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Open Badges Letter

Distinction between induction and maintenance dosing in continuous renal replacement therapy

Graeme MacLaren

Author Affiliations

Cardiothoracic ICU, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074

Critical Care 2011, 15:419  doi:10.1186/cc10137

See related review by Prowle et al.,

Published: 26 April 2011

First paragraph (this article has no abstract)

In their excellent review of dosing continuous renal replacement therapy (CRRT), Dr Prowle and colleagues concluded that patients should be prescribed 20 to 25 ml/kg/h [1]. However, by averaging CRRT dose over time, studies in this area obfuscate the benefits of appropriately higher dose therapy early in the course of illness, potentially misguiding clinicians into blindly adopting a 'one-size-fits-all' approach and consequently prescribing inadequate doses in life-threatening emergencies. To take a crude example, it would be inappropriate to prescribe 20 ml/kg/h CRRT in a patient with serum potassium 9 mmol/L. Rather, the highest possible dose of CRRT should be initially prescribed to maximize solute clearance. This depends on the maximum circuit flow permitted by the access catheter, which in turn determines the maximum dose, assuming that the countercurrent flow to blood flow ratio should be <0.3 with diffusive CRRT, or a filtration fraction with convective therapy <0.2 [2]. As the potassium level falls, the dose can be lowered to more conventional levels.