Adenosine A1 receptor antagonist improves intradialytic hypotension

Intradialytic Hypotension and Mortality in Adolescents and Young Adults With Kidney Failure Receiving Maintenance Hemodialysis

Rationale & Objective

Intradialytic hypotension (IDH) is associated with mortality in adults with kidney failure requiring hemodialysis (HD); however, large-scale pediatric studies are lacking. Moreover, there is no evidence-based consensus definition of IDH in pediatric literature. We aimed to examine the association of commonly used definitions of IDH with mortality in adolescents and young adults.

Study Design

This was a retrospective observational cohort study.

Setting & Participants

In total, 1,199 adolescents and young adults (N = 320, aged 10-18 years and N = 879, aged 19-21 years) who initiated HD in a large dialysis organization were included.

Exposures

This study used different definitions of IDH.

Outcome

The study outcome was 2-year all-cause mortality.

Analytical Approach

Several definitions of IDH were selected a priori based on a literature review. Patients were classified as having IDH if it was present in at least 30% of HD treatments during the first 90 days after dialysis initiation. Cox proportional hazards regression was used to test whether IDH associated with 2-year all-cause mortality.

Results

Over a 2-year follow-up period, 54 (4.5%) patients died. Dependent on its definition, IDH was present in 2.9%-61.1% of patients. After the multivariable adjustment for sociodemographic and clinical characteristics, we found no association of IDH with mortality. Results were consistent across subgroups stratified by age (aged <18 and 19-21 years) and predialysis systolic blood pressure (<120, 120-150, and >150 mm Hg). We also examined IDH as occurring in <5%, 5%-29%, 30%-50%, and >50% of baseline treatments, and did not find a dose-response association with mortality (P > 0.05).

Limitations

Owing to low event rates, our current sample size may have been too small to detect a difference in mortality.

Conclusions

Our study found that IDH was not associated with mortality in adolescents and young adults.

Bradykinin B2 receptor blockade and intradialytic hypotension

INTRODUCTION

Intradialytic hypotension (IDH) is a common clinical complication and is associated with increased morbidity and mortality in patients undergoing maintenance hemodialysis (MHD). The pathogenesis of IDH has been attributed to the rapid reduction of plasma volume during hemodialysis and the inadequate compensatory mechanisms in response to hypovolemia, such as the lack of vasoconstriction. This may be due to the increased production of vasodilators, such as bradykinin. In this study we test the hypothesis that bradykinin B2 receptor blockade prevents intradialytic hypotension.

METHODS

We performed a post-hoc analysis of a double-blind, placebo-controlled, randomized, 2 × 2 crossover clinical trial comparing the continuous infusion of icatibant, a bradykinin B2 receptor blocker, and placebo during hemodialysis. Icatibant or placebo was infused for 30 min before and during hemodialysis in 11 patients on MHD.

RESULTS

Seven of the patients had IDH, defined as a reduction of systolic blood pressure equal to or greater than 20 mmHg during hemodialysis. Stratified analysis, based on the presence of IDH, revealed that icatibant prevented the decrease in blood pressure compared to placebo in patients with IDH [blood pressure at average nadir (2.5 h after hemodialysis): Placebo,114.3 ± 8.9 vs. icatibant, 125.6 ± 9.1 mmHg, mean ± S.E.M]. Icatibant did not affect blood pressure in the group of patients without IDH.

CONCLUSION

Bradykinin B2 receptor blocker may prevent the occurrence of IDH. Further studies should evaluate the hemodynamic effects of icatibant during hemodialysis and the symptomatology associated with IDH.

Cardiovascular autonomic nervous system dysfunction in chronic kidney disease and end-stage kidney disease: disruption of the complementary forces

PURPOSE OF REVIEW

Several nontraditional risk factors have been the focus of research in an attempt to understand the disproportionately high cardiovascular morbidity and mortality in chronic kidney disease (CKD) and end-stage kidney disease (ESKD) populations. One such category of risk factors is cardiovascular autonomic dysfunction. Its true prevalence in the CKD/ESKD population is unknown but existing evidence suggests it is common. Due to lack of standardized diagnostic and treatment options, this condition remains undiagnosed and untreated in many patients. In this review, we discuss current evidence pointing toward the role of autonomic nervous system (ANS) dysfunction in CKD, building off of crucial historical evidence and thereby highlighting the areas in need for future research interest.

