[Blood pressure changes in chronically haemodialysed patients]

Poor blood pressure control in chronically haemodialysed patients leads to increased cardiovascular morbidity and mortality. Information on valid values of blood pressure during haemodialysis and out of office is very important in order to set up adequate treatment.

To measure blood pressure during the haemodialysis and the subsequent 24-hour period using an ambulatory blood pressure monitoring (ABPM) in patients with normal blood pressure (BP) and patients with high normal BP and hypertension. Relationship between time-dependent blood pressure changes, ultrafiltration (UF) and interdialytic weight gain (IDWG) was analysed.

Fifty chronically haemodialysed (> 3 months) patients (males/females 33/18) aged 57.5 (53-63; median, interquartile interval) years were studied. Systolic and diastolic pressures (SP, DP) were measured during haemodialysis every hour (H0-H4) and over following 24 hours using Spacelab 90217 monitor. Pulse pressure (PP) values were calculated as a difference between SP and DP. The patients were stratified into two groups based on the cut-off-point calculated as the mean of two mean arterial pressure (MAP) values obtained at the beginning and after the first hour of HD: Group A (n = 25), MAP < 100 mm Hg; Group B (n = 25), MAP 100 mm Hg. Interdialytic weight gain was measured before HD (IDWG1) and after the ABPM (IDWG2); also ultrafiltration (UF) was obtained. The post-dialysis 24-h ABPM period was divided into eight 3-hour intervals (M1-8).

During HD no significant change in SP, DP or PP was found in both group, but there was a significant difference (p = 0.01) between both groups in SP, DP and PP. Values of BP at the end of dialysis were in group A: SP 125 (120-130) mm Hg, DP 75 (60-80) mm Hg and PP 50 (40-60) mm Hg in group B: SP 150 (140-160) mm Hg, DP 80 (80-90) mm Hg a PP 60 (60-70) mm Hg. We did not find any influence of IDWG1 or IDWG2 on SP or DP in both groups. Relationship between UF 3 000 (2 500-4 300) ml and SP (Δ sTK -5 mm Hg) was confirmed only in group A (p = 0.04). In group A, we found a decrease in SP during the third and sixth 3-hour interval (p = 0.01; p = 0.02) including sleeping period, all compared to the end of HD (H4). In group B, such a decrease in SP was found only in the second sleep interval (p = 0.01) and in the sixth 3-hour interval (p = 0.03), all compared to the end of HD (H4). As to DP at the end of dialysis (H4) in group A, it differed only in the third 3-hour interval (p = 0.02), but not during the sleeping period. In group B, the decrease of DP compared to the end HD (H4) was recorded during the two sleep intervals (p = 0.01), and also in the sixth and seventh 3-hour intervals (p = 0.01; p = 0.03). In group A, PP was compared to the end of HD (PPH4) significantly decreased in the first 3-hour interval (p = 0.02) and in seventh and eight 3-hour interval (p = 0.03; p = 0.04). In group B, PP did not significant change from the end of HD. Difference in SP between both groups was maintained over the entire course of ABPM (p = 0.01). However, DP values in both groups were different in the first and third 3-hour intervals (p = 0.01) but in following intervals DP in group B decreased to the level of that in group A. There was no significant difference in the proportion of non-dippers and reverse dippers in both groups.

Systolic, diastolic, mean arterial and pulse pressure pressures were not significantly changed during the haemodialysis in both groups. Relationship between ultrafiltration and systolic pressure was confirmed only in group A. No influence of interdialytic weight gain on blood pressure during 24 hours was seen in either group. Systolic pressure decreased in both groups during the nighttime compared to post-HD values, but diastolic pressure decreased only in group B. PP did not decrease during the night in any group. There was no significant difference in the proportion of non-dippers and reverse dippers in both groups.