#730 Dialysis-induced changes in systolic, diastolic, and pulse pressure in maintenance hemodialysis patients
Authors: Pstras Leszek , Waniewski Jacek , Malyszko Jolanta 
Published: May 2024

Abstract

Background and Aims
Hemodialysis (HD) therapy has a strong impact on cardiovascular function in both the short and long term. In the short term, the dialysis-induced changes in blood volume directly affect the arterial blood pressure (BP), frequently leading to intradialytic hypotension or hypertension, both associated with adverse outcomes. The aim of this study was to investigate the dialysis-induced changes in systolic (SBP), diastolic (DBP), and pulse pressure (PP) in maintenance HD patients and to assess their relationship with pre-HD BP.

Methods
197 maintenance HD patients were studied during the middle dialysis session of the week. The mean pre-dialysis fluid overload was 2.0 ± 1.6 L (calculated as the difference between the pre-dialysis body weight and the target weight). All HD sessions lasted approximately 4 h and were performed using mainly low-flux dialyzers. SBP and DBP were measured pre-HD and post-HD using a sphygmomanometer. PP was calculated as SBP minus DBP. The patients were divided into two groups: A) patients with an intradialytic decline in SBP (∆SBP &lt;0), and B) patients with an increase or no change in SBP during HD (∆SBP ≥0). Paired data were compared using the Student's t-test. Correlations between variables were assessed using Spearman's rho (ρ).

Results
During HD, SBP decreased in 120 (61%) patients (in 20 cases by more than 30 mmHg), remained unchanged in 11 (6%) patients, and increased in 66 (33%) patients (in 13 cases by more than 20 mmHg). DBP decreased in 94 (48%) patients, remained unchanged in 46 (23%) patients, and increased in 57 (29%) patients. In 76 (39%) patients both SBP and DBP decreased, whereas in 33 (17%) patients both SBP and DBP increased. In group A (n = 120), SBP, DBP, and PP decreased by 21 ± 16 mmHg (P &lt; 0.001), 8 ± 11 mmHg (P &lt; 0.001), and 13 ± 14 mm Hg (P &lt; 0.001), respectively. In group B (n = 77), SBP, DBP, and PP increased by 12 ± 10 mmHg (P &lt; 0.001), 4 ± 11 mmHg (P &lt; 0.001), and 8 ± 13 mmHg (P &lt; 0.001), respectively. Pre-HD SBP was 144 ± 23 mmHg in group A and 128 ± 25 mmHg in group B (P &lt; 0.001). Pre-HD DBP was 80 ± 15 mmHg in group A and 68 ± 11 mmHg in group B (P &lt; 0.001). In all patients combined, ∆SBP was similarly correlated with pre-HD SBP and pre-HD DBP (ρ = −0.42 in both cases, P &lt; 0.001), whereas ∆DBP was more strongly correlated with pre-HD DBP (ρ = −0.52, P &lt; 0.001) than with pre-HD SBP (ρ = −0.22, P &lt; 0.01). ∆SBP was correlated with ∆DBP (ρ = 0.55, P &lt; 0.001) and highly correlated with ∆PP (ρ = 0.78, P &lt; 0.001). According to linear regression, SBP tended to increase during HD in patients with pre-HD SBP &lt;118 mmHg (Fig. 1A), whereas DBP tended to increase in patients with pre-HD DBP &lt;68 mmHg (Fig. 1B).

Conclusions
Patients with dialysis-induced decline in SBP (group A) had a significantly higher pre-HD BP (both SBP and DBP) compared with patients with an increasing or stable SBP (group B). This suggests that a high decline in SBP during HD appears to be more likely in patients with elevated pre-HD BP and that HD appears to have a pressure-normalizing effect in such patients. Similarly, a dialysis-induced increase in SBP or DBP appears to be more likely in patients with low values of pre-HD SBP or DBP, respectively.