What is hypertension in chronic haemodialysis? The role of interdialytic blood pressure monitoring

Why is Intradialytic Hypotension the Commonest Complication of Outpatient Dialysis Treatments?

Intradialytic hypotension (IDH) is the most frequent complication of hemodialysis (HD) treatments with a frequency of 10% to 12% for patients with chronic kidney disease attending for outpatient treatments and is associated with both temporary ischemic stress to vital organs, including the heart and brain, and increased patient mortality. Although there have been many different definitions of IDH over the years, an absolute nadir systolic blood pressure (SBP) has the strongest association with patient outcomes. The unifying pathophysiology is one of reduced effective blood volume, resulting in lower plasma tonicity, and if this cannot be adequately compensated for by activation of neurohumeral systems, then arteriolar tone and blood pressure fall. The risk factors for developing IDH are numerous, ranging from patient-related factors, including age and comorbidity with reduced cardiac reserve, to patient compliance with dietary and lifestyle advice, to reactions with the extracorporeal circuit and medications, choice of dialysate composition and temperature, setting of postdialysis target weight, ultrafiltration rate, and profiling. Advances in dialysis machine technology by providing real time estimates of the effective circulating volume and adjusting dialysate composition to maintain vascular tonicity are being developed, but currently require more sophisticated biofeedback loops to be clinically effective in preventing IDH. While awaiting advances in artificial intelligence, the clinician continues to rely on patient education to limit interdialytic weight gains, frequent assessment of the postdialysis target weight, adjusting dialysate composition and temperature, introducing convective therapies to increase thermal losses, and altering dialysis session duration and frequency to reduce ultrafiltration rate requirements.

Weekly pattern of dialysis unit blood pressure is a promising marker for prognosis evaluation in hemodialysis population

BACKGROUND

Dialysis unit blood pressure (BP) pattern showed superiority in prognostic evaluation and interdialytic BP burden assessment. However previous studies mainly focused on the recurrent BP pattern within a session (intradialytic BP change or intradialytic BP slope), the clinical value of the weekly pattern of dialysis unit BP is unknown.

METHODS

We performed a prospective cohort study in adult end stage renal disease (ESRD) patients on thrice weekly hemodialysis (HD). The slope and the change of the postdialysis systolic BP (SBP) in the course of a week (post-SBP slope and post-SBP change) were used to characterize the weekly pattern of dialysis unit BP. Outcomes included all-cause mortality, cardiovascular mortality, and first cardiovascular event. We also measured the home BP in our cohort.

RESULTS

One hundred and twenty-nine subjects were followed over a median of 31 months. Higher post-SBP slope (≥0.185) was independently associated with increased risk of all-cause mortality, cardiovascular mortality, and first cardiovascular event. Results were similar for increased post-SBP change. HD patients with a higher post-SBP slope or an increased post-SBP change also had significant increased interdialytic BP burden measured by home SBP on both dialysis days and non-dialysis days.

CONCLUSIONS

Post-SBP slope and post-SBP change might be promising dialysis unit BP markers for prognostic evaluation and interdialytic BP burden assessment.

Changes in total and segmental extracellular and intracellular volumes with hypotension during hemodialysis measured with bioimpedance spectroscopy

BACKGROUND

Bioelectrical impedance analysis (BIA) devices have been advocated to guide volume management in hemodialysis (HD) patients. We hypothesized that understanding the dynamics of fluid shifts in different body segments may provide additional insight on preventive measures to reduce the risk of intradialytic hypotension.

METHODS

A prospective observational study was conducted among 42 HD patients at risk of hypotension who were admitted as emergencies inpatient.

RESULTS

A total of 191 BIA measurements were made during the 42 HD sessions, and hypotension occurred during 52 measurements (27%). The extracellular water (ECW) to intracellular water ratio (EIR) was measured in different body segments and declined significantly only in the non-access arm with increasing HD session duration (β = -0.04; 95% confidence interval (CI): -0.05 to -0.03, p < 0.01). There was no significant association between EIR and hypotension with respect to the different body segments. Only pre-HD N-terminal-pro b-type natriuretic peptide was significantly associated with hypotension (β = 0.20, 95% CI: 0.04 to 0.89, p = 0.04). There was no association between relative blood volume monitoring change and EIR.

CONCLUSION

In summary, we found that segmental BIA during HD was unable to detect or predict hypotension during dialysis. Although BIA is able to provide information about ECW and guide clinical assessment of volume in HD patients prior to dialysis, our findings did not suggest the use of serial measurements of changes in EIR in different body segments during HD provided sufficient information to predict intradialytic hypotension. Similarly, changes in EIR did not provide information on changes in plasma volume that could potentially trigger interventions to prevent or reduce intra-dialytic hypotension.

Usefulness of ABPM and bioimpedance for the treatment and control of hypertension in patients on chronic haemodialysis

INTRODUCTION

Hypertension is very common in haemodialysis (HD) patients, and is associated with increased morbidity and mortality rates. The goals of our research were to: 1. Measure blood pressure (BP) during HD sessions; 2. Study BP in between HD sessions with 44-h Ambulatory Blood Pressure Monitoring (ABPM); 3. Evaluate changes in treatment after the ABPM; 4. Perform bioimpedance spectroscopy (BIS) on all patients and, in those hyper-hydrated or hypertensive according to ABPM, assess for changes in BP after adjusting the dry weight; 5. Identify factors associated with average systolic and diastolic BP measured by ABPM.

MATERIAL AND METHODS

Prospective observational study, which included 100 patients from our dialysis unit. We measured BP before and after the HD sessions for two weeks and then, mid-week, we attached the ABPM device to the patients for 44 h. Before starting the following dialysis session, we performed BIS. A second ABPM was performed on hyper-hydrated patients and patients hypertensive according to ABPM to evaluate changes in BP values.

RESULTS

According to the ABPM, 65% of patients had daytime BP > 135/85 mmHg, 90% night-time BP > 120/70 mmHg and 76% average BP > 130/80 mmHg; 11% had a dipper pattern, 51% non-dipper and 38% riser. The average systolic and diastolic BP readings were 4.7 mmHg (3.8%) and 1.1 mmHg (1.64%) higher on the second day. The dose of antihypertensive medication had to be lowered in 6% of patients, 9% had to stop taking it, 28% needed increased doses and 17% had to add a new drug. The pre-HD diastolic BP best matched the ABPM. After performing the bioimpedance and adjusting dry weight, there was a statistically significant decrease in all BP values. The univariate analysis showed that the average systolic BP was higher in patients with a high-calcium dialysis bath, more antihypertensive drugs and higher doses of EPO. The multivariate analysis showed significant association for EPO and number of drugs (p < 0.01). The average diastolic BP was higher in younger patients and patients with lower Charlson index, lower body mass index and less diuresis, those on higher doses of EPO and non-diabetics. The linear regression study showed age (p < 0.005), body mass index (p < 0.03) and EPO (p < 0.03) as significant variables.

CONCLUSIONS

Our study shows: 1. The variability of hypertension criteria according to use of BP values from during the HD session or ABPM; 2. The variability of BP in the interdialysis period; 3. That the pre-dialysis diastolic BP best corresponds with the ABPM. 4. That the use of both BIS and ABPM improves the control of BP; 5. That the dose of EPO is the most important factor associated with hypertension in our patients.

