Relative blood volume based biofeedback during haemodialysis.

Intra-dialytic hypotension is the most frequently occurring complication during haemodialysis and can lead to serious complications. Devices that continuously and non-invasively monitor relative blood volume (RBV) changes during HD are being advocated as a tool to maintain an adequate volume of the intravascular compartment in order to avoid dialysis hypotension. Nowadays, most manufacturers have incorporated a RBV monitor in their dialysis apparatus and two manufacturers have designed biofeedback devices that control intra-dialytic RBV changes. The goal of RBV based biofeedback systems is to prevent a severe or abrupt decrease in blood volume in order to prevent the development of dialysis hypotension. Biofeedback technologies can diminish the severity and/or frequency of dialysis hypotension. At present, however, a completely symptom-free HD is not a reality. The major reasons for this are patient characteristics such as cardiovascular co-morbidity and high UF rates and a lack of understanding of the relation between RBV changes and blood pressure/cardiovascular stability.