1. Acute Renal Failure

2. Approach to acute renal failure… Classifying the cause: –PreRenal (30%). –IntraRenal/Intrinsic cause (65%). –PostRenal (5%).

3. Acute Renal Failure Pre-Renal Think of it as anything that reduces renal perfusion – i.e. altered hemodynamics. –Volume depletion. –Hypotension. –Cardiovascular (CHF, arrythmias). –Intrarenal vasoconstriction. ACE-I, NSAIDs (inhibit prostaglandin), Ampho B, cyclosporine/tacrolimus, radiographic contrast. –Hypercalcemia –Hepatorenal syndrome.

4. Acute Renal Failure IntraRenal/Intrinsic Causes –Vascular – renal infarct, cortical necrosis, renal vein thrombosis, malignant HTN, scleroderma renal crisis, atheroemboli. –Tubular injury – ischemic or nephrotoxic. –Glomerular – acute GN, vasculitides, TMA. –Interstitial damage – tumor infiltration, medication (Acute interstitial nephritis).

5. Acute Renal Failure Post-Renal Causes Obstruction… –Prostatic hypertrophy. –Neurogenic bladder. –Intraureteral obstruction – stones, tumor, clot, crystals. –Extraureteral obstruction – extrinsic tumors, retroperitoneal fibrosis.

6. Acute Renal Failure Nonoliguric v. Oliguric v. Anuric. What does this mean and why does this matter? Oliguric renal failure. –Functionally, urine output less than that required to maintain solute balance (can’t excrete all solute taken in). –Defined as urine output < 400ml/24hr. Anuric renal failure. –Defined as urine output < 100ml/24hr. –Less common – suggests complete obstruction, major vascular catastrophy, or more commonly severe ATN.

7. Acute Renal Failure Classifying by urine output may help establish a cause. –Oliguria – more common with obstruction, prerenal azotemia –Nonoliguric – intrarenal causes – nephrotoxic ATN, acute GN, AIN. More importantly, assists in prognosis. –Significantly higher mortality with oliguric renal failure. –Approaches 80% in some series. –Nonoliguric renal failure may also suggest greater liklihood of recovery of function.

8. Acute Renal FAilure Symptoms: –Fever, rash, joint pains, myalgias Concern for SLE, vasculitis, acute interstitial nephritis. –Dyspnea – heart failure. –Hemoptysis – Goodpasture’s, Wegener’s. –Preceding bloody diarrhea – HUS. –Preceding pharyngitis – post-Strep GN, post- infectious GN.

9. Acute Renal Failure Urine output. –Abrupt anuria. Acute obstruction, severe acute GN, sudden vascular catastrophe. –Slowly diminishing. Ureteral stricture. Prostatic enlargement. –Presence of hematuria Painless – suggests GN. Painful – suggest ureteral obstruction.

10. Acute Renal Failure Physical Exam. –Skin – new rashes. Petechiae – HSP. Malar rash – SLE. –Eye Papilledema – malignant HTN. Roth’s spots – endocarditis. –CVs Rub – suggestive of uremic pericarditis, lupus. Gallop – suggesting CHF.

11. Acute Renal Failure Physical Exam. –Assessing volume status. Is the patient intravascularly volume depleted? –Neck veins – JVP –Peripheral edema or lack of. –Orthostatic vitals. –Not always straightforward. –Pt. may be edematous (low albumin) or have significant right sided heart disease.

13. Acute Renal Failure Imaging… –Renal U/S – we ALWAYS like to see one. Rules out obstruction. Evaluates chronicity – small size, echogenic. Makes sure there are 2 kidneys. –MRA or Doppler U/S may be useful in looking for renal artery stenosis.

14. Acute Renal Failure Drugs: –Prerenal – cyclosporine, tacrolimus, contrast, ACE-I, ampho B, NSAIDs. –ATN – AG’s, ampho B, cisplatin –AIN – PCN, cephalosporins, sulfa drugs, rifampin, NSAIDs, interferon, quinolones. –Post-Renal – acyclovir, indinavir, analgesics.

15. Management Correct fluid & electrolyte abnormalities –Diuresis –Treat hyperkalemia Correct Acid – base abnormalities Antibiotics if sepsis Management of cause Renal replacement therapy - Dialysis

16. Chronic kidney disease Causes –Congenital - PKD –Glomerular - Glomerulonephritis –Vascular – Hypertension, Renal a. stenosis –Tubulointerstitial – TI nephritis –Obstructive - stones

18. Symptoms Asymptomatic Loss of appetite MalaisePruritus Bone pain Paraesthesias – low calcium Fluid overload anaemia

20. Management of CKD Renoprotection –BP < 120/80 mmHg –Proteinuria - < 0.3 g / 24 h –Lower cholesterol –Stop smoking –Treat diabetes –Normal protein diet

21. Management of complications Correction of anaemia Treatment of hyperkalemia Management of acute renal failure (Acute on CKD) –Haemodialysis