Is the inverse relation between blood pressure and mortality normalized in 'low-risk' dialysis patients?

A new technique for the detection of dry weight in hemodialysis patients: Estimated pulmonary capillary wedge pressure. A tissue Doppler imaging study

BACKGROUND AND OBJECTIVE

Fluid overload is an important factor of morbidity and mortality in hemodialysis patients. Today correct determination of dry weight (DW) remains an important issue of hemodialysis practice. Within this context, it is subjected to new method searching. The objective of this study was to calculate estimated pulmonary capillary wedge pressure (ePCWP) with Tissue Doppler Imaging (TDI) in hemodialysis patients and to evaluate its correlation with the other volume markers and to evaluate whether it can be a new method for detection of DW.

MATERIALS AND METHODS

Echocardiographic, hemodynamic, and biochemical volume markers of 41 hemodialysis patients were evaluated in the pre- and post-dialysis periods. Patients were divided into two groups based on ePCWP values (Group 1 ePCWP<20mmHg, Group 2 ePCWP>20mmHg).

RESULTS

In the pre-dialysis period; parameters related to volume load including ePCWP, systolic blood pressure, mean arterial pressure, pulse pressure, left atrial diameter, left atrial volume, E/é, ratio and E/V_p ratio were statistically significantly higher in Group2 compared to Group1. On the other hand, strong correlations were found between pre-dialysis ePCWP and systolic blood pressure, mean arterial pressure, pulse pressure, NT-ProBNP, left atrial diameter, E/é ratio and E/V_p ratio.

CONCLUSIONS

Strong correlations found between ePCWP which was calculated with TDI and the other volume markers both in pre-dialysis and post-dialysis periods. These findings can provide a significant contribution to routine evaluating of DW in hemodialysis patients. From this aspect, the prediction of ePCWP with TDI can be a new practical and reproducible method for the determination of DW.

A new technique for the detection of dry weight in hemodialysis patients: Estimated pulmonary capillary wedge pressure. A tissue Doppler imaging study

BACKGROUND AND OBJECTIVE

Fluid overload is an important factor of morbidity and mortality in hemodialysis patients. Today correct determination of dry weight (DW) remains an important issue of hemodialysis practice. Within this context, it is subjected to new method searching. The objective of this study was to calculate estimated pulmonary capillary wedge pressure (ePCWP) with Tissue Doppler Imaging (TDI) in hemodialysis patients and to evaluate its correlation with the other volume markers and to evaluate whether it can be a new method for detection of DW.

MATERIALS AND METHODS

Echocardiographic, hemodynamic, and biochemical volume markers of 41 hemodialysis patients were evaluated in the pre- and post-dialysis periods. Patients were divided into two groups based on ePCWP values (Group 1 ePCWP<20mmHg, Group 2 ePCWP>20mmHg).

RESULTS

In the pre-dialysis period; parameters related to volume load including ePCWP, systolic blood pressure, mean arterial pressure, pulse pressure, left atrial diameter, left atrial volume, E/é, ratio and E/Vp ratio were statistically significantly higher in Group2 compared to Group1. On the other hand, strong correlations were found between pre-dialysis ePCWP and systolic blood pressure, mean arterial pressure, pulse pressure, NT-ProBNP, left atrial diameter, E/é ratio and E/Vp ratio.

CONCLUSIONS

Strong correlations found between ePCWP which was calculated with TDI and the other volume markers both in pre-dialysis and post-dialysis periods. These findings can provide a significant contribution to routine evaluating of DW in hemodialysis patients. From this aspect, the prediction of ePCWP with TDI can be a new practical and reproducible method for the determination of DW.

