Complications of Parenteral Nutrition

Question 1

Which one of the following factors is most likely to contribute to metabolic bone disease in PN-dependent patients?

1: Aluminum toxicity
2: Calcium supplementation
3: Moderate amino acid intake in PN
4: Balanced acetate load in PN

Answer 1

Aluminum toxicity
Metabolic bone disease including osteomalacia, osteoporosis and osteopenia has been reported in PN-dependent patients. Aluminum contaminants can be mainly found in parenteral calcium and phosphate salts, trace minerals and vitamins used in making PN solutions. Patients with renal insufficiency are at higher risk for aluminum toxicity due to impaired kidney aluminum excretion. Aluminum toxicity causes osteomalacia by impairing calcium bone fixation, inhibiting the conversion of 25-hydroxyvitamin D to the active 1, 25-dihydroxyvitamin D or reducing parathyroid hormone secretion. In 2000, the FDA issued a rule specifying acceptable aluminum concentrations in large volume parenterals and defined a possible safe upper limit for parenteral aluminum intake at less than 4-5 mcg/kg/day.

Question 2

Which of the following is a risk factor for the development of PN-associated liver complications in PN-dependent patients?

1: Short bowel syndrome
2: Cyclic infusion of PN
3: Supplemental trophic enteral feeding
4: Medication therapy with ursodiol

Answer 2

Short bowel syndrome
Patients with short bowel syndrome are at high risk for developing PN-associated liver complications. Risk factors that predispose patients with short bowel syndrome to liver dysfunction include chronic PN use as a result of reduced intestinal length and absorption, abnormal bile acid cycling following ileal resection which interrupts the biliary enterohepatic cycling causing bile stagnation, and potentially, intestinal bacterial translocation that may cause direct liver injury by bacteria and their toxins. Prolonged PN dependence is expected in patients who had more than 75% of their small intestinal length resected, or with less than 80-100 cm of their small bowel remaining. Chronic cholestasis has been associated with a small bowel remnant

Question 3

A 70-kg adult patient receiving PN providing 3000 kcal/day presents with mild to moderate elevations of serum aminotransferases and mild elevations of bilirubin and serum alkaline phosphatase. This patient is most likely exhibiting what type of PN-associated liver disease (PNALD)?

1: Hepatic steatosis
2: Cholestasis
3: Gallbladder sludging
4: Fulminant hepatic failure

Answer 3

Hepatic steatosis
Although the relationship between PN and liver disease has been established, its prevention and treatment remain a relevant clinical dilemma. Often, the etiology of PNALD is multifactorial and diligence is required to identify and treat causative factors. There are 3 basic types of hepatobiliary disorders associated with PN: steatosis, cholestasis, and gallbladder sludging (stones). Hepatic steatosis generally occurs in adults and presents with mild elevations in aminotransferases, serum alkaline phosphatase, and bilirubin concentrations. This particular type of hepatobiliary disorder is most often a complication of overfeeding. Cholestasis, occurring primarily in children, is characterized by impaired biliary secretion. Elevated conjugated bilirubin levels are the most common laboratory manifestation in this population. Finally, gallbladder sludging or stones is thought to result from the lack of enteral stimulation in the GI tract and occurs with long-term PN use. In this question, this adult patient is receiving an inappropriately high amount of calories (overfeeding) and has the accompanying lab values consistent with hepatic steatosis.

Question 4

Patients at risk for refeeding syndrome should receive supplementation of

1: vitamin A.
2: vitamin K.
3: thiamine.
4: ascorbic acid.

Answer 4

thiamine.
Thiamine is a water-soluble vitamin and body stores can be easily depleted by malnutrition, weight loss and chronic alcoholism. Dextrose infusion places additional demand on thiamine as it is an essential coenzyme in carbohydrate metabolism. Thiamine requirements are increased in patients with malnutrition, weight loss and chronic alcoholism, and additional supplementation (50-100 mg/day IV or at least 100 mg/day PO for 5-7 days) is suggested for patients at risk for deficiency. Supplementation with a multi-vitamin and additional folic acid at 1 mg/day, may be indicated.

Question 5

Hyperglycemia is associated primarily with what type of sodium/fluid imbalance?

1: Hypertonic hyponatremia
2: Hypotonic hyponatremia
3: Isotonic hypernatremia
4: Hypertonic hypernatremia

Answer 5

Hypertonic hyponatremia
Hypertonic hyponatremia may result from hyperglycemia or administration of hypertonic sodium free solutions. Hyperglycemia causes a shift of water out of cells into the extracellular space, resulting in dilution of serum sodium. For every 100 mg/dL increase in serum glucose concentration above 100 mg/dL, the serum sodium would be expected to decrease by approximately 1.6 mEq/L. Treatment should consist of correction of the underlying hyperglycemia, not changes in sodium and water administration, as this is not a true sodium or water imbalance.

Question 6

A long-term PN patient presents with involuntary movements, tremor, and rigidity. Which of the following etiologies may explain these symptoms?

