Dialysis hypotension: a role for inadequate increase in arginine vasopressin levels? A systematic literature review and meta-analysis

Association of serum sodium levels with fractures and mortality in patients undergoing maintenance hemodialysis

BACKGROUND

Hyponatremia is implicated in pathological bone resorption and has been identified as a risk factor for bone fracture in the general population. However, there are limited data on the association between serum sodium levels and fracture risk in patients undergoing hemodialysis (HD).

METHODS

We analyzed a historical cohort of 2220 maintenance HD patients to examine the association between serum sodium levels and the risk of fracture and mortality. We also examined the association between serum sodium levels and osteoporosis, based on metacarpal bone mineral density, in a subcohort of 455 patients with available data. In addition, we examined the association between serum sodium levels and bone turnover markers in a separate cross-sectional cohort of 654 maintenance HD patients.

RESULTS

During a median follow-up of 5.4 years, 712 patients died, 113 experienced clinical fractures, and 64 experienced asymptomatic vertebral fractures. Lower serum sodium levels were associated with an increased risk of mortality (HR 1.06 per 1 mEq/L decrease; 95% CI 1.03-1.09) but not with the risk of clinical fracture (HR 1.04 per 1 mEq/L decrease; 95% CI 0.97-1.11). A similar lack of association was observed for asymptomatic vertebral fracture and any fracture. Serum sodium levels were also not associated with osteoporosis in a subcohort with available data (n = 455) or with bone alkaline phosphatase or tartrate-resistant acid phosphatase-5b in a separate cross-sectional cohort.

CONCLUSION

Serum sodium levels were associated with mortality but not with fracture risk, osteoporosis, or bone turnover markers in maintenance HD patients.

Hypertensive Emergency During Dialysis: A Paradoxical Physiologic Response

Most end-stage renal disease patients experience a reduction in blood pressure during their hemodialysis session compared to predialysis. Surprisingly, a small subset of patients will experience an unusual physiological response to dialysis that results in a paradoxical increase in blood pressure. We discuss a case that involved an exaggerated elevation in blood pressure, ultimately requiring immediate cessation of dialysis and admission to the intensive care unit for intravenous treatment of a hypertensive emergency. This case serves as a framework to introduce the infrequently discussed concept of intradialytic hypertension. The underlying pathogenesis is poorly understood with multiple theoretical etiologies including activation of the renin-angiotensin-aldosterone system, imbalances in circulating levels of endothelium-derived mediators, clearance of antihypertensive medications, increased cardiac output, and changes in arterial thickness. It is important to be cognizant of this phenomenon as emerging evidence suggests that patients with any elevation in blood pressure during hemodialysis have increased rates of both short-term and long-term mortality.

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.

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.

Multilayer Perceptron-Based Real-Time Intradialytic Hypotension Prediction Using Patient Baseline Information and Heart-Rate Variation

Intradialytic hypotension (IDH) is a common side effect that occurs during hemodialysis and poses a great risk for dialysis patients. Many studies have been conducted so far to predict IDH, but most of these could not be applied in real-time because they used only underlying patient information or static patient disease information. In this study, we propose a multilayer perceptron (MP)-based IDH prediction model using heart rate (HR) information corresponding to time-series information and static data of patients. This study aimed to validate whether HR differences and HR slope information affect real-time IDH prediction in patients undergoing hemodialysis. Clinical data were collected from 80 hemodialysis patients from 9 September to 17 October 2020, in the artificial kidney room at Yeungnam University Medical Center (YUMC), Daegu, South Korea. The patients typically underwent hemodialysis 12 times during this period, 1 to 2 h per session. Therefore, the HR difference and HR slope information within up to 1 h before IDH occurrence were used as time-series input data for the MP model. Among the MP models using the number and data length of different hidden layers, the model using 60 min of data before the occurrence of two layers and IDH showed maximum performance, with an accuracy of 81.5%, a true positive rate of 73.8%, and positive predictive value of 87.3%. This study aimed to predict IDH in real-time by continuously supplying HR information to MP models along with static data such as age, diabetes, hypertension, and ultrafiltration. The current MP model was implemented using relatively limited parameters; however, its performance may be further improved by adding additional parameters in the future, further enabling real-time IDH prediction to play a supporting role for medical staff.

