Introduction

Hemodialysis (MHD) is the most common method of renal replacement therapy, and the number of MHD is increasing all over the world [1], As of 2014, there were about 340,000 MHD patients in China, with an annual growth rate of about 20-30% [2]. MHD not only brings huge economic burden, but also signifcantly increases mortality, among which Cardiovascular Disease (CVD) is the main complication and death cause of MHD patients [3]. MHD not only brings huge economic burden, but also significantly increases mortality, among which Cardiovascular Disease (CVD) is the main complication and death cause of MHD patients [4]. Abnormal Blood Pressure Variability (BPV) often occurs in MHD patients [5], Usually manifested as Intradialytic Hypotension (IDH) and Intradialytic Hypertension (IDHT), which increase the risk of CVD, and IDHT has worse short-term and long-term prognosis and higher mortality [6]. Many studies have confirmed that BPV is an independent risk factor for cardiovascular death in MHD patients [7,8]. Therefore, controlling HPV during dialysis is of great significance to improve the prognosis of MHD patients.

Methodology

Patient recruitment and methods

• Subjects: MHD patients in Yuedong Hospital of the Third Affiliated Hospital, Sun Yat-Sen University, Yuedong Hospital, from April 2021 to June 2020 were selected and followed up for one month.

• Inclusion criteria: (1) MHD patients; (2)age ≥18 years.

• Exclusion criteria: (1) cerebrovascular accident; (2) the cardiac function is grade III~IV; (3) Patients with malignant tumor, mental illness or pregnancy.

• Grouping of research objects: The research objects were randomly divided into two groups. The experimental group used adjustable sodium dialysis, and the sodium concentration of dialysate gradually decreased from 141mmol/L to 135mmol/L 30min minutes before dialysisAnd the sodium concentration was maintained at 140mmol/L 30min before the end of dialysis. Patients in control group were treated with constant sodium 140mmol/L.

Baseline data collection and Biochemical Evaluation

The baseline variables included: demographic indicators (age, sex, height, weight after last dialysis, weight before this dialysis); Use electronic sphygmomanometer to measure blood pressure (including the blood pressure values of 0h, 1h, 2h and 3h during dialysis and after dialysis); Ultrafiltration volume of this dialysis (ml); Dry weight (kg), weight gain during dialysis (idwg);Weight growth rate during dialysis (IDWG%)=(Weight before dialysis-Weight after the first dialysis)/Dry weight×100%; Coefficient Of Variation(CV)=(Standard Deviation(SD)/Average Value (Mean) x100%.

Definition

Statistical analyses

SPSS(Statistical Product and Service Solutions)22.0 software was used to analyze the data, and continuous variables were expressed by mean±standard deviation. The measurement data conforming to normal distribution is expressed by x±s, and t test is adopted; Counting data were expressed in percentage, and χ² test was used for comparison between groups.

Results

Baseline characteristics of all the patients

There were 130 cases in the baseline group, including 65 cases in the experimental group and 35 cases (53.8%) in males, Age 63.32±12.78 years old, Coefficient of variation of systolic blood pressure 8.71%±4.44%, Coefficient of variation of diastolic blood pressure 7.78%±3.71%; IDWG% 4.2%±12.92%; Control group 65 cases, male 40 cases (61.5%), Age 60.82±13.41 years old, Coefficient of variation of systolic blood pressure 8.63±4.2%, Coefficient of variation of diastolic blood pressure 8.01%±4.7%; IDWG% 3.09%±2.26%; There was no significant difference in the observed indexes between the two groups at baseline (P > 0.05) (Table 1).

Analysis of follow-up results

One month later, the differences between the two groups were compared, and the coefficient of variation of systolic blood pressure in the experimental 7.06%±3.18%, Coefficient of variation of systolic blood pressure compared with the control group 8.97%±5.06% Obvious decline (P=0.011). There was no significant difference in other observation indexes such as ultrafiltration, dry weight, coefficient of variation of diastolic blood pressure, interdialysis weight growth and interdialysis body weight growth between the two groups (P > 0.05) (Table 2).

