[Cross-sectional study of relation between blood pressure and heart rate variability in patients with peritoneal dialysis].

Objective: To analyze the possible relationship between heart rate variability (HRV) and blood pressure in peritoneal dialysis patients.

Methods: In this cross-sectional study, 93 continuous ambulatory peritoneal dialysis patients (CAPD) patients were enrolled. Patients were divided into three groups according blood pressure. HRV which reflects autonomic nerve function (ANF) were measured by using 5-minutes recordings of a stationary system by a standardized method. Both time-domain and frequency domain parameters were analyzed.

Results: HRV time domain indices [the standard deviation of all normal RR intervals (SDNN), the square root of the mean of the squared differences between adjacent normal RR intervals (rMSSD), the standard deviation of differences between adjacent NN intervals (SDSD), the percentage of differences between adjacent normal RR intervals that were >50 ms computed (PNN50)] and frequency domain indices [the low-frequency energy in the power spectrum 0.04-0.15 Hz (LF), the high-frequency energy in the power spectrum 0.15-0.4 Hz (HF)] were significantly lowest in hypertensive group (P<0.05) whereas LF/HF was highest as compared to normal BP group (P<0.05). Univariable correlation analysis showed that both systolic and diastolic blood pressure were negatively correlated with SDNN (r=-0.386, P<0.001; r=-0.399, P<0.001), rMSSD (r=-0.373, P<0.001; r=-0.426, P<0.001), SDSD (r=-0.375, P<0.001; r=-0.425, P<0.001), PNN50 (r=-0.223, P=0.032; r=-0.245, P=0.018), TP (r=-0.328, P=0.001; r=- 0.312, P=0.002), LF (r=-0.260, P= 0.012; r=-0.194, P=0.063), HF (r=-0.394, P<0.001; r=-0.365, P<0.001), and positively correlated with LF/HF (r=0.275, P=0.008; r=0.171, P=0.1). Multivariable regression analysis showed that HRV indicators were independently factor affecting both systolic and diastolic blood pressure in PD patients.

Conclusion: ANF assessed by HRV were significantly different in PD patients with blood status, parasympathetic nerve were activated in hypotension group whereas sympathetic nerve were activated in hypertension group. ANF was independently factors associated with blood pressure.