The Optimal Blood Pressure Target in Different Dialysis Populations

Hypertension is common and contributes to adverse outcomes in patients undergoing dialysis. However, the proper blood pressure (BP) target remains controversial and several factors make this difficult. This study aimed to investigate the adequate BP target in patients undergoing prevalent dialysis. Data were retrieved from the Clinical Research Center for End-Stage Renal Disease (2009–2014). 2,299 patients undergoing dialysis were evaluated. Patients were assigned into eight groups according to predialysis systolic blood pressure (SBP). The primary outcome was all-cause mortality. During the median follow-up of 4.5 years, a U-shape relation between SBP and mortality was found. The risk of mortality was increased in the SBP <110 and ≥170 mmHg groups. In subgroup analysis, the risk of mortality was similarly shown U-shape with SBP in subjects with no comorbidities, and no use of antihypertensive agents. However, only lowest SBP was a risk factor for mortality in patients with older, having diabetes or coronary artery disease, whereas highest SBP was an only risk factor in younger patients. In respect of dialysis characteristics, patients undergoing hemodialysis showed U-shape between SBP and mortality, while patients undergoing peritoneal dialysis did not. Among hemodialysis patients, patients with shorter dialysis vintage and less interdialytic weight gain showed U-shape association between SBP and mortality. This study showed that the lowest or highest SBP group had higher risk of mortality. Nevertheless, the optimal target BP should be applied according to individual condition of each patient.

Blood pressure targets for hemodialysis patients: Aspirational or practical?

Whereas there is strong relationship between high blood pressure and increased overall and cardiovascular mortality for the general population, observational studies in hemodialysis patients have reported a "U" shaped relationship between pre-hemodialysis blood pressure recordings and patient survival. Previous attempts to introduce pre and post-hemodialysis blood pressure targets were associated with an increased frequency of intra-dialytic hypotension, itself an independent risk factor for mortality. Conversely, meta-analyses of trials of antihypertensive medications in hemodialysis patients, reported survival benefit for those prescribed medication. More recently, further meta-analyses have suggested a reduced risk for cardiovascular mortality benefit with a systolic blood pressures (SBPs) of less than 140 mmHg, the absolute benefit, in terms of risk reduction was greatest in those with the highest vascular disease burden. Even though data from current observational studies and studies of antihypertensive medications would suggest that patient survival would be greater with pre-dialysis SBP should be less than 160 mmHg, there is no current data to propose specific blood pressure targets. Defining blood pressure targets can only be answered by adequately powered prospective randomized controlled trials comparing different targets. As the benefits of lowering blood pressure appear to be greatest for those with most vascular disease, then blood pressure targets may have to be adjusted on an individual risk basis, and future trials should therefore stratify patients according to vascular morbidity and have different targets for patients with differing degrees of pre-existing cardiovascular disease.

Blood Pressure and Mortality in Hemodialysis Patients: A Systematic Review of an Ongoing Debate

Hypertension is prevalent in 75-80% of hemodialysis patients and remains the most controversial prognostic marker in end stage kidney disease patients. In contrast to the general population where systolic blood pressure of ≤120 mm Hg is considered normal, a debate remains regarding the ideal target blood pressure in hemodialysis patients. Using the PUBMED and EMBASE databases, the research studies that evaluated the relationship between blood pressure measurements and mortality in hemodialysis patients were searched. Thirteen studies were identified from different regions of the world. Five studies reported low predialysis systolic blood pressure as a prognostic marker of mortality. Other studies showed varying results and reported postdialysis systolic blood pressure as well as ambulatory blood pressure as better predictors of mortality and emphasized their optimized control. One study in this review concluded that there is no direct relationship between mortality and blood pressure if the patients are on anti-hypertensive medications. The observed all-cause mortality varied from 12% to 36%, whereas the cardiovascular mortality varied from 16% to 60%. On the basis of studies included in the current review, a low predialysis systolic blood pressure (<120 mm Hg) is shown to be a widely accepted prognostic marker of mortality while ambulatory blood pressure best predicts CV mortality. Therefore, we recommend that apart from routine BP (pre, post and intradialysis) monitoring in centers, assessment of ambulatory BP must be mandatory for all patients to reduce CV mortality in hemodialysis patients.

Haemodialysis Impairs the Human Microcirculation Independent from Macrohemodynamic Parameters

Hemodynamic changes during haemodialysis are common. Often these changes are associated with symptoms that are thought to be the result of reduced microcirculatory blood flow and oxygen delivery. The microcirculatory effect of hemodialysis is scarcely researched, though of possible influence on patient outcome. New techniques have become available to visualise and analyse microvascular blood flow. We performed an observational study using Sidestream Dark Field imaging, a microscopic technique using polarised light to visualise erythrocytes passing through sublingual capillaries, to analyse the effect of haemodyalisis on central microvascular blood flow. We showed that there is a substantial impairment of microvascular blood flow and a discrepancy between micro- and macro-vascular parameters.