RECENT FINDINGS

There are several key mediators and pathways leading to cardiovascular autonomic dysfunction in CKD and ESKD. We review studies exploring the mechanisms involved and discuss the current measurement tools and indices to evaluate the ANS and their pitfalls. There is a strong line of evidence establishing the temporal sequence of worsening autonomic function and kidney function and vice versa. Evidence linking ANS dysfunction and arrhythmia, sudden cardiac death, intradialytic hypotension, heart failure and hypertension are discussed.

SUMMARY

There is a need for early recognition and referral of CKD and ESKD patients suspected of cardiovascular ANS dysfunction to prevent the downstream effects described in this review.There are many unknowns in this area and a clear need for further research.

Management of acute intradialytic cardiovascular complications: Updated overview (Review)

An increasing number of patients require renal replacement therapy through dialysis and renal transplantation. Chronic kidney disease (CKD) affects a large percentage of the world's population and has evolved into a major public health concern. Diabetes mellitus, high blood pressure and a family history of kidney failure are all major risk factors for CKD. Patients in advanced stages of CKD have varying degrees of cardiovascular damage. Comorbidities of these patients, include, on the one hand, hypertension, hyperlipidemia, hyperglycemia, hyperuricemia and, on the other hand, the presence of mineral-bone disorders associated with CKD and chronic inflammation, which contribute to cardiovascular involvement. Acute complications occur quite frequently during dialysis. Among these, the most important are cardiovascular complications, which influence the morbidity and mortality rates of this group of patients. Chronic hemodialysis patients manifest acute cardiovascular complications such as intradialytic hypotension, intradialytic hypertension, arrhythmias, acute coronary syndromes and sudden death. Thus, proper management is extremely important.

The oxygen cascade in patients treated with hemodialysis and native high-altitude dwellers: lessons from extreme physiology to benefit patients with end-stage renal disease

Patients treated with hemodialysis (HD) repeatedly undergo intradialytic low arterial oxygen saturation and low central venous oxygen saturation, reflecting an imbalance between upper body systemic oxygen supply and demand, which are associated with increased mortality. Abnormalities along the entire oxygen cascade, with impaired diffusive and convective oxygen transport, contribute to the reduced tissue oxygen supply. HD treatment impairs pulmonary gas exchange and reduces ventilatory drive, whereas ultrafiltration can reduce tissue perfusion due to a decline in cardiac output. In addition to these factors, capillary rarefaction and reduced mitochondrial efficacy can further affect the balance between cellular oxygen supply and demand. Whereas it has been convincingly demonstrated that a reduced perfusion of heart and brain during HD contributes to organ damage, the significance of systemic hypoxia remains uncertain, although it may contribute to oxidative stress, systemic inflammation, and accelerated senescence. These abnormalities along the oxygen cascade of patients treated with HD appear to be diametrically opposite to the situation in Tibetan highlanders and Sherpa, whose physiology adapted to the inescapable hypobaric hypoxia of their living environment over many generations. Their adaptation includes pulmonary, vascular, and metabolic alterations with enhanced capillary density, nitric oxide production, and mitochondrial efficacy without oxidative stress. Improving the tissue oxygen supply in patients treated with HD depends primarily on preventing hemodynamic instability by increasing dialysis time/frequency or prescribing cool dialysis. Whether dietary or pharmacological interventions, such as the administration of L-arginine, fermented food, nitrate, nuclear factor erythroid 2-related factor 2 agonists, or prolyl hydroxylase 2 inhibitors, improve clinical outcome in patients treated with HD warrants future research.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

Effect of renal replacement therapy modalities on renal recovery and mortality for acute kidney injury: A PRISMA-compliant systematic review and meta-analysis

