# # Pediatric Critical Care Review Hasan Pappas

1. The risk of development of acute renal failure after cardiac surgery is highest in: A. Neonates B. Infants C. Children D. Adults Click here for answer 2. Which of the following causes vasodilation of the cortical vasculature: A. Mannitol B. Furosemide C. Both D. Neither Click here for answer 3. Clinical settings in which mannitol has definitely been shown to be effective in preventing the deterioration of renal function is: A. During and after cardiopulmonary bypass B. During and after aortic cross-clamping C. During and after hypovolemic shock D. Before the administration of cisplatin E. None of the above Click here for answer 4. A neonate with gastroschisis underwent surgical repair and is subsequently admitted to the Neonatal ICU for post-operative care. Anuria has persisted for 8 hours in spite of aggressive fluid resuscitation to a central venous pressure of 12 mm Hg. The echocardiogram shows normal myocardial function and abdominal ultrasound does not show any evidence of urinary outflow obstruction. The complete blood count is within normal limits and urinalysis does not show any hematuria or sediments. The most likely explanation for the anuria is: A. Acute tubular degeneration B. Acute cortical necrosis C. Increased intra-abdominal pressure D. Dysplastic kidneys E. None of the above Click here for answer 5. Which of the following statements is least accurate regarding acute renal failure: A. Adults with no underlying renal disease who develop acute renal failure have a poorer prognosis compared to children B. Following cardiac surgery, the incidence of acute renal failure is higher in children than in adults C. Children over the age of 2 years with acute renal failure have a much better outlook with meticulous medical care D. Spontaneous recovery from acute renal failure is likely to begin 1-3 weeks after the onset E. The mortality rate for children with acute renal failure is much higher than adults Click here for answer 6. The earliest EKG changes of an elevated serum K+ is: A. First degree AV block and peaked T-wave B. Widened QRS complex and peaked T-wave C. Absent P-waves, wide QRS and peaked T-wave D. Shortened QT interval E. None of the above Click here for answer 7. Which of the following statements are true regarding management of suspected acute renal failure: A. In euvolemic patients, the rapid intravenous administration of mannitol should result in a urine output > 0.5 ml/kg within one hour if a pre-renal etiology dominates B. The vasodilatory and natriuretic properties of furosemide is beneficial when administered early in the course of acute renal failure C. In euvolemic patients, furosemide in an incremental dose of up to 10 mg/kg may be used D. If there is no response to a fluid challenge, low dose dopamine could be added E. All of the above Click here for answer 8. In a patient who has just been admitted to the Pediatric ICU with new onset of acute renal failure, which of the following pathophysiologic changes is least likely to occur: A. BUN and creatinine will rise at 10 mg/dl/day and 0.5 mg/dl/day respectively B. Serum HCO3 decreases by 2 mEq/l/day due to release of tissue phosphate C. Serum K+ increases by 0.3-0.5 mEq/l/day D. Hypernatremia is commonly observed E. Hypophosphatemia and associated hypocalcemia may develop rapidly after the onset of acute renal failure Click here for answer 9. Which of the following is least appropriate in the treatment of acute renal failure: A. Treatment of hyperkalemia B. Aggressive treatment of hypocalcemia in the absence of tetany C. Treatment of hyperphosphatemia with calcium carbonate or lactate D. Early institution of dialysis in patients with hemolytic-uremic syndrome E. Aggressive correction of respiratory acidosis Click here for answer 10. Which of the following statements least accurately describes the process of dialysis: A. When compared to HCO3, acetate dialysis is characterized by greater hemodynamic stability B. To prevent the dysequilibrium syndrome, mannitol may be administered in the first hour of an acute dialysis in patients with BUN > 150 mg/dl C. Hemodialysis seems to be more efficient than peritoneal dialysis in decreasing blood uric acid when it is the etiologic factor in acute renal failure D. The efficacy of peritoneal dialysis is greatest in infants, compared to children and adults E. The dysequilibrium syndrome results from a rapid decline in serum osmolality due to the overly rapid removal of solutes from the circulation and manifests as seizures Click