Dialysis-Associated Nonarteritic Anterior Ischemic Optic Neuropathy: A Case Series and Review

BACKGROUND

Dialysis-associated nonarteritic ischemic optic neuropathy (DA-NAION) occurs secondary to intradialytic hypotension often with catastrophic consequences and is one of the rare situations where NAION can recur in the same eye. We describe 3 cases of DA-NAION associated with hypotension, review the current literature on DA-NAION, and provide recommendations for decreasing the risk of intradialytic hypotension.

METHODS

In addition to describing 3 cases of DA-NAION, PubMed was searched for all reports of DA-NAION in adults with documented episodes of hypotension preceding the onset of NAION. A total of 50 eyes of 31 patients were included. Age, visual acuity at presentation, rate of bilateral involvement at presentation, sequential involvement of the fellow eye, and recurrence of NAION in the same eye were analyzed.

RESULTS

We found that most cases of DA-NAION occur in relatively young patients (47.7 ± 14.7 years) with a high rate of bilateral involvement at presentation (23%) and bilateral sequential involvement (39%). Vision loss is severe with 64% of patients presenting with 20/200 acuity or worse in the involved eye and 19% of patients with final visual acuity of 20/200 or worse in both eyes. 3 patients (9.7%) had recurrence of NAION in the previously affected eye.

CONCLUSIONS

Neuro-ophthalmologists have an important role in identifying patients who have suffered DA-NAION and communicating their findings to nephrologists to minimize the chance of involvement of the fellow eye and recurrence in the same eye. Intradialytic blood pressure must be closely monitored, and fluid balance, dialysate composition, and dialysis protocol must be optimized to prevent occurrence of intradialytic hypotension, which is the culprit for DA-NAION.

Efficacy and safety of furosemide for prevention of intradialytic hypotension in haemodialysis patients: protocol for a multicentre randomised controlled trial

INTRODUCTION

Intradialytic hypotension (IDH) is a frequent and serious complication of maintaining haemodialysis (HD) patients and associated with subsequent cardiovascular events and higher mortality. Furosemide is commonly used in non-dialysis chronic kidney disease patients and can effectively manage the volume and blood pressure. However, these agents are often discontinued on initiation of dialysis. Two large observational studies have demonstrated that furosemide can lower the rate of IDH episodes. However, there is still no randomised controlled trial (RCT) to investigate the efficacy and safety of furosemide for prevention of IDH in HD patients. The purpose of this study was to assess the efficacy of furosemide in reducing IDH in HD patients with residual renal function.

METHODS AND ANALYSIS

A two-arm, parallel, multicente RCT will be conducted at 12 hospitals in China. An estimated sample of 560 HD patients will be recruited. Eligible patients will be randomly assigned to treatment group (patients receive oral furosemide 80 mg/day; after a 2-week treatment, if their urine volume is less than 400 mL/day, the dose of furosemide is adjusted to 160 mg/day) and blank control group via a central randomisation system using 1:1 ratio. The primary outcome is the occurrence of IDH. Outcome assessors and data analysts will be blinded and participants will be asked not to reveal their allocation to assessors. The outcome analyses will be performed both on the intention-to-treat, which includes all patients randomised, and per-protocol population, which includes eligible patients who adhere to the planned treatment and follow-ups.

ETHICS AND DISSEMINATION

The trial protocol has been approved by the Biomedical Research Ethics Committee of West China Hospital of Sichuan University (2019.385)Results will be presented at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ChiCTR2000039724.

Effects of diuretics on intradialytic hypotension in maintenance dialysis patients: a systematic review and meta-analysis

PURPOSE

Intradialytic hypotension (IDH) is a serious complication in dialysis patients. Diuretics might reduce the incidence of IDH by decreasing ultrafiltration. However, the effect of diuretics on IDH in maintenance dialysis patients is still unclear.

METHODS

We searched Medline, Embase, the Cochrane Library, China National Knowledge Infrastructure and clinical trials registries from 1945 to May 2019. Randomized controlled trials (RCTs) or observational studies about IDH in maintenance dialysis with diuretics were included.