Usefulness of ABPM and bioimpedance for the treatment and control of hypertension in patients on chronic haemodialysis

INTRODUCTION

Hypertension is very common in haemodialysis (HD) patients, and is associated with increased morbidity and mortality rates. The goals of our research were to: 1. Measure blood pressure (BP) during HD sessions; 2. Study BP in between HD sessions with 44-hour Ambulatory Blood Pressure Monitoring (ABPM); 3. Identify differences between the BP recorded during HD and with the ABPM; 4. Evaluate changes in treatment after the ABPM; 5. Perform bioimpedance spectroscopy (BIS) on all patients and, in those hyper-hydrated or hypertensive according to ABPM, assess for changes in BP after adjusting the dry weight; 6. Identify factors associated with average systolic and diastolic BP measured by ABPM.

MATERIAL AND METHODS

Prospective observational study, which included 100 patients from our dialysis unit. We measured BP before and after the HD sessions for two weeks and then, mid-week, we attached the ABPM device to the patients for 44 hours. Before starting the following dialysis session, we performed BIS. A second ABPM was performed on hyper-hydrated patients and patients hypertensive according to ABPM to evaluate changes in BP values.

RESULTS

According to the ABPM, 65% of patients had daytime BP > 135/85 mmHg, 90% night-time BP > 120/70 mmHg and 76% average BP > 130/80 mmHg; 11% had a dipper pattern, 51% non-dipper and 38% riser. The average systolic and diastolic BP readings were 4.7 mmHg (3.8%) and 1.1 mmHg (1.64%) higher on the second day. The dose of antihypertensive medication had to be lowered in 6% of patients, 9% had to stop taking it, 28% needed increased doses and 17% had to add a new drug. The pre-HD diastolic BP best matched the ABPM. After performing the bioimpedance and adjusting dry weight, there was a statistically significant decrease in all BP values. The univariate analysis showed that the average systolic BP was higher in patients with a high-calcium dialysis bath, more antihypertensive drugs and higher doses of EPO. The multivariate analysis showed significant association for EPO and number of drugs (p < 0.01). The average diastolic BP was higher in younger patients and patients with lower Charlson index, lower body mass index and less diuresis, those on higher doses of EPO and non-diabetics. The linear regression study showed age (p < 0.005), body mass index (p < 0.03) and EPO (p < 0.03) as significant variables.

CONCLUSIONS

Our study shows: 1. The variability of hypertension criteria according to use of BP values from during the HD session or ABPM; 2. The variability of BP in the interdialysis period; 3. That the pre-dialysis diastolic BP best corresponds with the ABPM. 4. That the use of both BIS and ABPM improves the control of BP; 5. That the dose of EPO is the most important factor associated with hypertension in our patients.

Which dialysis unit blood pressure is the most accurate for predicting home blood pressure in patients undergoing hemodialysis?

BACKGROUND/AIMS

We investigated which dialysis unit blood pressure (BP) is the most useful for predicting home BP in patients undergoing hemodialysis (HD).

METHODS

Patients undergoing HD who had been treated > 3 months were included in this study. Exclusion criteria were hospitalized patients with acute illness and changes in dry weight and anti-hypertensive drugs 2 weeks before the study. We used the dialysis unit BP recording data, such as pre-HD, intra-HD, post-HD, mean pre-HD, and post-HD (pre-post-HD), mean pre-HD, intra-HD, and post-HD (pre-intra-post-HD) BP. Home BP (the same period of dialysis unit BP) was monitored as a reference method during 2 weeks using the same automatic oscillometric device. Patients were asked to record their BP three times daily (wake up, between noon and 6:00 PM, and at bedtime).

RESULTS

Significant differences were detected between home systolic blood pressure (SBP) and pre-HD, post-HD, and intra-HD SBP (p = 0.003, p = 0.001, p = 0.016, respectively). In contrast, no differences were observed between home SBP and pre-intra-post-HD and pre-post-HD SBP (p = 0.235, p = 0.307, respectively). Areas under the receiver operating characteristic curve for pre-intra-post-HD and prepost-HD SBP with 2-week home BP as the reference standard were 0.812 and 0.801, respectively.

CONCLUSIONS

These results suggest that pre-intra-post-HD and pre-post-HD SBP had similar accuracy for predicting mean 2-week home SBP in HD patients. Therefore, pre-intra-post-HD and pre-post-HD SBP should be useful for predicting home SBP in HD patients if ambulatory or home BP measurements are unavailable.

Management of Patient Care in Hemodialysis While Focusing on Cardiovascular Disease Events and the Atypical Role of Hyper- and/or Hypotension: A Systematic Review

Background. Hemodialysis related hemodynamic instability is a major but an underestimated issue. Moreover, cardiovascular events are the leading cause of morbidity and mortality associated with blood pressure in hemodialysis patients. However, there have been many controversies regarding the role and management of hyper- and/or hypotension during hemodialysis that needs to be addressed. Objective. To critically review the available published data on the atypical role of hyper- and/or hypotension in cardiovascular associated morbidity and mortality in patients on hemodialysis and to understand the discrepancies in this context. Methods. A comprehensive search of literature employing electronic as well as manual sources and screening 2783 papers published between Jan 1980 and Oct 2015 was conducted to collect, identify, and analyze relevant information through peer-reviewed research articles, systematic reviews, and other published works. The cardiovascular events, including accelerated atherosclerotic cardiovascular disease (ASCVD), stroke, heart failure, myocardial infarction, myocardial ischemia, and stress induced myocardial dysfunction, leading to death were considered relevant. Results. A total of 23 published articles met the inclusion criteria and were included for in-depth review and analysis to finalize a comprehensive systematic review article. All the studies showed a significant association between the blood pressure and cardiovascular disease events in hemodialysis patients. Conclusions. Both intradialytic hypertension/hypotension episodes are major risk factors for cardiovascular mortality with a high percentage of probable causality; however, clinicians are faced with a dilemma on how to evaluate blood pressure and treat this condition.

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.

Is Hypertension Beneficial to the Conventional Hemodialysis Patient?

Hypertension is common in the conventional hemodialysis population. While hypertension in the general population has been shown to reduce survival, the issue is less clear in the dialysis population. This review focuses on recent studies showing a favorable outcome in hypertensive hemodialysis patients compared to those with lower blood pressure. Possible explanations for this paradoxical relationship are examined and practical suggestions given for the management of hypertension in the hemodialysis patient.

Assessment and management of hypertension in patients on dialysis

Hypertension is common, difficult to diagnose, and poorly controlled among patients with ESRD. However, controversy surrounds the diagnosis and treatment of hypertension. Here, we describe the diagnosis, epidemiology, and management of hypertension in dialysis patients, and examine the data sparking debate over appropriate methods for diagnosing and treating hypertension. Furthermore, we consider the issues uniquely related to hypertension in pediatric dialysis patients. Future clinical trials designed to clarify the controversial results discussed here should lead to the implementation of diagnostic and therapeutic techniques that improve long-term cardiovascular outcomes in patients with ESRD.

