Acute renal failure following cardiac surgery

Sir, We noted with interest the paper by Conlon et al. [1] on factors associated with the development of acute renal failure (ARF) in adults following cardiac surgery, having undertaken a similar study in children and demonstrated comparable results. The incidence of ARF in children following cardiac surgery varies between 1–5% depending on the definition of ARF and has a reported mortality of between 50–83%. In order to assess the discriminatory value of pre-operative, operative and post-operative variables in predicting recovery of renal function in those developing ARF, we carried out a retrospective review of 2473 infants and children who underwent cardiac surgery between January 1985 and December 1994. The diagnosis of ARF was made in the presence of an increase in age related plasma creatinine and two or more of the following: (i) Urine output <1 ml/kg/h (infant) and <0.5 ml/kg/h (child) averaged over 4 h and resistant to volume repletion, and intravenous diuretic therapy (Frusemide 2–5 mg/kg); (ii) hyperkalaemia, plasma potassium level on two separate occasions of >6.0 mmol/l; (iii) presence of clinical fluid overload.