RESULTS

Seven studies including 28,226 patients were included, of which 4 were RCTs involving mineralocorticoid receptor antagonists (MRAs) and 3 were observational studies involving loop diuretics. There was a trend that a lower incidence rate of IDH in maintenance dialysis patients who used loop diuretics than control, although the result was not statistically significant (OR 0.65, 95% CI 0.34-1.22, P = 0.18). Similarly, lower incidence rate of all-cause mortality (OR 0.92, 95% CI 0.87-0.99; P = 0.02) and cardiovascular (CV) mortality (OR 0.86, 95% CI 0.75-0.99, P = 0.03) in dialysis patients who used loop diuretics than control. On the contrary, there were no significant difference in the incidence of IDH (OR 1.35, 95% CI 0.78-2.34, P = 0.29) and all-cause mortality (OR 0.73, 95% CI 0.26-2.01; P = 0.54) and CV mortality (OR 0.57, 95% CI 0.14-2.25; P = 0.42) in maintenance dialysis patients who used MRAs compared with control.

CONCLUSION

Loop diuretics, but not MRAs, might have a potential benefit to reduce the incidence rate of IDH, all-cause mortality and CV mortality. More high-quality studies are needed to strengthen the arguments.

Prolactin and Other Pituitary Disorders in Kidney Disease

Prolactin levels are increased in chronic kidney disease (CKD) as a result of reduced clearance and increased secretion. Hyperprolactinemia manifests as galactorrhea and hypogonadism. Treatment of hyperprolactinemia should focus on improving bothersome galactorrhea or hypogonadism by using dopamine agonists and/or replacement of sex hormone(s). Changes in the hypothalamic-pituitary-adrenal axis in CKD are characterized by increases in adrenocorticotropic hormone (ACTH) and cortisol levels, largely preserved circadian rhythms of ACTH and cortisol, and a normal response of cortisol to ACTH, metyrapone, and insulin-induced hypoglycemia. However, the hypothalamic-pituitary-adrenal axis is less inhibited by 1 mg dexamethasone but retains normal suppression by higher-dose dexamethasone. Diagnosis of adrenal insufficiency in CKD patients, as in normal subjects, usually is made by finding a subnormal cortisol response to ACTH. The mainstay of treatment of adrenal insufficiency is to replace glucocorticoid hormone. Cushing's disease in CKD is difficult to diagnose and relies on the dexamethasone suppression test and the midnight salivary cortisol test because the 24-hour urine free cortisol test is not useful because it is increased already in CKD. Treatment of Cushing's disease involves surgery, complemented by radiation and/or medical therapy if necessary. Growth hormone levels are increased and insulin-like growth factor 1 levels are normal in patients with CKD. In a normal patient with CKD, as in one with acromegaly, there can be a paradoxic increase in growth hormone after an oral glucose load. Therefore, diagnosis of acromegaly in renal insufficiency is challenging. The treatment of choice for acromegaly is surgery, although data for medical treatment for acromegaly in CKD are rare. In patients with renal impairment, arginine vasopressin levels are increased as a result of decreased clearance, and there also is impairment of arginine vasopressin signaling in renal tubules. Diabetes insipidus can be masked in advanced kidney disease until kidney transplantation. Diagnosis of the syndrome of inappropriate antidiuretic hormone is similar in mild or moderate kidney disease as in normal subjects, but is challenging in patients with advanced kidney disease owing to the impairment in urine dilution.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Blood pressure and volume management in dialysis: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Blood pressure (BP) and volume control are critical components of dialysis care and have substantial impacts on patient symptoms, quality of life, and cardiovascular complications. Yet, developing consensus best practices for BP and volume control have been challenging, given the absence of objective measures of extracellular volume status and the lack of high-quality evidence for many therapeutic interventions. In February of 2019, Kidney Disease: Improving Global Outcomes (KDIGO) held a Controversies Conference titled Blood Pressure and Volume Management in Dialysis to assess the current state of knowledge related to BP and volume management and identify opportunities to improve clinical and patient-reported outcomes among individuals receiving maintenance dialysis. Four major topics were addressed: BP measurement, BP targets, and pharmacologic management of suboptimal BP; dialysis prescriptions as they relate to BP and volume; extracellular volume assessment and management with a focus on technology-based solutions; and volume-related patient symptoms and experiences. The overarching theme resulting from presentations and discussions was that managing BP and volume in dialysis involves weighing multiple clinical factors and risk considerations as well as patient lifestyle and preferences, all within a narrow therapeutic window for avoiding acute or chronic volume-related complications. Striking this challenging balance requires individualizing the dialysis prescription by incorporating comorbid health conditions, treatment hemodynamic patterns, clinical judgment, and patient preferences into decision-making, all within local resource constraints.

