneumonia. Several studies document increased protein and energy delivery and a shorter time to target rate with small bowel feeding.

Question 17

Which of the following interventions may assist with the appropriate placement of a nasogastric feeding tube in an alert patient?

1: Administer IV metoclopramide
2: Keep patient NPO during insertion
3: Have the patient flex his head slightly forward
4: Place the patient supine for tube insertion

Answer 17

3: Have the patient flex his head slightly forward

Elevating the head of the bed to a sitting position, having the patient flex his head slightly forward once the tube tip is in the posterior nostril, and asking the patient to swallow small sips of water are all interventions utilized to prevent respiratory misplacement. Proper patient positioning during insertion narrows the airway passage to facilitate esophageal placement. Having the patient swallow during insertion decreases the risk of placing tube into the larynx. IV metoclopramide is a prokinetic agent that may assist with transpyloric tube passage.

Question 18

Which of the following is LEAST likely to facilitate transpyloric placement of a nasoenteric feeding tube?

1: Endoscopic placement
2: Bedside electromagnetic imaging system
3: Fluoroscopic Placement
4: Weighted tube tips

Answer 18

4: Weighted tube tips

Both fluoroscopic and endoscopic placements have the highest percentage of successful transpyloric passage. Bedside electromagnetic imaging systems have shown greater than 90% success with placement.

Question 19

Which of the following is LEAST likely to be problematic for placement of a percutaneous endoscopic gastrostomy (PEG) tube in a patient with liver disease?

1: Ascites
2: Coagulopathy
3: Gastric varices
4: Hepatitis C

Answer 19

4: Hepatitis C

The presence of ascites at the time of tube placement may prevent the gastric and abdominal walls being in close proximity which results in the inability of the trocar to pass through the stomach wall. Ascites may also permit a poor seal between the abdominal and gastric wall allowing the egress of ascites fluid or the passage of the feeding formula into the peritoneal cavity. Therefore, the presence of ascites is a relative contraindication for PEG placement. Appropriate assessment of risks vs. benefits of tube feeding must be made regarding esophageal and gastric varices, coagulopathy, hepatic encephalopathy, ascites, fulminant hepatic failure, and portal hypertension. The cause of liver failure does not affect the decision in placement of a PEG.

Question 20

Which of the following is an advantage of a gastrostomy feeding tube compared to a nasogastric feeding tube?

1: Reduced incidence of aspiration
2: Is appropriate for long term feeding
3: More successful delivery of calories
4: Reduced incidence of gastric perforation

Answer 20

2: Is appropriate for long term feeding

When enteral feeding is required for more than four weeks, gastrostomy feeding tubes are preferred. Feeding through a gastrostomy tube does not reduce aspiration risk. Provided the nasal feeding tube does not become frequently displaced and occluded, the calories delivered by both methods are similar. Gastric perforation is greater with a gastrostomy placed tube than a nasal placed tube.

Question 21

Which of the following is most often a CONTRAINDICATION to percutaneous endoscopic gastrostomy (PEG) tube placement?

1: Ascites
2: Partial gastrectomy
3: Obesity
4: Prior PEG

Answer 21

1: Ascites

Ascites is considered a relative contraindication to percutaneous endoscopic gastrostomy (PEG) placement because of the increased risk of peritonitis. Provided adequate transillumination is found during endoscopy, partial gastrectomy, prior PEG, and obesity are not contraindications to placement.

Question 22

A patient is admitted with a traumatic brain injury and upon assessment it is determined that the patient will require enteral nutrition for the next three weeks. Which of the following is the preferred method of feeding tube placement?

1: Laparoscopic
2: Open surgical
3: Nasoenteric
4: Percutaneous endoscopic

Answer 22

3: Nasoenteric

Placement of a feeding tube via the open surgical route, laparoscopically, or endoscopically is not without risk. Risks include bleeding, anesthesia complication, bowel perforation, and infection. Although complications can occur with nasally placed tubes, they are much less common. If a feeding tube is required short term (i.e. less than 4 - 6 weeks), a nasally placed tube is the preferred method.

