conventional hemodialysis patients

Prevalent conventional HD (CHD) patients (dialysing 3 days a week during 4 hours per dialysis session) will undergo, in random order, a mid-week 4-hour HD session, a mid-week 4-hour HDF session, a mid-week 8-hour HD session, and a mid-week 8-hour HDF session with a 2-week interval between every session to assess the influence of treatment duration and of convection on the removal of uremic toxins and on the haemodynamic responses and autonomic nervous regulation. In between the study dialysis sessions these patients will receive routine CHD treatments.

To measure uremic toxin and electrolyte removal, reduction ratios, dialytic clearances and mass removal in collected dialysate will be determined. Blood samples will be taken from the inlet blood lines immediately before the onset of dialysis and at 15, 30, 60, 120, 240 minutes (4-hour and 8-hour sessions) and at 360 and 480 minutes (8-hour sessions). Furthermore, ultrafiltrate and dialysate will be continuously collected in a fractionated way.

BP, heart rate, heart rate variability, cardiac output and systemic vascular resistance will be measured every 30 minutes by the Task Force Monitor. Skin microcirculation will be measured with laser Doppler flowmetry every 120 min until the end of the treatment.