A brief review of intradialytic hypotension with a focus on survival

Ultrafiltration rates and intradialytic hypotension: A case-control sampling of pooled haemodialysis data

BACKGROUND

Intradialytic hypotension (IDH) is one of the most critical adverse events during maintenance haemodialysis. Previous studies reported the association of fluid removal rate with the occurrence of IDH.

OBJECTIVE

We aimed to identify the optimal threshold of ultrafiltration rate to prevent the occurrence of IDH events. DESIGN, PARTICIPANTS AND MEASUREMENTS: Prognostic factor research with a retrospective case-control design was conducted. Patient data were gathered from four haemodialysis units from January to December 2017. All the haemodialysis records were independently justified, whether IDH occurred or not, based on the standard definition. A total of 10 haemodialysis sessions were sampled from each patient's pool based on the incidence of events. The association of ultrafiltration rates and IDH events was explored by multivariable multilevel logistic regression.

RESULTS

A total of 1080 haemodialysis sessions from 108 patients were included: 149 (13.8%) with IDH and 931 (86.2%) without IDH. After adjusting for all pre-specified risk factors and imbalance baselines, the odds ratio of IDH were 1.22 (95% confidence interval [CI]: 0.59, 2.52) for rate 10-12 ml/kg/h; 2.52 (95% CI: 1.20, 5.29) for rate 12-14 ml/kg/h; 4.02 (95% CI: 1.61, 10.03) for rate 14-16 ml/kg/h; and 7.41 (95% CI: 2.53, 21.68) for rate >16 ml/kg/h comparing to the referent rate of <10 ml/kg/h.

CONCLUSION

The ultrafiltration rate should be limited to 12 ml/kg/h. If a higher rate of fluid removal was indicated, it should not exceed 16 ml/kg/h to avoid the occurrence of IDH.

Towards personalized fluid monitoring in haemodialysis patients: thoracic bioimpedance signal shows strong correlation with fluid changes, a cohort study

Background

Haemodialysis (HD) patients are burdened by frequent fluid shifts which amplify their comorbidities. Bioimpedance (bioZ) is a promising technique to monitor changes in fluid status. The aim of this study is to investigate if the thoracic bioZ signal can track fluid changes during a HD session.

Methods

Prevalent patients from a single centre HD unit were monitored during one to six consecutive HD sessions using a wearable multi-frequency thoracic bioZ device. Ultrafiltration volume (UFV) was determined based on the interdialytic weight gain and target dry weight set by clinicians. The correlation between the bioZ signal and UFV was analysed on population level. Additionally regression models were built and validated per dialysis session.

Results

66 patients were included, resulting in a total of 133 HD sessions. Spearman correlation between the thoracic bioZ and UFV showed a significant strong correlation of 0.755 (p < 0.01) on population level. Regression analysis per session revealed a strong relation between the bioZ value and the UFV (R² = 0.982). The fluid extraction prediction error of the leave-one-out cross validation was very small (56.2 ml [− 121.1–194.1 ml]) across all sessions at all frequencies.

Conclusions

This study demonstrated that thoracic bioZ is strongly correlated with fluid shifts during HD over a large range of UFVs. Furthermore, leave-one-out cross validation is a step towards personalized fluid monitoring during HD and could contribute to the creation of autonomous dialysis.

Integrated strategies to prevent intradialytic hypotension: research protocol of the DialHypot study, a prospective randomised clinical trial in hypotension-prone haemodialysis patients

INTRODUCTION

In patients on maintenance haemodialysis (HD), intradialytic hypotension (IDH) is a clinical problem that nephrologists and dialysis nurses face daily in their clinical routine. Despite the technological advances in the field of HD, the incidence of hypotensive events occurring during a standard dialytic treatment is still very high. Frequently recurring hypotensive episodes during HD sessions expose patients not only to severe immediate complications but also to a higher mortality risk in the medium term. Various strategies aimed at preventing IDH are currently available, but there is lack of conclusive data on more integrated approaches combining different interventions.

