September 2 nd , 2010

1. September 2nd, 2010

2. Acute Renal Failure • Prerenal (Most Common) • Results from hypoperfusion to kidney • Dehydration, CHD, Sepsis • Decreased perfusion -> ischemic injury -> fall in GFR • Compensation: • Relax afferent arterioles (decreasing renal vasc resistance) • Increased catecholamines • Increased vasopressin • Renin-angiotensin system • Enhanced Na and water reabsorption to increase perfusion • May secondarily worsen oliguria • Vasodilatory prostaglandins -> relax microvasculature • *Recognize the causes of acute renal failure in infants and children

3. Diagnosis: Prerenal ARF • History should fit • Renal imaging normal

4. Intrinsic Renal Disease • Parenchymal injury (ischemic or toxic) • ATN, interstitial nephritis, HUS, glomerulonephritis, nephrotoxic drugs • May see RBC or granular casts

5. Intrinic Renal Failure • Renal scans (Mg-3) may identify areas of poor function • Bx may be needed

6. Postrenal Failure • Obstruction to urinary flow • Calculi, posterior urethral valves, UPJ obstruction • Renal damage results from increased pressure • Urinary sediment findings variable • Imaging • U/S • Radioisotope scan

7. ARF: Management • Renal perfusion • Balancing fluid/ electrolytes • Controlling BP • Anemia • Adequate nutrition • Renal dosing of meds • Dialysis (when needed) • *Plan the initial treatment for a child with acute renal failure • *Recognize the complications of ARF

8. Renal Perfusion • Adequate CVP • May require fluid administration • Vasoactive agents • Low-dose dopamine can improve renal blood flow, but the actual benefit is debated in literature

9. Fluid Management • If unstable, bolus! • If stable but ?volume depleted, gentle bolus • Once intravascular volume re-established, minimal fluids • Know that coexisting volume depletion should be corrected in patients with acute renal failure

10. Fluid Management • Diuretics (Furosemide, Mannitol) • Benefit: • May help volume overload • Decrease intratubular obstruction • Remove K+ (furosemide) • Downfall: • Do not prevent need for dialysis • Could worsen renal perfusion and injury • Restore intravascular volume and measure urine lytes prior to diuretics

11. Lytes • Hyponatremia • Hyperkalemia • Acidosis • Hypocalcemia

12. Anemia • Consider transfusion: • Active bleeding • Hemodynamic instability • Hct < 25

13. Hypertension • Secondary to volume overload, increased vasctone • Diuresis or dialysis may be required • IV antihypertensives if >99%ile • Labetalol, nicardipine, enalapril

14. Nutrition • Patients are in catabolic state, malnutrition is common • For infants, low phos formula • Older kids, may need low phos, K+, Na+ • Balance nutrition with fluid restriction • TPN • Know the importance of nutrition in a child with ARF

15. Meds • Renal dose and interval • Know that drug dosages must be modified in ARF

16. Dialysis • Indications • CHF • Anemia • Hyperkalemia • Severe acidosis • Pericarditis • Inadequate nutrition • CVVH most commonly used acutely • Can use with low BPs

17. Glomerular Disease

18. Determine the Pattern • Nephrotic Pattern: • No inflammation on histology • Nephrotic range proteinuria • Inactive urine sediment (few cells or casts) • Nephritic Pattern: • Inflammation by histology • Urine sediment: RBCs, WBCs, granular and RBC casts, variable proteinuria

19. Indicators of Glomerular Bleeding

21. What about function? • Reduction in GFR • Progression of disease • Superimposed insult • Decreased perfusion • Possibly reversible • Schwartz formula • May overestimate GFR

22. Schwartz Formula GFR = k X Ht(cm) / Serum Creat k = 0.33 preterm infants k = 0.45 infants k = 0.55 children/ adolescent girls k = 0.7 adolescent boys

23. Blood Tests *Differentiate acute post-strep GN from other forms

24. Renal Biopsy • Goals • Confirm Dx • Determine extent of injury • Predict outcome • Timing • Dependant on clinical setting

25. Rapidly Progressive (Crescentic) GN • Clinical Syndrome • Features of glomerular disease • Progressive loss of renal function (days, weeks) • May be presentation of many underlying dx • Tx • Pulse methylprednisolone • Cyclophosphamide • Consideration of plasmapheresis (anti-GBM)

26. Membranoproliferative GN • Most common chronic GN in older kids and adults • May present with nephroticsyn OR acute nephritic syndrome • Renal function normal to severely decreased • 50% progress to end stage renal disease in 10yrs • No proven therapy

27. Post-Streptococcal Glomerulonephritis • Acute nephritic syndrome 1-2wks after strep pharygitis, or up to 6wks after impetigo • Strep Antibody titers positive • Hematuria, edema, HTN, renal insufficiency. • U/A: RBC casts, proteinuria, WBC • Low C3 • Very similar presentation to MPGN, but resolves by 2mos

28. Membranoproliferative GN Post-strep GN • Acute onset • Hematuria, edema, HTN • Impaired renal function • U/A: RBC casts, proteinuria, WBC • Low C3 • Lasts longer than 2 months • Confirmed on Biopsy • Acute onset • Hematuria, edema, HTN • Impaired renal function • U/A: RBC casts, proteinuria, WBC • Low C3 • Strep antibodies positive • Resolves by 2 months

29. Post-Streptococcal Glomerulonephritis • Treatment: • Manage the acute effects of renal insufficiency, HTN • Amoxicillin • Prevent spread of nephritogenic organisms • Does not affect natural course of disease • *Plan the initial management of PSGN

30. Post-Streptococcal Glomerulonephritis • Prognosis • Complete recovery 95% • Renal function and C3 normalize by 6wks • HTN up to 3mos • Hematuria/proteinuria for prolonged periods • If chronic, think MPGN • *Know sequence of resolution: C3, hematuria, proteinuria