Previous investigations showed inconsistent results for comparison in renal recovery, in-hospital, and in-intensive care unit (ICU) mortalities between acute kidney injury (AKI) patients treated with continuous renal replacement therapy (CRRT) and some kinds of intermittent renal replacement therapies (IRRTs). We systematically searched for articles published in the databases (PubMed, Web of Science, EMBASE, Medline, and Google Scholar) until June 2019. We made all statistical analysis using STATA 12.0 software. In the present meta-analysis, relative risks with 95% confidence intervals were calculated for binary outcomes (renal recovery status or mortality). The present study indicated no significant differences in renal recovery, in-hospital mortality, and in-ICU mortality between AKI patients given CRRT and those given sustained low-efficiency dialysis (SLED). Additionally, the study showed no significant difference in in-hospital mortality between AKI patients given CRRT and those given intermittent hemodialysis (IHD), whereas elevated in-ICU mortality was detected in AKI patients given CRRT, compared to those given IHD. The three modalities (CRRT, IHD, and SLED) have their own advantages and disadvantages. More rigorous trials design with large cohort should be made to explore the differences in renal recovery, in-hospital, and in-ICU mortalities between different kinds of RRTs.

Measuring the prevalence of intradialytic hypotension in a satellite dialysis clinic: Are we too complacent?

AIMS AND OBJECTIVES

To measure the prevalence of symptomatic (S-IDH) and asymptomatic intradialytic hypotension (A-IDH) or postdialysis overhydration in a satellite haemodialysis clinic in Western Australia.

BACKGROUND

Intradialytic hypotension is one of the most common side effects of haemodialysis caused by ultrafiltration provoking a temporary volume depletion. The prevalence of asymptomatic hypotension during dialysis has been rarely reported, but is considered to have the same negative consequences as symptomatic hypotension on various end organs like the brain and the gastrointestinal tract.

DESIGN

Observational study on a retrospective 3-month period of nursing recorded fluid-related adverse events.

METHODS

Data collection on the occurrence of S-IDH and A-IDH during a total of 2,357 haemodialysis treatments in 64 patients. Body weight of patients at the time of cessation of treatment was recorded, and patients, whose weight exceeded their ideal body weight by at least 0.5 kg, were classified as overhydrated. Data analysis was performed using spss version 24 software.

RESULTS

Symptomatic intradialytic hypotension was the most common adverse event measured in this cohort, and occurred during 221 (9.4%) of all treatments, whereas asymptomatic intradialytic hypotension occurred in 88 (3.7%) of all treatments. The total occurrence of intradialytic hypotension was 13.1%, and symptomatic was observed in 30 patients, implying that nearly every second patient had at least one symptomatic episode within 3 months. Overhydration occurred in a total of 103 (4.4%) of all treatments, and involved 17 patients.

CONCLUSIONS

Symptomatic and asymptomatic intradialytic hypotension were the most commonly observed adverse events in this cohort; overhydration occurrence was considerably less common.

RELEVANCE TO CLINICAL PRACTICE

The high occurrence of hypotension-related events demonstrates that ultrafiltration treatment goals in satellite dialysis clinics are sometimes overestimated, resulting in regular significant symptomatic episodes for the patient. Raising the awareness of the prevalence of IDH amongst renal nurses could be an essential initial step before collectively preventative strategies in haemodialysis satellite units are implemented.

Hemodialysis Ultrafiltration Rate Targets Should Be Scaled to Body Surface Area Rather than to Body Weight

The association between higher ultrafiltration rates and poor outcomes in hemodialysis patients has received increased attention, to the point that various regulatory entities are considering adding ultrafiltration rate as a quality measure to be monitored and controlled. Most of the discussion to date has focused on ultrafiltration rate scaled to body weight, or more correctly, body mass (ml/hour per kg). One outcome study suggests that ultrafiltration rate might best be not scaled at all to body size, as modestly higher ultrafiltration rate in very small-size patients may be associated with some survival benefit, probably via increased dietary intake. Outcomes studies also suggest that the risk of exceeding a weight-scaled ultrafiltration target may be magnified in very large patients, and that body weight-scaled ultrafiltration targets in such patients should be set a lower level. Here, we present an analysis, based on physiological hemodynamic arguments, that it would be better to scale ultrafiltration rate to body surface area rather than to body mass. Whatever ultrafiltration rate is scaled to, attempts to restrict ultrafiltration rate by limiting interdialytic weight gain in small, possibly malnourished patients, should be done cautiously, to prevent an inadvertent lowering of intake of calories and dietary protein.

