- Reduction in renal excretory or regulatory function
- Results in the retention of waste products normally excreted by the
kidney
- Normal adult urine output = 0.5 ml/kg/hr
- Renal failure can be:
Causes of acute renal failure
| Type |
Causes |
| Pre-renal failure |
Hypovolaemia secondary to acute blood or plasma
loss |
|
Fluid and electrolyte depletion |
|
Hypotension secondary to cardiogenic shock |
|
Hypotension secondary to sepsis |
| Intrinsic renal failure |
Acute tubular necrosis due to prolonged renal
hypoperfusion |
|
Acute tubular necrosis due to contrast
nephropathy |
|
Acute glomerulonephritis |
|
Drug induced nephrotoxic damage |
|
Athero-embolic disease |
|
Acute pyelonephritis |
| Renal outflow obstruction |
Calculi |
|
Blood clot |
|
Ureteric damage and ligation |
|
Prostatic hypertrophy |
Biochemical changes of acute renal failure
- Hyponatraemia
- Hyperkalaemia
- Hypocalcaemia
- Metabolic acidosis
Urinary biochemistry
- In pre-renal failure
- Urine specific gravity - >1.016
- Low urinary sodium - <20 mmol/l
- High urinary urea - >250 mmol/l
- High osmolality - > 500 mosm/kg
- In intrinsic renal failure
- Urine specific gravity - <1.010
- High urinary sodium - >40 mmol/l
- Low urinary urea - <185 mmol/l
- Isotonic urine - 300-350 mosm/kg
Management of renal failure
- Remove precipitating cause
- Most surgical patients are hypovolaemic
- Require volume resuscitation
- If inadequate perfusion pressure consider inotropic support
- Oxygen
- Consider bicarbonate if
- Base excess > 10
- Arterial pH <7
Hyperkalaemia
- Requires urgent treatment if
- Symptomatic
- ECG changes - increased pr interval, tented t waves, ventricular
tachycardia
- Serum potassium > 6 mmol/l
- Treatment options
- 10 ml 10% calcium chloride intravenously
- 10u Actrapid in 50 ml 50% dextrose
- Salbutamol nebuliser
- Calcium resonium 15-30 mg pr twice daily
Bibliography
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Kapadia F N, Bhojani K, Shah B. Special issues in the
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Hilton R. Acute renal failure. BMJ 2006; 333:
786-790
Mehta R L, Clark W C, Schetz M. Techniques for
assessing and achieving fluid balance in acute renal failure.
Curr Opin Crit Care 2002; 8: 5350543.
Singri N, Ahya S N, Levin M L. Acute renal failure.
JAMA 2003; 289: 747-751. |