Question 23

What is the primary advantage of a direct percutaneous endoscopic placed jejunal tube (PEJ) versus a percutaneous endoscopic transgastric-placed jejunal tube (PEG-J)?

1: Reduced difficulty of placement
2: Reduced incidence of bleeding
3: Reduced incidence of migration
4: Reduced incidence of gastric outlet obstruction

Answer 23

3: Reduced incidence of migration

Placement of a direct PEJ has less potential for migration or flipping back into the stomach compared to the PEG-J method. Although gastric outlet obstruction may occur more in the PEG-J method by virtue of it crossing the pylorus, this is not the primary advantage of using direct PEJ. Bleeding risk is no different between methods. The ability to place a PEG-J depends on the skill and training of the endoscopist.

Question 24

Which characteristic of enteral formulas is MOST likely to increase splanchnic blood flow in a critically ill patient?

1: High fat
2: High carbohydrate
3: High fiber
4: High osmolarity

Answer 24

1: High fat

Research has shown that blood flow to the bowel is maximized with use of high fat formulas over high carbohydrate formulas. An isotonic, fiber-free formula is ideal for patients at high risk for intestinal ischemia as adequate bowel perfusion is necessary for tolerance of high fiber, high osmolarity feedings.

Question 25

Hospital-prepared enteral nutrition formulas should be stored at approximately what temperature?

1: 4° C (39° F)
2: 6° C (43° F)
3: 8° C (46° F)
4: 10° C (50° F)

Answer 25

1: 4° C (39° F)

To prevent microbial growth and contamination, hospital prepared formulas should be stored at 4° C (39° F). The danger zone for food contamination falls between 5 and 57 degrees Celsius (41° and 135° F).

Question 26

A 60-year old female is admitted with a stroke and fails a swallowing evaluation. A nasogastric tube is placed, and the physician requests an isotonic formula. Which of the following calorie densities of enteral formulas is isotonic?

1: 1.0 kcal/mL
2: 1.2 kcal/mL
3: 1.5 kcal/mL
4: 2.0 kcal/mL

Answer 26

1: 1.0 kcal/mL

The osmolality of gastrointestinal secretions is approximately 300 mOsm/kg. A formula that is isotonic would have a similar osmolality to gastrointestinal secretions. The following are enteral formula caloric densities with typical osmolality: 1.0 kcal/mL (300-350 mOsm/kg), 1.2 kcal/mL (400-450 mOsm/kg), 1.5 kcal/mL (500-650 mOsm/kg), 2 kcal/mL (700-800 mOsm/kg).

Question 27

Which of the following is the best initial enteral feeding regimen for a critically ill adult?

1: Full strength formula initiated at low rate
2: Diluted formula initiated at low rate
3: Full strength formula initiated at goal rate
4: Diluted formula initiated at goal rate

Answer 27

1: Full strength formula initiated at low rate

Research has failed to show a benefit to diluting enteral formulations, and the act of dilution may increase the rate of feeding intolerance by creating an environment that supports microbial growth. Dilution of enteral formulas during initiation may also result in a long period of inadequate nutrition. Generally, a starter regimen for enteral nutrition includes beginning the enteral formula at full strength at a lower rate and then advance to goal rate as tolerated.

Question 28

What is the most important intervention to reduce the risk of pulmonary aspiration during gastric tube feedings?

1: Elevate the head of bed 30 to 45 degrees.
2: Provide mouth care every 2 to 4 hours.
3: Turn the tube feeding off when repositioning the patient.
4: Hold tube feedings for a gastric residual > 200 mL.

Answer 28

1: Elevate the head of bed 30 to 45 degrees.

Raising the head of bed 30 to 45 degrees is the most important intervention to decrease esophageal and pharyngeal reflux of gastric contents to decrease the incidence of aspiration. The patient must be properly positioned in the bed for effectiveness. Oral hygiene is another intervention to reduce the risk of aspiration. There is no benefit to holding the tube feeding during brief periods of supine positioning or elevated gastric residuals.

Question 29

Which of the following medications has NOT been shown to lead to diarrhea in a patient receiving enteral nutrition?