Autonomic dysfunction as a mechanism of intradialytic blood pressure instability

The autonomic nervous system (ANS) is the principal endogenous defense mechanism that maintains blood pressure in the setting of hypotension. Disruption of the ANS impairs this ability and can contribute to blood pressure instability, including hypotension and hypertension. In this narrative review, we provide an overview of the ANS and the consequences of its dysfunction in patients with end-stage kidney disease treated with dialysis. We also discuss possible mechanisms of this autonomic dysfunction that may need future investigation.

Impact of drugs on intradialytic hypotension: Antihypertensives and vasoconstrictors

Intradialytic hypotension (IDH) is a common complication of hemodialysis and is associated with numerous adverse outcomes including cardiovascular events, inadequate dialysis, loss of vascular access, and death. It is estimated that approximately 20%-30% of all dialysis sessions are affected by IDH. In seeking ways to reduce the occurrence of IDH, dialysis providers often turn to pharmacological approaches: withholding antihypertensive medications prior to hemodialysis or administering vasoconstrictor medications. This review will focus on what is known about the relation between antihypertensive medications and IDH, and summarize studies that have examined the efficacy of vasoconstrictor medications on IDH, including midodrine, arginine vasopressin, and droxidopa. However, there is currently scant evidence that any pharmacological approach is particularly effective in reducing IDH. Additional studies of potential treatments for IDH are needed, and should examine not only hemodynamic effects such as changes in nadir blood pressure during dialysis, but also on patient-centered and clinical outcomes such as symptoms of IDH, quality of life, and cardiovascular events.

The relationship between dialysis adequacy and serum uric acid in dialysis patients; a cross-sectional multi-center study in Iranian hemodialysis centers

Introduction: Uric acid is one of the most significant uremic toxins accumulating in chronic renal failure patients treated with standard dialysis. Its clearance has not any exact relation with urea and creatinine clearance.

Objectives: The aim of this study was to investigate the relationship between adequacy of dialysis and serum level of uric acid in dialysis patients of some dialysis centers in Iran.

Patients and Methods: In this study 1271 hemodialysis patients who have been treated for more than 3 months were evaluated. Their information and examinations from their files in all over the country were gathered and analyzed using SPSS versin18.0.

Results: In this study, a significant relationship between dialysis duration and serum level of uric acid was not detected, however, a significant relationship between patients Kt/V and uric acid (R=0.43, P=0.029) was seen. Patients who had higher adequacy of dialysis had a higher level of plasma uric acid.

Conclusion: For better controlling of plasma uric acid level of hemodialysis patients, increasing of the adequacy of dialysis or its duration is not effective. Other modalities of decreasing of serum uric acid like, changing diet or lifestyle or medical therapy may be necessary.

Increased Hepato-Splanchnic Vasoconstriction in Diabetics during Regular Hemodialysis

Background and Objectives

Ultrafiltration (UF) of excess fluid activates numerous compensatory mechanisms during hemodialysis (HD). The increase of both total peripheral and splanchnic vascular resistance is considered essential in maintaining hemodynamic stability. The aim of this study was to evaluate the extent of UF-induced changes in hepato-splanchnic blood flow and resistance in a group of maintenance HD patients during regular dialysis.

Design, Setting, Participants, & Measurements

Hepato-splanchnic flow resistance index (RI) and hepato-splanchnic perfusion index (QI) were measured in 12 chronic HD patients using a modified, non-invasive Indocyaningreen (ICG) dilution method. During a midweek dialysis session we determined RI, QI, ICG disappearance rate (k_ICG), plasma volume (V_p), hematocrit (Hct), mean arterial blood pressure (MAP) and heart rate (HR) at four times in hourly intervals (t₁ to t₄). Dialysis settings were standardized and all patient studies were done in duplicate.

Results

In the whole study group mean UF volume was 1.86 ± 0.46 L, V_p dropped from 3.65 ± 0.77L at t₁ to 3.40 ± 0.78L at t₄, and all patients remained hemodynamically stable. In all patients RI significantly increased from 12.40 ± 4.21 mmHg∙s∙m²/mL at t₁ to 14.94 ± 6.36 mmHg∙s∙m²/mL at t₄ while QI significantly decreased from 0.61 ± 0.22 at t₁ to 0.52 ± 0.20 L/min/m² at t₄, indicating active vasoconstriction. In diabetic subjects, however, RI was significantly larger than in non-diabetics at all time points. QI was lower in diabetic subjects.

