Fluid overload modifies ambulatory blood pressure and pulse wave characteristics in hemodialysis patients undergoing targeted fluid management.

BACKGROUND: Ambulatory blood pressure (BP) and pulse wave characteristics (PWCs) are stronger predictors of mortality than conventional pre-/post-dialytic BP in hemodialysis. While BP is recommended to be managed primarily by reducing fluid overload (FO), associations of FO with interdialytic BP/PWCs remain unknown. METHODS: Bioimpedance-derived FO and interdialytic 44-h BP/PWCs were analyzed at baseline and follow-up of a quality improvement project involving targeted fluid management. Trended cosinor linear mixed-effects models assessed intra-patient associations of post-dialysis FO with interdialytic BP/PWCs. RESULTS: We analyzed 120 visits (77/43 at baseline/follow-up) from 80 patients (70% male; mean age 68 ± 14 years; median dialysis vintage 38 [18-64] months). Post-dialysis FO decreased in baseline hypervolemic patients from 2.7 ± 1.3 L to 0.9 ± 1.7 L. Every 1 L increase in post-dialysis FO at the patient level was associated with increased peripheral BP (systolic: 4.54 mmHg, P < 0.001; diastolic: 2.55 mmHg, P < 0.001), peripheral resistance (0.03 s*mmHg/mL, P = 0.011), augmentation index (1.38%, P = 0.007), wave amplitudes (forward: 0.56 mmHg, P = 0.025; backward: 0.61 mmHg, P = 0.027), reservoir pressure peak (3.83 mmHg, P < 0.001), and pulse wave velocity (0.12 m/s, P = 0.007). Higher FO was associated with decreased interdialytic slopes of all BPs, peripheral resistance, backward wave amplitude, reservoir peak pressure, and pulse wave velocity. FO interacted with circadian rhythms of stroke volume, peripheral resistance, forward wave amplitude, and excess pressure peak. CONCLUSIONS: We showed that FO in hemodialysis is associated with increased interdialytic BP and PWCs on a patient level, and that FO blunts interdialytic BP/PWC trends. We further establish that physiological BP/PWC patterns may be associated with euvolemic fluid status, hence making the case for tailoring target weight using bioimpedance spectroscopy.