1: Sorbitol-containing preparations
2: Alpha-2 adrenergic agonists
3: Antibiotics
4: Magnesium-containing preparations

Answer 29

2: Alpha-2 adrenergic agonists

Drugs may cause diarrhea due to hypertonicity, direct laxative action (e.g. sorbitol- or magnesium-containing preparations), or increased susceptibility to infectious enteritis (antibiotics). High osmolality of tube feeding, rapid bolus technique or significantly compromised albumin levels have also been cited. Alpha-2 adrenergic agonists, such as clonidine, have been shown to have significant antimotility effects and often prolong instead of reduce intestinal transit time.

Question 30

Tube feeding is often held before and after enteral administration of all the following medications EXCEPT

1: Warfarin
2: Metoprolol
3: Ciprofloxacin
4: Phenytoin

Answer 30

2: Metoprolol

Metoprolol administration does not require any alteration in tube feeding schedules. The bioavailability of warfarin, phenytoin, carbamazepine, and fluoroquinolones, such as ciprofloxacin, may be altered with enteral nutrition and the enteral feeding is often held for up to two hours before and after administration to reduce interactions. When enteral feedings are held, then feeding schedules will need to be altered to achieve target nutrition goals. However, there is controversy surrounding the holding of enteral nutrition. Many practitioners do not recommend holding enteral nutrition around medication administration due to suboptimal nutrition delivery and lack of evidence. Many practitioners will justify continuing enteral nutrition around medications that could potentially interact and for adjustment of medication to help maintain therapeutic serum drug levels.

Question 31

Which of the following strategies can be employed to reduce the risk of feeding tube occulsion?

1: Flush with water before and after medications
2: Increase total daily free water flushes
3: Switch enteral feeding to a fiber-containing enteral formula
4: Switch enteral feeding to a lower fat enteral formula

Answer 31

1: Flush with water before and after medications

Most common reasons for occlusion of feeding tubes are inadequate flushing, improper medication administration, and formula precipitates. Hydrolyzed or free amino acid formulas may be considered, however, they are more expensive, and are not the preferred intervention. Fiber containing formulas may increase risk for physical drug interactions over fiber-free formulas. The fat or water content of the enteral formula does not seem to affect the risk of physical interaction with drugs, however high fat formulas may alter drug absorption through delayed gastric emptying.

Question 32

Drugs in microencapsulated bead or pellet form are most effectively administered through large-bore feeding tubes when mixed with

1: orange juice.
2: gingerale.
3: oral electrolyte solution.
4: warm water.

Answer 32

1: orange juice.

An acidic juice such as orange juice can reduce the risk of microencapsulated beads or pellets sticking to the tube. The tube should be flushed with 30 mL water before and after administration of the drug-juice mixture to avoid physical interactions between the acidic juice and the EN formulation. Mixing drugs with carbonated beverages such as gingerale may be problematic due to physical drug-nutrient interaction with the EN formulation. The use of water or an oral electrolyte solution to administer granules may cause them to become sticky and adhere to the tube, thereby increasing the risk for feeding tube occlusion.

Question 33

Which of the following enteral formulas is LEAST likely to be contaminated with micro-organisms?

1: Reconstituted powdered formula
2: Decanted liquid formula
3: Ready to hang formula
4: Blenderized tube feeding formula

Answer 33

3: Ready to hang formula

Sterile, liquid formulas are preferred in the clinical setting as powdered formulas requiring reconstitution are not sterile and can result in increased bacterial growth. Liquid formulas decanted from a flip top may be at further risk of bacterial contamination than those from a screw top container. Closed ready-to-hang systems have a longer hang time compared to open systems and the risk of touch contamination is less. Reconstituted enteral formulas must be prepared aseptically and by trained personnel. Hang time is limited to 4 hours at room temperature for reconstituted powdered formulas and to 8 hours for canned or bottled sterile, liquid formulas. Closed systems have may hang for 24-48 hours depending on connection set. Hang time for blenderized formulas varies from 2-8 hours depending on if it is homemade or commercial.