Significance of white-coat and masked hypertension in chronic kidney disease and end-stage renal disease

Hypertension is a frequent and modifiable cardiovascular risk factor with a cyclic relationship with chronic kidney disease (CKD). The diagnosis, treatment, monitoring and control of high blood pressure are all mandatory not only in CKD but also in end-stage renal disease (ESRD). As demonstrated by studies using population and hypertensive patients, white-coat hypertension (WCHT) and masked hypertension (MHT) carry a particular degree of risk. The advantages of ambulatory techniques in the management and prognostic stratification of patients with CKD and ESRD have also been recognized. However, most of the evidence underlines the importance of nocturnal hypertension and neglects WCHT and MHT. The absence of specific reports involving untreated and treated patients hinders the ability to significantly discriminate WCHT from the white-coat effect and MHT from masked uncontrolled hypertension. The heterogeneous definitions that are used add additional difficulty in translating experimental evidence into clinical practice. Reaching a consensus in definitions is mandatory for designing future research. Cross-sectional studies underscore the frequency of misdiagnosis, potentially leading to undertreatment (MHT) and overtreatment (WCHT) in renal disease. The divergent prevalence of WCHT and MHT reported in CKD could be related to the diverse definitions of hypertension and the heterogeneity of the pathologies pooled under the CKD definition. Even in the absence of randomized clinical trials specifically addressing this issue, the scarce longitudinal studies confirm that WCHT carries a risk close to that of sustained normotension, whereas MHT is associated with a risk close or identical to that of sustained hypertension.

Ambulatory blood pressure in chronic kidney disease

Chronic kidney disease (CKD) affects approximately 20 million adults in the United States. Patients with CKD have an increased risk of cardiovascular (CV) disease. Ambulatory blood pressure monitoring (ABPM) provides superior BP measurements when compared to office BP measurements in normotensive, hypertensive and CKD patients. ABPM measurements are often abnormal in CKD, with CKD patients frequently showing an altered circadian rhythm with an increased rate of non-dipping and reverse dipping. The prevalence of non-dippers and reverse-dippers increases progressively as stage of CKD progresses. ABPM has been shown to be a better tool for predicting CV risk, CKD progression, end stage renal disease (ESRD) or death than office-based pressures. ABPM is also additive and adds prognostic value for predicting CKD and CV outcomes when added to estimated glomerular filtration rate (eGFR). Although ABPM is time consuming, it is worth considering, as the data demonstrates that information from ABPM can potentially impact future CV and renal outcomes in patients with CKD.

Forty-four-hour interdialytic ambulatory blood pressure monitoring and cardiovascular risk in pediatric hemodialysis patients

Background

Children undergoing chronic hemodialysis are at risk of cardiovascular disease and often develop left ventricular hypertrophy (LVH). Twenty-four-hour ambulatory blood pressure monitoring (ABPM) is known to better predict cardiovascular morbidity than casual blood pressure (BP) measurement. Given the BP variability attributed to interdialytic fluid overload, 44-h ABPM should better delineate cardiovascular morbidity in pediatric hemodialysis patients.

Methods

In this cross-sectional study, 17 children (16.7 ± 2.9 years) on chronic hemodialysis underwent 44-h interdialytic ABPM and routine echocardiogram. Left ventricular mass index (LVMI) was calculated by height-based equation; LVH was defined as an LVMI in the ≥95th percentile for height-age and gender. Hypertension was defined by the recommendations of the Fourth Report of the National High Blood Pressure Education Program for casual measurements, and by those of the American Heart Association for ABPM.

Results

Twenty-four percentage of patients were hypertensive by casual post-dialytic systolic BP, whereas 59% were hypertensive by ABPM. Eighty-eight percentage of patients had abnormal cardiac geometry: 53% had LVH. Thirty-five percentage (6 of 17) had masked hypertension, including four with abnormal cardiac geometry, of which, three had LVH. LVMI correlated with ABPM, but not with casual measurements. Strongest correlations with an increased LVMI were with 44-h diastolic BP: at night (r = 0.53, P = 0.03) and total load (r = 0.57, P = 0.02). LVH was similarly associated with 44-h nighttime BP: systolic (P = 0.02), diastolic (P = 0.01) and mean arterial (P = 0.01).

Conclusions

Casual BP measurement underestimates hypertension in pediatric hemodialysis patients and does not correlate well with indicators of cardiovascular morbidity. In contrast, 44-h interdialytic ABPM better characterizes hypertension, with nighttime parameters most strongly predicting increased LVMI and LVH.

Obstructive sleep apnea in incremental hemodialysis: determinants, consequences, and impact on survival

Sleep disorders are common in hemodialysis patients, although causes and consequences remain unclear. We sought to establish prevalence, determinants, and outcomes of sleep disturbances in patients receiving incremental dialysis. One hundred two unselected patients undergoing incremental high-flux hemodialysis or hemodiafiltration underwent limited overnight sleep study. Large subsets underwent echocardiography, interdialytic ambulatory blood pressure monitoring, and brain natriuretic peptide measurements. Patients were followed up to 44 months. Full sleep data were obtained in 91 patients. All had sleep disturbance as evidenced by an apnea-hypopnea index >5/min. We defined major obstructive sleep apnea (MOSA) as an apnea-hypopnea index ≥ 15, together with either significant oxygen desaturation or symptoms of daytime sleepiness. Forty patients met these criteria. Significant independent predictors of MOSA were age <65 years, male gender, has diabetes, and has a brain natriuretic peptide >2500 pg/mL. Mean ambulatory blood pressure and left ventricular mass index were significantly higher in these patients. In a model controlling for body mass index, high C-reactive protein, and the presence of cancer, MOSA was associated with a twofold increased risk of mortality, although this did not reach statistical significance. MOSA was common, and was associated with hypertension and high left ventricular mass index. Whether obstructive sleep apnea contributes to the high mortality remains to be firmly established.

Intradialytic hypertension and the association with interdialytic ambulatory blood pressure

BACKGROUND AND OBJECTIVES

Increasing BP during maintenance hemodialysis or intradialytic hypertension is associated with increased morbidity and mortality. In hemodialysis patients, ambulatory BP measurements predict adverse cardiovascular outcomes better than in-center measurements. We hypothesized that patients with intradialytic hypertension have higher interdialytic ambulatory systolic BP than those without intradialytic hypertension.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a case-control study in adult hemodialysis patients. Cases consisted of subjects with intradialytic-hypertension (systolic BP increase ≥10 mmHg from pre- to posthemodialysis in at least four of six treatments), and controls were subjects with ≥10 mmHg decreases from pre- to posthemodialysis in at least four of six treatments. The primary outcome was mean interdialytic 44-hour systolic ambulatory BP.

RESULTS

Fifty subjects with a mean age of 54.5 years were enrolled (25 per group) among whom 80% were men, 86% diabetic, 62% Hispanic, and 38% African American. The mean prehemodialysis systolic BP for the intradialytic-hypertension and control groups were 144.0 and 155.5 mmHg, respectively. Mean posthemodialysis systolic BP was 159.0 and 128.1 mmHg, for the intradialytic-hypertension and control groups, respectively. The mean systolic ambulatory BP was 155.4 and 142.4 mmHg for the intradialytic-hypertension and control groups, respectively (P = 0.005). Both daytime and nocturnal systolic BP were higher among those with intradialytic hypertension as compared with controls. There was no difference in interdialytic weight gain between groups.

