Answers to Self-Assessment Questions - ACCP

during continuous venovenous hemodiafiltration in critically
ill patients. Am J Clin Nutr 2004;80:410–6.
2. Story DA, Ronco C, Bellomo R. Trace element and vitamin
concentrations and losses in critically ill patients treated
with continuous venovenous hemofiltration. Crit Care Med
1999;27:220–3.
18. Answer: D
W.G.’s serum glucose concentration has been consistently
elevated. The best approach for managing his hyperglycemia
would be to start regular insulin by continuous intravenous
infusion (Answer D); thus Answer D is correct. Using a
sliding scale regimen of insulin aspart (Answer B) would
be a reactive approach to hyperglycemia as opposed to
a proactive approach with the insulin infusion. Sliding
scale insulin regimens are no longer widely used in ICUs.
Although adding regular insulin to the PN formulation
(Answer C) is more convenient for the nursing staff, it is
not ideal for a patient like W.G. who is receiving CRRT.
If insulin is in the PN formulation and CRRT is stopped
for any reason (e.g., because of filter clotting), the glucose
delivery from the dialysis and replacement solutions will
abruptly stop, creating the potential for hypoglycemia unless
the PN formulation is also stopped. Similarly, administering
insulin glargine subcutaneously every night (Answer A)
would place the patient at risk of hypoglycemia in the event
that any glucose source is discontinued.
1. Wooley JA, Btaiche IF, Good KL. Metabolic and nutritional
aspects of acute renal failure in critically ill patients requiring
continuous renal replacement therapy. Nutr Clin Pract
2005;20:176–91.
2. Scheinkestel CD, Adams F, Mahony L, Bailey M, Davies
AR, Nyulasi I, et al. Impact of increasing parenteral protein
loads on amino acid levels and balance in critically ill anuric
patients on continuous renal replacement therapy. Nutrition
2003;19:733–40.
19. Answer: B
Various formulas are available for calculating nitrogen
balance. Standard formulas have been revised to be used
in patients receiving CRRT. W.G.’s nitrogen balance is
negative 6.5 (-6.5) g of nitrogen (Answer B). This value can
be calculated using the following equation:
Nitrogen balance (g/day) = nitrogen intake (g/day) −
nitrogen loss (g/day). In patients receiving CRRT, nitrogen
loss (g/day) = effluent urea nitrogen loss (g/day) + amino
acid losses across CRRT membrane (g/day) + urine urea
nitrogen [UUN] (g/day) + insensible losses (2–4 g/day).
W.G. is receiving 175 g of protein per day through his
enteral formulation and additional protein supplementation.
This intake provides 28 g of nitrogen per day (175 g of
protein/6.25 g of protein per gram of nitrogen). The effluent
urea nitrogen loss (grams per day) = total volume of
replacement fluid (liters) + dialysate fluid (liters) + volume
(liters) of parenteral volume removed from the patient over
24 hours × the average urea nitrogen from the effluent
sample (51 mg/dL). Convert 51 mg/dL to grams per liter
by multiplying by 0.01 = 0.51 g of nitrogen per liter. Total
replacement fluid plus dialysate fluid plus parenteral volume
removed = 36,000 mL + 12,000 mL + 8,000 mL = 56,000
mL = 56 L. Therefore, 56 L × 0.51 g of N per liter = 28.5
g of nitrogen is lost as dialysate urea nitrogen. Dialysate
plus replacement fluids are infusing at 2 L/hour; therefore,
amino acid losses across the CRRT membrane = 2 g of N
per day. Because W.G. is anuric, the UUN is omitted from
the calculation. Adding 4 g of nitrogen for insensible losses
gives a total of 34.5 g of nitrogen out. Nitrogen balance = 28
g of nitrogen in – 34.5 g of nitrogen out = − 6.5 g of nitrogen.
Answer A [negative 9 (−9) g of N], Answer C [negative 1.5
(−1.5) g of N], and Answer D [positive 1 (+1) g of N] are
incorrect based on the above calculations.
1. Liu KD, Stralovich-Romani A, Chertow GM. Nutrition support
for adult patients with acute renal failure. In: Merritt R, ed. The
A.S.P.E.N. Nutrition Support Practice Manual, 2nd ed. Silver
Spring, MD: American Society for Parenteral and Enteral
Nutrition, 2005:281–6.
2. Manning EM, Shenkin A. Nutritional assessment in the
critically ill. Crit Care Clin 1995;11:603–34.
20. Answer: D
W.G. has been converted from intermittent hemodialysis
to CRRT. A high-nitrogen feeding formulation (Answer
D) should be initiated because it will meet the high protein
needs of this patient receiving CRRT. Also, additional
protein supplementation will be needed. A low-electrolyte,
renal disease–specific enteral formulation (Answer A) is not
needed at this time because the low-electrolyte composition
of these products is not needed during CRRT. Immuneenhancing
feeding formulations (Answer B) may have a
role, but currently neither clinical nor literature support is
available to justify the use of these expensive formulations
in patients receiving CRRT. Calorie-dense feeding
formulations (Answer C) often lead to gastroparesis, which
is common in patients such as W.G. who have diabetes
mellitus and are receiving CRRT; thus Answer C is not the
best answer.
1. Wooley JA, Btaiche IF, Good KL. Metabolic and nutritional
aspects of acute renal failure in critically ill patients requiring
continuous renal replacement therapy. Nutr Clin Pract
2005;20:176–91.
2. Kapadia FN, Bhojani K, Shah B. Special issues in the
patient with renal failure. Crit Care Clin 2003;19:233–5
Home Parenteral Nutrition
21. Answer: D
A 70-year-old man was hospitalized with pancreatitis
associated with biliary tract disease. Fifteen days after
admission, after undergoing cholecystectomy, he is unable
to tolerate oral nutrition. Two pancreatic pseudocysts were
identified by ultrasound examination. The best nutrition
support regimen for home nutrition support for this patient
is Answer D (enteral feeding with the tip of the feeding
tube located past the ligament of Treitz). There are several
studies demonstrating that a nasojejunal feeding tube
with the tip past the ligament of Treitz provides effective
nutrition without pancreatic stimulation, which is the cause
of the pain when oral feedings are attempted. Although
difficult, this type of feeding can be done at home and, if
it is tolerated, saves the high cost and complication rate of
home PN. Answer A (PN though a central venous access
device [CVAD]) is incorrect because PN is not indicated
Pharmacotherapy Self-Assessment Program, 6th Edition 39 Gastroenterology and Nutrition Answers