METHODS AND ANALYSIS

This is a prospective, randomised, open-label, crossover trial (each subject will be used as his/her own control) that will be performed in two distinct phases, each of which is divided into several subphases. In the first phase, 27 HD sessions for each patient will be used, and will be aimed at the validation of a new ultrafiltration (UF) profile, designed with an ascending/descending shape, and a standard dialysate sodium concentration. In the second phase, 33 HD sessions for each patient will be used and will be aimed at evaluating the combination of different UF and sodium profiling strategies through individualised dialysate sodium concentration.

ETHICS AND DISSEMINATION

The trial protocol has been reviewed and approved by the local Institutional Ethics Committee (Comitato Etico AVEN, prot. 43391 22.10.19). The results of the trial will be presented at local and international conferences and submitted for publication to a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT03949088).

Sepsis With Preexisting Heart Failure: Management of Confounding Clinical Features

Preexisting heart failure (HF) in patients with sepsis is associated with worse clinical outcomes. Core sepsis management includes aggressive volume resuscitation followed by vasopressors (and potentially inotropes) if fluid is inadequate to restore perfusion; however, large fluid boluses and vasoactive agents are concerning amid the cardiac dysfunction of HF. This review summarizes evidence regarding the influence of HF on sepsis clinical outcomes, pathophysiologic concerns, resuscitation targets, hemodynamic interventions, and adjunct management (ie, antiarrhythmics, positive pressure ventilatory support, and renal replacement therapy) in patients with sepsis and preexisting HF. Patients with sepsis and preexisting HF receive less fluid during resuscitation; however, evidence suggests traditional fluid resuscitation targets do not increase the risk of adverse events in HF patients with sepsis and likely improve outcomes. Norepinephrine remains the most well-supported vasopressor for patients with sepsis with preexisting HF, while dopamine may induce more cardiac adverse events. Dobutamine should be used cautiously given its generally detrimental effects but may have an application when combined with norepinephrine in patients with low cardiac output. Management of chronic HF medications warrants careful consideration for continuation or discontinuation upon development of sepsis, and β-blockers may be appropriate to continue in the absence of acute hemodynamic decompensation. Optimal management of atrial fibrillation may include β-blockers after acute hemodynamic stabilization as they have also shown independent benefits in sepsis. Positive pressure ventilatory support and renal replacement must be carefully monitored for effects on cardiac function when HF is present.

Intradialytic hypotension prevalence, influencing factors, and nursing interventions: prospective results of 744 hemodialysis sessions

INTRODUCTION

The aim of this study was to evaluate intradialytic hypotension (IDH) prevalence, influencing factors, and nursing interventions in hemodialysis (HD) patients.

METHODS

This descriptive and cross-sectional study was conducted at a private dialysis center. The patients were followed-up in terms of IDH development based on the European Best Practice Guidelines criteria during six consecutive HD sessions. The study followed the STROBE checklist.

RESULTS

A total of 744 hemodialysis sessions of 124 patients were monitored. IDH developed in 51.6% of the patients and the prevalence was 17.60%. The most common nursing interventions were stopping ultrafiltration and isotonic saline solution administration. White blood cell (WBC) (p = 0.017) and creatinine (p = 0.005) values were statistically significantly higher in patients developing IDH. WBC was found to increase IDH development risk 0.796 times (95% CI [0.657-0.996], p = 0.021).

CONCLUSION

Nursing staff awareness regarding the frequency of IDH in hemodialysis patients and the related symptoms needs to be increased.

Non-invasive venous waveform analysis (NIVA) for volume assessment in patients undergoing hemodialysis: an observational study

BACKGROUND

Accurate assessment of volume status to direct dialysis remains a clinical challenge. Despite current attempts at volume-directed dialysis, inadequate dialysis and intradialytic hypotension (IDH) are common occurrences. Peripheral venous waveform analysis has recently been developed as a method to accurately determine intravascular volume status through algorithmic quantification of changes in the waveform that occur at different volume states. A noninvasive method to capture peripheral venous signals is described (Non-Invasive Venous waveform Analysis, NIVA). The objective of this proof-of-concept study was to characterize changes in NIVA signal with dialysis. We hypothesized that there would be a change in signal after dialysis and that the rate of intradialytic change in signal would be predictive of IDH.

