Aims: The aim of this study was to evaluate the hemodynamic pattern, vascular compliance, as well as the levels of vasoregulatory hormones and markers of inflammation and oxidative stress in a group of chronic hypotensive (CH) patients undergoing hemodialysis (HD) and to compare them with a group of normotensive HD patients.
Material and methods: 14 normotensive and 10 CH hemodialysis patients were included in the study. Hemodynamic characteristics were evaluated by means of the pulse waveform analysis. Plasma levels of nitrites, interleukin-6 (IL-6), malondialdehyde (MDA), PTH-related peptide (PTHrp), catecholamines, angiotensin II and endothelin were measured.
Results: Blood pressure (BP) and peripheral vascular resistances (PVR) were lower in the hypotensive group (p < 0.001 and p = 0.005, respectively), whereas cardiac output was similar in both groups. Large (C1) (p = 0.001) and small (C2) (p = 0.022) artery elasticity indices were higher in hypotensive patients. In the whole group, C1 and C2 inversely correlated with mean BP (MBP). Plasma levels of nitrites (p = 0.011) were higher in hypotensive patients and inversely correlated with MBP (r = -0.516, p = 0.012). Time on HD correlated with plasma nitrites (r = 0.478, p = 0.024) and inversely with MBP (r = -0.598, p = 0.003).
Conclusions: CH in HD patients is characterized by decreased PVR, a preserved cardiac output and greater vascular compliance. CH is associated with longer time on HD and higher plasma levels of nitrites/nitrates, suggesting that an enhanced production of nitric oxide induced by long-term HD, could be involved in CH. These findings suggest that functional vascular changes, likely related to an enhanced production of vasodilator agents, are responsible for CH in HD patients.