Osmotic diuresis by SGLT2 inhibition stimulates vasopressin-induced water reabsorption to maintain body fluid volume

Most of the filtered glucose is reabsorbed in the early proximal tubule by the sodium-glucose cotransporter SGLT2. The glycosuric effect of the SGLT2 inhibitor ipragliflozin is linked to a diuretic and natriuretic effect that activates compensatory increases in fluid and food intake to stabilize body fluid volume (BFV). However, the compensatory mechanisms that are activated on the level of renal tubules remain unclear. Type 2 diabetic Goto-Kakizaki (GK) rats were treated with vehicle or 0.01% (in diet) ipragliflozin with free access to fluid and food. After 8 weeks, GK rats were placed in metabolic cages for 24-hr. Ipragliflozin decreased body weight, serum glucose and systolic blood pressure, and increased fluid and food intake, urinary glucose and Na+ excretion, urine volume, and renal osmolar clearance, as well as urine vasopressin and solute-free water reabsorption (TcH2O). BFV, measured by bioimpedance spectroscopy, and fluid balance were similar among the two groups. Urine vasopressin in ipragliflozin-treated rats was negatively and positively associated with fluid balance and TcH2O, respectively. Ipragliflozin increased the renal membrane protein expression of SGLT2, aquaporin (AQP) 2 phosphorylated at Ser269 and vasopressin V2 receptor. The expression of SGLT1, GLUT2, AQP1, and AQP2 was similar between the groups. In conclusion, the SGLT2 inhibitor ipragliflozin induced a sustained glucosuria, diuresis, and natriuresis, with compensatory increases in fluid intake and vasopressin-induced TcH2O in proportion to the reduced fluid balance to maintain BFV. These results indicate that the osmotic diuresis induced by SGLT2 inhibition stimulates compensatory fluid intake and renal water reabsorption to maintain BFV.

Low Copeptin Levels in Patients With Intradialytic Hypotension

Intradialytic hypotension (IDH) is related to high morbidity and mortality. There is evidence that arginine-vasopressin (AVP) responses could play a role. Copeptin is a reliable biomarker of AVP. In this study, copeptin, aldosterone, epinephrine, and norepinephrine levels in patients with IDH were evaluated throughout a hemodialysis (HD) session and compared with the control group. The study includes 15 patients who were normotensive during HD and 15 patients with IDH with a minimum HD vintage of 1 year. Blood samples were collected before the initiation of an HD session (T₀ ), in the mid-session for control group, 30 min after mean arterial pressure drop for IDH patients (T₁ ), and at the end of the session (T₂ ). Groups had similar demographic features and health parameters, interdialytic weight gains, and ultrafiltration amounts. The IDH group had a mean arterial pressure decline of 39.9 (±6.4) mm Hg. Copeptin levels of the control group increased an average of 79.9 (±97.5) pmol/L at T₁ and an additional 24.8 (±33.9) pmol/L at T₂ . In the IDH group, copeptin level increases at T₁ and T₂ were 3.2 (±5.5) pmol/L and 34 (±44.6) pmol/L, respectively_. Copeptin levels of the IDH group were significantly lower at T₁ (P < 0.001) and at the T₀ -T₂ interval than control group (P = 0.05). In the control group, aldosterone levels distinctly decreased, and in the IDH group, aldosterone levels were elevated (P < 0.001). Small changes were detected in epinephrine and norepinephrine levels for both groups but did not reach significance (P = 0.6 and P = 0.3, respectively). Lower copeptin level alterations suggest inadequate AVP responses in patients with IDH.