METHODS

Fifty subjects undergoing inpatient hemodialysis were enrolled. A 10-mm piezoelectric sensor was secured to the middle volar aspect of the wrist on the extremity opposite to the access site. Signals were obtained fifteen minutes before, throughout, and up to fifteen minutes after hemodialysis. Waveforms were analyzed after a fast Fourier transformation and identification of the frequencies corresponding to the cardiac rate, with a NIVA value generated based on the weighted powers of these frequencies.

RESULTS

Adequate quality (signal to noise ratio > 20) signals pre- and post- dialysis were obtained in 38 patients (76%). NIVA values were significantly lower at the end of dialysis compared to pre-dialysis levels (1.203 vs 0.868, p < 0.05, n = 38). Only 16 patients had adequate signals for analysis throughout dialysis, but in this small cohort the rate of change in NIVA value was predictive of IDH with a sensitivity of 80% and specificity of 100%.

CONCLUSIONS

This observational, proof-of-concept study using a NIVA prototype device suggests that NIVA represents a novel and non-invasive technique that with further development and improvements in signal quality may provide static and continuous measures of volume status to assist with volume directed dialysis and prevent intradialytic hypotension.

Correlation between body composition measurement by bioelectrical impedance analysis and intradialytic hypotension

OBJECTIVE

To explore the correlation between body composition measurement by bioelectrical impedance analysis (BIA) and intradialytic hypotension (IDH).

METHODS

The clinical data of 127 patients with end-stage renal disease (ESRD) who underwent regular dialysis in the Blood Purification Center of the Second Affiliated Hospital of Chongqing Medical University were retrospectively analyzed. According to the occurrence of IDH, the patients were divided into IDH group and intradialytic normotension group. The difference in body composition measured by BIA and its relationship with IDH were compared between the two groups.

RESULTS

Compared with intradialytic normotension group, the intracellular water (ICW) ratio (P = 0.009), extracellular water (ECW) ratio (P = 0.029), total body water (TBW) ratio (P = 0.012), protein ratio (P = 0.010), soft lean mass (SLM) ratio (P = 0.011), fat-free mass (FFM) ratio (P = 0.012) and skeletal muscle mass (SMM) ratio (P = 0.009) in IDH group were significantly decreased. However, the fat mass (FM) ratio (P = 0.016), percentage body fat (PBF) ratio (P = 0.001), extracellular water/total body water (ECW/TBW) ratio (P = 0.036), extracellular water/total body water in trunk (ECW/TBWT) ratio (P = 0.045) and visceral fat area (VFA) (P = 0.003) in IDH group were significantly increased when compared with intradialytic normotension group. In addition, there was a positive correlation between systolic blood pressure (SBP) during IDH and ECW ratio, ECW/TBW ratio, and ECW/TBWTR ratio before dialysis.

CONCLUSIONS

The body composition of dialysis patients is closely related to the occurrence of IDH. Strengthening the body composition management of dialysis patients outside the hospital may reduce the occurrence of IDH and improve the long-term prognosis of dialysis patients.

Intradialytic hypotension and associated factors among patients on maintenance hemodialysis: A single-center study in cameroon

Intradialytic hypotension (IDH), one of the most frequent acute complications of hemodialysis (HD), is associated with increased patient's morbidity and mortality. The aim of this study was to determine its prevalence and associated factors among patients on maintenance HD in Cameroon. This was a prospective longitudinal study carried out from June 20, to July 30, 2016 (5 weeks), including adult patients on HD >3 months at a tertiary hospital in Douala. During this period, patients were followed up at each HD session, and their blood pressure and occurrence of clinical events possibly related to IDH were recorded. In this study, IDH was defined as a decrease in systolic BP by >20 mm Hg or a decrease in mean arterial pressure by >10 mm Hg, associated to a clinical event. Logistic regression analysis was used to determine associated factors. We included 104 patients (69 males) with a mean age of 50.74 ± 15.18 years and a median duration on HD of 30.5 (interquartile range: 12.25-58.75) years. Hypertension 99/104 (95.2%) and diabetes 32/104 (30.8%) were the main comorbidities encountered. A total of 1032 HD sessions were followed up with an average of 9.88 ± 1.57 sessions per patient. IDH occurred in 11.6% of HD sessions. Associated factors were age, female sex, HIV infection, feeding during dialysis, and use of antihypertensive drug during or within 2 h before dialysis. The prevalence of IDH in our study was low. Associated factors were mainly related to patient's characteristics and comorbidities.