Question 34

A 45-year-old male was admitted with chronic stage IV pressure areas, sepsis and acute respiratory failure requiring mechanical ventilation. The patient’s BUN is stable, he has no additional excess GI losses via drains or tubes. A polymeric high protein enteral nutrition formula was started on day 1 of admission. On day 7 of admission, the primary care team requested an evaluation of the protein dose provided by the enteral nutrition. Enteral nutrition was the patient’s sole source of nutrition and provides 136 grams (1.5gm/kg) protein per day. What is the best method to assess protein requirement and adequacy?

1: Grams protein/kg body weight
2: Pre-albumin level
3: Nitrogen balance study
4: Wound healing

Answer 34

3: Nitrogen balance study

After injury, sepsis or critical illness, protein turnover rates, synthesis and breakdown are increased. Pre-albumin is significantly affected by inflammation and renal function making it a poor indicator of nutrition or protein status. Wound healing may serve as a long-term indicator that protein needs are being met but is not effective in the acute setting. Protein needs are often estimated using grams per kilogram of weight but recommendations on the optimal or ideal amount are highly debated. Nitrogen balance studies are currently considered the gold standard for assessing adequacy of protein intake in the hospitalized patient. Nitrogen balance is calculated by subtracting nitrogen output from nitrogen intake. Nitrogen output is derived using urinary urea nitrogen and requires a 24-hour urine collection. Nitrogen intake is calculated from the patient’s enteral and/or parenteral intake. It is worth noting that there are limitations to the nitrogen balance study. Many factors can affect its accuracy including renal dysfunction, errors in estimating intake/output or ostomy losses. Though other methods to assess protein turnover exist they are more expensive and invasive. Nitrogen balance = Nitrogen intake - nitrogen output. Nitrogen output (g/day) = urinary urea nitrogen (mg/100mL) X urinary volume (L/day)/100 + 20% of urinary urea losses + 2g (estimated other nitrogen from skin, GI losses). For example: Enteral nutrition provided 136 grams of protein (21.8 g nitrogen), urine output was 2920mL, and urine urea nitrogen was 16 g. Therefore: 21.8 – [16 + 3.2(20% for other urinary losses) +2] = 0.6 or nitrogen equilibrium

Question 35

Use of a semi-elemental or elemental formula in place of a polymeric formula should be considered with

1: initiation of enteral nutrition.
2: intolerance to polymeric formula.
3: intestinal failure.
4: pancreatitis.

Answer 35

2: intolerance to polymeric formula.

Elemental and semi-elemental formulas are those with partially or completely hydrolyzed macronutrient content designed for patients with gastrointestinal dysfunction. This may include patients with known malabsorptive disorders or those having difficulty absorbing or digesting standard polymeric formulas. Use of hydrolyzed formulas is often based on the perception that individuals will experience better tolerance and, thus, better outcomes. However, studies comparing efficacy of elemental and semi-elemental formulas with polymeric formulas have resulted in conflicting results. There have been a number of studies on patients with malabsorptive disorders such as intestinal failure, Crohn’s disease and pancreatitis that have shown polymeric formulas to be as well tolerated as elemental formulas. Polymeric formulas may also have more benefits than elemental formulas in patients with intestinal failure as these formulas are more isotonic and may better enhance intestinal adaptation. Overall, little evidence appears to support the routine use of elemental or semi-elemental formulas which should be reserved for patients who have failed a trial of polymeric formula.

Question 36

Use of an immune-modulating formula may be beneficial in all of the following patient scenarios EXCEPT

1: elective surgery patient.
2: severe sepsis patient.
3: traumatic brain injury patient.
4: patient with abdominal and torso injuries from motor vehicle accident.

Answer 36

2: severe sepsis patient.

Immune -modulating formulas usually include the addition of key immune-modulating nutrients such as arginine, glutamine, nucleotides, and omega- 3 fatty acids. Despite extensive research in this area, use of immune-modulating formulas remain controversial. Though there is a biochemical basis for adding these nutrients, extensive clinical trials have not been done. The variations amongst these formulas make it difficult to compare to each other. In addition, population heterogenicity, study design variability and quality contribute to difficulties comparing study results and applying outcomes to clinical practice. Based on the heterogenicity of the populations studied and the inconsistency in outcomes, these formulas are not recommended for routine use in the medical ICU. Consideration for these formulas should be reserved for trauma patients, patients with traumatic brain injuries and surgical ICU patients. They are contraindicated in septic patients due to the adverse effects seen with arginine supplementation in these individuals.