Mechanisms, Clinical Implications, and Treatment of Intradialytic Hypotension

Individuals with ESKD requiring maintenance hemodialysis face a unique hemodynamic challenge, typically on a thrice-weekly basis. In an effort to achieve some degree of euvolemia, ultrafiltration goals often involve removal of the equivalent of an entire plasma volume. Maintenance of adequate end-organ perfusion in this setting is dependent on the institution of a variety of complex compensatory mechanisms. Unfortunately, secondary to a myriad of patient- and dialysis-related factors, this compensation often falls short and results in intradialytic hypotension. Physicians and patients have developed a greater appreciation for the breadth of adverse outcomes associated with intradialytic hypotension, including higher cardiovascular and all-cause mortality. In this review, we summarize the evidence for adverse outcomes associated with intradialytic hypotension, explore the underlying pathophysiology, and use this as a basis to introduce potential strategies for its prevention and treatment.

Osmolality and blood pressure stability during hemodialysis

Homeostatic regulation of plasma osmolality (POsm) is critical for normal cellular function in humans. Arginine vasopressin (AVP) is the major hormone responsible for the maintenance of POsm and acts to promote renal water retention in conditions of increased POsm. However, AVP also exerts pressor effects, and its release can be stimulated by the development of effective arterial blood volume depletion. Patients with end-stage renal disease on hemodialysis, particularly those with minimal or no residual renal function, have impaired ability to regulate water retention in response to AVP. While hemodialysis can assist with this task, patients are subject to relatively rapid shifts in volume and electrolytes during the procedure. This can result in the development of transient osmotic gradients that lead to the movement of water from the extracellular to the intracellular space. Hypotension may result-both as a consequence of water movement out of the intravascular compartment, but also from impaired AVP release and inadequate vascular tone. In this review, we explore the evidence for POsm changes during hemodialysis, associations with adverse outcomes, and methods to minimize the rapidity of changes in POsm in an effort to reduce patient symptoms and minimize intra-dialytic hypotension.

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.

Risk of Nonarteritic Anterior Ischemic Optic Neuropathy Following End-Stage Renal Disease

To investigate the risk of nonarteritic anterior ischemic optic neuropathy (NAION) following end-stage renal disease (ESRD).A retrospective, nationwide, matched cohort study.ESRD patients identified by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 585.The study cohort included 93,804 ESRD patients registered with the Taiwan National Health Insurance Research Database between January 2000 and December 2009. An age- and sex-matched control group comprised 93,804 patients (case:control = 1:1) selected from the Taiwan Longitudinal Health Insurance Database 2000. Information for each patient was collected from the index date until December 2011. The incidence and risk of NAION were compared between the ESRD and control groups. The adjusted hazard ratio (HR) for NAION after adjustment for potential confounders was obtained by a Cox proportional hazard regression analysis. A Kaplan-Meier analysis was used to calculate the cumulative incidence rate of NAION.The incidence of NAION following ESRD.In total, 133 ESRD patients (0.14%) and 51 controls (0.05%) had NAION (P < 0.001) during the follow-up period, leading to a significantly elevated risk of NAION in the ESRD patients compared with the controls (incidence rate ratio = 3.14, 95% confidence interval [CI] = 2.11-4.67). After adjustment for potential confounders including diabetes mellitus, hypertension, hypotension, hyperlipidemia, and 2-way interaction terms between any 2 factors, ESRD patients were 3.12 times more likely to develop NAION than non-ESRD patients in the full cohort (adjusted HR = 3.12, 95% CI = 2.10-4.64). Additionally, patients with hypertension and hyperlipidemia showed higher incidence rates of NAION in the ESRD group compared with the controls: 2.31 (95% CI = 1.40-3.82) for hypertension and 2.72 (95% CI = 1.14-6.50) for hyperlipidemia.ESRD increased the risk of NAION, which is an interdisciplinary emergency. Close collaboration between nephrologists and ophthalmologists is important in NAION management following ESRD to prevent fellow eye involvement.

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.