1: Manganese deficiency
2: Manganese toxicity
3: Selenium deficiency
4: Selenium toxicity

Answer 6

Manganese toxicity
The early phase of manganese toxicity is characterized by weakness, anorexia, headache, and apathy followed by Parkinson-like features including muscle rigidity, mask-like face, staggered gait, and fine tremor. Toxicity may occur in patients on long-term therapy supplemented with a combination multiple trace element preparation. Cholestatsis and biliary obstruction may also increase the risk of toxicity as greater than 90% of manganese excretion is via the bile into the feces, but these abnormalities are not always present.

Question 7

In order to prevent rebound hypoglycemia upon discontinuation of parenteral nutrition (PN), it is recommended the PN infusion rate be reduced over what time span?

1: 0 hours
2: 1-2 hours
3: 2-3 hours
4: 3-4 hours

Answer 7

1-2 hours
Rebound hypoglycemia upon discontinuation of PN may occur, especially in individuals with underlying conditions that affect glucose regulation or those patients requiring large doses of insulin. To reduce the risk of hypoglycemia with cessation of PN, a 1-2 hour taper (eg 50% rate reduction) prior to discontinuation is recommended, especially when the patient is unable to take adequate oral or EN feeding. Ordering a point-of-care glucose 30-60 minutes after cessation of PN is recommended to identify and treat rebound hypoglycemia.

Question 8

Which of the following would be the most likely complication of hypertriglyceridemia?

1: Azotemia
2: Pancreatitis
3: Polyuria
4: Peripheral neuropathy

Answer 8

Pancreatitis
Hypertriglyceridemia may occur in some patients receiving intravenous fat emulsion (IVFE). If unnoticed and untreated, it may lead to the development of pancreatitis and altered pulmonary function. These complications can be avoided by prudent monitoring of serum triglyceride levels during the administration of PN formulations including IVFE. Safe Practices for Parenteral Nutrition (2004) include recommendations to infuse IVFE at rates to avoid serum triglyceride levels greater than 400 mg/dL in adults and greater than 200 mg/dL in neonates. If serum triglycerides are elevated, withholding IVFE may be indicated.

Question 9

All of the following are risk factors for the development of hyperglycemia in a patient receiving PN EXCEPT

1: cirrhosis.
2: obesity.
3: pancreatitis.
4: hypothyroidism.

Answer 9

hypothyroidism
Insulin resistance accounts for the increased incidence of hyperglycemia in patients with cirrhosis and who are obese. Patients with pancreatitis often develop hyperglycemia due to insulin insufficiency. Hypoglycemia (not hyperglycemia) is an abnormal laboratory finding associated with hypothyroidism.

Question 10

All of the following are risk factors for the development of rebound hypoglycemia after cessation of PN EXCEPT

1: malnutrition.
2: hepatic dysfunction.
3: hypertension.
4: renal insufficiency.

Answer 10

hypertension
Rebound hypoglycemia occurs when elevated endogenous insulin levels do not adjust to the reduced dextrose infusion following cessation of PN. Although rebound hypoglycemia is not a universal occurrence, some patients may be at higher risk because of underlying conditions that affect glucose regulation. These patients include those with malnutrition and renal or liver disease however hypertension alone should not predispose one to hypoglycemia.

Question 11

The preferred site for placement of central venous catheters for adult patients to reduce the risk of infection is

1: subclavian.
2: internal jugular.
3: femoral.
4: external jugular.

Answer 11

subclavian
The density of skin flora at the catheter site is a major contributing factor for catheter-related blood stream infections (CRBSI). Authorities recommend that central venous catheters (CVCs) be placed in a subclavian site instead of a jugular or femoral site to reduce the risk of infection.

Question 12

Fibrin that builds up on the wall of blood vessels may also adhere to the catheter creating a

1: fibrin sheath.
2: fibrin tail.
3: intraluminal thrombus.
4: mural thrombus.

Answer 12

mural thrombus
mural thrombus develops when fibrin builds up inside the vein which may cause the vascular access device to adhere to the vessel wall. The aggregation of fibrin resulting from the presence of a venous access device in the vein often develops as a fibrin layer (fibrin sheath) that forms around the outside of the catheter. In some cases, the fibrin sheath can grow over the tip of the catheter, or may accumulate exclusively at the distal tip of the catheter creating a “fibrin tail.” An intraluminal thrombus occurs as fibrin or blood products build up inside the catheter lumen, creating a partial or total occlusion.

Question 13

The use of 0.1N hydrochloric acid is most effective for clearing catheter occlusions due to precipation of

1: calcium-phosphate.
2: tobramycin.
3: phenytoin.
4: lipid residue.

Answer 13

calcium-phosphate
The use of 0.1N hydrochloric acid has been reported effective in clearing catheters with crystalline occlusions because its acidic pH is favorable for calcium and phosphate solubility. Clinicians should be aware, however, that direct infusion of hydrochloric acid into the venous system can be associated with fever, phlebitis, and sepsis. For catheter occlusions due to precipitates associated with medications in the high pH range such as tobramycin and phenytoin, sodium bicarbonate 1 mEq/mL has been anecdotally reported to be effective. 70 percent ethanol is the most effective solvent to dissolve lipid residue.

Question 14

A 40-year-old male receiving chronic PN therapy (initiated 15 years ago) secondary to massive bowel resection develops metabolic bone disease. His current 12-hour cyclic PN formula provides 5 g/kg/day dextrose, 2 g/kg/day protein and 1 g/kg/day of fat. What is the most appropriate intervention to reduce hypercalciuria?

