Effect of exponentially decreasing conductivity and ultrafiltration profiles on vascular stability during hemodialysis

Many side effects, such as hypotension cramps, headaches and arrhythmias ca n occur during hemodialysis. The main cause of dialysis hypotension is the decrease in plasma volume (PV). This reduction during hemodialysis depends on the amount of fluid removed and the refilling of plasma volume from the interstitium. The aim of this study was to evaluate the changes on PV and tolerance to di alysis of two different sessions: constant conductivity ad ultrafiltration hemodialysis (S-HD) and exponential decrease of dialysate conductivity (15. 9 mSv at start of dialysis, 14.4 mSv at middle and 13.9 mSv for the final o f dialysis) and ultrafiltration (1.7 l/h at start and 0.1 l/h at the end of dialysis) (P-HD). We studied 108 dialysis sessions (54 S-HD and 54 P-HD) in 27 patients. The duration of each hemodialysis session, the blood flow race, the dialysate f low rate and the dialysis membrane were the same for the two hemodialysis r egimes. A lower percent reduction of PV (Delta PV) was evident on P-HD (-7.28 +/- 5 .5%) compared with S-HD (-9.7 +/- 5.9%) (p < 0.05). The difference became s ignificant after 120'. No significant differences were seen in systolic, me an or diastolic blood pressure. pre-HD, weight before and after dialysis an d weight change, with dialysis between S-HD and P-HD. Following dialysis, s ystolic, mean and diastolic blood pressure are lower in S-HD (< 0.01). There were no significance differences in cramps, nauseas, vomiting or thir st between the two protocols. Hypotensive episodes were seen in 50% of SH-D and 18.5% in P-HD Ip < 0.05). The predialysis sodium plasma levels were similar with the two different d ialysis modalities, However at the middle of dialysis the sodium was 136.8 +/- 2.3 and 138.5 +/- 2.4 mEq/l in S-HD and P-HD respectively (p < 0.01), a nd after dialysis was 136.1 +/- 2.2 and 137 +/- 2.1 mEq/l respectively (p < 0.011. Kt/V was 1.26 +/- 0.25 in S-HD and 1.33 +/- 0.29 in P-HD (p < 0.05). These data suggest that hemodialysis using exponential decrease of dialysat e conductivity and ultrafiltration can preserve vascular stability, reducin g the incidence of hypotension during dialysis. Urea removal was higher in patients on P-HD than on S-HD.