AUTONOMIC NERVOUS FUNCTION AND BLOOD-VOLUME MONITORING DURING HEMODIALYSIS

We studied the autonomic reflex response to hypovolemia during HD by m eans of spectral analysis of heart rate variability (SAHRV) in 10 hypo tension prone (group A) and 10 hemodynamically stable patients (group B). UF rate normalized per total body wafer and blood volume fall were similar in the two groups. The sympatho-vagal balance index, calculat ed as the ratio between the integrals of the spectrum in the low (0.02 -0.15 Hz) and in the high frequency range (0.2-0.35 Hz) rose in group B progressively from the beginning of the treatments, reaching a top a t the 90(th) minute and remained subsequently high until the end. On t he contrary this index did not show remarkable increases in group A. T he differences between the two groups were statistically significant a t 0 (4.6+/-2.9 vs 1.5+/-1.3), 60(th) (8.3+/-7.8 vs 2.2+/-2.6), 90(th) (17.9+/-13.4 vs 3.7+/-2.8), 150(th) (8.8+/-3.7 vs 2.7+/-2.8) and 210(t h) minute (8.6+/-5.O vs 2.9+/-2.5). In conclusion SAHRV shows an impai rment of autonomic reflex response to hypovolemia in hypotension-prone patients.