CONCLUSIONS

Time-integrated BP burden as measured by 44-hour ambulatory BP is higher in hemodialysis patients with intradialytic hypertension than those without intradialytic hypertension.

Median intradialytic blood pressure can track changes evoked by probing dry-weight

BACKGROUND

Median BP obtained over a single dialysis treatment can diagnose hypertension among hemodialysis patients. Whether median BP is as useful to track change in BP is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among patients participating in the dry-weight reduction in hypertensive hemodialysis patients (DRIP) trial, interdialytic ambulatory BP was recorded at baseline, 4 weeks, and 8 weeks. The mean interdialytic ambulatory BP was compared to the following recordings: predialysis on one dialysis treatment (Pre1), predialysis averaged over 2 weeks of dialysis treatment (Pre6), postdialysis on one dialysis treatment (Post1), postdialysis averaged over 2 weeks of dialysis treatment (Post6), and median intradialytic BP over one treatment.

RESULTS

Pre1 was unable to detect change in ambulatory BP. Although Pre6 was able to detect change, it overestimated the ambulatory BP. On average, the magnitude of reduction in Post1 in response to probing dry-weight was nearly twice that obtained by ambulatory BP monitoring. Even Post6 overestimated the magnitude of reduction in BP at 8 weeks. Median systolic BP was responsive to probing dry-weight and neither overestimated nor underestimated the interdialytic ambulatory systolic BP at baseline or over time. However, the SD of the differences between median systolic BP and interdialytic ambulatory systolic BP varied from 16 to 20 mmHg.

CONCLUSIONS

Median intradialytic BP recordings can detect change in ambulatory BP evoked by reduction in dry-weight at the population level. Because of wide agreement limits between intradialytic and interdialytic BP, the individual prediction of ambulatory BP from median intradialytic BP can be misleading.

Ultrafiltration Volume Is Associated with Changes in Blood Pressure in Chronically Hemodialyzed Patients

INTRODUCTION

Volume overload is a main factor in development of hypertension in hemodialysis patients. In order to demonstrate impact of ultrafiltration volume on blood pressure during 15-months period in a group of patients undergoing chronic hemodialysis therapy, we conducted this study. We hypothesized that ultrafiltration volume different affects the pre/postdialysis systolic pressure, diastolic pressure, mean arterial pressure (MAP), and pulse pressure (PP) values.

SUBJECTS AND METHODS

Study subjects were 23 anuric chronically hemodialyzed patients. The overall study time was 15 months, and 136 single hemodialysis treatments were analyzed.

RESULTS

Ultrafiltration was negatively correlated with predialysis systolic blood pressure (r = -0.169, p = 0.025), postdialysis systolic blood pressure (r = -0.292, p < 0.001), postdialysis MAP (r = -0.186, p = 0.015), predialysis PP (r = -0.290, p < 0.001), and postdialysis PP (r = -0.370, p < 0.001). Ultrafiltration/dry body mass (UF/W) ratio was negatively correlated with predialysis PP (r = -0.222, p = 0.005), postdialysis PP (r = -0.340, p < 0.001), and postdialysis systolic blood pressure (r = -0.243, p = 0.002). We found significant difference in postdialysis PP between dialyses with UF/W ratio < or = 0.05 an dialyses with UF/W ratio > 0.05 (63.49 +/- 20.76 vs. 56.27 +/- 16.33 mmHg, p = 0.033).

CONCLUSION

The ultrafiltration volume strongly affects postdialysis PP values. Evaluation of elevated blood pressure treatment in patients undergoing chronic hemodialysis therapy must be considered in respect of postdialysis PP values, not just depending on pre/postdialysis systolic and diastolic pressur or MAP values.

[Influence of blood pressure control on maintenance of residual function in patients treated by haemodialysis]

INTRODUCTION

Residual renal function (RRF) in the patients treated by haemodialysis (HD) is associated not only with better volume and blood pressure control but also with better metabolic control.The condition of the cardiovascular system significantly affects RRF.

OBJECTIVE

The aim of the study was to find if there was any association between blood pressure regulation and the achieved HD ultrafiltration in the first year of haemodialysis treatment and the maintenance of RRF.

METHODS

In this retrospective study, 53 patients were analyzed in the period 1994-2002. Residual clearance of urea (RCU) was measured for the first time at the beginning of HD treatment, and for the second time one year later. Laboratory data and values of blood pressure as well as the achieved HD ultrafiltration were taken from the electronic database of the Nephrology Hospital.

RESULTS

The value of RCU less than 1 ml/min was considered as the loss of RRF and, at the beginning of HD treatment, 14 patients (26.4%) had that result. The rise of mean arterial pressure (MAP) was associated in linear regression analysis with a drop of residual diuresis volume (beta = -0.28; p = 0.04), but there was no association with RCU. The patients with MAP > 105 mm Hg had RKU less than the patients with MAP < 105 mm Hg (t = 2.23; p = 0.03). The rise of the HD ultrafiiltration significantly affected the loss of RRF obtained by the linear regression analysis (beta = -0.44; p = 0.0001).

CONCLUSION

The greater HD ultrafiltration is related to a drop of RCU values. Only prospective randomised trials with the use of multiple regression analysis could define a more precise association between hypertension and RKU.

Hypertension in dialysis and kidney transplant patients

For the first time, the Canadian Hypertension Education Program has studied the evidence supporting blood pressure control in people requiring renal replacement therapy for end-stage kidney disease, including those on dialysis and with renal transplants. According to the Canadian Organ Replacement Registry's 2008 annual report, there were an estimated 33,832 people with end-stage renal disease in Canada at the end of 2006, an increase of 69.7% since 1997. Of these, 20,465 were on dialysis and 13,367 were living with a functioning kidney transplant. Thus, it is becoming more likely that primary care practitioners will be helping to care for these complex patients. With the lack of large controlled clinical trials, the consensus recommendation based on interpretation of the existing literature is that blood pressure should be lowered to below 140/90 mmHg in hypertensive patients on renal replacement therapy and to below 130/80 mmHg for renal transplant patients with diabetes or chronic kidney disease.

Blood volume monitoring to adjust dry weight in hypertensive pediatric hemodialysis patients

The aim of this study was to adjust dry weight by short-term blood volume monitoring (BVM)-guided ultrafiltration and evaluate the effects of optimizing dry weight on blood pressure (BP) control and intradialytic symptoms (IDS) in a group of hypertensive hemodialysis (HD) patients. The study was performed in four sequential phases, each of which lasted for 1 week, on nine hypertensive HD patients (six girls, age 16.9 +/- 3.1 years). In phase I, patients were observed by BVM. In phase II, BVM was used to guide ultrafiltration to adjust dry weight. Antihypertensive drugs were gradually tapered or withheld in phase III, when the patients were hypotensive and/or their IDS increased. In phase IV, this particular weight was maintained without any intervention. Pre- and post-HD body weight, pre-HD, post-HD, 30 min after HD casual BP values, and IDS in each HD session were recorded. The BP was also assessed by 44-h ambulatory BP monitoring (ABPM), which is an ideal method to determine BP changes throughout the interdialytic period at the beginning of phase I and at the end of phase IV. There was a decrease in mean dry weight, all casual systolic BPs, and systolic/diastolic ABPM at the end of the study (all p < or = 0.05). Antihypertensive drugs were stopped in five patients and reduced in two during phase III of the study. The IDS was more frequent (36%) in phase IV than in phase I (16%); however, this increase did not reach statistical significance. The results of this study suggest that short-term BVM guided-ultrafiltration may be a useful tool to diagnose volume overload and to adjust dry weight and, consequently, to achieve a better control of BP in pediatric HD patients.

