SYMPATHETIC ACTIVITY IS NEGATIVELY ASSOCIATED TO UREMIC STATE AND HEMODYNAMIC INSTABILITY DURING HEMODIALYSIS SESSIONS

ABSTRACT Introduction: Hemodynamic instabilities, characterized by oscillations of blood pressure, are common during hemodialysis sessions (HD), culminating in intradialytic hypotension owing to volume withdrawal from the cardiovascular system. The ability to carry out immediate adjusts in cardiovascular system, mainly mediated by the autonomic nervous system, is essential to the maintenance of hemodynamic stability during HD. Objective: This study aimed to investigate the relationship between the sympathetic activity, and the hemodynamic stability from chronic kidney disease (CKD) patients during the HD, as well as the relationship between sympathetic activity and the uremic state. Methods: Fourteen CKD patients (8 women and 6 men) with no history of recurrent intradialytic hypotension (ID) episodes had the successive RR intervals recorded during HD. Blood pressure measurements were recorded at regular intervals of 30 minutes along 4 hours of each session. Hemodynamic stability was established by the standard deviation (SD), coefficient of variation (CV) and the Delta (difference between the highest and the lowest measure) of systolic (SBP), diastolic (DBP), and mean (MBP) blood pressures, as well as the pulse pressure (PP) from the 8 recordings obtained during each session. As a measure of autonomic heart control, the low-transformed low frequency (lnLFnu) spectral band was used. The uremic state was established by the mean of uremia from the last 12 months. Pearson's correlation was used to analyze the correlation between the studied variables. Results: The lnLFnu values were negatively associated SD (SBP [r = -0.480; p = 0.010], PP [r = -0.504; p = 0.006] and MBP [r = -0.449; p = 0.017]), CV (SBP [r = -0.390; p = 0.040]) and delta (SBP [r = -0.438; p = 0.020], PP [r = -0.490; p = 0.008] and MBP [r = -0.382; p = 0.045]). lnLFnu was also negatively associated to the uremic state (r = -0.601; p = 0.01). Conclusions: Our results indicate that higher values of the lnLFnu are associated with better hemodynamic stability (i.e., smaller blood pressure oscillations) during HD sessions, in turn, the mean of blood urea concentration in the last 12 months, defined here as the uremic state, was associated with lower values of the lnLFnu during HD sessions.