Nephrol Dial Transplant (1996) 11 [Suppl 2]: 68-74 Nephrology Dialysis Transplantation Measurement of effective delivery of the prescribed dialysis treatment C. Ronco, A. Brendolan, C. Crepaldi, D. Dissegna, F. Gastaldon, P. M. Ghezzi, S. Zamboni and G. La Greca Department of Nephrology, St Bortolo Hospital, Vicenza, Italy Introduction Renal replacement therapy by haemodialysis is aimed at obtaining adequate blood purification of metabolic waste products, electrolyte and acid-base correction and achievement of the patient's dry body weight. Such aims must be obtained with the best clinical tolerance to treatment in order to achieve an effective rehabilitation of the patient. Recent advances in technology have permitted the application of highly efficient dialysis treatments in which solute clearances and ultrafiltration rates are significantly greater than those obtained in standard haemodialysis. These developments have made possible the reduction of dialysis treatment time without redu- cing the quantity of treatment delivered in the chronic patient. However, the successful application of high- efficiency therapy in clinical practice requires a compre- hensive approach and a recognition of the underlying clinical principles and technical aspects of the extracor- poreal circuit. Reduction of dialysis treatment time must avoid a parallel reduction in quantity of treatment, therefore, in highly efficient treatments of short duration, the efficiency of treatment must be proportionally increased per unit of time. Furthermore, a strict control must be carried out in order to measure the real amount of treatment delivered per session. Haemodialysis is a form of therapy and it must be accurately prescribed, correctly administered, and it must produce the desired effects. When highly efficient treatments are applied, an accurate prescription of the quantity of therapy is even more necessary. The process must include the definition of reliable criteria of treat- ment adequacy, and guidelines to ensure that pre- scribed therapy is delivered. The quality of life of the patient will finally reveal if the treatment prescription and delivery were really adequate as initially hypothes- ized [1-10]. Correspondence and offprint requests to: C. Ronco MD, Department of Nephrology, St Bortolo Hospital, Via Rodolfi 10, 36100 Vicenza, Italy. Guidelines for prescription Several approaches have been attempted in the past to define 'adequacy' of dialysis therapy. In a general sense, the treatment is adequate if uraemic solutes are maintained within acceptable ranges in the presence of a sufficient dietary protein intake, and the interdialytic weight gain is removed with the lowest incidence of side effects. These requirements are time independent and therefore, treatment time may be adapted to the solute removal (clearance) and the ultrafiltration capa- city of the dialyser. Since highly efficient treatments are today available and clearance and ultrafiltration do not further represent limiting factors, the treatment time must be set according to the patient's cardiovas- cular tolerance to fluid withdrawal per unit of time and to the speed of solute equilibration between the different compartments of the body. After several indexes and proposals, Kt/V index has been established to be a reliable parameter to investi- gate dialysis adequacy in a given treatment. Percent urea reduction, solute removal index and weekly solute removal have also been proposed as important para- meters to define dialysis adequacy. There is a general consensus that weekly dialysis prescription, in litres of urea clearance, should reach a minimum of three times the patient's urea distribution space or total body water. This means an average of 126 litres of clearance per week in a 70 kg patient or 144 litres in an 80 kg patient. This value must take into account the residual renal function. Several formulae have been proposed to calculate Kt/V at the bedside [11-17]. All these formulae may introduce some errors in the calculation of Kt/V and therefore the value found in a single dialysis session has to be critically evaluated and matched with the expected efficiency of the treatment. It should be noted, however, that the concept of adequacy of treatment must probably include other aspects of the dialytic therapy including fluid balance, electrolyte and acid- base equilibration, and blood pressure control. Urea represents a good marker for adequacy of blood puri- fication but it does not represent the whole meaning of chronic renal replacement therapy. © 1996 European Dialysis and Transplant Association-European Renal Association by guest on June 8, 2015 http://ndt.oxfordjournals.org/ Downloaded from