1: Increase calcium gluconate
2: Decrease phosphorus supplementation
3: Shorten PN infusion time to 10 hours
4: Decrease amino acid content of PN solution

Answer 14

Decrease amino acid content of PN solution
The most important contributor to metabolic bone disease is a negative calcium balance. Hypocalcemia occurs as a result of decreased calcium intake and/or increased calcium urinary excretion. Factors that cause hypercalciuria include: excessive calcium and inadequate phosphorus supplementation, excessive protein in PN solutions, cyclic PN infusions, and chronic metabolic acidosis. The most appropriate intervention for this patient is protein reduction. Ideally, protein doses for long-term PN provision should not exceed 1.5 g/kg/day. Although the exact mechanism of protein-induced hypercalciuria is unknown, it could be related to an increased glomerular filtration rate or increased excretion of sulfates, ammonia, and urinary titratable acidity that decreases renal calcium reabsorption.

Question 15

The best approach to prevent PN-induced cholelithiasis is administration of

1: choline.
2: cholecystokinin-octapeptide (CCK-OP).
3: ursodiol.
4: oral or enteral feeding.

Answer 15

oral or enteral feeding.
The best approach to preventing cholelithiasis is early initiation of oral or enteral feeding, even in small amounts, to stimulate cholecystokinin secretion, bowel motility and gall bladder emptying. Injections of CCK-OP to induce gall bladder contractions and reduce biliary sludge have yielded mixed results and caused gastrointestinal intolerance in some patients. Although ursodiol has been shown to improve bile flow, doses of 6-15 mg/kg/day have yielded mixed and limited results. In addition, ursodiol is only available in an oral dosage form and its absorption may be limited in patients with intestinal resection. The role of choline in the pathogenesis of cholelithiasis has not been determined.

Question 16

All of the following may be short-term complications of home parenteral nutrition EXCEPT

1: dehydration.
2: metabolic bone disease.
3: refeeding syndrome.
4: catheter malposition.

Answer 16

metabolic bone disease.
Electrolyte abnormalities, dehydration and catheter malposition are more common short-term complications of home parenteral nutrition. Metabolic bone disease has been recognized as a concern in long-term home parenteral nutrition patients.

Question 17

Which of the following is most likely responsible for elevated serum bicarbonate levels in a home parenteral (PN) patient?

1: Excess chloride salts in the PN
2: Diarrhea
3: Excess acetate salts in the PN
4: Acute renal failure

Answer 17

Excess acetate salts in the PN
An elevated serum bicarbonate level is one of the markers of metabolic alkalosis. Metabolic alkalosis may be caused by nasogastric suctioning, volume depletion and diuretic use. In a PN patient, excess use of acetate, which is metabolized to bicarbonate, may precipitate a metabolic alkalosis. Excess chloride, diarrhea and acute renal failure (ARF) are common causes of metabolic acidosis.

Question 18

The clinical presentation of refeeding syndrome includes all of the following EXCEPT

1: respiratory failure.
2: muscle weakness.
3: cardiac arrythmias.
4: dehydration

Answer 18

dehydration
Electrolyte abnormalities that may occur with refeeding syndrome include sodium retention, hypophosphatemia, hypokalemia, and hypomagnesemia. Sodium retention usually occurs in the early phase of the refeeding syndrome and is exacerbated by excessive sodium and fluid intake. This may lead to fluid overload, pulmonary edema, and cardiac decompensation. Severe hypophosphatemia has been reported to cause respiratory failure and seizures. Severe hypokalemia and hypomagnesemia predispose patients to cardiac arrhythmias and neuromuscular adverse effects such as weakness and muscle cramps.

Question 19

A 75-year-old female status-post radical cystectomy with ileal conduit urinary diversion with poor intravenous access weighing 50 kg is initiated on 3L of peripheral parenteral nutrition (PPN) daily, containing 210 grams of dextrose, 75 grams of amino acids, and 45 grams of IVFE. Which of the following complications is she at greatest risk for developing?

1: Fluid overload
2: Hypertriglyceridemia
3: Azotemia
4: Hyperglycemia

Answer 19

Fluid overload
Current guidelines for adults recommend the following maximum amounts for PN components: 30-40 mL/kg/day of fluid, 7 g/kg/day of carbohydrates, 2.5 g/kg/day of fat, and 2 g/kg/day of protein. The provision of PPN necessitates larger volumes in order to deliver a beneficial caloric load to the patient without compromising venous access (thrombophelbitis or infiltration of peripheral veins). This formula provides 60 mL/kg/day which exceeds the recommended maximum daily fluid intake.

Question 20

A critically ill 68-year-old female in acute renal failure status-post colon resection is receiving PN. She has the following arterial blood gas (ABG) results: pH=7.31, PaCO2=36 mm Hg, and serum bicarbonate=20 mEq/L. What is the most appropriate PN intervention?