Question 37

Which of the following would be the most appropriate tube feeding formula for a patient with extensive second and third degree burns?

1: High fat
2: High protein
3: High carbohydrate
4: High fiber

Answer 37

2: High protein

As part of the stress response, patients with burns exhibit increased breakdown of lean muscle tissue as a preferred source of energy. They also lose protein from open wounds. Therefore, patients with burns require increased intake of protein until significant wound healing is achieved.

Question 38

Which of the following combinations represents modular products?

1: Safflower oil, protein, glucose, and selenium
2: Glucose, glutamine, water, and MCT oil
3: Protein, cholecalciferol, fiber, and safflower oil
4: MCT oil, glucose, fiber, and protein

Answer 38

4: MCT oil, glucose, fiber, and protein

Modular products are commonly used to fortify enteral nutrition regimens or meals served. Modular products are typically single-nutrient products and are available for use in addition to the selected oral or enteral regimens. They increase the protein, calorie, or fiber content of the feeding regimen. Vitamins, minerals, and water are required nutrients but are not considered modular products. The products can be mixed with water according to package directions for administered via the feeding tube or they may be mixed with supplements, or foods on meal trays. They should not be added directly to the enteral nutrition formula.

Question 39

Early initiation of enteral nutrition (EN) has been suggested to benefit ICU patients by reducing infectious complications, length of hospital stay and even possibly reducing mortality. Which group of patients might be at significant risk from early enteral feeding?

1: Cancer patients who underwent surgery of the gastrointestinal tract
2: Patients with increasing vasopressor support
3: Traumatic brain injury patients with intracranial pressure controlled by hypertonic saline
4: Patients admitted to the hospital with acute pancreatitis

Answer 39

2: Patients with increasing vasopressor support

According to current evidence, EN in critically ill patients with hemodynamic instability is still a clinical controversy. Feeding a patient before hemodynamic stability has been achieved may increase the risk of intestinal ischemia. Blood perfusion of the gut may be compromised in a patient who is still requiring high doses of vasopressor drugs to maintain blood pressure. The consensus is that enteral feeding should be delayed until patient is fully resuscitated and on stable or declining doses of vasopressors. Gastrointestinal surgery, pancreatitis, and head trauma are not necessarily contraindications to early enteral nutrition.

Question 40

A patient with acute respiratory distress syndrome (ARDS) receiving enteral nutrition will benefit most from

1: supplemental arginine.
2: formulas containing omega-6 fatty acids.
3: formulas containing omega-3 fatty acids.
4: avoidance of overfeeding.

Answer 40

4: avoidance of overfeeding.

Acute respiratory distress syndrome (ARDS) is associated with an inflammatory response leading to diffuse alveolar damage and lung capillary endothelial injury. Inflammatory mediators, including prostaglandins and leukotrienes derived from arachidonic acid metabolism have been implicated in both acute lung injury (ALI) and ARDS. Formulas containing omega-3 fatty acids may down regulate the inflammatory response through the productions of less inflammatory prostaglandins and leukotrienes. Based published guidelines, it is recommended that patients with ARDS and severe ALI be placed on an enteral formulation characterized by an anti-inflammatory lipid profile. Subsequent to the publication of those guidelines and recommendations have been studies published in 2011 showing that enteral supplementation of omega-3 fatty acids did not result in improved biomarkers of inflammation or clinical outcomes. Similarly, a meta-analysis published in 2014, also found no additional benefits. The research remains inconclusive in this area. The reader is encouraged to peruse the current literature for up-to-date recommendations in this evolving area of research.

Question 41

The use of enteral nutrition formulas enriched with branched-chain amino acids may benefit patients with

1: cirrhosis.
2: hepatic failure.
3: liver transplantation.
4: refractory encephalopathy.

Answer 41

4: refractory encephalopathy.

