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Acute Renal Failure Deb Goldstein Argy Resident September, 2005.

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Presentation on theme: "Acute Renal Failure Deb Goldstein Argy Resident September, 2005."— Presentation transcript:

1 Acute Renal Failure Deb Goldstein Argy Resident September, 2005

2 Acute Renal Failure Rapid decline in the GFR over days to weeks. Cr increases by >0.5 mg/dL GFR <10mL/min, or <25% of normal Acute Renal Insufficiency Deterioration over days-wks GFR mL/min

3 Definitions Anuria: No UOP Oliguria: UOP< mL/d Azotemia: Incr Cr, BUN May be prerenal, renal, postrenal Does not require any clinical findings Chronic Renal Insufficiency Deterioration over mos-yrs GFR mL/min, or 20-50% of normal ESRD = GFR <5% of nl

4 ARF: Signs and Symptoms Hyperkalemia Nausea/Vomiting HTN Pulmonary edema Ascites Asterixis Encephalopathy

5 Causes of ARF in hospitalized pts 45% ATN Ischemia, Nephrotoxins 21% Prerenal CHF, volume depletion, sepsis 10% Urinary obstruction 4% Glomerulonephritis or vasculitis 2% AIN 1% Atheroemboli

6 ARF: Focused History Nausea? Vomiting? Diarrhea? Hx of heart disease, liver disease, previous renal disease, kidney stones, BPH? Any recent illnesses? Any edema, change in urination? Any new medications? Any recent radiology studies? Rashes?

7 Physical Exam Volume Status –Mucus membranes, orthostatics Cardiovascular –JVD, rubs Pulmonary –Decreased breath sounds –Rales Rash (Allergic interstitial nephritis) Large prostate Extremities (Skin turgor, Edema)

8 W/U for ARF Chem 7 Urine –Urine electrolytes and Urine Cr to calculate FeNa –Urine eosinophils –Urine sediment: casts, cells, protein –Uosm Kidney U/S - r/o hydronephrosis

9 FeNa = (urine Na x plasma Cr) (plasma Na x urine Cr) FeNa <1% 1. PRERENAL Urine Na < 20. Functioning tubules reabsorb lots of filtered Na 2. ATN (unusual) Postischemic dz: most of UOP comes from few normal nephrons, which handle Na appropriately ATN + chronic prerenal dz (cirrhosis, CHF) 3. Glomerular or vascular injury Despite glomerular or vascular injury, pt may still have well-preserved tubular function and be able to concentrate Na

10 More FeNa FeNa 1%-2% 1. Prerenal-sometimes 2. ATN-sometimes 3. AIN-higher FeNa due to tubular damage FeNa >2% 1.ATN Damaged tubules can't reabsorb Na

11 Calculating FeNa after pt has gotten Lasix... Caution with calculating FeNa if pt has gotten Loop Diuretics in past h Loop diuretics cause natriuresis (incr urinary Na excretion) that raises U Na-even if pt is prerenal So if FeNa>1%, you don’t know if this is because pt is euvolemic or because Lasix increased the U Na So helpful if FeNa still 1% 1. Fractional Excretion of Lithium (endogenous) 2. Fractional Excretion of Uric Acid 3. Fractional Excretion of Urea

12 A 22yo male with sickle cell anemia and abdominal pain who has been vomiting nonstop for 2 days. BUN=45, Cr=2.2. A. ATN B. Glomerulo- nephritis C. Dehydration D. AIN from NSAIDs

13 Prerenal ARF Hyaline casts can be seen in normal pts –NOT an abnormal finding UA in prerenal ARF is normal Prerenal: causes 21% of ARF in hosp. pts Reversible Prevent ATN with volume replacement –Fluid boluses or continuous IVF –Monitor Uop

14 Prerenal causes Intravascular volume depletion –Hemorrhage –Vomiting, diarrhea –“Third spacing” –Diuretics Reduced Cardiac output –Cardiogenic shock, CHF, tamponade, huge PE.... Systemic vasodilation –Sepsis –Anaphylaxis, Antihypertensive drugs Renal vasoconstriction –Hepatorenal syndrome

15 Intrinsic ARF 1.Tubular (ATN) 2.Interstitial (AIN) 3.Glomerular (Glomerulonephritis) 4.Vascular

16 You evaluate a 57yo man w/ oliguria and rapidly increasing BUN, Cr. A.ATN B.Acute glomerulonephritis C.Acute interstitial nephritis D.Nephrotic Syndrome

17 ATN Muddy brown granular casts (last slide) Renal tubular epithelial cell casts (below)

18 More ATN Broad casts (form in dilated, damaged tubules)

19 ATN Causes 1. Hypotension Relative low BP May occur immediately after low BP episode or up to 7 days later! 2. Post-op Ischemia Post-aortic clamping, post-CABG 3. Crystal precipitation 4. Myoglobinuria (Rhabdo) 5. Contrast Dye –ARF usually 1-2 days after test 6. Aminoglycosides (10-26%)

