Acute Renal Failure

Anil Menon

11/27/06

A simple algorithm

• Malingering

• Rapid fall in GFR leading to increased waste products

Relevance

• Complicates up to 7% of admissions

• Mortality when dialysis is required ranges 50%-75%

DDX

Diagnostic Approach

• Cr/BUN, UOP, serum cystatin K, IL18

• H&P

• Meds

• Labs

• Imaging

Acute or Chronic?

• History

• Previous creatinine

• Small kidneys on u/s

Obstruction excluded?

• History

• Complete anuria

• Palpable bladder

• Renal u/s

Euvolemic?

• Pulse, JVP/CVP, orthostatic, wgt, I/O

• Disproportionate inc in urea:Cr ratio

• FENA

• Fluid challenge

Evidence of parenchymal dz? Other than ATN

• H+P (systemic factors)

• Urine dipstick and micro

(red cells, red cell casts, eosinophils, prot)

Major vascular occlusion?

• Athreosclerosis

• Renal Assymetry

• Groin pain

• Complete Anuria

• Macro Hematuria

Treatment

• Prevention– Risk factors (age,DM,HTN,Vasc,renal)– Maintain BP and Volume, avoid neprhotox– Measure plasma aminoglycoside– Allopurinol/urine alk in cancer

General

• Correct prerenal/postrenal factors

• Optimise CO, RBF

• Review meds

• Monitor I/O

• Nutritional support

• Treat infection, bleeding

• Start dialysis before uremic

No strong evidence

• Loop diuretic

• Dopamine

• Natriuretic peptide

• Intermittent HD vs Continuous

• ILF

• Thyroxine

ATN

• Sepsis in ICU 35-50%• Prerenal azotemia spectrum

with ischemic ATN• Initiation, maintenance,

recovery• BUN/Cr normal 10:1• Rapid rise plasma Cr• Muddy brown epi casts• FENa > 2%• Ucr / PCr

Post Op

• 18-40% hospital aquired. 1.2% surgery.• Pre-op BP control (Carmaichael J Surgery 2003)

• Hydration and prevention• Poor prognosis of ARF when adjusted

(Svensson J Vasc Surg 1989)

• Nephrology

Contrast

• Isotonic crystalloid 1-1.5ml/kg for 3-12 hours pre proc and 6-24 hours post

• Mucomyst not consistently useful• Current eval of theophyline, statins, vit c, pg E• CCB, L-arg, fenoldopam, dopamine, ANP not

useful • Prophylactic HD no gain(Stacul 2006 CIN consensus working panel)