Diagnosing hypertension by intradialytic blood pressure recordings

BACKGROUND AND OBJECTIVES

The diagnosis of hypertension among hemodialysis patients by predialysis or postdialysis blood pressure (BP) recordings is imprecise and biased and has poor test-retest reliability. The use of intradialytic BP measurements to diagnose hypertension is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A diagnostic-test study was done with interdialytic ambulatory BP as reference standard. Index BP recordings tested were: predialysis (method 1), postdialysis (method 2), intradialytic (method 3), intradialytic including predialyis and postdialysis (method 4), and the average of predialysis and postdialysis (method 5). Each index BP was recorded over six consecutive dialysis treatments.

RESULTS

There were differences among index BP measurements in reproducibility, bias, precision, and accuracy. Method 4 was the most reproducible (intraclass correlation coefficient = 0.70 for systolic and diastolic BP). All 5 measurement methods overestimated 44-h ambulatory systolic BP. Methods 2, 3, or 4 overestimated ambulatory systolic BP by only a small amount. Method 4 was the most precise and accurate. For diagnosis of hypertension, BP cut-point by method 4 of 135/75 mmHg, had a sensitivity of 90.4% and specificity of 75.9% for systolic BP (area under ROC curve 0.90). Median cut-off systolic BP of 140 mmHg from a single dialysis provides approximately 80% sensitivity and 80% specificity in diagnosing systolic hypertension; a median cut-off diastolic BP of 80 mmHg provides approximately 75% sensitivity and 75% specificity in diagnosing diastolic hypertension.

CONCLUSIONS

Consideration of intradialytic BP measurements together with predialysis and postdialysis BP measurements improves the reproducibility, bias, precision, and accuracy of BP measurement compared with predialysis or postdialysis measurements.

The association between blood pressure and mortality in ESRD-not different from the general population?

Hypertension (HTN) is a traditional cardiovascular risk factor and is prevalent in end-stage renal disease (ESRD). There are no adequately powered prospective studies that explore the natural history and outcomes of HTN and blood pressure management in ESRD. Observational studies have not uniformly showed a relationship between HTN and mortality risk in this population. Furthermore, many studies paradoxically show an increased risk of death associated with low and "normal" blood pressure (BP), sometimes referred to as "reverse epidemiology." We review findings from observational studies specifically performed in ESRD and provide an alternative interpretation-that patients with kidney disease on dialysis therapy are indeed different from the general population. At minimum, these differences may be based on the prevalence of cardiovascular morbidity, specifically the excessive prevalence of congestive heart failure. However, there are other reasons for ESRD patients, especially those on hemodialysis, to exhibit differential effects with regard to blood pressure and outcomes. We explore the implications of available observational evidence and recommend studies that elucidate the differences between ESRD and the general population. Because of the higher mortality risk associated with low or "normal" BP, diagnostic and therapeutic options and strategies for ESRD patients whose BP falls within "goal" should be addressed in future iterations of clinical practice guidelines. These strategies may include assessment of cardiac function and careful attention to achieving optimal fluid balance.

Pre- and postdialysis blood pressures are imprecise estimates of interdialytic ambulatory blood pressure

BP readings that are obtained in the dialysis unit are commonly used to make therapeutic decisions by clinicians and to predict morbidity and mortality by epidemiologists. Dialysis unit BP are also incorporated in the recent guidelines to target BP control. The magnitude of the difference, overestimation or underestimation, and agreement between dialysis unit BP and ambulatory BP (ABP) are unknown. Articles were selected from Medline to identify those that reported both ABP and dialysis unit BP in hemodialysis patients. Bias was calculated as the difference between dialysis unit and the corresponding ABP. Agreement limits between the BP measurement techniques were assessed by pooled SD of the difference using Bland-Altman methods. Predialysis systolic BP generally overestimated ABP by a variable amount. The heterogeneity between BP measurements did not allow for pooling of the estimates. The agreement limits between the two BP was 41.7 to -25.2 mmHg. Predialysis diastolic BP also generally overestimated the ABP with wide agreement limits (23.7 to -18.9 mmHg). In contrast, postdialysis BP underestimated average ABP with wide agreement limits for both postdialysis systolic BP (33.1 to -36.3 mmHg) and diastolic BP (19.3 to -23.9 mmHg). Dialysis unit BP measurements are imprecise estimates of ABP. Better methods are needed for the assessment of BP in hemodialysis patients for clinical decision making.

Acquired cystic kidney disease and arterial hypertension in hemodialysis patients

BACKGROUND

Acquired cystic kidney disease (ACKD) and arterial hypertension (AH) are both frequent complications in hemodialysis (HD) patients. Until now, AH has not been described as a complication of ACKD.

PATIENTS AND METHODS

Our study included 86 HD patients (46 men and 40 women; mean age 51.3 years; mean duration of HD treatment 55.3 months). Their native kidneys were examined with an ATL-HDI 3000 ultrasound device (2-4 MHz convex probe). Depending on the number of cysts in the kidney, the manifestations were divided into three grades: grade 0: no cysts; grade 1: fewer than ten cysts in both kidneys; grade 2: more than ten cysts in both kidneys. Blood pressure was measured 30 minutes before and after HD. Mean one-month values were analyzed. AH was defined as systolic blood pressure > or = 150 mmHg, diastolic blood pressure > or = 90 mmHg and/or antihypertensive treatment. The diameter of the inferior vena cava (indicator of dry weight) was measured with the same ultrasound device as the kidneys three hours after HD.

RESULTS

ACKD was present in 48 (55.8%) patients, there was no statistically significant difference regarding sex. Twenty-four (50%) patients had grade 1 ACKD and 24 (50%) grade 2 ACKD. Sixty-eight (79.1%) patients suffered from AH, which was significantly more common among the men (P = 0.048). AH was detected before HD in 68 (79.1%) patients and in 54 (62.8%) patients also after HD. Thirty-nine (45.3%) patients suffered simultaneously from ACKD and AH; 22 (56.4%) of them were men and 17 (43.6%) women. No significant correlation between AH and ACKD was established. The prevalence and grade of ACKD were significantly associated with the duration of dialysis treatment (P < 0.01). Multiple regression analysis detected a significant correlation only between AH and the diameter of the inferior vena cava (P < 0.05).

CONCLUSIONS

ACKD is common in HD patients. Its prevalence and grade increase with the duration of dialysis treatment. ACKD is not associated with AH. There is a correlation between the diameter of the inferior vena cava, as a factor of circulating fluid volume, and AH in HD patients.

