The management of acute renal failure

Abstract

Acute renal failure (ARF) is an uncommon problem in most developed countries because of the low incidence of and usually prompt treatmenl~ for dehydrating and infectious illnesses. The majority of patients with ARF are likely to be seen in major centres with renal, neonatal, cardiothoracic or oncology units. Acute renal failure can be defined as a sudden decrease in renal function with disturbance of water and electrolyte homeostasis and retention of nitrogenous wastes. It is usually accompanied by oliguria (urine output < 1 ml/kg body weight/hr in the young child or 300 mls/m2/day in an adult) but occasionally patients may have polyuria. The reader is referred to more specialist texts for discussion on pathophysiology a'nd special considerations in the newborn. 1-5 Pre-renal Causes are those conditions which reduce perfusion to the kidneys. This is an important group to recognise because prompt treatment may prevent the development of acute tubular necrosis and established renal failure. In this situation a comparison of plasma and urine biochemistry may be helpful. In pre-renal failure the urine should have a high osmolality with a low sodium and high urea and creatinine content. The urine to plasma urea and creatinine ratios should be raised but are of little use in clinical practice. Evidence of oliguria with a raised plasma urea and creatinine level in a child'with nephrotic syndrome is one of the few indications for albumin infusions (1 g/ kg body weight using 20% salt poor albumin) combined with careful doses of frusemide (1-2mg/kg body weight).