Discussion

Most patients with MHD have BPV [9-11], It is especially obvious during hemodialysis, which further promotes the occurrence of CVD, and the abnormality of BPV is an independent risk factor for all-cause death in MHD patients [12]. BPV in patients with MHD is associated with cardiovascular disease, and the main mechanism is the aggravation of left ventricular hypertrophy [13], Aggravate the occurrence of arteriosclerosis [14], The correlation between systolic BPV abnormality and cardiovascular death is stronger. Studies have shown that ultrafiltration volume during dialysis is related to systolic Blood Pressure (BPV) during dialysis [9], In patients with high Interdialysis Weight Gain (IDWG), ultrafiltration volume increases accordingly, so controlling the growth of IDWG may help to reduce systolic Blood Pressure (BPV).

The main BPV manifestations of MHD patients were hypertension or hypotension. The incidence of hypertension during dialysis is about 18-31.1% [15], USRDS study showed that systolic blood pressure increased by 10mmHg during dialysis, and the risk of death increased by 6% [16]. The research of Inrig et al. [17] shows that, The difference of blood pressure changes during dialysis is more related to the prognosis. The incidence of hypotension during dialysis is also high, and hypotension during dialysis is also an independent risk factor for all-cause death in MHD patients [18], Avoiding high or low blood pressure during dialysis helps to reduce BPV. The coefficient of variation of systolic blood pressure in the experimental group was significantly lower than that in the control group. The function of regulating water and sodium in patients with MHD is impaired and they need to maintain the balance of sodium in the body through hemodialysisIf the concentration of sodium in the dialysate is too high, the patient will have water and sodium retention [19,20], and will cause the blood pressure to be on the high side [21]. At the same time, due to the increase in water content in the next dialysis ultrafiltration, the risk of hypotension increases accordingly studies have shown that lower dialysate sodium concentration is beneficial to the control of hypertension [22]. But lower dialysate sodium concentrations correspondingly increase the risk of hypotension and muscle spasm [23]. In this study, the sodium concentration of dialysate decreased gradually from 141 mmol/L at the beginning of dialysis to 135 mmol/L before dialysis, and the 30min maintained 140 mmol/L of sodium before the end of dialysis, and maintained a low level of dialysate sodium during dialysis, because 30min was adjusted to normal serum sodium level before the end of dialysis to avoid hyponatremia in patients with MHD. In this study, the sodium concentration of dialysate decreased gradually from the beginning of dialysis to 135 mmol/L before dialysis, and the dialysate sodium concentration was maintained at 140 mmol/L before the end of dialysis.

Limitations of the study

Due to the limited sample size, this study has some limitations and is retrospective. In addition, serum uric acid was evaluated only at baseline and there was no follow-up data.