Predicting mortality in patients with diabetes starting dialysis

Background

While some prediction models have been developed for diabetic populations, prediction rules for mortality in diabetic dialysis patients are still lacking. Therefore, the objective of this study was to identify predictors for 1-year mortality in diabetic dialysis patients and use these results to develop a prediction model.

Methods

Data were used from the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), a multicenter, prospective cohort study in which incident patients with end stage renal disease (ESRD) were monitored until transplantation or death. For the present analysis, patients with DM at baseline were included. A prediction algorithm for 1-year all-cause mortality was developed through multivariate logistic regression. Candidate predictors were selected based on literature and clinical expertise. The final model was constructed through backward selection. The model's predictive performance, measured by calibration and discrimination, was assessed and internally validated through bootstrapping.

Results

A total of 394 patients were available for statistical analysis; 82 (21%) patients died within one year after baseline (3 months after starting dialysis therapy). The final prediction model contained seven predictors; age, smoking, history of macrovascular complications, duration of diabetes mellitus, Karnofsky scale, serum albumin and hemoglobin level. Predictive performance was good, as shown by the c-statistic of 0.810. Internal validation showed a slightly lower, but still adequate performance. Sensitivity analyses showed stability of results.

Conclusions

A prediction model containing seven predictors has been identified in order to predict 1-year mortality for diabetic incident dialysis patients. Predictive performance of the model was good. Before implementing the model in clinical practice, for example for counseling patients regarding their prognosis, external validation is necessary.

Risk of sudden cardiac death in chronic kidney disease

The review discusses the epidemiology and the possible underlying mechanisms of sudden cardiac death (SCD) in chronic kidney disease (CKD), and highlights the unmet clinical need for noninvasive risk stratification strategies in these patients. Although renal dysfunction shares common risk factors and often coexists with atherosclerotic cardiovascular disease, the presence of renal impairment increases the risk of arrhythmic complications to an extent that cannot be explained by the severity of the atherosclerotic process. Renal impairment is an independent risk factor for SCD from the early stages of CKD; the risk increases as renal function declines and reaches very high levels in patients with end-stage renal disease on dialysis. Autonomic imbalance, uremic cardiomyopathy, and electrolyte disturbances likely play a role in increasing the arrhythmic risk and can be potential targets for treatment. Cardioverter defibrillator treatment could be offered as lifesaving treatment in selected patients, although selection strategies for this treatment mode are presently problematic in dialyzed patients. The review also examines the current experience with risk stratification tools in renal patients and suggests that noninvasive electrophysiological testing during dialysis may be of clinical value as it provides the necessary standardized environment for reproducible measurements for risk stratification purposes.

Reverse epidemiology of hypertension-mortality associations in hemodialysis patients: a long-term population-based study

BACKGROUND

Although hypertension (HTN) is a predictor of mortality, recent data have questioned the link between baseline HTN and mortality in incident hemodialysis (HD) patients. We used Taiwan's National Health Insurance claim data (NHRI-NHIRD-99182) to investigate the association.

METHODS

In 1999, this longitudinal cohort study enrolled 5752 new HD patients. Follow-up began from the initiation of HD until death, the end of HD, or the end of 2008. A Kaplan-Meier survival analysis was done. Cox proportional hazard analysis was used to identify the risk factors for mortality.

RESULTS

The prevalence of baseline HTN was 75.47%. Patients with HTN had a higher prevalence of diabetic mellitus (DM) and cardiovascular diseases. The 1-, 5-, and 9-year cumulative survival rates were 95.5, 63.7 and 41.8% in patients with HTN, and 95.5, 71.0, and 52.0% in those without HTN (log-rank test: P <0.001). Multivariate analysis showed that patients with baseline HTN may have a higher survival rate (hazard ratio (HR) 0.901, 95% confidence interval (CI): 0.819-0.992). After stratification by age and DM, only elderly (≥65) patients without DM had a significantly higher survival rate (HR 0.769, 95% CI: 0.637-0.927). HTN predicts lower mortality with increasing age in patients with congestive heart failure (CHF) or coronary artery disease (CAD).

CONCLUSIONS

There is a reverse (counterintuitive) association between baseline HTN and mortality in elderly HD patients without DM and a clear tendency for a reverse association with increasing age in patients with CHF or CAD. Further study of the association between HTN and mortality in older HD patients may be warranted.

