Blood pressure and blood volume: acute and chronic considerations in hemodialysis

Investigation of heart rate variability and heart rate turbulence in chronic hypotensive hemodialysis patients

BACKGROUND

Sudden cardiac death is the leading cause of cardiac-related death in hemodialysis patients. Hypotensive episodes in pre-, intra-, and post-dialytic periods can present serious clinical challenges that affect a patient's quality of life and prognosis. The aim of the present study was to evaluate cardiac autonomic control and arrhythmogenic risk by analyzing 24-h heart rate variability (HRV) and heart rate turbulence (HRT) in hypotensive hemodialysis patients.

METHODS

A total of 79 patients on maintenance hemodialysis treatment, 39 normotensive and 40 with frequent hypotension episodes during non-dialysis periods, were included in the study. Dialysis-free periods were recorded with a 24-h Holter rhythm and ambulatory blood pressure monitor device. The time-domain parameters of HRV and HRT, including turbulence onset (TO) and turbulence slope (TS), were calculated.

RESULTS

Values for SDNN (105.5 ± 7.02, 127.6 ± 6.2 p < 0.001), SDANN (95.1 ± 5.9, 111.8 ± 5.01 p < 0.001), and SDNN index (50.04 ± 2.7, 55.6 ± 3.7 p = 0.03), in the hypotensive group were significantly lower than in the normotensive group, respectively. Values for RMSSD (26.5 ± 2.5, 27.3 ± 2.7 p = 0.178), pNN50 (17 ± 1.7, 55.6 ± 3.7 p = 0.03), and Tİ (35.1 ± 3.1, 34.7 ± 2.6 p = 0.542) in both groups were not significantly different; however, there was a significant difference between HRT parameters, TO (- 1.8 ± 0.37, - 2.4 ± 0.39 p < 0.001) and TS (6.9 ± 0.71, 8.2 ± 0.97 p < 0.001), respectively, hypotensive and normotensive group.

CONCLUSION

Dialysis patients that experience frequent hypotensive episodes may also undergo significant changes in HRT and HRV which may be indicative of serious cardiac sequela. Thus, in such cases, a complete cardiologic evaluation is warranted.

Effectiveness of self-management support in maintenance haemodialysis patients with hypertension: A pilot cluster randomized controlled trial

AIM

Uncontrolled hypertension is an independent risk factor for cardiovascular disease and is the leading cause of mortality in haemodialysis patients. The aim of this study was to examine the effectiveness of self-management support (SMS) for blood pressure (BP) control and health behaviours.

METHODS

We conducted a cluster randomized controlled trial (RCT) in which 90 adult haemodialysis patients were assigned to either an SMS or common intervention (CI) group. The SMS group received an intervention consisting of self-management education and motivational interviewing. The CI group received standard care and routine health education. The primary outcome was the BP monitored before each haemodialysis. Secondary outcomes included salt intake (measured using a balance formula), home BP monitoring (HBPM) (assessed using two self-administered questions), and medication adherence (measured using the Medication-taking Behavior Scale). Data were collected at baseline and at 1, 3 and 6 months post-intervention.

RESULTS

The SMS group showed continuous reductions in systolic BP from baseline: -9.2, -8.7, and -8.4 mmHg at 1, 3 and 6 months after the intervention, respectively (P < 0.01). Compared with the CI group, the SMS group had a greater decrease in systolic BP at 1 month: -5.9 mmHg (P = 0.0388), but no significant difference was found at 3 or 6 months (P > 0.05). SMS patients showed an improvement in health behaviours relative to baseline (less salt intake, more consistent HBPM, and greater medication adherence) (P < 0.05).

CONCLUSIONS

Self-management support obtained short-term success in improving salt restriction, regular performance of HBPM and medication adherence, which led to better BP control.

Individualization of Ultrafiltration in Hemodialysis

OBJECTIVES

There are approximately 660 000 end-stage renal disease patients in the USA, with hemodialysis (HD) the primary form of treatment. High ultrafiltration rates (UFRs) are associated with intradialytic hypotension, a complication associated with adverse clinical outcomes including mortality. Individualized UFR profiles could reduce the incidence of intradialytic hypotension.

METHODS

The patient's fluid dynamics during HD is described by a nonlinear model comprising intravascular and interstitial pools, whose parameters are given by the patient's estimated nominal parameter values with uncertainty ranges; the output measurement is hematocrit. We design UFR profiles that minimize the maximal UFR needed to remove a prescribed volume of fluid within a set time, with hematocrit not exceeding a specified time-varying critical profile.

RESULTS

We present a novel approach to design individualized UFR profiles, and give theoretical results guaranteeing that the system remains within a predefined physiologically plausible region and does not exceed a specified time-invariant critical hematocrit level for all parameters in the uncertainty ranges. We test the performance of our design using a real patient data example. The designed UFR maintains the system below a time-varying critical hematocrit profile in the example.

CONCLUSION

Theoretical results and simulations show that our designed UFR profiles can remove the target amount of fluid in a given time period while keeping the hematocrit below a specified critical profile.

SIGNIFICANCE

Individualization of UFR profiles is now feasible using current HD technology and may reduce the incidence of intradialytic hypotension.

