Impact of ultrafiltration rate on heart rate variability parameters

OBJECTIVE We attempted to study the impact of the ultrafiltration (UF) rate on heart rate variability (HRV) parameters by maintaining sufficient session time, Kt/V, and UF. METHODS The 16 Chinese hemodialysis (HD) patients in the study were divided into 3 subgroups according to UF rate: 5 patients in subgroup A with a UF rate ≤0.5 L/h, 7 patients in subgroup B with a UF rate > 0.5 L/h and ≤1 L/h, and 4 patients in subgroup C with a UF rate > 1 L/h. The research included 3 phases. In the first phase, baseline Holter and blood pressure recording was performed. In the second phase, the patients were admitted for HD with continuous Holter and blood pressure recording. The third phase was after HD with continuous Holter and blood pressure recording. The tape recordings were analyzed by an independent, blinded investigator. RESULTS In our study, systolic blood pressure, diastolic blood pressure, and mean arterial pressure remained unchanged in the 3 subgroups before, during, and after the HD process. In HRV, several parameters began to show changes at the start of HD. PNN50 was reduced significantly ( p  < 0.05) in subgroup C after HD for 3 hours. Subgroups A and B demonstrated the same trend ( p  < 0.05). The differences between the 3 subgroups were not significant ( p   >  0.05). The SDNN and low‐frequency/high‐frequency ratio increased significantly ( p  < 0.05) in subgroup C after HD for 3 hours until 1 hour after HD. The differences were significant compared with the other 2 subgroups ( p  < 0.05). During the post‐HD state, almost all HRV parameters showed a little recovery to the pre‐HD state. CONCLUSIONS Our study suggested a prevalence of sympathetic activity in 4‐hour HD patients with a UF rate > 1 L/h, especially at the 3‐hour point during HD. To prevent HD‐related augmented sympathetic activity, prolonged HD sessions with low UF rates (<1 L/h), careful titration of target weight, and low interdialytic weight gain are recommended.