20 ATN—What to do Remove any offending agent –IVF –Try Lasix if euvolemic pt is not peeing –Dialysis Most pts return to baseline Cr in 7-21 days

21 ATNPrerenal Crincreases at /day increases slower than 0.3 /day U Na, FeNa UNa>40 FeNa >2% UNa<20 FeNa<1% UAepi cells, granular casts Normal Response to volume Cr won’t improve much Cr improves with IVF BUN/Cr10-15:1>20:1

22 Which UA is most compatible w/contrast-induced ATN? A.Spec grav 1.012, RBC, WBC, +Eos B.Spec grav 1.010, 1-3 WBC, 5-10 renal tubular cells, many granular casts, occasional renal tubular cell casts, no eos C.Spec grav 1.012, 5-10 RBC, WBC, many bact, occasional fine granular casts, no eos D.Spec grav 1.020, RBC, 2-4 WBC, 1-3 RBC casts, no eos

23 ATN B. Spec grav 1.010, 1-3 WBC, 5-10 renal tubular cells, many granular casts, occasional renal tubular cell casts, no eos Dilute urine: failure to concentrate urine No RBC casts or WBC casts in ATN Eos classically in AIN or renal atheroemboli, but nonspecific

24 56yo woman with previously normal renal function now has BUN=24, Cr 1.8. Which drug is responsible? A.Indinavir for her HIV B.Gentamicin for her SBE C.Motrin for her OA D.Cyclosporin for her SLE

25 WBC Casts Cells in the cast have nuclei (unlike RBC casts) Pathognomonic for Acute Interstitial Nephritis

26 Acute Interstitial Nephritis 70% Drug hypersensitivity 30% Antibiotics: PCNs (Methicillin), Cephalosporins, Cipro Sulfa drugs NSAIDs Allopurinol... 15% Infection Strep, Legionella, CMV, other bact/viruses 8% Idiopathic 6% Autoimmune Dz (Sarcoid, Tubulointerstitial nephritis/Uveitis)

27 AIN from Drugs Renal damage is NOT dose-dependent May take wks after initial exposure to drug Up to 18 mos to get AIN from NSAIDS! But only 3-5 d to develop AIN after second exposure to drug Fever (27%) Serum Eosinophilia (23%) Maculopapular rash (15%) Bland sediment or WBCs, RBCs, non-nephrotic proteinuria WBC Casts are pathognomonic! Urine eosinophils on Wright’s or Hansel’s Stain –Also see urine eos in RPGN, renal atheroemboli...

28 AIN Management Remove offending agent Most patients recover full kidney function in 1 year Poor prognostic factors –ARF > 3 weeks –Advanced age at onset

29 You evaluate a 32yo woman with HTN, oliguria, and rapidly increasing Cr, BUN. You spin her urine: A.ATN B.Acute glomerulonephritis C.Acute interstitial nephritis D.Nephrotic Syndrome

30 Acute Glomerulonephritis RBC casts: cells have no nuclei Casts in urine: think INTRINSIC renal dz If she has Lupus w/recent viral prodrome, think Rapidly Progressive Glomerulonephritis If she had a sore throat 10 days ago, think Postinfectious Proliferative Glomerulonephritis

31 What are these?

32 Glomerular Dz Hematuria (dysmorphic RBCs) RBC casts Lipiduria (increased glomerular permeability) Proteinuria (may be in nephrotic range) Fever, rash, arthralgias, pulmonary sx Elevated ESR, low complement levels

33 Type 1: Anti-GBM dz Type 2: Immune complex IgA nephropathy Postinfectious glomerulonephritis Lupus nephritis Mixed cryoglobulinemia Type 3: Pauci-immune Necrotizing glomerulonephritis (often ANCA-positive, assoc. w/vasculitis) Can present with viral-like prodrome Myalgias, arthralgias, back pain, fever, malaise Kidney bx : Extensive cellular crescents with or w/o immune complexes Can develop ESRD in days to weeks. Treat w/glucocorticoids & cyclophosphamide. Rapidly Progressive Glomerulonephritis

34 Usually after strep infxn of upper respiratory tract or skin – 8-14 day latent period –Can also occur in subacute bacterial endocarditis, visceral abscesses, osteomyelitis, bacterial sepsis Hematuria, HTN, edema, proteinuria Positive antistreptolysin O titer (90% upper respiratory and 50% skin) Treatment is supportive –Screen family members with throat culture and treat with antibiotics if necessary Postinfectious Proliferative Glomerulonephritis