Management of hypertension in hemodialysis patients

The relationship of hypertension with adverse outcomes is uncertain in the hemodialysis population. If hypertension is an etiologically significant cardiovascular risk factor in hemodialysis patients, the first step would be to assess the level of BP accurately. BP obtained at home over a week and averaged using a validated oscillometric automatic device can prove valuable. To the extent BP lowering influences cardiovascular outcomes, home BP of 150/90 mm Hg would warrant therapy, since it correlates with target organ damage and hypertension diagnosed by ambulatory BP monitoring. To manage hypertension, limiting dietary sodium intake and individualizing dialysate sodium delivery would be first steps. The magnitude of reduction in BP with dietary sodium restriction and the whether dialysate sodium can be safely limited in those who are hypotension-prone is unclear. Antihypertensive drug therapies can effectively reduce BP and are needed by the vast majority of hemodialysis patients. Whether control of hypertension translates into better outcomes is not known, but collective evidence suggests that hypertension should be controlled in hemodialysis patients.

The role of ambulatory blood pressure monitoring in chronic and end-stage renal disease

In the past 30 years or so, the introduction of 24-h ambulatory blood pressure monitoring (ABPM) has enabled a more comprehensive estimate of a patient's true blood pressure (BP) and its changes. Although this tool has been used in the general population for the diagnosis of white coat hypertension, its role in the clinical management of patients with chronic and end-stage kidney disease is less well defined. In patients with kidney disease, routine clinic and dialysis center BP measurements may be poor indicators of BP control. Loss of the normal nocturnal decline in BP is also common. Moreover, there is increasing evidence that this loss, which ABPM alone can detect, is associated with poor renal and cardiovascular outcomes. To slow the progression of renal disease and lessen cardiovascular morbidity and mortality in patients with kidney disease, tight BP control is needed. However, the traditional methods of measuring BP intermittently in the medical setting may fail to provide an accurate picture of BP load. Ambulatory or some form of home BP monitoring should be more widely adopted in patients with chronic and end-stage renal disease.

Home blood pressure monitoring improves the diagnosis of hypertension in hemodialysis patients

Using interdialytic ambulatory blood pressure (BP) recordings as the reference standard, we compared the performance of routine, standardized and home BP monitoring in 104 predominantly black patients on chronic hemodialysis for at least 3 months. Dialysis unit BP recordings were averaged over 2 weeks and home BP over 1 week. Awake ambulatory BP of > or =135 mmHg systolic or > or =85 mmHg diastolic was taken as evidence of hypertension. Average awake ambulatory BP was 128.1+/-21.6/73.5+/-13.5 mmHg, home BP 141.3+/-21.9/78.7+/-11.9 mmHg, standardized pre-dialysis BP 141.7+/-22.6/74.2+/-13.5 mmHg and post-dialysis 119.9+/-20.5/69.1+/-13.1 mmHg, routine pre-dialysis 145.4+/-21.8/79.0+/-13.1 mmHg and post-dialysis 131.5+/-19.2/72.5+/-11.4 mmHg. Sixty-three percent of the patients had well-controlled BP by ambulatory BP monitoring and isolated diastolic hypertension was rare (3%). The standard deviation of the differences between ambulatory and routine pre-dialysis BP was 17.6 mmHg, routine post-dialysis was 16.1 mmHg, standardized pre-dialysis was 16.4 mmHg, standardized post-dialysis was 14.1 mmHg, and home BP was 14.2 mmHg. The area under receiver operating characteristic curves was similar for home and standardized BP but lower for routine BP. Home systolic BP of > or =150 mmHg averaged over 1 week had the best combination of sensitivity (80%) and specificity (84.1%) in diagnosing systolic hypertension--present in 94% of the hypertensive dialysis patients. Home BP monitoring is similar to standardized recording of BP in hemodialysis patients. A systolic BP threshold of 150 mmHg at home averaged over 1 week serves as a useful predictor of hypertension diagnosed by ambulatory BP monitoring.

Haemodialysis-unresponsive blood pressure: cardiovascular mortality predictor?

AIM

The importance of 'conventional' cardiovascular risk factors in haemodialysis (HD) patients has been questioned following evidence that pre-HD blood pressure (BP) might be inversely related to mortality in contrast to post-HD BP. To evaluate this reverse BP epidemiology in HD patients, HD-induced BP changes were compared with aortic pulse wave velocity (PWV), an independent predictor of cardiovascular mortality.

METHOD

Aortic PWV was evaluated in a limited care HD cohort, all of whom were asymptomatic of cardiovascular disease.

RESULTS

Of 47 limited care patients, 45% were classified as HD responsive, with a 17% fall in mean arterial pressure compared with a 6% increase in the HD-unresponsive group. While there were no significant differences between the two groups in traditional vascular disease risk factors or interdialytic weight loss, PWV was significantly elevated in the HD-unresponsive group (12.9 +/- 2.7 compared with 10.8 +/- 2.9; P < 0.05). Furthermore, there was a positive correlation between the change in BP during HD and PWV in all subjects (r = 0.500; P < 0.001 for systolic blood pressure (SBP), a correlation that also existed for diastolic blood pressure (DBP) (P < 0.01).

CONCLUSION

This study suggests that patients with HD-unresponsive BP are more likely to have vascular disease and this association between PWV and HD-induced BP changes might partly explain the apparent paradox of pre- and post-HD BP with mortality. It is proposed that a population with elevated post-HD BP is more likely to be composed of subjects with vascular disease (overt or occult), in contrast to a group with high pre-HD BP, which will be more heterogeneous.

Recent insights from studies using ambulatory blood pressure monitoring in patients with renal disease

PURPOSE OF REVIEW

To identify and evaluate recent (2000-2003) published studies employing ambulatory blood pressure monitoring in patients with chronic renal failure, on dialysis, and after renal transplantation.

RECENT FINDINGS

We discuss several studies that have employed ambulatory blood pressure monitoring to refine the analysis of the link between blood pressure levels, and diurnal alterations, and end-organ damage or patient survival. There is now some evidence that an abnormal diurnal blood pressure profile, although intrinsically not a very reproducible label, has predictive value for patient survival, and that the non-dipping phenomenon is linked to a high incidence of cardiovascular disease and autonomic dysfunction.

SUMMARY

Ambulatory blood pressure monitoring remains an important adjunct to the comprehensive cardiovascular evaluation of patients with chronic, end-stage renal failure or after renal transplantation.

Diurnal variation of blood pressure; reproducibility and association with left ventricular hypertrophy in hemodialysis patients

OBJECTIVE

The objective of this paper is to describe the pattern of diurnal blood pressure (BP) change in hemodialysis patients, determine the association of the non-dipping pattern of diurnal BP with left ventricular mass index (LVMI), and to determine if the nocturnal profile of BP is reproducible when repeated over time.

METHODS

In a cross-sectional study, ambulatory blood pressure monitoring (ABPM) was performed over a midweek 44-h period and echocardiography was performed on the interdialytic day. Patients with a night/day systolic and diastolic BP ratio on both days >0.9 were defined as non-dippers. Ambulatory blood pressure monitoring was repeated at 6 and 12 months follow-up.

RESULTS

Of the 59 patients, 88% were African-American, and 48% were non-dippers. Mean LVMI was significantly higher in the non-dipper (68.3+/-25 g/height) compared to the dipper patients (55.6+/-16, P<0.05). Mean nocturnal systolic BP (r=0.35) and the night/day systolic BP ratio (r=0.39) had a higher correlation with M-mode LVMI than pre-dialysis (r=0.32). After adjustment for 44-h mean SBP, night/day systolic BP ratio remained independently associated with LVMI (beta coefficient 147.62, P=0.004). Of 12 patients who had a non-dipper profile at baseline, 11 (92%) demonstrated the same profile after 6 months and 1 year of follow-up.