Dialysis-specific factors and incident atrial fibrillation in hemodialysis patients

Background

Atrial fibrillation (AF) is common in end-stage renal disease patients. Besides the traditional risk factors, we aimed to find dialysis-specific factors for developing incident AF.

Methods

From March 2017 to August 2018, we retrospectively reviewed all outpatient-based prevalent hemodialysis patients in our artificial kidney room, and they were followed up until August 2019. Dialysate calcium concentration (3 versus 2.5 mEq/L), time length (4 versus 3.5 h), frequency (thrice weekly versus twice weekly), dialyzer size (effective surface area of 1.4 m² versus 1.8 m²), membrane permeability (high flux versus low flux), ultrafiltration rate (mL/kg/hour), and blood flow rate (mL/min) were evaluated.

Results

Among a total of 84 patients, 15 (17.9%) had newly detected AF with a follow-up period of 21 (13.3–24) months. By performing multivariate Cox regression analysis, blood flow rate (mL/min) and ultrafiltration rate (mL/kg/h) were considered significant factors for developing incident AF (adjusted hazard ratio [HR], 0.977; p = 0.011 and adjusted HR, 1.176; p = 0.013, respectively), while dialysis bath, time length, and frequency, dialyzer size, and membrane type were not considered significant factors. Ultrafiltration cutoff rate of 8.6 mL/kg/h was the best predictive factor for incident AF (area under the curve-receiver operating characteristic [AUC-ROC], 0.746; p < 0.005), while blood flow rate was not considered a significant factor for incident AF in ROC analysis (AUC-ROC, 0.623; p = 0.126). Ultrafiltration rate was largely dependent on interdialytic weight gain (p < 0.005, linear-by-linear association).

Conclusion

Higher ultrafiltration rate was associated with incident AF in hemodialysis patients.

Evaluation of peripheral perfusion index and heart rate variability as early predictors for intradialytic hypotension in critically ill patients

BACKGROUND

Intradialytic hypotension is a serious complication during renal replacement therapy in critically ill patients. Early prediction of intradialytic hypotension could allow adequate prophylactic measures. In this study we evaluated the ability of peripheral perfusion index (PPI) and heart rate variability (HRV) to predict intradialytic hypotension.

METHODS

A prospective observational study included 36 critically ill patients with acute kidney injury during their first session of intermittent hemodialysis. In addition to basic vital signs, PPI was measured using Radical-7 (Masimo) device. Electrical cardiometry (ICON) device was used for measuring cardiac output, systemic vascular resistance, and HRV. All hemodynamic values were recorded at the following time points: 30 min before the hemodialysis session, 15 min before the start of hemodialysis session, every 5 min during the session, and 15 min after the conclusion of the session. The ability of all variables to predict intradialytic hypotension was assessed through area under receiver operating characteristic (AUROC) curve calculation.

RESULTS

Twenty-three patients (64%) had intradialytic hypotension. Patients with pulmonary oedema showed higher risk for development of intradialytic hypotension {Odds ratio (95% CI): 13.75(1.4-136)}. Each of baseline HRV, and baseline PPI showed good predictive properties for intradialytic hypotension {AUROC (95% CI): 0.761(0.59-0.88)}, and 0.721(0.547-0.857)} respectively.

CONCLUSIONS

Each of low PPI, low HRV, and the presence of pulmonary oedema are good predictors of intradialytic hypotension.

Systematic Fluid Assessment in Haemodialysis: Development and Validation of A Decision Aid

BACKGROUND

About a third of patients undergoing haemodialysis have poorly controlled fluid status, which may affect survival. Clinical assessment is subjective and imprecise, which has led to the increasing use of devices based on bioimpedance spectroscopy (BIS). However, BIS cannot provide a simple target applicable to all patients. Our aim was to develop and validate a decision aid combining clinical assessment of fluid status with information from BIS in target weight determination.