35 A 19yo woman with Breast Cancer s/p chemo in the ER has weakness, fever, rash. WBC=15.4, Hct 24, Cr 2.9, LDH 600, CK=600. UA=3+ prot, 3+blood, 20 RBC. What next test do you order? What’s her likely dx? A.Nephrotic Syn B.Systemic Vasculitis C.Acute Glomerulonephritis D.Hemolytic-Uremic Syn E.Rhabdomyolysis

36 TTP Order blood smear to r/o TTP TTP associated with malignancy, chemo TTP may mimic Glomerulonephritis on UA (RBCs, WBCs) Thrombocytopenia, anemia not consistent with nephrotic or nephritic syndrome Need CK in the thousands to cause ARF

37 Microvascular ARF TTP/HUS HELLP syndrome Platelets form thrombi and deposit in kidneys  Glomerular capillary occlusion or thrombosis Plasma exchange, steroids, Vincristine, IVIG, splenectomy....

38 Macrovascular ARF Aortic Aneurysm Renal artery dissection or thrombosis Renal vein thrombus Atheroembolic disease –New onset or accelerated HTN? –Abdominal bruits, reduced femoral pulses? –Vascular disease? – Embolic source?

39 A.Renal Artery Stenosis B.Contrast- Induced Nephropathy C. Abdominal Aortic Aneurysm D. Cholesterol Atheroemboli Your 68yo male inpatient with baseline Cr=1.2 had negative cardiac cath 4 days ago, now Cr=1.8 and blanching rash.

40 Why do his toes look like this?

41 Renal Atheroembolic Dz 1% of Cardiac caths: atheromatous debris scraped from the aortic wall will embolize –Retinal –Cerebral –Skin (Livedo Reticularis, Purple toes) –Renal (ARF) –Gut (Mesenteric ischemia) Unlike in Contrast-Induced Nephropathy, Cr will NOT improve with IVF Diagnosis of exclusion: will NOT show up on MRI or Renal U/S; WILL show up on renal bx Tx: supportive

42 Post-Renal ARF Urethral obstruction: prostate, urethral stricture. Bladder calculi or neoplasms. Pelvic or retroperitoneal neoplams. Bilateral ureteral obstruction (neoplasm, calculi). Retroperitoneal fibrosis.

43 “Doc, your pt hasn’t peed in 5 hrs....what do you want to do?” Examine pt: Dry? Septic (vasodilated)? Flush foley (sediment can obstruct outflow) Check I/Os (has she been drinking?) Give IV BOLUS ( cc IVF), see if pt pees in next min –If she pees, then she was dry –If she doesn’t pee, then she’s either REALLY dry or in renal failure Check UA, UCx, urine lytes Consider Renal U/S if reasonable

44 You’re called to the ER to see... A 35yo woman with previously normal renal function now with BUN=60, Cr=3.5. Do you call the Renal fellow to dialyze this pt? What if her K=5.9? What if her K=7.8?

45 Indications for acute dialysis AEIOU Acidosis (metabolic) Electrolytes (hyperkalemia) Ingestion of drugs/Ischemia Overload (fluid) Uremia

46 You admit this pt to telemetry and aggressively hydrate her. You recheck labs 6h later and BUN=85, Cr=4.2. Suddenly the pt starts to seize. Now what?

47 Uremia—So what? General –Fatigue, weakness –Pruritis Mental status change –Uremic encephalopathy –Seizures –Asterixis GI disturbance –Anorexia, early satiety, N/V, Uremic Pericarditis Plt dysfunction/bleeding

48 A pt with chronic lung disease has acute pleuritic pain and desats to 92%RA. You want to r/o PE but her Cr=1.4. Can you get a CT with IV contrast? A.Send her for Stat CT with IV contrast B.Send her for Stat CT without IV contrast C. Just give her heparin D.Begin IV hydration E.Begin pre-procedure Mannitol F.Get a VQ scan instead

49 Contrast-Induced Nephrotoxicity Cr increases by 25% or >0.05 post- procedure Contrast causes renal vasoconstriction  renal hypoxia Iodine itself may be renally toxic If Cr>1.4, use pre-procedure prophylaxis

50 Pre-Procedure Prophylaxis 1. IVF ( 0.9NS) mg/kg/hour x12 hours prior to procedure and 6-12 hours after 2. Mucomyst (N-acetylcysteine) Free radical scavenger; prevents oxidative tissue damage 600mg po BID x 4 doses (2 before procedure, 2 after) 3. Bicarbonate (JAMA 2004) Alkalinizing urine should reduce renal medullary damage D5W with 3 amps HCO3; bolus 3.5 mL/kg 1 hour preprocedure, then 1mL/kg/hour for 6 hours postprocedure 4. Possibly helpful? Fenoldopam, Dopamine 5. Not helpful! Diuretics, Mannitol


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