[The impact of changes in levels of calcium, phosphate and magnesium during hemodialysis on autonomic system reactivity as measured by heart rate variability analysis].

The aim of the study was to analyze the response of autonomic nervous system to dialysis related systemic volume reduction using heart rate variability (HRV) analysis. The possible relationship between changes in serum levels of calcium-phosphate balance parameters and HRV measurements results was also analyzed. The study was performed in 32 patients (20 men, 12 women) aged between 27 and 71 years (mean 44 years) treated with maintenance dialysis due to end-stage renal disease from 3 months to 15 years (mean 4.4 years). All parameters mentioned above were analyzed during 4-hour dialysis session. Mean value of LF/HF ratio at the beginning of the procedure was 5.36, with continuous increase in consecutive measurements performed 30-minute intervals to the maximal value 8.2 in 120th minute of HD session (p < 0.05). In the next measurements continuous decrease in the mentioned parameter was noticed, to the mean value 6.99 in minute 240. The values of LF/HF ratio were also lower for the whole HD session in the group of patients with initial predialytic concentration of calcium lower than 2.35 mmol/l as compared to those with initial calcium concentration higher than 2.35 mmol/l. Higher values of LF/HF ratio and bigger oscillation amplitude of this parameter were also noted in those patients, in whom the percentage reduction of magnesium level during dialysis exceeded 20%. In addition, statistically significant relationship between percentage reduction in magnesium ion concentration and LF/HF ratio during HD was found. Obtained results let us to conclude, that hemodialysis leads to important change in the activity of both components of autonomic nervous system. The factors which may adversely influence the quality of this response may be, among others, low total calcium ion concentration as well as low percentage reduction in magnesium level during hemodialysis session.