Conclusions

In chronic HD-patients hepato-splanchnic blood flow substantially decreases during moderate UF as a result of an active splanchnic vasoconstriction. Our data indicate that diabetic HD-patients are particularly prone to splanchnic ischemia and might therefore have an increased risk for bacterial translocation, endotoxemia and systemic inflammation.

Intradialytic Blood Pressure Abnormalities: The Highs, The Lows and All That Lies Between

BACKGROUND

Frequent blood pressure (BP) measurements are necessary to ensure patient safety during hemodialysis treatments. Intradialytic BPs are not optimal tools for hypertension diagnosis and cardiovascular risk stratification, but they do have critical clinical and prognostic significance. We present evidence associating intradialytic BP phenomena including fall, rise and variability with adverse clinical outcomes and review related pathophysiologic mechanisms and potential management strategies.

SUMMARY

Observational studies demonstrate associations between intradialytic hypotension, hypertension and BP variability and mortality. Lack of consensus regarding diagnostic criteria has hampered data synthesis, and prospective studies investigating optimal management strategies for BP phenomena are lacking. Mechanistic data suggest that cardiac, gut, kidney and brain ischemia may lie on the causal pathway between intradialytic hypotension and mortality, and endothelial cell dysfunction, among other factors, may be an important mediator of intradialytic hypertension and adverse outcomes. These plausible pathophysiologic links present potential therapeutic targets for future inquiry. The phenomenon of intradialytic BP variability has not been adequately studied, and practical clinical measures and treatment strategies are lacking.

KEY MESSAGES

Intradialytic BP phenomena have important prognostic bearing. Clinical practice guidelines for both intradialytic hypotension and hypertension exist, but their underlying evidence is weak overall. Further research is needed to develop consensus diagnostic criteria for intradialytic hypotension, hypertension and BP variability and to elucidate optimal treatment and prevention strategies for each BP manifestation.

Association of mortality risk with various definitions of intradialytic hypotension

Intradialytic hypotension is a serious and frequent complication of hemodialysis; however, there is no evidence-based consensus definition of intradialytic hypotension. As a result, coherent evaluation of the effects of intradialytic hypotension is difficult. We analyzed data from 1409 patients in the HEMO Study and 10,392 patients from a single large dialysis organization to investigate the associations of commonly used intradialytic hypotension definitions and mortality. Intradialytic hypotension definitions were selected a priori on the basis of literature review. For each definition, patients were characterized as having intradialytic hypotension if they met the corresponding definition in at least 30% of baseline exposure period treatments or characterized as control otherwise. Overall and within subgroups of patients with predialysis systolic BP<120 or 120-159 mmHg, an absolute nadir systolic BP<90 mmHg was most potently associated with mortality. Within the subgroup of patients with predialysis BP≥160 mmHg, nadir BP<100 mmHg was most potently associated with mortality. Intradialytic hypotension definitions that considered symptoms, interventions, and decreases in BP during dialysis were not associated with outcome, and when added to nadir BP, symptom and intervention criteria did not accentuate associations with mortality. Our results suggest that nadir-based definitions best capture the association between intradialytic hypotension and mortality.

How should we manage adverse intradialytic blood pressure changes?

Variations in intradialytic blood pressure (BP) are a common and predictable occurrence in ESRD patients. These are caused by a decrease in blood volume provoked by ultrafiltration, lack of normal compensatory responses to fluid removal, underlying cardiac disease, and electrolyte changes that may adversely affect cardiovascular function. Intradialytic hypotension is the most frequent complication of the hemodialysis (HD) procedure and is fundamentally a consequence of an ultrafiltration rate that surpasses mechanisms activated to avert a decline in BP. Intradialytic hypertension is a less well-understood problem that has been recently associated with increased mortality. Fundamental patient characteristics and components of the HD procedure are involved in the pathophysiology of intradialytic hypotension and intradialytic hypertension. Correction of patient factors, modulation of HD prescription, and management of pharmacologic agents are the strategies to deal with adverse intradialytic BP changes.