Theoretically there is believed to be an increased ratio of aromatic amino acids (AAA) to branched-chain amino acids (BCAA) in patients experiencing hepatic encephalopathy. The decrease in BCAA is suspected to be due to an increased breakdown in BCAA from skeletal muscles and utilization. The increased levels of AAA generate false neurotransmitters, resulting in hepatic encephalopathy symptoms. Enteral formulas with higher amounts of BCAA and less AAA are available. Published randomized trials have shown mixed results in patients with hepatic failure receiving these specialized formulas. Due to the lack of evidence supporting their use and the increased cost of such products, it has been suggested that the use of these hepatic formulas be limited to patients with encephalopathy that is unresponsive to standard medical therapy (i.e. lactulose, non-absorbed antibiotics).

Question 42

Enteral nutrition (EN) may be contraindicated in the early post-transplant period in adult patients with hematopoietic cell transplants because of

1: increased incidence of sinusitis with nasoenteric feeding tubes.
2: lack of benefit with EN in this population.
3: potential mucosal toxicities related to the conditioning regimen.
4: reduced mortality among autologuous patients receiving parenteral nutrition (PN).

Answer 42

3: potential mucosal toxicities related to the conditioning regimen.

Several investigators have attempted to use enteral feeding with little success. Gastrointestinal (GI) toxicities such as nausea, vomiting, delayed gastric emptying, and diarrhea seen in the first 2-3 weeks post-stem cell transplant may preclude EN. Gastrointestinal toxicity is most often related to chemotherapy and total body irradiation; however, GI toxicity may also result from other medications or early acute graft-versus-host disease in this patient population. Currently, there is insufficient data to establish benefits of enteral nutrition over parenteral nutrition with hematopoietic cell transplants. More future research is needed to develop evidence-based practice guidelines on whether the nutrition support provided should be PN or EN.

Question 43

Which of the following medications would be appropriate to crush and deliver via an enteral feeding tube?

1: Nifedipine XL
2: Metoprolol immediate release
3: Enteric coated aspirin
4: Diltiazem CD

Answer 43

2: Metoprolol immediate release

Only immediate release tablets should be crushed for administration via an enteral feeding tube. Enteric coated or film coated tablets do not crush well and tend to clump and increase the risk of clogging the tube. Modified release dosage forms (often designated with abbreviations such as XL, XR, SR, CD, etc.) are inappropriate to crush and give via enteral feeding tube because crushing these dosage forms destroys their modified releasing properties. This may lead to an excessive dose of the drug being released at one time (instead of slowly over a longer period of time), which can lead to adverse effects and has even been reported as a cause of death.

Question 44

Which of the following describes an optimal method of preparing and administering medications via an enteral feeding tube?

1: Crush tablets and add them directly into the enteral formula
2: Administer liquid formulations undiluted to minimize fluid overload
3: Crush individual tablets and mix with water prior to separate administration
4: Add crushed tablets to liquid medications and administer the mixture all together

Answer 44

3: Crush individual tablets and mix with water prior to separate administration

Flushing the tube with water before and after each medication (including between each individual medication administered) helps to avoid physical interactions, both between medications and between medications and formula. Many liquid medications are hyperosmolar which can lead to diarrhea and/or may have high viscosity which can lead to tube clogging, so liquid dosage forms should be diluted with water prior to administration.

Question 45

In patients with severe acute pancreatitis enteral nutrition has been documented to provide the following benefits over parenteral nutrition EXCEPT

1: decreased infection rate.
2: decreased hospital length of stay.
3: decreased pain.
4: decreased mortality.

Answer 45

3: decreased pain.

EN has been associated with a significant reduction in infectious morbidity, decreased hospital length of stay, reduced need for surgical intervention, reduced multiple organ failure, and decreased mortality.

Question 46

In a patient with fat malabsorption, an enteral product containing which of the following can provide a concentrated source of energy?

1: Medium chain triglycerides
2: Free amino acids
3: Fructooligosaccharides
4: Long chain triglycerides

Answer 46

1: Medium chain triglycerides

Medium chain triglycerides (MCT) are absorbed directly into the bloodstream and enter portal circulation bypassing the need for pancreatic enzymes, bile, bile transport in the lymphatic system, and carnitine dependent transport into the mitochondria. Because of this, MCT can be used to provide a concentrated source of energy to patients with fat malabsorption or damage to lymphatic vessels.