METHODS

The decision aid was based on empirical experience and a literature review identifying physiological parameters already used in the clinical assessment of fluid status. Content validity was established by patient representatives, interdisciplinary stakeholders and external experts, who assessed item relevance and comprehensiveness. Reliability was assessed by inter-rater agreement analysis between nurses assessing typical patient cases.

RESULTS

The decision aid for Recognition and Correction of Volume Alterations (RECOVA) consists of three parts (1) a scoring system; (2) thresholds and triggers; (3) a decision aid algorithm. Agreement between raters in the assessment of symptoms was almost perfect, with Intraclass Correlation Coefficient > 0.90. Agreement in clinical response was only fair, but increased to moderate, with training and self-reported confidence.

CONCLUSION

RECOVA may enable systematic clinical assessment of fluid status, facilitating early recognition of fluid alterations, and incorporation of bioimpedance into target weight management. However, implementation into clinical practice will require training of staff. Clinical intervention studies are required to evaluate if RECOVA facilitates response to and correction of recognised fluid alterations.

Intradialytic hypotension: beyond hemodynamics

Intradialytic hypotension is a major complication during hemodialysis session, associated with increased risk of cardiovascular events and mortality. Its pathophysiology is believed to be multifactorial and remains not well elucidated. The aim of this study is to put forward new mechanisms behind the development of intradialytic hypotension. The study included sixty-five subjects on chronic hemodialysis, divided into two groups: intradialytic hypotensive (n=12) and normotensive (n=53), according to the variation of systolic blood pressure between post-dialysis and pre-dialysis measurements. Renin and angiotensin converting enzyme I plasma concentrations increased in both groups but more likely in normotensive group. Aldosterone plasma concentration is increased in the normotensive group while it decreased in the intradialytic hypotension group. Plasma endothelin concentrations showed higher values in intradialytic hypotension group. Post-dialysis asymmetric dimethylarginine and angiotensin converting enzyme 2 plasma concentrations were significantly higher in intradialytic hypotension group as compared to normotensive one. Collectrin plasma concentrations were significantly lower in intradialytic hypotension group. Finally, post-dialysis vascular endothelial growth factor C plasma concentration significantly increased in intradialytic hypotension group. In conclusion, endothelial dysfunction characterized by a lower level of vasoactive molecule seems to play a critical role in intradialytic hypotension development.

Racial and Ethnic Disparities in the Obesity Paradox

Obesity is a major risk factor for cardiovascular disease and worse survival in the general population. However, in patients with end-stage renal disease (ESRD), higher body mass index and indexes of body fat and muscle are associated with better survival. Furthermore, these associations, which some have described as the obesity paradox, are more consistent in African American patients being treated with hemodialysis when compared with other racial-ethnic groups. This is in view of data indicating that although the rate of progression to ESRD is faster in African American patients, they have a survival advantage after transition to ESRD when compared with their white counterparts. These observations indicate that there may be significant interaction between race/ethnicity and association of body mass index with outcomes in patients with ESRD. In addition, it is possible that mechanisms underlying improved survival in African American hemodialysis patients are partly related to the association of body mass index with outcomes observed in this patient population. Some of these potential mechanisms may include comparatively reduced risk for protein-energy wasting and malnutrition, possible salutary effects of factors that play a role in energy preservation, resistance to deleterious effects of inflammation, and enhanced muscle mass and body composition. Given that ESRD is associated with significantly increased risk for morbidity and mortality, understanding the pathophysiologic mechanisms responsible for the obesity paradox across race-ethnic populations might help identify potential therapeutic targets that can be used to improve survival in this patient population.

Non-invasive hemodynamic profiling of patients undergoing hemodialysis - a multicenter observational cohort study

Background

Intradialytic blood pressure (BP) measurement is currently the main parameter used for monitoring hemodynamics during hemodialysis (HD). Since BP is dependent on cardiac output and total peripheral resistance, knowledge of these parameters throughout the HD treatment would potentially be valuable.

