Interdialysis Blood Pressure Increase: Unexplored Relationships

Background: Dry weight increases due to water retention are associated to higher blood pressure (BP) and adverse cardiovascular effects in HD patients. However, weight changes between a dialysis session and the next one, do not have a predictable relation with the interdialytic BP changes. Inconsistencies may be due in part to unreliability of clinic BP measurements but factors other than fluid overload may also play a determinant role. We examined the association of interdialytic weight gain (IDWG) with serum angiotensin II (AngII), norepinephrine (NE), copeptin and inflammatory markers levels with the changes in clinic BP and mean interdialytic ambulatory blood pressure measurements (ABPM). Methods: We studied 30 patients on regular and stable HD thrice weekly. Ultrafiltration was prescribed during HD, in order to reach the clinically estimated dry weight. ABPM was monitored during 23-44 hours in the interdialytic period. Predialysis serum samples were used for laboratory determinations. Three groups were defined according to ABPM. Results: Table 1 Conclusion: AngII levels play an important role in hypertension of HD patients (correlation between ABPM and AngII levels r=0.42; 95% CI 0.07 to 0.70; p=0.02). There was no correlation between IDWG and AngII levels. Interdialysis blood pressure changes and mean interdialysis ambulatory blood pressure were unrelated to IDWG. Results. Table 1. - ABPM Markers A.<130(n=14) A.130-139 (n=8) A.≥140 (n=8) p Interdialysis clinic SBP change (mmHg) 10.5±4.49(0.8 to 20.2) -4.1±6.36*(-19.6 to 10.9) 23.9±10.02*(0.2 to 47.6) *(B vs C)0.03 IDWG (% of dry weight, kg) 2.85±0.38(2.0 to 3.7) 3.43±0.66(1.86 to 4.98) 2.56±0.52(1.34 to 3.79) 0.533 Ang II (pg/ml) 106.9±12.4&(80.1 to 133.6) 178.0±35.5(94.1 to 262) 273.5±39.9&(129.2 to 317.9) &(A vs C)0.011 Norepinephrine (pg/min) 117.4±31.4(49.7 – 185.2) 146.1±51.6(24.1 to 268) 140.5±52.2(17.1 to 263.9) 0.867 Copeptin (pg/ml) 155.2±9.8 (n=11)(133.6 to 176.6) 115.2±12.0 (n=7)(85.8 to 144.5) 154.2±20.3 (n=7)(104.6 to 203.9) 0.10 TNFα (pg/ml) 20.7±6.36 (n=12)(6.70 to 34.7) 20.3±7.50(2.56 to 38.0) 14.4±5.0 (n=6)(1.5 to 27.4) 0.845 Inflammation index 0.88± 0.18(0.58 to 1.58) 0.93±0.20 (n=7)(0.56 to 1.30) 1.07±1.12 (7)(0.56 to 1.30) 0.71 Data are mean±SE (95%CI). p=one-way ANOVA and Tukey post-tests.