here for answer 11. Correct statements regarding the “dysequilibrium syndrome” include all of the following except: A. Can be prevented by limiting the rate of flow through the hemodialysis to approximately 4 ml/kg/min B. Can be prevented by limiting the total dialysis time to two hours at the initiation of hemodialysis C. Can be prevented by using a dialysate with a higher Na+ concentration D. Is seen with the same frequency with peritoneal dialysis compared to hemodialysis Click here for answer 12. Regarding nutritional support of patients with acute renal failure, which of the following options is not true: A. Supplementation of calories from carbohydrate, protein and fat spares the breakdown of endogenous protein and minimizes the need for dialysis B. Higher amounts of B-complex vitamins are required C. Vitamin C intake should be increased to 1,000 mg/day D. Providing a hypertonic glucose and amino acids solution is more beneficial than glucose alone Click here for answer A. Renal failure due to rapidly progressive glomerulonephritis B. Post-operative renal failure C. Both D. Neither 13. ____ Hypertension with hypertensive encephalopathy is common Click here for answer 14. Calculation of the loading dose of gentamycin to be used in the treatment of gram negative urinary tract infection in a 6-year-old girl depends on: A. Desired plasma concentration and volume of distribution B. Volume of distribution and clearance C. Clearance and desired plasma concentration D. Plasma half life and volume of distribution E. Plasma half life and clearance Click here for answer 15. The most appropriate therapeutic intervention for severe hypercalcemia is: A. Intravenous dimercaprol B. Oral dimercaprol C. Intravenous EDTA D. Intravenous furosemide E. Hydrochlorothiazide Click here for answer 16. Match the following drug with its most likely effect: A. Captopril B. Enalapril C. Both D. Neither ____ Pruritus, rash and eosinophilia ____ Temporary loss of taste ____ Initial severe hypotensive response ____ Inhibits the breakdown of bradykinin ____ Postural hypotension and reflex tachycardia ____ Neutropenia Click here for answer 17. Regarding the perioperative management of a patient with end stage renal disease who are undergoing cadaveric kidney transplantation, which of the following is the most accurate statement: A. Acute preoperative dialysis should be performed since the very high BUN is undesirable post-operatively B. Post-operatively, high normal intravascular volume (central venous pressure 10-15 mm Hg) should be avoided because of loss of auto-regulation in the cadaveric kidney C. Pre-operative transfusion to a hematocrit of 40% is essential D. After the clamps are released, a dose of furosemide (1-2 mg/kg) is useful in inducing renal vasodilatation and solute diuresis E. Cadaveric transplant survival is reduced in patients who have received multiple blood transfusions Click here for answer 18. Regarding the relationship between transfusion of blood products and graft survival in the recipients of cadaveric kidney transplantation, which of the following statements is true: A. Graft survival improves with increasing number of blood transfusions received B. The positive effect of transfusion on the graft is greatest with packed red blood cells and whole blood transfusion C. Patients receiving intraoperative transfusions have some improvement in survival compared with patients who do not receive transfusions D. All of the above E. None of the above Click here for answer 19. Match the diagnosis(es) below with the most likely effect(s): A. Hemolytic uremic syndrome B. Disseminated intravascular coagulopathy C. Both D. Neither ____ Increased platelet consumption ____ Deficiency of prostaglandin I2 activity Click here for answer 20. Degradation of atracurium is primarily via: A. Hepatic conjugation B. Renal excretion unchanged C. Ester hydrolysis D. Hoffman degradation Click here for answer 21. Regarding adjustment of drug dosage for renal failure, which of the following statements is/are true: A. Adjustment of dosage is not indicated for drugs with a very wide therapeutic range such as penicillins, unless renal failure is profound B. Adjustment for drugs with a narrow therapeutic index is not indicated unless renal function is less than 70% of normal C. Dosage adjustments of £ 25% are not worthwhile D. When ¦ (fraction filtered unchanged by kidneys) is < 25%, the adjustment for renal failure is not necessary unless non-renal routes of elimination are also decreased E. All of the above Click here for answer 