References

1. Thomas B, Wulf S, Bikbov B (2015) Maintenance Dialysis throughout the World in Years 1990 and 2010. J Am Soc Nephrol 26: 2621-2633.
2. Zhang L, Wang H (2009) Chronic kidney disease epidemic: cost and health care implications in China. Semin Nephrol 29: 483-486.
3. Collins AJ, Foley RN, Herzog C (2011) US Renal Data System 2010 Annual Data Report. Am J Kidney Dis 57: e1-e526.
4. Mancia G, Grassi G (2000) Mechanisms and clinical implications of blood pressure variability. J Cardiovasc Pharmacol 35: S15-S19.
5. Tonbul Z, Altintepe L, Sozlu C (2002) Ambulatory blood pressure monitoring in haemodialysis and continuous ambulatory peritoneal dialysis (CAPD) patients. J Hum Hypertens 16: 585-589.
6. Assimon MM, Flythe JE (2015) Intradialytic Blood Pressure Abnormalities: The Highs, The Lows and All That Lies Between. Am J Nephrol 42: 337-350.
7. Tripepi G, Fagugli RM, Dattolo P (2005) Prognostic value of 24-hour ambulatory blood pressure monitoring and of night/day ratio in nondiabetic, cardiovascular events-free hemodialysis patients. Kidney Int 68: 1294-1302.
8. Liu M, Takahashi H, Morita Y (2003) Non-dipping is a potent predictor of cardiovascular mortality and is associated with autonomic dysfunction in haemodialysis patients. Nephrol Dial Transplant 18: 563-569.
9. Flythe JE, Kunaparaju S, Dinesh K (2012) Factors associated with intradialytic systolic blood pressure variability. Am J Kidney Dis 59: 409-418.
10. Jiang D, Tokashiki M, Hayashi H (2016) Augmented Blood Pressure Variability in Hypertension Induced by Angiotensin II in Rats. Am J Hypertens 29: 163-169.
11. de Jager DJ, Grootendorst DC, Jager KJ (2009) Cardiovascular and noncardiovascular mortality among patients starting dialysis. JAMA 302: 1782-1789.
12. Rothwell PM, Howard SC, Dolan E (2010) Prognostic significance of visit-to-visit variability, maximum systolic blood pressure, and episodic hypertension. Lancet 375: 895-905.
13. Rahman M, Griffin V, Heyka R (2005) Diurnal variation of blood pressure; reproducibility and association with left ventricular hypertrophy in hemodialysis patients. Blood Press Monit 10: 25-32.
14. Mitsuhashi H, Tamura K, Yamauchi J (2009) Effect of losartan on ambulatory short-term blood pressure variability and cardiovascular remodeling in hypertensive patients on hemodialysis. Atherosclerosis 207: 186-190.
15. Tanaka S, Ninomiya T, Hiyamuta H (2019) Apparent Treatment-Resistant Hypertension and Cardiovascular Risk in Hemodialysis Patients: Ten-Year Outcomes of the Q-Cohort Study. Sci Rep 9: 1043.
16. Inrig JK, Patel UD, Toto RD (2009) Association of blood pressure increases during hemodialysis with 2-year mortality in incident hemodialysis patients: a secondary analysis of the Dialysis Morbidity and Mortality Wave 2 Study. Am J Kidney Dis 54: 881-890.
17. Inrig JK, Oddone EZ, Hasselblad V (2007) Association of intradialytic blood pressure changes with hospitalization and mortality rates in prevalent ESRD patients. Kidney Int 71: 454-461.
18. Shoji T, Tsubakihara Y, Fujii M (2004) Hemodialysis-associated hypotension as an independent risk factor for two-year mortality in hemodialysis patients. Kidney Int 66: 1212-1220.
19. Fisch BJ, Spiegel DM (1996) Assessment of excess fluid distribution in chronic hemodialysis patients using bioimpedance spectroscopy. Kidney Int 49: 1105-1109.
20. Plum J, Schoenicke G, Kleophas W (2001) Comparison of body fluid distribution between chronic haemodialysis and peritoneal dialysis patients as assessed by biophysical and biochemical methods. Nephrol Dial Transplant 16: 2378-2385.
21. Inrig J K, Molina C, D'Silva K (2015) Effect of low versus high dialysate sodium concentration on blood pressure and endothelial-derived vasoregulators during hemodialysis: a randomized crossover study. Am J Kidney Dis 65: 464-473.
22. Hecking M, Karaboyas A, Saran R (2012) Predialysis serum sodium level, dialysate sodium, and mortality in maintenance hemodialysis patients: the Dialysis Outcomes and Practice Patterns Study (DOPPS). Am J Kidney Dis 59: 238-248.
23. Geng X, Song Y, Hou B (2020) The efficacy and safety of low dialysate sodium levels for patients with maintenance haemodialysis: A systematic review and meta-analysis. Int J Surg 79: 332-339.