1: Do nothing
2: Increase chloride:acetate ratio
3: Decrease chloride:acetate ratio
4: Decrease calorie content of PN

Answer 20

Decrease chloride:acetate ratio
This patient is experiencing a metabolic acidosis, likely related to acute renal failure, as evidenced by a decrease in pH (7.35-7.45), a normal PaCO2 (35-45 mm Hg), and a decreased serum bicarbonate (23-30 mEq/L). The most appropriate nutrition intervention is to decrease the chloride:acetate ratio in the PN solution. Acetate is converted to bicarbonate by the liver which should correct the metabolic acidosis.

Question 21

What feature of a Groshong PICC reduces the risk of catheter occlusion?

1: Pressure sensitive three-way valve
2: Large lumen(s) size
3: Heparin coated tip
4: Soft grade medical silicon tubing

Answer 21

Pressure sensitive three-way valve
A Groshong PICC has a pressure sensitive three-way valve at the IV tip of the catheter that prevents reflux of blood into the catheter which should decrease the risk of occlusion. Since blood cannot reflux into the catheter, the Groshong catheter need only be flushed with saline. Flushing with heparin is not necessary to maintain patency. Although additional features of Groshong catheters include soft medical grade tubing, presence of antimicrobial cuff and large lumen size, none of these contribute to a decreased incidence of catheter occlusion. Groshong catheters are not coated with heparin.

Question 22

A patient receiving chronic PN therapy develops an intraluminal clot in their central venous access device. What is the most appropriate pharmacological intervention to clear this access device?

1: Heparin 100 units/mL
2: Alteplase 2mg/2mL
3: Argatroban 350 mcg/kg
4: Streptokinase 10,000 units

Answer 22

Alteplase 2mg/2mL
Conventional therapy for an occluded central venous access device (CVAD) due to an intraluminal clot or sleeve is local thrombolytic therapy with a low dose agent in a single or repeated bolus. Alteplase is the only FDA-approved thrombolytic agent for CVAD occlusions. A dose of 2 mL, or 110% of the volume of the catheter lumen if less than 2 mL (maximum dose 2 mg), is placed in the catheter lumen. Alteplase catalyzes the conversion of clot-bound plasminogen to plasmin and initiates fibrinolysis. In clinical trials, one 2 mg/2 mL dose of alteplase restored function in 67-74% of occluded CVADs and was found to be more effective than urokinase 500 IU. Use of heparin 100 units/mL is appropriate for catheter flushing not for treatment of CVAD occlusions. Argatroban does not have an approved indication as an anticoagulant for prophylaxis or treatment of thrombosis in patients with heparin induced thrombocytopenia. Streptokinase is not an approved thrombolytic agent for treatment of CVAD occlusions.

Question 23

A patient receiving PN is afebrile, has negative blood cultures, but presents with redness and purulence at the catheter exit site. How is this exit site infection best managed?

1: Remove central venous catheter (CVC)
2: Exchange catheter over a guidewire
3: Initiate systemic antimicrobial therapy
4: Apply topical antibiotic ointment

Answer 23

Initiate systemic antimicrobial therapy
A clinical exit site infection is defined as erythema, tenderness or purulence within 2 cm of the catheter exit site. Management of catheter exit site infection includes culture of any drainage from the catheter exit site in addition to blood cultures.Topical antimicrobial agent can be used if there is no purulence from the catheter exit site and no clinical signs of sepsis. Systemic antimicrobial treatment is used in the presence of purulent drainage from the catheter exit site or if topical treatment is unsuccessful. The catheter should be removed if systemic antimicrobial treatment fails or if the patient has clinical signs of sepsis.

Question 24

A PN-dependent patient with an average daily ileostomy output of 3L presents with elevated BUN/serum creatinine ratio and mild hyponatremia. What is the most appropriate PN intervention for this patient?

1: Increase sodium, restrict protein
2: Increase sodium, increase fluid
3: Increase fluid, restrict protein
4: Increase sodium, restrict fluid

Answer 24

Increase sodium, increase fluid
Patients with ileostomy or small bowel fistula output are at risk for loss of water and electrolytes. Sodium content of ileostomy output can be as high as 100 mEq/L. The high BUN/SCr ratio indicates volume depletion. Hyponatremia can result when fluid replacement does not contain adequate sodium to account for ileostomy losses.

Question 25

The use of 70% ethyl alcohol is most effective for clearing catheter occlusions due to precipitation of

1: calcium-phosphate.
2: lipid residue.
3: phenytoin.
4: tobramycin

Answer 25

lipid residue.
Lipid deposits/complexes can develop due to aggregation of lipid particle by divalent and trivalent cations. These types of occlusions are most common when using 3-in-1 PN solutions and develop gradually over several days before complete catheter obstruction occurs. 70% ethyl alcohol is effective for lipid complexes because lipids are soluble in alcohol. The treatment of catheter occlusions due to calcium-phosphate and other drug precipitates depends on the acid-base properties of the compound. For crystalline occlusions (calcium-phosphate precipitates) and acidic medications, 0.1N HCl is effective. For basic medications (i.e., phenytoin, tobramycin), 0.1N NaOH or 8.4% sodium bicarbonate is effective.

Question 26

The most common route of infection for a tunneled central venous catheter (CVC) is

1: extraluminal colonization of the catheter.
2: contamination of the catheter hub.
3: infusate contamination.
4: hematogenous seeding from another focus of infection.

