On-line monitoring and convective treatment modalities: short-term advantages

Background. Despite technological advances in dialysis equipment, the morbi dity and quality of life of uraemic patients undergoing regular haemodialyt ic treatment are still severely affected by acute intradialytic complicatio ns possibly related to the treatment itself. Cardiovascular instability sti ll affects > 30% of dialytic sessions and, although its pathogenesis is mul tifactorial, dialysate sodium concentration land, consequently, intradialyt ic sodium removal) is one of the main factors affecting intradialytic hypot ension. Convective treatment modalities and so-called biocompatible membran es increasingly are recognized as improving acute and particularly chronic dialytic complications because a number of the pathways activated in patien ts during dialysis with 'bioincompatible' membranes have the potential to p roduce many side effects. Methods. The main clinical studies are reviewed to highlight the advantages of on-line monitoring and convective modalities on acute intradialytic sym ptoms. Results. The conductivity kinetic model has been shown to be a reliable and inexpensive method of matching intradialytic sodium removal and interdialy tic load. By applying this model to patients prone to dialysis hypotension, a smaller reduction in intradialytic systolic blood pressure has been obse rved, without any change in dialysate and reinfusate sodium concentrations or dry body weight. Furthermore, a new model of haemodialysis potassium rem oval based on a decreasing intradialytic potassium concentration and a cons tant plasma-dialysate potassium gradient is capable of reducing the arrhyth mogenic effect of standard haemodialysis. Despite the proven biological sup eriority of biocompatible membranes, there is no definitive evidence that m embrane biocompatibility and/or flux lead to a decrease in acute intradialy tic clinical symptoms. Conclusions. On-line monitoring of intradialytic sodium removal and the pot assium gradient is capable of reducing intradialytic hypotension and the ar rhythmogenic effect of haemodialysis, and thus having a considerable clinic al impact on acute intradialysis complications. As far as the effects of bi ocompatibility and/or flux on the incidence of acute intradialytic clinical symptoms are concerned, further trials involving a sicker patient populati on with higher prevalence of intradialytic hypotension are needed in order to achieve statistical power.