Methods

The use of a novel non-invasive monitoring system for profiling hemodynamic response patterns during HD was explored: a whole-body bio-impedance system was used to assess cardiac index (CI), total peripheral resistance index (TPRI), cardiac power index (CPI) among other parameters in chronic HD patients from 4 medical centers. Measurements were made pre, during and post dialysis. Patients were grouped into 5 hemodynamic profiles based on their main hemodynamic response during dialysis i.e. high TPRI; high CPI; low CPI; low TPRI and those with normal hemodynamics. Comparisons were made between the groups for baseline characteristics and 1-year mortality.

Results

In 144 patients with mean age of 67.3 ± 12.1 years pre-dialysis hemodynamic measurements were within normal limits in 35.4% but only 6.9% overall remained hemodynamically stable during dialysis. Intradialytic BP decreased in 65 (45.1%) in whom, low CPI (47 (72.3%)) and low TPRI (18 (27.7%) were recorded. At 1-year follow-up, mortality rates were highest in patients with low CPI (23.4%) and low TPRI (22.2%).

Conclusions

Non-invasive assessment of patients’ response to HD provides relevant hemodynamic information that exceeds that provided by currently used BP measurements. Use of these online analyses could potentially improve the safety and performance standards of dialysis by guiding appropriate interventions, particularly in responding to hypertension and hypotension.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1542-4) contains supplementary material, which is available to authorized users.

Effects of sertraline in the prevention of low blood pressure in patients undergoing hemodialysis

INTRODUCTION

Intradialytic hypotension (IDH) is a major complication of hemodialysis, with a prevalence of about 25% during hemodialysis sessions, causing increased morbidity and mortality.

OBJECTIVE

To study the effects of sertraline to prevent IDH in hemodialysis patients.

METHODS

This was a double-blind, crossover clinical trial comparing the use of sertraline versus placebo to reduce intradialytic hypotension.

RESULTS

Sixteen patients completed the two phases of the study during a 12-week period. The IDH prevalence was 32%. A comparison between intradialytic interventions, intradialytic symptoms, and IDH episodes revealed no statistical difference in the reduction of IDH episodes (p = 0.207) between the two intervention groups. However, the risk of IDH interventions was 60% higher in the placebo group compared to the sertraline group, and the risk of IDH symptoms was 40% higher in the placebo group compared to the sertraline group. Survival analysis using Kaplan-Meier estimator supported the results of this study. Sertraline presented a number needed to treat (NNT) of 16.3 patients to prevent an episode from IDH intervention and 14.2 patients to prevent an episode from intradialytic symptoms.

CONCLUSION

This study suggests that the use of sertraline may be beneficial to reduce the number of symptoms and ID interventions, although there was no statistically significant difference in the blood pressure levels.

Emergency department visits and hospitalizations among hemodialysis patients by day of the week and dialysis schedule in the United States

Background and objective

Previous reports indicated that patients on thrice-weekly hemodialysis (HD) had higher mortality rates after the 3-day interdialytic interval. However, day-of-the-week patterns of emergency department (ED) visits and hospitalizations remain under-investigated.

Methods

We conducted a retrospective cohort study of HD patients on thrice-weekly dialysis, using 2013 data from the United States Renal Data System (USRDS). We estimated crude incidence rates of ED visits and hospitalizations by day of the week and dialysis schedule (Monday, Wednesday, Friday or Tuesday, Thursday, Saturday). Using Poisson regression, we estimated case-mix adjusted rate ratios of all-cause ED visits and hospitalizations, and adjusted rates of cause-specific ED visits and hospitalizations.

Results

We identified 241,093 eligible HD patients in 2013, who had 514,773 ED visits and 301,674 hospitalizations that year. Three distinct but related patterns of outcome events were observed. Crude and adjusted incidence rates of all-cause, cardiovascular, and infection-related ED visits and hospitalizations, but not vascular-access-related events, were higher on all three HD treatment days (“dialysis-day effect”). Rates for ED visits and hospitalizations were lower on weekends than weekdays, rising appreciably from Sunday to Monday for both dialysis schedules (“post-weekend effect”); and rates were highest after the long 3-day interval between dialysis sessions for both dialysis schedules (“interdialytic-gap effect”). In contrast, rates of hospitalizations not preceded by an ED visit were nearly the same Monday through Friday and lower on weekends for both dialysis schedules.