Answer 26

contamination of the catheter hub.
Contamination of the catheter hub and intraluminal infection is the most common route of infection for tunneled CVCs or implantable devices. In contrast, the pathogenesis of nontunneled CVC infection is often related to extraluminal colonization of the catheter or intraluminal colonization of the hub and lumen of the CVC. Occasionally, catheters might become hematogenously seeded from another focus of infection. Rarely, infusate contamination leads to catheter-related bloodstream infection.

Question 27

A patient arrives in your clinic complaining of intermittent catheter malfunction. You identify that the catheter malfunction is relieved by raising the patient’s arm where the catheter is located. Which condition should be suspected?

1: Fibrin sheath
2: Pinch-off syndrome
3: Superior vena cava syndrome
4: Catheter migration

Answer 27

Pinch-off syndrome
Pinch-off syndrome occurs when the catheter is being compressed between the first rib and the clavicle, causing intermittent compression and pinching. This can lead to intermittent occlusion of infusion and aspiration and an increased risk of catheter fracture. Changes in the patient’s position can widen or narrow the angle between the rib and clavicle, usually by raising or lowering the arm, which can relieve occlusion of the catheter. This is the hallmark sign of the syndrome. The external portion of the catheter may frequently tear, requiring repair as a result of the increased pressure required to overcome the compressed catheter. The treatment is removal of the catheter and reinsertion in a more lateral position in the subclavian vein or placement in the internal jugular vein.

Question 28

All of the following conditions predispose a patient to the refeeding syndrome EXCEPT

1: chronic alcoholism.
2: malabsorptive syndromes.
3: weight loss after bariatric surgery.
4: poor oral intake for 3 days.

Answer 28

poor oral intake for 3 days.
Conditions that predispose patients to the refeeding syndrome include chronic starvation, prolonged fasting or minimal oral intake (>7 days), chronic alcoholism, anorexia nervosa, malabsorption syndromes, morbid obesity followed by significant weight loss, and wasting diseases, such as cancer and AIDS.

Question 29

Which of the following illustrates the most common electrolyte imbalances observed in patients with refeeding syndrome?

1: Hypokalemia, hyperphosphatemia, hypocalcemia
2: Hyperkalemia, hyperphosphatemia, hypocalcemia
3: Hypokalemia, hypophosphatemia, hypermagnesemia
4: Hypokalemia, hypophosphatemia, and hypomagnesemia

Answer 29

Hypokalemia, hypophosphatemia, and hypomagnesemia
Refeeding syndrome is a potentially lethal condition that can result from fluid and electrolyte shifts in malnourished patients undergoing refeeding of oral, enteral, or parenteral nutrition. The syndrome is characterized by alterations in electrolytes and vitamins. Hypokalemia, hypophosphatemia, and hypomagnesemia commonly occur and are associated with significant morbidity and mortality. Identification of patients at high risk for refeeding syndrome is essential in providing nutrition support to malnourished patients.

Question 30

Hyperkalemia is most likely to be associated with

1: pregnancy.
2: hyperinsulinemia.
3: respiratory failure.
4: metabolic acidosis.

Answer 30

metabolic acidosis.
Hyperkalemia can develop due to extracellular shifts of potassium, increased potassium ingestion, or impaired potassium elimination. Metabolic acidosis results in an extracellular shift of potassium, without changes in total body potassium. Correction of the underlying metabolic acidosis redistributes potassium into the intracellular space and corrects the hyperkalemia. Hyperinsulinemia is most likely to result in hypokalemia. Pregnancy and respiratory failure alone are not causes of hyperkalemia.

Question 31

A patient with refractory hypokalemia should be assessed for what related electrolyte disorder?

1: Hyperglycemia
2: Hyponatremia
3: Hyperphosphatemia
4: Hypomagnesemia

Answer 31

Hypomagnesemia
Magnesium is important in the regulation of intracellular potassium. Hypomagnesemia may result in refractory hypokalemia, likely due to accelerated renal potassium loss or impairment of sodium-potassium pump activity. When hypokalemia and hypomagnesemia coexist, magnesium deficiency should be corrected to facilitate the correction of hypokalemia.

Question 32

Manganese toxicity is a concern for long-term parenteral nutrition (PN) patients due to its presence in trace element mixtures and as a contaminant from other PN solution components. Symptoms of manganese toxicity are associated with accumulation of the mineral in which organ?

1: Kidney
2: Brain
3: Muscle
4: Heart

Answer 32

Brain
Manganese absorption from the gastrointestinal tract is normally 6-16% of dietary intake. When manganese is provided by the parenteral route there is 100% bioavailability because the gastrointestinal tract is bypassed. Manganese is primarily excreted in the feces via bile. Therefore patients with impaired biliary excretion or those who receive amounts in excess of needs are at risk for brain tissue accumulation and subsequent affects on the central nervous system. Manganese toxicity can be monitored by MRI brain imaging or erythrocyte or whole-blood assessment since 60-80% of manganese is contained in red blood cells.

Question 33

A critically ill 75-year-old male with pneumonia and sepsis who weighs 63 kg is receiving PN containing 2800 kcal and 100 g amino acids per day. He has the following arterial blood gas (ABG) results: pH=7.32, PaCO2=49 mm Hg, and serum bicarbonate=29 mEq/L. What is the most appropriate PN intervention?