22. The letters on the diagram above represent the site of action for the medications listed below. Match the medications to their appropriate site(s) of action: ____ 1. Furosemide ____ 2. Chlorothiazide ____ 3. Spironolactone ____ 4. Mannitol Click here for answer 23. A 6-month-old infant presents with generalized tonic-clonic seizures and is poorly responsive to intravenous lorazepam and phenytoin. The trachea is intubated and he has been admitted to PICU on mechanical ventilation. Physical examination shows a heart rate of 95 bpm, BP of 90/65, and capillary refill is 3 seconds. Examination of genitalia is within normal limits. Laboratory analysis shows: Na 114, K 3.9, Cl 88, total CO2 20 mEq/L. Urine specific gravity is 1.008, urine osmolality is 288 msomol/L and urine Na is 20 mEq/L. No urinary sediments are seen. BUN is 10 mg%, creatinine is 0.5 mg% and blood glucose is 95 mg%. The most likely diagnosis is: A. SIADH B. Severe dehydration C. Acute cortical necrosis D. Water intoxication E. Congenital adrenal hyperplasia (CAH) The most appropriate initial intervention is: A. 3% NaCl B. ADH C. Cortisol D. Dialysis E. Massive fluid resuscitation Click here for answer Answers 1. A Kidneys are able to maintain renal blood flow over a wide range of systemic blood pressure by autoregulation of intrarenal vascular resistance, so that hypotension with renal hypoperfusion may or may not produce ischemic renal injury. However, these autoregulatory mechanisms are not well developed in neonates. Neonates have high rennin levels, which in turn, are associated with decreased GFR and reduced outer cortical blood flow. The cortical glomeruli are immature and so are their corresponding tubules. This pattern of high rennin and reduced outer cortical blood flow makes neonates more vulnerable to renal dysfunction due to hypotension of systemic pressures only slightly below the normal range. In animal studies, newborn animals have decreased production of atrial natriuretic peptide (ANP) in response to saline challenge. All these factors combined make the incidence of acute renal failure in neonates, after cardiac surgery, higher than in older infants and children. (Nichols DG, et al. Critical Heart Disease in Infants and Children. Mosby 1995; pp 125, 562) 2. C Furosemide causes vasodilation of the cortical vasculature by direct action and through release of prostaglandins. Furosemide maintains renal blood flow and tubular blood flow when cardiac output is compromised.. Mannitol is also a vasodilator of the cortical vasculature, that increases renal blood flow either directly, by drawing fluid from extravascular to intravascular space, thus increasing total plasma volume OR by increasing prostaglandin production. Increased plasma volume alone does not fully explain the effects of Mannitol, since volume expansion with saline improves renal blood flow without improving GFR. The improvement in GFR seen with Mannitol is associated with a decrease in afferent and efferent arteriolar resistance which is probably mediated by prostaglandins. 3. D Clinical studies comparing prophylactic administration of Mannitol (or furosemide) with maintenance of adequate intravascular volume during cardiopulmonary bypass failed to reduce the incidence of post-operative renal dysfunction. However, there are expe5rimental studies that have shown some beneficial effects of Mannitol. Mannitol has been shown to be effective in preventing deterioration of renal function before administration of Amphotericin B and Cis-Platinum. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; pp 1194-1195. Nichols DG. Critical Heart Disease in Infants and Children. Mosby 1995; pp 129-130. Olivero JJ, et al. Br Med J, 1975; Vol. 1:550. Hayes D, et al. Cancer, 1977; 39:1372) 4. C Etiologies of post-operative oliguria in this patient include: 1) Intra-operative blood loss; 2) Third space volume loss; 3) Bilateral ureteral obstruction; 4) Cardiac failure; and 5) Increased intra-abdominal pressure. In this patient, the latter is important to recognize (since it appears that intravascular volume has been expanded and cardiac output is normal) because prompt surgery to relieve increased intra-abdominal pressure is associated with rapid diuresis. The development of this problem is best avoided by direct measurement of intra-abdominal pressure either via the esophageal route or per gastrostomy. Data indicate that the abdominal wall should not be closed if pressure exceeds 20 mmHg. In this case, it is best to employ a silo with delayed closure to allow time for the compliance of the abdominal wall to increase. (Yaster M, et al. Anesthesiology, 1986; 65:A449) 5. E Children have a lower mortality compared to adults. ((Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; pp 1198-1201) 6. A Increased P-R interval is seen before changes in P-wave because the A-V node is much more sensitive to hyperkalemia than the S-A node. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; p 1201) 7-8. E, D All of the strategies mentioned are appropriate for oliguria in a setting of suspected renal insufficiency. With the onset of acute renal failure, hyponatremia is more commonly seen due to the dilutional effect of intake of fluid orally, which is mostly hypotonic. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; p 1202. Nichols DG. Critical Heart Disease in Infants and Children. Mosby 1995; pp 128-138) 9-12. B, A, D, C In the absence of significant symptoms, hypocalcemia does not need to be aggressively treated. Aggressive treatment with calcium in the presence of hyperphosphatemia, and particularly when the product of calcium and phosphorus exceeds 60, increases the risk of calcium deposition in various tissues within the body. Acidosis raises the level of ionized calcium and thus mitigates against the occurrence of symptomatic hypocalcemia. Caution must be exercised in correcting acidosis abruptly as a rapid decline in the level of ionized calcium may precipitate tetany. Dysequilibrium syndrome is not seen with peritoneal dialysis, as the process is very slow, as compared to hemodialysis, which is done over a few hours. Such a high dose of Vitamin C is unnecessary in patients with renal failure. Patients with HUS seem to have a better outcome with early institution of dialysis. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; pp 1201-1205. Kaplan BS, et al. Acute Renal Failure Induced by Hyperphosphatemia in Acute Lymphoblasic Leukemia. Can Med Assoc J, 1981; Vol. 124:429) 13. A Severe hypertension with hypertensive encephalopathy is a recognized feature of rapidly progressive glomerulonephritis. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 2nd Edition; p 1214) 14. A The initial concentration of a drug equals the dose administered divided by volume of distribution: C = D ¸ Vd (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 766-768) 15. D Saline diuresis is the most appropriate treatment for hypercalcemia. (Bilezikian J. Management of Acute Hypercalcemia. N Engl J Med, 1992; Vol. 326:1196) 16. A, A, A, C, D, A (Williams GH. Review: Converting Enzyme Inhibitors in the Treatment of Hypertension. N Engl J Med, 1988; Vol. 319:1517) 17-18. D, D High levels of urea act as an osmotic diuretic in the post-operative period. High normal intravascular volume is precisely what is desirable in the post-operative period in order to avoid the risk of thrombosis in the graft. Pre-operative transfusion (with consequent hypervolemia) would increase the risk of congestive cardiac failure in the post-operative period. For cadaveric kidney transplantation, there is a positive correlation between the number of transfusions and the graft survival, and the survival seems to be optimal with a transfusion from 5 or more different donors. With living related donors, it is unclear whether transfusion has any beneficial effects on the survival of the graft. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1237-1240) 19. C, A Increased platelet consumption is a feature of both hemolytic uremic syndrome and disseminated intravascular coagulopathy. However, deficiency of prostaglandin I2 activity is associated only with hemolytic uremic syndrome. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1231-1235) 20. C Atracurium undergoes spontaneous degradation referred to as Hofmann degradation, however, some authorities believe that ester hydrolysis is the major pathway for degradation of atracurium. (Fuhrman BP. Pediatric Critical Care, 2nd Edition; pp 1346-1347) 21. E (Bennet WM. Guide to Drug Dosage in Renal Failure. Clin Pharmacokinetics, 1988; Vol. 5:326) 22. B, C, D, A 23. D, A Water intoxication is characterized by absence of clinical signs of dehydration, hyponatremia and a low urinary sodium. In SIADH, the urine osmolality continues to be high in spite of low serum sodium and osmolality. CAH is associated with hyperkalemia and acidosis. 3% salt given at an initial dose of 4 ml/kg will increase serum sodium by approximately 3-4 mEq/L and will abort the seizure. (Rogers MC. Textbook of Pediatric Intensive Care, 2nd Edition; Williams & Wilkins, pp 1249-1250)