Xerostomia, thirst, sodium gradient and inter-dialytic weight gain in hemodialysis diabetic vs. non-diabetic patients

Background

In hemodialysis (HD) patients, xerostomia and hyposalivation may intensify sensations of thirst, and contribute to the intake of fluids and excessive inter-dialytic weight gain (IWG). Since IWG is regarded to be higher in diabetic patients than in non-diabetics HD enhancing their mortality, it is crucial to define plausible underlying causes. Therefore, the study investigates factors contributing to the increased IWG in diabetic HD patients.

Material and Methods

The study included 97 HD patients (38 diabetics) receiving hemodialysis. All participants completed surveys comprising the Dialysis Thirst Inventory (DTI) and Xerostomia Inventory. Unstimulated whole saliva flow rate (USWFR) was measured, with USWFR below 0.1 mL/min being regarded as hyposalivation. Additionally, pre- and post-dialysis serum sodium concentration, sodium gradient and IWG were assessed. In diabetic HD patients, hemoglobin A1c (HbA1c) level was measured.

Results

Significantly higher scores were found in diabetic than non-diabetic HD patients with regard to DTI (21.2±7.7 vs. 17.1±6.2: Z=2.44, p=0.03) and xerostomia (40.5±6.1 vs. 29.9±14.4: Z=4.15, p=0.003). Hyposalivation was observed more often in diabetic HD patients (Z=2.23, p=0.04). IGW was significantly higher in participants with diabetes (Z=2.44, p=0.03), as was the pre-dialysis sodium serum (Z=3.4, p=0.008). High levels of HbA1c were associated with lower levels of serum sodium (r=-0.67 p<0.05). HbA1c positively correlated with pre-dialysis sodium gradient (r=0.66 p<0.05). However, multiple regression analysis found that the only predictors of increased IWG (>4.8 IWG%) in diabetic patients remained saliva flow rate and pre-dialysis sodium gradient.

Conclusions

Concomitant diabetes in hemodialysis patients appears to intensify subjective xerostomia and thirst sensation. It also leads to excessive IWG by the increase of pre-dialysis serum sodium gradient.

Key words:Diabetes mellitus, hemodialysis, hyposalivation, inter-dialytic weight gain, sodium gradient.

Adherence to hemodialysis dietary sodium recommendations: influence of patient characteristics, self-efficacy, and perceived barriers

OBJECTIVE

To identify characteristics of hemodialysis patients most likely to experience difficulty adhering to sodium restrictions associated with their dietary regimen.

DESIGN

Secondary analysis using baseline data from an ongoing randomized clinical trial examining the effects of a technology-supported behavioral intervention on dietary sodium intake in hemodialysis patients.

SETTING

Thirteen dialysis centers in southwestern Pennsylvania.

SUBJECTS

We included 122 participants (61% women; 48% African American) aged 61 ± 14 years undergoing maintenance, intermittent hemodialysis for end-stage renal disease.

MAIN OUTCOME MEASURES

Normalized dietary sodium intake, adjusted interdialytic weight gain, perceived problems, and self-efficacy for restricting dietary sodium.

RESULTS

Younger participants were more likely to report problems managing their hemodialysis diet and low self-efficacy for restricting sodium intake. Consistent with these findings, younger participants had a higher median sodium intake and higher average adjusted interdialytic weight gain. Females reported more problems managing their diet. Race, time on dialysis, and perceived income adequacy did not seem to influence outcome measures.

CONCLUSION

Our findings suggest that patients who are younger and female encounter more difficulty adhering to the hemodialysis regimen. Hence, there may be a need to individualize counseling and interventions for these individuals. Further investigation is needed to understand the independent effects of age and gender on adherence to hemodialysis dietary recommendations and perceived self-efficacy.

Supplements and Foods with Potential Reduction of Blood Pressure in Prehypertensive and Hypertensive Subjects: A Systematic Review

Although the dietary approaches for stop hypertension (DASH) is well established and effective in reduction of blood pressure, in recent years, new scientific studies have indicated that specific food, nutrients isolated from foods, and even commercial food supplements are not covered by DASH. In this research, these nutrients were evaluated through a review using the databases of PubMed with the terms “dietary supplements and blood pressure” without a limit of date. Vitamins (C, D, and E) and minerals (potassium and copper) promote the greatest reductions in BP, around 7 to 14 mmHg for systolic blood pressure (SBP) and 4 to 5 mmHg for diastolic blood pressure (PAD). Antioxidants reduce SBP and DBP in 3 to 27 mmHg and 3 to 4 mmHg, respectively. Among the amino acids, only L-arginine was effective in promoting reduction of 20 and 15 mmHg for SBP and DBP, respectively. In food, the grape juice promoted the highest reductions in SBP and DBP, around 8 mmHg and 6 mmHg, respectively. Finally, for commercial supplements, the fermented milk product GAIOR, the grain salba, and fish oil promoted reductions of about 4,4; 6; and 5 mmHg and 3,4; 3; and 1 mmHg for SBP and DBP, respectively. Therefore, new nutrients, foods, and supplements can enrich the recommendations of the DASH.