1: Do nothing
2: Increase chloride:acetate ratio
3: Decrease chloride:acetate ratio
4: Decrease calorie content of PN

Answer 33

Decrease calorie content of PN
This patient is experiencing a respiratory acidosis as evidenced by a decrease in pH (7.35-7.45), an elevated PaCO2 (35-45 mm Hg), and a normal serum bicarbonate (23-30 mEq/L). He is currently receiving ~45 kcal/kg/day. The most appropriate nutritional intervention is to decrease the total calorie content of the PN regimen. Overfeeding should be avoided as excessive calorie supplementation can lead to hypercapnia due to excessive carbon dioxide production relative to oxygen consumption.

Question 34

The most accurate method of diagnosing PN-associated metabolic bone disease is to measure

1: bone mineral density.
2: serum calcium concentrations.
3: serum phosphate concentrations.
4: serum parathyroid hormone concentrations.

Answer 34

bone mineral density.
It is unclear how often PN-associated metabolic bone disease occurs. It is often asymptomatic and occurs in the face of normal biochemical parameters. The risk for metabolic bone disease is greatest for patients receiving long-term PN and corticosteroid therapy. Fortunately, bone mineral density can be assessed accurately and metabolic bone disease can be diagnosed early so that appropriate treatment can be instituted.

Question 35

Which one of the following co-morbidities is NOT a risk factor for the development of metabolic bone disease?

1: Crohn’s disease
2: Malignancy
3: Short bowel syndrome
4: Hypothyroidism

Answer 35

Hypothyroidism
Nearly every condition requiring long-term PN can predispose a patient to metabolic bone disease (MBD.) Patients with Crohn’s diesase are at risk for MBD if they have malabsorption of calcium and vitamin D or use corticosteroids to control their disease. Patients with cancer may have decreased food intake and altered calcium and vitamin D metabolism associated with surgery or chemoradiation. MBD may also develop in cancer patients as a result of therapy-induced amenorrhea or the elevation of cytokines or parathyroid-like peptides. There is also evidence that renal wasting of calcium may occur in individuals with short bowel syndrome. Hyperthyroidism (not hypothyroidism) is a secondary cause of osteoporosis.

Question 36

A rise in which of the following laboratory values would most likely indicate cholestasis?

1: Prothrombin time
2: Asparate aminotransferase/Alanine aminotransferase ratio
3: Cholesterol
4: Alkaline phosphatase, gamma glutamyltransferase and conjugated (direct) bilirubin

Answer 36

Alkaline phosphatase, gamma glutamyltransferase and conjugated (direct) bilirubin
Elevations of alkaline phosphatase, gamma glutamyltransferase and conjugated (direct) bilirubin most likely represent cholestasis or biliary obstruction. Elevated serum conjugated bilirubin, typically defined as >2 mg/dL, is considered a prime indicator of cholestasis. Prothrombin time is an important marker of synthetic function, but is not specific for cholestasis. Abnormalities in aminotransferases are indicative of hepatocellular injury. Cholesterol is not a marker of cholestasis.

Question 37

During long-term PN administration, hepatobiliary complications can best be prevented by

1: adding carnitine to the PN formula.
2: discontinuing IV fat emulsion (IVFE).
3: converting to cyclic administration.
4: reducing trace elements.

Answer 37

converting to cyclic administration.
Hepatic dysfunction can result from long-term administration of PN. Conversion to cyclic administration allows the body to oxidize fat and results in lower insulin levels as well as improved liver enzymes. It is important to avoid excess calories as excess calorie administration will result in steatosis. In addition, initiation of enteral feeding stimulates bile flow and may protect against gut bacterial translocation. If hepatic dysfunction occurs, serum concentrations of trace elements such as manganese and copper should be monitored on a regular basis. These elements may need to be removed from the PN solution if serum levels are elevated

Question 38

Inability to aspirate blood and the ability to infuse through a central vascular catheter suggests what type of occlusion?

1: Pinch-off syndrome
2: Intraluminal thrombus
3: Calcium precipitate occlusion
4: Fibrin sheath formation at the catheter tip

Answer 38

Fibrin sheath formation at the catheter tip
Occlusion can be defined as the inability to infuse and/or the inability to aspirate without resistance. Fibrin sheath formation at the distal catheter tip often presents as a withdrawal occlusion. Catheters remain functional for infusion; however, blood cannot be aspirated from the lumen. Physiologically, the fibrin acts as a one-way valve. The negative pressure used to aspirate blood causes the fibrin to be pulled over the catheter tip and prevent blood aspiration. Pinch-off syndrome occurs when the catheter is being compressed between the first rib and the clavicle, causing intermittent compression and pinching, leading to intermittent occlusion of infusion and aspiration. An intraluminal thrombus and calcium precipitate occlusion typically present as the inability to infuse and the inability to aspirate without resistance.

Question 39

After placement of a central line, discovery of a pneumothorax during PN administration should be viewed as a

1: sentinel event.
2: process indicator.
3: resource indicator.
4: structural indicator.