Excessive fall of blood pressure during maintenance hemodialysis in patients with chronic renal failure is induced by vascular malfunction and imbalance of autonomic nervous activity

Acute hypotension during maintenance hemodialysis (HD) is not only a critical complication, but also an independent risk factor for mortality in patients with chronic renal failure (CRF). This study was designed to clarify the mechanisms underlying excessive fall of blood pressure during HD. Fifty-six CRF patients with HD thrice a week were divided into two groups according to the intradialytic hypotension episodes after 4 weeks of the observation period; the hypotension group, showing four or more episodes of intradialytic hypotension, and the non-hypotension group, showing three episodes of intradialytic hypotension or less. The intradialytic hypotension was defined as a fall of ≥30 mm Hg in the systolic blood pressure during HD. The brachial-ankle pulse wave velocity (ba-PWV), serum high-sensitivity (hs)-CRP, reactive oxygen species (ROS) generation, and serum malondialdehyde-modified LDL (MDA-LDL) were measured before HD. The high- frequency (HF) and low-frequency components (LF) of the heart rate variability and entropy were analyzed by the maximal entropy method. The ba-PWV, hs-CRP, ROS generation, and MDA-LDL were significantly higher in the hypotension group than in the non-hypotension group. HF, LF/HF, and entropy during HD increased significantly in the non-hypotension group, while entropy during HD decreased significantly in the hypotension group as compared with the baseline. LF/HF and entropy during HD were significantly lower in the hypotension group than in the non-hypotension group. These findings suggest that the major factors causing excessive fall of blood pressure during HD in patients with CRF might be vascular malfunction and imbalance of autonomic nervous activity.

Sustained low-efficiency dialysis versus continuous veno-venous hemofiltration for postsurgical acute renal failure

BACKGROUND

In postsurgical acute renal failure patients with moderate unstable hemodynamics or fluid overload, the choice of dialysis modality is difficult. This study was performed to compare the outcomes between the sustained low-efficiency dialysis (SLED) and continuous veno-venous hemofiltration (CVVH) in these patients.

METHODS

Sequential postsurgical acute renal failure patients undergoing acute dialysis with CVVH (2002-2003), or SLED (2004-2005) as a result of severe fluid overload or moderately unstable hemodynamics were analyzed. Multivariate analyses of comorbidity, disease severity before initiating dialysis, biochemical measurements, and hemodynamic parameters for 3 days after the first dialysis session were performed by fitting multiple logistic regression models to predict patient's 30-day after hospital discharge (AHD) mortality.

RESULTS

Among the 101 recruited patients, 38 received SLED and the rest received CVVH. The 30-day AHD mortality was 62.4%. The independent risk factors of 30-day AHD mortality included older age (P = .008), lower first postdialysis mean arterial pressure (MAP) (P = .021), higher first postdialysis blood urea nitrogen level (P = .009), and absence of a history of hypertension (P = .002). A further linear regression analysis found that dialysis using SLED was associated with higher first postdialysis MAP (P = .003).

CONCLUSIONS

Among the postsurgical patients requiring acute dialysis with severe fluid overload or moderately unstable hemodynamics, the patients treated with SLED had a higher first postdialysis MAP than those treated with CVVH, which led to lower mortality. Further multicenter randomized clinical trials of larger sample size are needed to compare the effects of SLED and CVVH on the outcomes of postsurgical acute dialysis patients.

Recent advances in the prevention and management of intradialytic hypotension

Intradialytic hypotension continues to play a significant role in the morbidity and in some cases the mortality associated with maintenance hemodialysis. Greater precision in the determination of dry weight using bioimpedance technology and biofeedback systems designed to prevent rapid fluctuations in blood volume have recently been shown to decrease the frequency of this complication. Pharmacologic strategies designed to maintain peripheral vascular resistance in patients with insufficient release of endogenous vasoconstrictors continue to be explored. The sudden development of intradialytic hypotension may respond to specific antagonists to hypotensive mediators.

Rolofylline (KW-3902): a new adenosine A1-receptor antagonist for acute congestive heart failure

Rolofylline (KW-3902 or MK-7418) is an adenosine A1-receptor antagonist that exerts its effect by blocking adenosine-mediated constriction of the afferent glomerular arteriole. By blocking A1 receptors, rolofylline increases the glomerular blood flow and filtration and inhibits sodium reabsorption in the proximal tubule, thereby enhancing natriuresis and diuresis. Early phase clinical research data provided the proof-of-concept of an incremental effect beyond standard diuretic therapy. A large Phase III program is currently ongoing for the intravenous formulation of rolofylline in the treatment of acute heart failure.