CONCLUSION

Many hemodialysis patients demonstrate a non-dipper profile; the degree of decline in nocturnal BP is independently associated with LVMI even after adjustment for mean BP. Patients who are identified as non-dippers consistently reproduce the same profile over time.

The use of peridialysis blood pressure and intradialytic blood pressure changes in the prediction of interdialytic blood pressure in haemodialysis patients

OBJECTIVE

It is uncertain which blood pressure values (pre- or post-haemodialysis) best represent the average daily blood pressure in haemodialysis patients. The purpose of this study was to verify the power of peridialysis blood pressure to predict interdialytic blood pressure, and to ascertain the influence of blood pressure fluctuations during dialysis on this predictive ability.

METHODS AND RESULTS

We performed ambulatory blood pressure monitoring during the interdialytic period on 60 stable haemodialysis patients (mean age 53 +/- 16 years, 33 male) between two mid-week haemodialysis sessions. Pre- and post-haemodialysis blood pressures were 154/82 and 142/77 mmHg, respectively, and 44-h interdialytic blood pressure was 136/77 mmHg. Overall, post-haemodialysis blood pressure values correlated with interdialytic ambulatory blood pressure marginally better than did pre-haemodialysis values (r = 0.52 versus 0.61 for pre- and post-dialysis systolic pressure, respectively; r = 0.67 versus 0.72 for pre- and post-dialysis diastolic pressure, respectively). The average of the pre- and post-haemodialysis values showed a slightly better correlation with interdialytic blood pressure (r = 0.65 and 0.75 for systolic and diastolic pressure, respectively). When we stratified patients according to systolic blood pressure behaviour during dialysis, pre-dialysis blood pressure was the stronger predictor of interdialytic blood pressure in the quartile with greatest intradialytic blood pressure fall (r = 0.67 versus 0.44 for pre- and post-dialysis systolic blood pressure, respectively), whereas post-dialysis values were substantially better in the group with a rise in systolic pressure during dialysis (r = 0.26 versus 0.59 for pre- and post-dialysis systolic blood pressure, respectively).

CONCLUSIONS

These data demonstrate that peridialysis blood pressure values are of limited accuracy in predicting interdialytic blood pressure, post-dialysis values are minimally better predictors than pre-dialysis blood pressures, and the average of pre- and post-haemodialysis values is marginally better than both. In addition, blood pressure fluctuations during dialysis have a sizable impact on this predictive ability. Clinical decisions related to blood pressure management and research design in haemodialysis hypertension should take these factors into account.

Blood pressure measurement in hemodialysis patients

Measurement of blood pressure (BP) poses some unique challenges in hemodialysis patients. Timing of BP measurement in relation to dialysis, changes in interdialytic weight gain, and inconsistent BP measurement technique in dialysis units contribute to the variability of BP readings in this population. This may contribute to the equivocal relationship between hypertension and cardiovascular outcomes documented in several epidemiologic studies in this population. Home BP readings are promising, but need to be validated as a measure of the burden of hypertension in this population. It is important to standardize BP measurement in all hemodialysis units according to published guidelines to improve the management of hypertension. Future research studies should carefully validate the technique used to measure BP.

Ambulatory blood pressure monitoring in hemodialysis patients: a critique and literature review

Ambulatory blood pressure (ABP) monitoring has been in use for nearly four decades. In that time, the advantages of using a more reproducible and accurate method to assess the true contribution of blood pressure to the cardiovascular risk profile of patients have steadily become more clearly established, balanced by the additional expense and expertise involved. In nephrology, and in particular in dialysis patients, there are significant difficulties in accurately registering truly representative blood pressure values and understanding the relationship between blood pressure, end-organ damage, and patient mortality. This arises because of the way in which hemodialysis acutely changes blood pressure values as well as the widespread abnormality of diurnal blood pressure rhythm seen in dialysis patients. Use of ABP monitoring can go some way to overcoming these obstacles. In this review we critically examine the use of ABP monitoring in the understanding of blood pressure control in dialysis patients.

Blood pressure measurement in dialysis patients

The best method and timing of blood pressure (BP) measurement in end-stage renal disease are subject to controversy. This issue is especially relevant in hemodialysis patients, where unique causes of inaccuracy may exist. The lack of standardization of BP measurement in the dialysis unit may lead to misdiagnosis, so close attention must be paid to technical methods to obtain BP. A composite of BP measurements over a period of 1 to 2 weeks rather than isolated readings should be used for guidance. Interdialytic BP monitoring with an ambulatory BP monitor is the most reproducible method and is thought to best represent BP in dialysis patients. If available, ambulatory BP is a useful tool to evaluate the quality of BP control in the interdialytic period. Alternative forms of BP measurement, such as home BP, 20-minute postdialysis BP, and short (3-hour to 4-hour) ambulatory blood pressure monitoring (ABPM), could prove useful when feasible or available. In this paper, we discuss the evidence regarding BP measurement in dialysis patients, new techniques under development, and recommendations for clinical practice.

Mean arterial pressure and pulse pressure are associated with different clinical parameters in chronic haemodialysis patients

The mean arterial pressure (MAP) usually serves as an expression of blood pressure in patients on chronic haemodialysis (PCHD), instead of using solely systolic or diastolic pressure. Pulse pressure (PP) has been recognized as an important correlate of mortality in PCHD. We conducted this study in order to demonstrate clinical and biochemical determinants and variability of predialysis and postdialysis MAP and PP values. A total of 136 single haemodialysis (HD) treatments in 23 subjects (PCHD, 11 male and 12 female patients) were processed during 15 months. MAP before HD was in negative correlation with haemoglobin (P<0.001) and body mass index (BMI) (P<0.001), and in positive correlation with weekly erythropoietin dosage (P=0.017). MAP after HD was in negative correlation with haemoglobin (P<0.001), ultrafiltration per HD (P=0.015), and BMI (P=0.001), and in positive correlation with weekly erythropoietin dosage (P=0.003). PP before HD was in negative correlation with parathyroid hormone (PTH) level (P=0.020), haemoglobin (P<0.001), ultrafiltration per HD (P=0.001), and years on the chronic HD treatment (P=0.001), and in positive correlation with weekly erythropoietin dosage (P<0.001) and age (P<0.001). PP after HD was in significant negative correlation with PTH (P=0.015), haemoglobin (P=0.005), ultrafiltration per HD (P<0.001), BMI (P=0.003), and in positive correlation with weekly erythropoietin dosage (P<0.001) and age (P=0.004). Multiple regression analyses unveiled the strongest and negative correlations between MAP before HD and BMI (beta=-0.37, P=0.01); MAP after HD and haemoglobin (beta=-0.36, P=0.01); PP after HD and ultrafiltration/body weight ratio (beta=-0.41, P<0.001). The strongest and positive correlation was found between PP before HD and erythropoietin dosage per week (beta=0.51, P&<0.001). In conclusion, our findings support the assumption that PP and MAP are associated with different clinical parameters. PP values have advantages as the method of blood pressure expression.