Answer 39

sentinel event.
A sentinel event is an unexpected occurrence involving death or serious physical or psychological injury, or the risk thereof. Serious injury specifically includes loss of limb or function. Such events are called “sentinel” because they signal the need for immediate investigation and response. The Joint Commission’s sentinel event policy is designed to help organizations identify sentinel events and take action to prevent their recurrence. Examples include medication errors, wrong site surgery, restraint-related deaths, blood transfusion errors, and operative or postoperative complications.

Question 40

All of the following are examples of nonthrombotic catheter occlusions EXCEPT

1: catheter migration during use.
2: lipid deposits.
3: calcium-phosphate precipitate.
4: fibrin sheath.

Answer 40

fibrin sheath
Nonthrombotic catheter occlusions can result from mechanical obstructions, drug or mineral precipitates, or lipid deposits. Mechanical obstruction may reflect catheter migration or malposition that occurs during insertion or use. Precipitates that form due to drug crystallization, drug-drug incompatibilities, or drug-solution incompatibilities can produce catheter occlusion. A fibrin sheath, or fibrin sleeve, is a thrombotic catheter occlusion and develops when fibrin adheres to the external surfaces of the catheter.

Question 41

The most effective strategy to DECREASE the risk of catheter-associated sepsis is use of

1: povidone-iodine as a skin preparation.
2: antibiotic ointment at catheter exit site.
3: antibiotic prophylaxis during catheter insertion.
4: full-barrier precautions during catheter insertion.

Answer 41

full-barrier precautions during catheter insertion.
Several strategies have been investigated to decrease the risk of catheter-associated sepsis. Use of full-barrier precautions during catheter insertion (mask, cap, sterile gloves, long-sleeve gowns, and sheet drapes) reduces the incidence of catheter-related infections compared with the use of only sterile gloves and drapes alone. Skin preparation with chlorhexidine results in lower incidence of microbial colonization than povidone-iodine. Prophylactic use of antibiotic ointment at the catheter exit site encourages the development of resistant flora and should be avoided. Antibiotic prophylaxis during catheter insertion has not been demonstrated to reduce the incidence of catheter-associated sepsis.

Question 42

Which of the following is an evidence-based intervention for reducing the risk of central venous catheter-related infections?

1: Administering antibiotics prior to catheter insertion
2: Using minimal barrier technique during catheter insertion
3: Cleansing insertion sites with 2% alcohol preparation
4: Training nurses to maintain central venous catheters

Answer 42

Training nurses to maintain central venous catheters
According to the Centers for Disease Control and Prevention, research supports the following recommendations as primary interventions for reducing risks of central venous catheter-related infections: (1) using maximal barrier technique during catheter insertion, (2) cleansing insertion sites with 2% chlorhexidine preparation, and (3) education and training of health care personnel. Administering antibiotics prior to inserting central venous catheters has not been shown to be effective in reducing the rates of central venous catheter-related infections.

Question 43

A patient receiving PN that has chills, fever, positive blood cultures, and no redness or purulence at the catheter exit site probably has which of the following types of catheter infection?

1: Tunnel
2: Exit site
3: Catheter-related phlebitis
4: Catheter-related bloodstream

Answer 43

Catheter-related bloodstream
Catheter-related infections have been defined to allow for more accurate identification of the type of infection. A catheter-related bloodstream infection includes bacteremia/fungemia in a patient with an intravascular device with at least one positive blood culture, clinical manifestations of infection such as fever, and no apparent source except the catheter. Catheter-related blood stream infections often present without redness or purulence at the catheter site.

Question 44

A critically ill patient has been receiving parenteral nutrition providing 45 kcals/kg with no clear indication that energy needs are above an estimate of 25-30 kcals/kg. The consequences of providing excessive calories to a critically ill patient include all of the following EXCEPT

1: Fatty infiltration of the liver.
2: Ventilator weaning failure.
3: Elevated phosphate.
4: Elevated blood sugar.

Answer 44

Elevated phosphate.
Overfeeding can contribute to adverse consequences, especially in mechanically ventilated patients. Providing calories in excess of 25-30 kcals/kg, unless indirect calorimetry results show an REE above this range, has been associated with hepatic steatosis, failure to wean from the ventilator with hypercapnia, and hyperglycemia. Elevated phosphate would be expected only if the amount in parenteral nutrition solution exceeded renal excretion.

Question 45

A patient presents to clinic with a suspected catheter occlusion. All of the following are appropriate initial actions EXCEPT to

1: determine if the occlusion is relieved with postural changes.
2: remove the dressing and check for kinks in the tubing.
3: replace the catheter over a guidewire.
4: review recent flushing techniques with the patient.

Answer 45

replace the catheter over a guide wire.
When a patient presents with a suspected catheter occlusion, a systematic approach should be taken to prevent unnecessary catheter removals and/or unnecessary instillations of compounds to relieve the catheter occlusion. Steps to insure this include: (1) obtain thorough history of signs/symptoms of catheter malfunction from the patient; (2) double-check catheter function for patency and blood aspiration; (3) check for mechanical causes of occlusions (clamps, kinked tubing, tight sutures, replace needle if implanted vascular access port) and assess if occlusion is related to postural changes (rolling of shoulder or raising or lowering of arm on the side of the catheter); (4) obtain thorough history of recent flushing techniques, medication infusions, and blood aspiration; and (5) assess for physical signs of edema, redness, pain, or dilated vessels. From these steps, a clinician can determine if further diagnostic tests are needed, the catheter requires removal, or if compounds should be instilled to clear a clot or precipitate within the catheter.