Diagnostic utility of blood volume monitoring in hemodialysis patients

BACKGROUND

Assessment of volume state is difficult in hemodialysis patients. Whether continuous blood volume monitoring can improve the assessment of volume state is unclear.

STUDY DESIGN

Diagnostic test study.

SETTINGS & PARTICIPANTS

Asymptomatic long-term hemodialysis patients (n = 150) in 4 university-affiliated hemodialysis units.

INDEX TESTS

Ultrafiltration rate (UFR) divided by postdialysis weight (UFR index), slopes of relative blood volume (RBV), RBV slope corrected for UFR and weight (volume index).

REFERENCE TESTS

Dialysis-related symptoms and echocardiographic signs of volume excess and volume depletion, assessed by using inferior vena cava (IVC) diameter after dialysis and its collapse on inspiration. Volume excess was defined as values in the upper third of IVC diameter or lower third of IVC collapse on inspiration. Volume depletion was defined as values in the lower third of IVC diameter or upper third of IVC collapse on inspiration.

RESULTS

Mean UFR was 8.3 +/- 3.8 (SD) mL/h/kg. Mean RBV slope was -2.32% +/- 1.50%/h. Mean volume index was -0.25% +/- 0.17%/h/mL/h ultrafiltration/kg. Volume index provided the best fit of observed RBV slopes. Volume index was related to dizziness, the need to decrease UFR, and placement in Trendelenburg position. RBV and volume index, but not UFR index, were related to echocardiographic markers of volume excess and depletion. Areas under the receiver operating characteristic curve to predict volume excess were 0.48 (95% confidence interval [CI], 0.33 to 0.63) for UFR index, 0.71 (95% CI, 0.60 to 0.83) for RBV slope, and 0.73 (95% CI, 0.59 to 0.86) for volume index. Areas under the receiver operating characteristic curve to predict volume depletion were 0.56 (95% CI, 0.38 to 0.74) for UFR index, 0.55 (95% CI, 0.38 to 0.72) for RBV slope, and 0.62 (95% CI, 0.48 to 0.76) for volume index.

LIMITATIONS

Dialysis-related symptoms and echocardiographic findings are not validated measures of volume. Our results were not adjusted for demographic or clinical characteristics; performance characteristics of the indices may differ across populations.

CONCLUSIONS

Volume index appears to be a novel marker of volume, but requires validation studies, and its utility needs to be tested in clinical trials.

Relationship between A2A Adenosine Receptor Expression and Intradialytic Hypotension during Hemodialysis

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of hemodialysis sessions (HDSs). Adenosine may contribute to the drop in blood pressure during IDH events because it has hypotensive effects. As A(2A) adenosine receptor expression is essential for blood pressure control, we compared the expression of A(2A) receptors (Bmax, K(D), and messenger ribonucleic acid [mRNA] levels) in peripheral blood mononuclear cells from IDH and non-IDH patients and from controls. We also evaluated adenosine plasma levels (APLs).

METHODS

We included 10 hemodialyzed patients with at least three IDH events per month. We also included 11 hemodialyzed patients with no history of IDH events and 10 healthy subjects as controls.

RESULTS

IDH patients had higher Bmax values than non-IDH patients (mean before HDS, +86%; after HDS, +112%), whereas non-IDH patients had lower Bmax values than controls (mean -72%). K(D) values were not significantly different between patients and controls. The levels of mRNA increased significantly during HDS but without an increase in receptor expression on the cell membranes. APLs were higher in hemodialyzed patients than in controls.

CONCLUSION

We found that A(2A) receptors are more expressed in IDH patients than in non-IDH patients, whereas APL was high in all patients. Both high APL and a relative increase in A(2A) receptor expression may favor IDH events.

Adenosine and dialysis hypotension

In this issue, Imai et al. report the results of a double-blind placebo-controlled study on the effect of an adenosine A1 receptor antagonist, FK352, on the incidence of dialysis hypotension in hypotension-prone patients. This Commentary discusses the use of selective adenosine A1 receptor antagonists for the prevention of dialysis hypotension from the perspective of the potential role of adenosine in its pathogenesis.