Approach to the Patient with Acute Renal Failure. Michael Ornes Abbott Northwestern Hospital

Transcription

1 Approach to the Patient with Acute Renal Failure Michael Ornes Abbott Northwestern Hospital

2 Definition Abrupt decrease in glomerular filtration rate Accumulation of urea and other metabolic byproducts Biochemical markers Creatinine > 1.5 Creatinine change > 0.5 Creatinine twice normal

3 Categories of ARF Prerenal (65%) Hypovolemia Effective hypovolemia (CHF,hepatorenal,sepsis) Intrarenal or intrinsic (25%) Vascular Glomerular Interstitial Tubular Postrenal or obstructive (10%)

4 Risks History of renal failure PMH DM HTN Nephrolithiasis Autoimmune disease BPH Medications (NSAID, ACE I, Ampho B, rifampin, cimetidine, allopurinol, etc)

5 Signs and symptoms May be asymptomatic Often associated with other disease exacerbations Non-specific signs and symptoms HTN Weakness, fatigue, or recent infection N/V Edema Specific signs and symptoms to the urinary tract Decreased urine output Urine color change Flank pain

6 Creatinine Clearance Cockcroft-Gault equation (if Cr stable) GFR= (140 - age)(lean weight)(.85 if female) (72)(Creatinine) Twenty-four hour urine for creatinine GFR= (Ucr)(volume) PCr Normal Creatinine clearance ml /min in women 120 ml /min in men

7 Level of Injury Risk, injury or failure Glomerular Filtration Rate Decrease by 25% Decrease by 50% Decrease by 75% Urine output < 0.5 cc/kg/hr for > 6 hours < 0.5 cc/kg/hr for > 12 hours < 0.3 cc/kg/hr for > 24 hours

8 Urinalysis Specific gravity defines concentration need and/or ability Color Protein (macroalbuminuria only on dipstick) Glucose, bilirubin ph Hemoglobin (in absence of RBC indicates possible rhabdomyolysis)

9 UA cells and sediment WBC, leukocyte esterase, and nitrite indicate UTI RBC casts indicate glomerulonephritis as can the combination of RBC and WBC WBC casts indicate pyelonephritis or tubulointerstitial disease Urine eosinophils may indicate interstitial nephritis Proteinuria with oval fat bodies without many cells indicates possible nephrotic syndrome Granular and epithelial casts indicate ATN

10 68 y/o female PMH HTN on HCTZ Hypothyroidism treated HPI Two days diarrhea, N/V, decreased appetite Today lightheaded Exam Temp 38.1 BP 88/50 HR 100 Dry mucosal membranes JVP < 3 cm H 2 O Abdomen mild diffuse tenderness

11 Data Sodium 132 Potassium 4.2 Chloride 98 Bicarbonate 17 BUN 47 Creatinine 2.0 UA SG no RBC or WBC WBC 13.9 Hemoglobin 14.8 Stool WBC s seen Lean weight 60 kg Urine Na 13 Urine Cr 40

12 Creatinine clearance and FENa (140-68)(60)(0.85) = 25.5 ml/min (72)(2.0) FENa = (UNa)(PCr) = 0.5% (PNa)(UCr) < 1% prerenal > 2% ATN

13 Causes of Prerenal ARF In general, any condition which results in decreased renal perfusion Decreased cardiac output Acute myocardial infarction Congestive heart failure Intravascular volume depletion Decreased effective volume (cirrhosis) Hypovolemia Peripheral vasodilatation Septic shock Anaphylaxis

14 75 y/o male PMH DJD DM HPI Nocturia times 3-4 Slow urinary stream Hesitency Mild dyspnea Exam Afebrile BP 165/97 HR 78 Few crackles bases Abdomen Soft Normal bowel sounds Spherical tender suprapubic mass

15 Data Sodium 132 Potassium 5.3 Bicarbonate 16 Chloride 98 BUN 56 Creatinine 3.6 UA SG No RBC or WBC No protein Ultrasound Bilateral hydronephrosis Distended bladder Mild thinning of bilateral cortices

16 Obstructive Nephropathy Bilateral ureteral obstruction Or unilateral obstruction in setting of a nonfunctional kidney Stones, tumor, etc Anything that obstructs urethral outflow Prostate or urethral stricture Neurogenic bladder Post-op, meds, cord lesion, neuropathy

17 45 y/o male PMH MVA 4 months ago DVT during hospitalization HPI Dyspnea Hemoptysis Headache Hematuria Exam Temp 38.3 BP 185/105 HR 110 RR 30; O 2 sats 88% RA Nasal mucosal ulcers with discharge Pulmonary crackles Palpable purpura

18 Data Sodium 132 Potassium 5.2 Chloride 96 Bicarbonate 20 BUN 39 Creatinine 2.9 Anion gap 16 Urinalysis SG RBC/HPF 75 WBC/HPF 2+ protein 1 RBC cast CXR Patchy alveolar opacities Possible nodule

19 Vasculitis Wegener s granulomatosis C-ANCA positive: anti-proteinase-3

20 Intrinsic Renal Failure Vascular Atheroemboli, malignant HTN, vasculitis Acute glomerulonephritis Post infectious, etc Acute interstitial nephritis Medications, rarely infectious ATN Ischemia, nephrotoxin

21 Treatment Prerenal: IV volume expansion in hypovolemia Diurese, etc in CHF Treat infection in septic shock Intrinsic renal: treatment of underlying condition Postrenal: remove obstruction Avoid nephrotoxic medications and dose adjust other drugs Maintain euvolemia as able

22 Indications for Dialysis Florid symptoms of uremia Encephalopathy, pericarditis Severe volume overload Severe acid-base imbalance AGMA Severe electrolyte abnormality Hyperkalemia (Toxins: Lithium, etc)

23 The End