The Effects of Dialysate Sodium Concentration on Interdialytic Blood Pressure in Hemodialysis Patients

Kim, Moon Jae; Song, Joon Ho; Park, Kyeong Soo; Lee, Kyung Joo; Lee, Seoung Woo

Abstract

Sodium concentration in the hemodialysis solution has been increased to prevent intradialytic hypotension after highly effective and shortened time hemodialysis(HD) was introduced in the late 70's. Many authors have pointed out that the high concentration in the dialysate sodium HD may be one of causes of increasing difficulty in the management of hypertension in HD patients. Sodium profiling hemodialysis (SPHD) is a modified form of high sodium dialysate HD. Even though sodium concentration is decreased progressively to the conventional level during the HD session, the time-averaged sodium concentration is usually higher compared to that of conventional HD. To evaluate the effect of dialysate sodium concentration on interdialytic blood pressure(BP) control, we conducted a cross over study. Eleven patients showing more than four episodes of intradialytic hypertension per month were studied(5 male, 6 female; 52+-13 years). All subjects underwent 8-week conventional HD(CHD)(dialysate Na+ 138mEq/L X 4 hour) and 8-week step-down SPHD(Na+ 150mEq/L X 2 hours> OR =140 X 1> OR =138 X 1) on the order of random assignment. At the end of each peiords, interdialytic 24-hour BP were measured by 24-hour Ambulatory BP monitor(ABPM : 90207, Space Labs, USA). 1) Time-averaged sodium concentration in dialy sate were 138mEq/L during SPHD and 144.5mEq/L during CHD. Pre HD serum sodium were not significantly different between two periods but post HD serum sodium and intradialytic increase of serum sodium significantly higher during SPHD period 138.1+/-0.5 v 141.1+/-0.6mEq/L, 0.5+/-0.6 v 2.6+/-0.4mEq/L, p<0.05). Dry weight was determined before the start of study and not changed throughout the study periods. Interdialytic weight gain and the amount of ulfrafiltration required to maintain the determined dry weight were significantly higher during SPHD period compared to those during CHD period(2.5+/-0.5 v 3.6+/-0.6 kg, 2.6+/-0.8 v 3.6+/-0.8kg, p<0.01). 2) The frequency of interdialytic hypotension was significantly reduced during SPHD period(23.9 v 15 %, p<0.01). But the frequency of symptoms requiring intervetion such as ultrafiltration adjustment or saline infusion was not different between two periods. Thirst during interdialytic period was significantly frequent during SPHD(37.8 vs 30% 138.1+/-0.5 v 141.1+/-0.6mEq/L, 0.5+/-0.6 v 2.6+/-0.4mEq/L, p<0.05). 3) Day-time, night-time and 24 hour mean systolic BP measured by 24 hour ABPM were significantly higher during SPHD period(149.2+/-4.8, 144.3+/-3.6, 146.6+/-4.1mmHg) than during CHD period(140.1+/-4.8, 133.0+/-4.1, 136.4+/-4.6mmHg, p<0.01). Day-time, night-time and 24 hour mean diastolic BP were also significantly higher during SPHD period(82.6+/-1.5, 84.1+/-1.4, 86.1+/-1.4mmHg) than during CHD period (78.7+/-2.2, 79.6+/-2.3, 81.8+/-2.2mmHg, p<0.05). 4) Systolic load and diastolic load by the criteria of higher than 150/90mmHg throughout the day increased significantly from 21.1+/-7.0 and 18.2+/-6.3% during CHD period to 41.7+/-9.9 and 28.4+/-4.7% during SPHD period. Diurnal difference was not different between the two periods but a significant number of dippers(36.4%) converted to nondipper during SPHD period. Our results shows SPHD increases interdialytic BP and its load. It also adversely alter diurnal variation and dipping status. The additional sodium load and an consequent excessive interdialytic weight gain aassociates with SPHD might contribute to this findings.