Acute Renal Failure

Acute Renal Failure Pathogenesis and Treatment Lestariningsih Subbag Nefrologi/Hipertensi Bagian Penyakit Dalam FK UNDIP/RS Dr. Kariadi Semarang

Definition • • • • • • •

Abrupt sustained decline in GFR Rising serum urea and creatinine Loss of water and salt homeostasis Life threatening metabolic sequelae Occurs over hours or days Incidence approximately 140 p.m.p. per year 5% of all surgical and medical admissions

Subtypes • • • •

Acute or acute on chronic Single organ or multi-organ failure Oliguric or polyuric Mild or severe

Aetiology • Pre-renal ARF • Intrinsic ARF • Post-renal ARF

Pre-renal ARF • Reversible fall in GFR due to renal hypoperfusion – Hypovolaemia • Haemorrhage, burns, GI fluid loss, renal fluid loss – Hypotension • Cardiogenic shock, sepsis – Renal hypoperfusion • renal vasoconstriction, drugs, liver disease, renal vascular disease

Renal ARF • Disease of the renal parenchyma – ATN • Ischaemia, direct toxicity, myoglobin, sepsis

– Vascular disease • Vasculitis, atheroemboli, infarction

– Diseases of glomeruli/arterioles • RPGN, myeloma, HUS, vasculitis, SLE

– Tubulo-interstitial nephritis • Drug related, paraneoplastic

Post-renal ARF • Renal failure secondary to urinary tract obstruction – Ureteric • Calculi, carcinoma, retroperitoneal fibrosis, stricture

– Bladder neck • prostatic hypertrophy/malignancy, carcinoma, neuropathy, blocked catheter

Prevention • Identify at risk patients – pre-existing CRF, diabetes, jaundice, myeloma, elderly

• Optimise renal perfusion – IV fluids, inotropes, central line

• Maintain adequate diuresis – Mannitol, frusemide, NOT dopamine

• Avoid nephrotoxic agents – ACE inhibitors, NSAIDS, radiological contrast, aminoglycosides

Cockcroft Gault equation

(140-age in years) x weight in kg serum creatinine (μmol/L) (corrected for males x 1.23, females x 1.04)

Principles of investigation • • • • •

Acute or acute on chronic? Exclude volume depletion Exclude renal tract obstruction Exclude major vascular occlusion Exclude renal parenchymal disease other than ATN

History • When did it start? • What was the baseline renal function? – Pre -existing medical conditions

• What were the likely insults? – Episodes of hypotension – Nephrotoxic agents – Sepsis

• Symptoms of other diseases

Examination • Current volume status – Skin turgor, oedema, lung bases, heart sounds, central pressures, blood pressure

• Bladder and kidneys • Signs of systemic disease – rashes, anaemia,

Investigations • Laboratory – – – – –

U+E’s, Bone, Glucose, Urate, Bicarbonate Urine urea, sodium, creatinine, protein FBC, Clotting, ESR Urine microscopy, MSU, blood cultures CRP, ANA, ANCA, anti GBM, myeloma screen

Investigation • Radiology – Plain abdomen, renal U/S, IVU, CT scanning, renal angiography, isotope renography

• Renal biopsy

Treatment • Correct renal perfusion – Optimise volume status – Inotropes ( dopamin 3 ug/kgBB/jam )

• Remove nephrotoxins • Relieve obstruction - Bladder catheter – Nephrostomies

Treatment • Make the patient safe • Hyperkalaemia – Volume overload – Uraemia – Acidosis

• Specific treatments – Antibiotics, steroids

Methods of treatment DRUG

DOSE

DURATION

Calcium Gluconate

10 ml of 10%

30 minutes

Glucose + Insulin

50 ml 50% + 8U

1 - 4 hours

IV Na Bicarbonate

1l of 1.4%

1 - 8 hours

Ventolin Nebuliser

5 ml

1 - 4 hours

Resonium

30 - 60 g (po/pr)

days

Bendrofluazide

5mg

days

and there is always dialysis!

Dialysis • Acute intermittent haemodialysis • Continuous dialysis treatments • Peritoneal dialysis

Outcome • • • •

Full recovery Partial recovery No recovery - progress to ESRF Death