Long-term survival and predictors for mortality among dialysis patients in an endemic area for chronic liver disease: a national cohort study in Taiwan

Background

Patients with end-stage renal disease (ESRD) are at a higher risk for chronic hepatitis, liver cirrhosis (LC) and mortality than the general population. Optimal modalities of renal replacement therapy for ESRD patients with concomitant end-stage liver disease remain controversial. We investigated the long-term outcome for chronic liver disease among dialysis patients in an endemic area.

Methods

Using Taiwan’s National Health Insurance claim data (NHRI-NHIRD-99182), We performed a longitudinal cohort study to investigate the impact of comorbidities on mortality in dialysis patients. We followed up 11293 incident hemodialysis (HD) and 761 peritoneal dialysis (PD) patients from the start of dialysis until the date of death or the end of database period (December 31, 2008). A Cox proportional hazards model was used to identify the risk factors for all-cause mortality.

Results

Patients receiving PD tended to be younger and less likely to have comorbidities than those receiving HD. At the beginning of dialysis, a high prevalence rate (6.16 %) of LC was found. Other than well-known risk factors, LC (hazard ratio [HR] 1.473, 95 % CI: 1.329-1.634) and dementia (HR 1.376, 95 % CI: 1.083-1.750) were also independent predictors of mortality. Hypertension and mortality were inversely associated. Dialysis modality and three individual comorbidities (diabetes mellitus, chronic lung disease, and dementia) interacted significantly on mortality risk.

Conclusions

LC is an important predictor of mortality; however, the effect on mortality was not different between HD and PD patients.

Systolic blood pressure and mortality in patients on hemodialysis

Hypertension is extremely common in patients with end-stage renal disease who are receiving hemodialysis, and cardiovascular disease remains the leading cause of death in these patients. However, optimal blood pressure management strategies in this high-risk population are still controversial. This review first discusses the complex association of systolic blood pressure with clinical outcomes in patients on hemodialysis, with a focus on several recent studies. Next, it updates the reader on issues related to optimal timing and methods of blood pressure measurement, appropriate blood pressure targets, and pharmacologic and nonpharmacologic hypertension treatment strategies for patients on hemodialysis.

Development and validation of a new dry weight estimation method using single frequency bioimpedance in hemodialysis patients

BACKGROUND

We proposed a new method to estimate dry weight (DW) using single frequency bioimpedance.

METHODS

We hypothesized that the change in whole body resistance at 50 kHz (R(50)) was proportional to the ultrafiltration volume (UFV) during a hemodialysis (HD) session. When the targeted resistance estimated in healthy subjects was reached, the patient achieved his/her DW. UFV and R(50) were monitored in 40 HD patients. Another 43 HD patients were stratified into 2 groups to validate this method.

RESULTS

The change in whole body resistance was proportional to UFV in each of the 40 HD patients. In the DW(decrease) group, pre-dialysis systolic blood pressure (n = 29, 154.5 ± 22.8 vs. 146.9 ± 22.3, p < 0.05) and antihypertensive medicine (4.7 ± 3.6 vs. 3.3 ± 2.2, p < 0.05) decreased without adverse symptoms change. In the DW(increase) group, the number of adverse symptoms in 1 week (n = 14, 26 vs. 6, p < 0.05) decreased without a change in systolic blood pressure.

CONCLUSION

This method may become a convenient and cheaper way to estimate DW in HD patients.

Blood pressure management in hemodialysis: what have we learned?

PURPOSE OF REVIEW

To review recent developments in the field of hypertension in hemodialysis patients.

RECENT FINDINGS

Despite the fact that hypertension is the most common complication of end-stage kidney disease, no evidence-based blood pressure (BP) targets exist for hemodialysis patients. There is growing evidence that outcomes are better predicted by out-of-office BP values, such as home or ambulatory BP monitoring. Intradialytic hypertension is associated with increased risk of death or hospitalization, and is probably mediated by volume overload. BP management should focus on volume control: dry weight 'probing' is well tolerated and effective in lowering BP, as are other strategies that minimize expansion of the extracellular fluid volume, such as avoidance of hypernatric dialysate. We discuss each of these issues in our review.

SUMMARY

Modest advances in the understanding of hypertension have occurred in the past 2 years. Clinical trials that focus on BP targets and treatment choices are essential to guide future practice.