Changes in Plasma Copeptin Levels during Hemodialysis: Are the Physiological Stimuli Active in Hemodialysis Patients?

OBJECTIVES

Plasma levels of copeptin, a surrogate marker for the vasoconstrictor hormone arginine vasopressin (AVP), are increased in hemodialysis patients. Presently, it is unknown what drives copeptin levels in hemodialysis patients. We investigated whether the established physiological stimuli for copeptin release, i.e. plasma osmolality, blood volume and mean arterial pressure (MAP), are operational in hemodialysis patients.

METHODS

One hundred and eight prevalent, stable hemodialysis patients on a thrice-weekly dialysis schedule were studied during hemodialysis with constant ultrafiltration rate and dialysate conductivity in this observational study. Plasma levels of copeptin, sodium, MAP, and blood volume were measured before, during and after hemodialysis. Multivariate analysis was used to determine the association between copeptin (dependent variable) and the physiological stimuli plasma sodium, MAP, excess weight as well as NT-pro-BNP immediately prior to dialysis and between copeptin and changes of plasma sodium, MAP and blood volume with correction for age, sex and diabetes during dialysis treatment.

RESULTS

Patients were 63 ± 15.6 years old and 65% were male. Median dialysis vintage was 1.6 years (IQR 0.7-4.0). Twenty-three percent of the patients had diabetes and 82% had hypertension. Median predialysis copeptin levels were 141.5 pmol/L (IQR 91.0-244.8 pmol/L). Neither predialysis plasma sodium levels, nor NT-proBNP levels, nor MAP were associated with predialysis copeptin levels. During hemodialysis, copeptin levels rose significantly (p<0.01) to 163.0 pmol/L (96.0-296.0 pmol/L). Decreases in blood volume and MAP were associated with increases in copeptin levels during dialysis, whereas there was no significant association between the change in plasma sodium levels and the change in copeptin levels.

CONCLUSIONS

Plasma copeptin levels are elevated predialysis and increase further during hemodialysis. Volume stimuli, i.e. decreases in MAP and blood volume, rather than osmotic stimuli, are associated with change in copeptin levels during hemodialysis.

Association of Predialysis Calculated Plasma Osmolarity With Intradialytic Blood Pressure Decline

BACKGROUND

The rapid reduction in plasma osmolality during hemodialysis (HD) may induce temporary gradients that promote the movement of water from the extracellular to the intracellular compartment, predisposing to the development of intradialytic hypotension (IDH).

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

3,142 prevalent patients receiving thrice-weekly HD from a single dialysis provider organization.

PREDICTOR

Predialysis calculated plasma osmolarity (calculated after the 2-day interval as 2 × serum sodium + serum urea nitrogen/2.8 + serum glucose/18).

OUTCOME

Magnitude of systolic blood pressure (SBP) decline (predialysis SBP - nadir intradialytic SBP) and risk of IDH (SBP decline > 35 or nadir SBP < 90 mm Hg).

MEASUREMENTS

Unadjusted and multivariable-adjusted generalized linear models were fit to estimate the association of calculated osmolarity with intradialytic SBP decline and the odds of developing IDH.

RESULTS

Mean age of participants was 62.6±15.2 (SD) years, 57.1% were men, and 61.0% had diabetes. Mean predialysis calculated osmolarity during follow-up was 306.4 ± 9.5 mOsm/L. After case-mix adjustment, each 10-mOsm/L increase in predialysis calculated osmolarity was associated with 1.48 (95% CI, 0.86-2.09) mm Hg (P < 0.001) greater decline in intradialytic SBP and 10% greater odds of IDH (OR, 1.10; 95% CI, 1.05-1.15). In adjusted models, lower predialysis sodium and higher serum urea nitrogen and serum glucose levels were associated with greater decline in intradialytic SBP.

LIMITATIONS

Measured serum osmolality, timing of changes in intradialytic osmolality, dialysate osmolality, and dialysate temperature were not available.

CONCLUSIONS

Higher predialysis calculated osmolarity is associated with greater decline in intradialytic SBP and greater risk of IDH in maintenance HD patients. Strategies to minimize rapid shifts in osmolality should be tested prospectively to minimize excess SBP decline in susceptible patients.