Question 46

A 60-year-old female (45 kg) is receiving PN for a rectovaginal fistula. The PN formula consists of the following components: 70 grams protein, 400 grams dextrose, and 25 grams fat infused continuously in a total volume of 1.5 liters. Which one of the following complications is she at greatest risk for developing? (24-hour continuous PN infusion; Total PN Volume with electrolytes and additives is 1.5 L)

1: Hypertriglyceridemia
2: Azotemia
3: Hyperglycemia
4: Pulmonary edema

Answer 46

Hyperglycemia
Current guidelines for adults recommend the following maximum amounts for PN components: 30-40 mL/kg/day of fluid, 7 g/kg/day of carbohydrates, 2.5 g/kg/day of fat, and 2 g/kg/day of protein. Hyperglycemia from dextrose is the most likely complication this patient will develop because she is receiving more than the recommended daily amount of carbohydrate (10.9 g/kg/day of carbohydrates). The other components in this PN formula are within recommended ranges.

Question 47

Discontinuation of intravenous fat emulsion (IVFE) is recommended treatment of catheter-related bloodstream infection due to

1: coagulase-negative staphylocci.
2: staphylococcus aureus.
3: pseudomonas aeruginosa.
4: malassezia furfur.

Answer 47

malassezia furfur.
Malassezia furfur is classically associated with superficial infections of the skin and associated structures. This yeast has been reported as a cause of catheter-related blood stream infections. This occurs most commonly in premature infants and patients receiving PN containing IVFE. The IVFE presumably provides growth factors required for replication of the organism. Appropriate treatment of patients requires administration of antifungal therapy, discontinuation of IVFE, and removal of the intravascular catheter, especially with nontunneled catheter infections.

Question 48

Excess carbohydrate administration in PN has been associated with

1: hypercalcemia.
2: hepatic steatosis.
3: decreased CO2 production.
4: metabolic bone disease.

Answer 48

hepatic steatosis.
Excess carbohydrate administration has been associated with hepatic steatosis. Excess carbohydrates deposit in the liver as fat. Providing balanced dextrose and fat calories seems to decrease the incidence of steatosis, possibly by decreasing hepatic triglyceride uptake and promoting fatty acid oxidation. Metabolic bone disease and hypercalcemia are unrelated to carbohydrate administration. Excess carbohydrate administration has been shown to cause increased carbon dioxide production.

Question 49

Patients with diabetes who are receiving PN

1: should have blood glucose checked every 2 hours.
2: have an increased incidence of catheter related infections.
3: often require high protein doses.
4: often develop micronutrient deficiencies.

Answer 49

have an increased incidence of catheter related infections.
The standard for glucose checks in a diabetic patient on PN is every 6 hours, more frequent monitoring is only indicated with poorly controlled blood sugars or insulin drip therapy. Diabetic patients receiving PN do not require additional protein solely based on their diabetes diagnosis. Diabetic patients receiving PN do not have an increased incidence of micronutrient deficiency. The increase in blood glucose levels seen in diabetic and critically ill patients is associated with higher frequency of infection. The intense counter-regulatory hormone and cytokine responses to severe disease and the excessive administration of glucose, usually as PN, could contribute to hyperglycemia and the associated infectious complications.

Question 50

A critically ill 42 year old male status post small bowel resection for Crohn’s disease is receiving PN for severe post-operative ileus with NG tube output of 2.5-3 liters per day. He has the following arterial blood gas (ABG) results: pH=7.49, PaCO2= 45 mm Hg, and serum bicarbonate=34 mEq/L. What is the most appropriate PN intervention?

1: Do nothing
2: Increase chloride:acetate ratio
3: Decrease chloride:acetate ratio
4: Decrease calorie content of PN

Answer 50

Increase chloride:acetate ratio
This patient is experiencing a metabolic alkalosis, likely related to large gastric acid losses through his NG tube output, as evidenced by an increase in pH (7.35-7.45), a normal PaCO2 (35-45 mm Hg), and an increased serum bicarbonate (23-30 mEq/L). The most appropriate nutrition intervention is to increase the chloride:acetate ratio in the PN solution.

Question 51

A home PN dependent patient with a peripherally inserted central catheter (PICC) presents with arm, shoulder and neck swelling. Which of the following is the most likely cause?

1: Pinch off syndrome
2: Catheter related central venous thrombosis
3: Fibrin sheath occlusion
4: Catheter migration

Answer 51

Catheter related central venous thrombosis
Central venous catheters cause endothelial trauma and inflammation which can lead to venous thrombosis. Inflammation of the vessel wall can cause pain and tenderness along the course of the vein. Obstruction of blood flow may cause collateral vein congestion and edema on the affected side. Arm, shoulder, or neck swelling, limb, jaw, or ear pain, and dilated collateral veins over the arm, neck or chest are hallmark symptoms of catheter related central venous thrombosis .