Preventing haemodynamic instability in patients at risk for intra-dialytic hypotension

Although as yet no major breakthroughs have occurred to improve long-term survival of haemodialysis patients with impaired cardiovascular function, it is possible to reduce morbidity by intra-dialytic hypotension in these patients by the use of relatively simple manoeuvres. In our experience, this can be achieved using the following approach (Table 1). First, the decline in plasma volume can be reduced by adequate estimation of the optimal dry weight by objective methods, such as echography of the inferior caval vein or bioimpedance measurements. Furthermore, the ultrafiltration rate during haemodialysis should be moderate and should be limited to a maximum value, which has to be defined empirically for each individual patient. Especially in patients with excess inter-dialytic weight gain, isolated ultrafiltration should be used when the required amount of fluid cannot be removed during haemodialysis. The use of low-sodium dialysate should be avoided. Probably it is best to use a physiological sodium concentration of the dialysate because a greater sodium concentration may result in increased thirst and intra-dialytic weight gain. Sodium profiling should be based on further studies concerning plasma volume changes during haemodialysis in different patient groups. Because of the deleterious impact of acetate on vascular reactivity, it should never be used in patients prone to hypotensive periods. Vascular reactivity can also be impaired by the use of vasoactive medication prior to haemodialysis treatment. Therefore, in patients prone to hypotensive periods, vasoactive medication should be withheld the morning before haemodialysis, if possible. Also, one should be very cautious with the use of low-calcium dialysate in patients with frequent hypotensive periods, and ideally it should be avoided. If the use of these manoeuvres fails to control intra-dialytic hypotension, one should consider the use of cold dialysate. Switching to haemofiltration or to continuous treatment modes such as CAPD are other options. Future studies should address haemodynamics during other treatment modes, such as haemodiafiltration or acetate-free biofiltration.