Effect of regulating dry weight by bioimpedance spectroscopy for volume evaluation on blood pressure and cardiac function in hypertensive hemodialysis patients

Abstract

Objective To modulate dry weight by bioimpedance analysis and evaluate its effect on hypertension and cardiac function in hemodialysis (HD) patients. Methods Ninety-six maintenance HD patients at Department of Nephrology of Taian City Central Hospital were enrolled in an HD group, and 106 healthy cases were included as a control group. Both groups underwent multi frequency bioimpedance spectroscopy to measure the intracellular water (ICW), ECW (extracellular water) and ECW/total body water (TBW). Seventy-nine HD patients of the HD group which had higher bioimpedance than the control group were selected as a group for dry weight adjustment (DWAG). Post-dialysis weight, blood pressure, bioimpedance and heart Doppler ultrasound of DWAG were measured before and after the adjustment of the dry weight. Comparisons of the general data between the control group and HD group were performed by the independent t-test. Evaluation of the data between the control group and HD group before and after HD was carried out by one-way analysis of variance (ANOVA). Evaluation of the data within the DWAG before and after adjustment was carried out by the paired t-test. Results The ICW, ECW and ECW/TBW of the HD group before and after HD were all significantly higher than those of the control group [(27.49±3.96) L vs (26.36±3.93) L vs (23.91±4.92) L; (18.42±2.66) L vs (17.07±3.03) L vs (15.99±4.23) L; (41.03±2.03)% vs (39.73±3.64)% vs (37.59±4.63)%] (t=5.660, 4.829, 6.717, P<0.001 for all; t=3.884, 2.067, 3.626, P<0.001, =0.040, <0.001). The ICW, ECW and ECW/TBW of the study group after HD were significantly lower than those before HD (t=1.984, P=0.049; t=3.281, P=0.001; t=3.056, P=0.003). ICW, ECW and ECW/TBW of the DWAG after dry weight adjustment were significantly lower than those before [(26.11±2.97) L vs (28.09±4.17) L, t=7.502, P<0.001; (17.01±1.98) L vs (19.06±2.77) L, t=9.406, P<0.001; (38.97±3.19)% vs (40.49±2.57)% , t=5.655, P<0.001]. Systolic pressure and diastolic pressure of the DWAG significantly decreased after dry weight adjustment [(148.52±7.31) mmHg vs (157.14±9.97) mmHg, t=8.641, P<0.001; (87.67±12.84) mmHg vs (92.30±11.71) mmHg, t=8.641, P<0.001]. Cardiac function test showed that the left atrial diameter, left ventricular end diastolic diameter, interventricular septum thickness at end-diastole and left ventricular posterior wall depth of the DWAG significantly decreased after dry weight adjustment [(43.23±5.90) mm vs (43.47±5.82) mm, t=3.128, P=0.0002; (48.76±6.42) mm vs (49.58±5.39) mm, t=2.251, P=0.027; (10.29±1.03) mm vs (10.45±0.79) mm, t=2.560, P=0.012; (10.53±1.04) mm vs (10.60±0.92) mm, t=2.221, P=0.029]. However, LVEF of the DWAG significantly increased after dry weight adjustment [(64.63±4.47)% vs (63.51±3.40)%, t=-3.569, P=0.001). Conclusion Adjustment of dry weight based on multifrequency bioimpedance spectroscopy decreases blood pressure and improves cardiac function of HD patients. Key words: Hemodialysis; Bioimpedance spectroscopy; Hypertension; Cardiac function