Effect of hypertension before beginning dialysis on survival of hemodialysis patients

BACKGROUND

The role of hypertension as a predictor of mortality in hemodialysis patients is controversial. The purpose of this study is to investigate the effect of hypertension before starting hemodialysis therapy on survival of patients without diabetes during renal replacement therapy.

METHODS

We reviewed 184 patients starting hemodialysis therapy. Variables studied were age, sex, renal disease, hypertension, comorbidity, vascular calcifications, left ventricular hypertrophy, body mass index, and albumin, cholesterol, and alkaline phosphatase levels. Regarding blood pressure control, three groups were considered: normotensive (NH), controlled hypertensive (c-HT), and uncontrolled hypertensive (uc-HT).

RESULTS

The Cox model was performed considering all-cause and cardiovascular mortality. The model was adjusted for age, sex, serum albumin level, vascular calcifications, history of hypertension, and comorbidity. Comorbidity included cardiovascular comorbidity. For all-cause mortality, comorbidity and history of uncontrolled hypertension were independent risk factors (comorbidity relative risk, 1.95; 95% confidence interval, 1.26 to 3.1; P = 0.003; uncontrolled hypertension relative risk, 1.79; 95% confidence interval, 1.15 to 2.8; P = 0.01). For cardiovascular mortality, uncontrolled hypertension was the main risk factor (relative risk, 2.93; 95% confidence interval, 1.68 to 5.12; P = 0.000). Mortality rates were 7.9/100 patient-years for NH, 8.7/100 patient-years for c-HT, and 14.1/100 patient-years for uc-HT patients.

CONCLUSION

This study suggests that uncontrolled hypertension in renal patients before starting dialysis therapy is a major risk factor for cardiovascular mortality during hemodialysis. Because hypertension usually starts in the initial stages of renal disease, we emphasize the importance of prompt and adequate control of blood pressure in this population.

Assessment of blood pressure in hemodialysis patients

It is self-evident that accurate measurement of blood pressure (BP) is essential for the diagnosis and treatment of hypertension. Patients on hemodialysis typically do not have their BP measured under standardized conditions, a source of error in the assessment of their BP. However, their are some unique sources of error involving interdialytic weight gain, occurrence of sleep apnea and consequent nocturnal hypertension, inability to take BP in both arms in patients who have hemodialysis angioaccess in the arm, and the white coat effect in these patients as well. Precise measurement of BP in hemodialysis patients requires interdialytic ambulatory BP monitoring. However, when ambulatory BP monitoring is not possible, BP obtained in the dialysis unit can be used in a qualitative sense for prediction of hypertension in these patients. A 2-week average predialysis BP of greater than 150/85 mmHg or a postdialysis BP of greater than 130/75 mmHg has at least 80% sensitivity in diagnosing hypertension. Specificity of at least 80% can be achieved if predialysis BP of greater than 160/90 mmHg or postdialysis BP of greater than 140/80 mmHg are used. However, poor agreement between hemodialysis unit BP and ambulatory BP precludes their use for the precise prediction of BP. Improving measurement techniques in the dialysis unit, averaging multiple BP values, using 20-minute postdialysis readings, or home BP monitoring can improve BP determination when interdialytic BP monitoring is not possible.

Prediction of hypertension in chronic hemodialysis patients

BACKGROUND

There are no universally accepted criteria for the diagnosis of hypertension in hemodialysis (HD) patients. We sought to determine the clinical performance of predialysis and postdialysis systolic and diastolic blood pressure values (BPs) in diagnosing hypertension or assessing its control.

METHODS

Seventy patients [77% African American, 46% females, mean age 59 +/- 17 (SD) years, 34% diabetics] on chronic HD underwent a single 44-hour interdialytic ambulatory blood pressure monitoring (ABPM) and concomitant recording of BP by conventional syphygmomanometer in the HD unit for two weeks. Hypertension was defined as systolic BP (SBP) > or =135 mm Hg or diastolic BP (DBP) > or =85 mm Hg on an average 44-hour ABPM.

RESULTS

Average ABP was 144 +/- 22/81 +/- 11 mm Hg. Seventy-three percent of the patients had systolic hypertension; 40% had diastolic hypertension, and 24% were normotensive or had well-controlled BP. Area under the curve of receiver operating characteristic (ROC) curves exceeded 80% for all BPs, but the thresholds for best sensitivity and specificity were markedly different for predialysis and postdialysis BPs. A two-week averaged predialysis BP of > 150/85 mm Hg or a postdialysis BP of > 130/75 mm Hg had at least 80% sensitivity in diagnosing hypertension. Specificity of at least 80% was achieved if predialysis BP of > 160/90 mm Hg or postdialysis BP of > 140/80 mm Hg was used. There was poor agreement between HD unit BP and ABP values.

CONCLUSIONS

HD unit BP values can be used to identify the presence or absence of hypertension, although prediction of ambulatory BPs from HD unit BP values cannot be made reliably in individual patients.

Reproducibility of ambulatory blood pressure monitoring in hemodialysis patients

Ambulatory blood pressure monitoring (ABPM) has been increasingly used in hemodialysis (HD) practice and research; however, no study has evaluated the reproducibility of ABPM in this population. To address this question, we performed 48-hour interdialytic ABPM on 21 HD patients (mean age, 53 +/- 16 years; 7 women) on two different occasions 68 +/- 34 days (range, 30 to 154 days) apart. To qualify for the protocol, patients had to be at the same dry weight and on the same vasoactive drug regimen at both monitoring periods. BP was analyzed according to three different methods: isolated pre-HD and post-HD values, average pre-HD and post-HD values for the five HD sessions surrounding each monitoring period, and 48-hour interdialytic ABPM. Reproducibility was determined by analysis of the SD of the differences (SDD) between the two monitoring periods and the coefficient of variation of each method of BP determination. Our results show better reproducibility of ABPM (SDD, 10.6/6.6 mm Hg; coefficient of variation, 7.5%/8.1%) compared with isolated pre-HD BP (SDD, 24.4/11.3 mm Hg; coefficient of variation, 16.7%/14.1%) or post-HD BP (SDD, 16.8/14.5 mm Hg; coefficient of variation, 11.7%/17.8%), and averaged pre-HD BP (SDD, 14.7/7.2 mm Hg; coefficient of variation, 10.1%/9.1%) or post-HD BP (SDD, 12.4/8.7 mm Hg; coefficient of variation, 8.9%/11.1%). The reproducibility of the decrease in BP during sleep was poor, with up to 43% of the subjects changing dipping category within or between interdialytic periods. We conclude that ABPM is the most accurate method to study BP in HD patients over time. However, variability is significant, and there is poor reproducibility of the nocturnal decline in BP.

Treatment of hypertension in the hemodialysis patient: beneficial or not?

Hypertension is common in the hemodialysis population. Although hypertension in the general population has been shown to reduce survival and to accelerate atherosclerosis, leading to serious cardiac and cerebrovascular morbidity, its effects are less clear in those undergoing dialysis. This review focuses on recent studies showing a favorable outcome in hypertensive hemodialysis patients when compared with those with lower blood pressure. The possible explanations for this paradoxic relationship are examined, and practical suggestions are given for the management of hypertension in the patient undergoing hemodialysis. We also present information on the morbiditiy associated with hypertension in the hemodialysis population.