High vibration perception threshold and autonomic dysfunction in hemodialysis patients with intradialysis hypotension

Background.Intradialysis hypotension is a common problem among hemodialysis patients. Some studies have shown that autonomic neuropathy could be a major cause of intradialysis hypotension, whereas others have not. Furthermore, whether there are parallel changes in the autonomic nervous system and somatic nerves remains unclear. Methods. We investigated the autonomic and peripheral nervous functions of 12 chronic hemodialysis patients who suffered from intradialysis hypotension, and of 12 age- and sex-matched hemodialysis patients who had stable blood pressure during hemodialysis. We used spectral analysis of their heart rate variability and systemic vascular resistance to evaluate autonomic functions. Vibrameter and nerve conduction studies to assess peripheral nervous function were also performed. Low-frequency/high-frequency ratio power index was used as a surrogate of sympathovagal balance. Results. The power index rose progressively in the control group and reached significantly high levels at hour 4 compared to the basal values (3.7 +/- 0.5 vs. 2.1 +/- 0.3; P < 0.05). However in the group prone to hypotension, the power index remained almost unchanged. In addition, their systemic vascular resistance was lower than that in the control group (13.7 +/- 1.8 vs. 22.3 +/- 2.6 Wood units; P < 0.05). The vibration perception thresholds of the index finger and great toe were significantly higher in the group prone to hypotension (4.7 +/- 0.7 vs. 2.2 +/- 0.3 vibration units and 3.1 +/- 0.4 vs. 1.5 +/- 0.2 vibration units, respectively; both P < 0.05). Conclusion. We found that more severe damage to autonomic and peripheral nervous system occurred in patients prone to hypotension.