Graeme MacLaren Warwick Butt Controversies in paediatric continuous renal replacement therapy Received: 18 October 2008 Accepted: 12 January 2009 Published online: 31 January 2009 Ó Springer-Verlag 2009 G. MacLaren Departments of Paediatrics and Cardiac Surgery, National University Health System, Singapore, Singapore G. MacLaren  W. Butt Intensive Care Unit, The Royal Children’s Hospital, Melbourne, Australia W. Butt Department of Paediatrics, The University of Melbourne, Melbourne, Australia G. MacLaren ( ) ) Cardiothoracic Intensive Care Unit, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore e-mail: gmaclaren@iinet.net.au Tel.: ?65-6779-5555 Fax: ?613-9345-4680 Abstract Background: Continu- ous renal replacement therapy (CRRT) is an invaluable means of supporting critically ill children with many illnesses, including acute renal failure, drug intoxication, inborn errors of metabolism, and multiorgan failure. However, the ideal method of applying the technique is unknown. Discussion: The indications for ini- tiation of CRRT, mode, dose, and means of anticoagulating the circuit to prolong filter life are all subjects of controversy. The formation of a pro- spective, multicentre paediatric CRRT registry has been a major step forward but large, randomised trials of the sort that exist in adult medicine are lacking. This review describes the basic technique of CRRT, highlights the differences between adult and paediatric prescription, and elaborates on the main controversies in the application of CRRT in children. Conclusions: Current evidence suggests that early initiation of CRRT before the onset of substantial fluid overload, considering continuous haemofiltration in disease states such as respiratory failure following stem cell transplantation, and the use of continuous haemodialysis and citrate anticoagulation to prolong circuit life may be associated with improved outcomes. Keywords Paediatric  Continuous renal replacement therapy  CRRT  Renal failure Introduction Continuous renal replacement therapy (CRRT) has been used in critically ill children for more than 20 years [1, 2]. Although its effectiveness is beyond doubt, CRRT is complex, expensive therapy that is prone to error [3, 4] and requires institutional expertise to minimise the iat- rogenic complications to which smaller infants and neonates are particularly vulnerable [5, 6]. Considerable debate exists about how best to utilise the technique in critically ill patients of all ages. Until recently, the epidemiologic characteristics of children requiring CRRT were described only in retro- spective, single-centre studies. In these reports, the use of paediatric CRRT was associated with mortality rates substantially greater than those in critically ill children not requiring renal replacement therapy, ranging from 31 to 76% [6–16]. However, identifying the reasons for these poor outcomes has been hampered by limited study design, small sample size, lack of adequate controls, use of different modalities of CRRT, poor stratification of severity of illness, and heterogeneous patient populations. To address these issues, several major North American centres set up a paediatric CRRT registry in 2001. This has provided much-needed prospective, multicentre data on the epidemiology of children requiring CRRT. To date, overall mortality has been 42%, but with substantial variation between different types of illness. For example, Intensive Care Med (2009) 35:596–602 DOI 10.1007/s00134-009-1425-4 REVIEW