Conclusions

Higher rates of ED visits and hospitalizations on the days of HD sessions and early in the week are a public-health concern that should stimulate research to explain these patterns and reduce the excessive morbidity and associated costs among patients on thrice-weekly HD, while improving quality of care and patient experience with dialysis.

Butyrate production in patients with end-stage renal disease

Background: Chronic kidney disease (CKD) is associated with a decreased intestinal barrier function, causing bacterial translocation over the intestinal wall and triggering a systemic inflammatory response. Butyrate, a short-chain fatty acid produced by certain bacterial strains, is considered instrumental to keep the intestinal barrier intact. There are indications that a decreased amount of these specific bacterial species is part of the cause of the decreased intestinal barrier function in CKD. The aim of this study is (i) to determine if Dutch patients with end-stage renal disease (ESRD) have a decreased amount of butyrate-producing species and butyrate-producing capacity and (ii) whether this correlates with systemic inflammation. Methods: We used qPCR to evaluate the most abundant butyrate-producing species F. prauznitzii, E. rectale and Roseburia spp. and the BCoAT gene, which reflects the butyrogenic capacity of the intestinal microbiota. Fecal samples were collected from healthy kidney donors (n=15), preemptive renal transplant recipients (n=4) and dialysis patients (n=31). Markers of inflammation (CRP and IL-6) and intestinal permeability (D-lactate) were measured in plasma. Results: Patients with ESRD did not have a significantly decreased amount F. prauznitzii, E. rectale and Roseburia spp. or the BCoAT gene. Neither was there a significant correlation with CRP, IL-6 or D-lactate. On the individual level, there were some patients with decreased BCoAT levels and increased levels of CRP, IL-6 and D-lactate. Conclusions: Patients with ESRD do not have a decreased amount of the most abundant butyrate-producing species nor a decreased butyrate-producing capacity.

Dialysis Prescription and Sudden Death

In the United States, end-stage renal disease patients receiving hemodialysis have an exceedingly high risk of sudden cardiac death (SCD), accounting for 29% of death events, likely relating to their uremic milieu, recurring exposure to fluid and electrolyte fluxes, and underlying cardiovascular pathology. Furthermore, epidemiologic studies have shown that SCD events, as well as mortality and hospitalizations, occur most frequently on the first dialysis day after the long interdialytic gap, suggesting that abrupt fluctuations in the accumulation and removal of electrolytes, fluid, and uremic toxins over the dialysis cycle may be contributory. Some population-based observational studies have suggested that lower dialysate potassium concentrations appear to be associated with a heightened risk of postdialysis cardiac arrest in hemodialysis patients, although the optimal serum-to-dialysate potassium gradient remains unclear. Some observational studies have suggested that low dialysate calcium concentrations and high serum-to-dialysate calcium gradients may predispose patients to SCD. There is ongoing controversy about an association between higher dialysate bicarbonate concentrations and higher risk of cardiac arrest, likely owing to confounding by indication. Some observational studies also have shown that large interdialytic weight gains, fluid retention, and high ultrafiltration rates are linked with higher risk of SCD and mortality. However, there remains considerable controversy regarding the pros and cons of designating a specific upper ultrafiltration limit with extended treatment times as a clinical practice measure, and further studies are needed to define the optimal tools, metrics, targets, and implementation measures for volume control in the hemodialysis population. In this review, we highlight the epidemiology and pathophysiology of how specific aspects of the hemodialysis procedure may relate to the risk of SCD, as well as preventative strategies and future research directions that can address this risk.

Associations between Hemodialysis Facility Practices to Manage Fluid Volume and Intradialytic Hypotension and Patient Outcomes

BACKGROUND AND OBJECTIVES

Fluid overload and intradialytic hypotension are associated with cardiovascular events and mortality in patients on hemodialysis. We investigated associations between hemodialysis facility practices related to fluid volume and intradialytic hypotension and patient outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were analyzed from 10,250 patients in 273 facilities across 12 countries, from phase 4 of the Dialysis Outcomes and Practice Patterns Study (DOPPS; 2009-2012). Cox regression models (shared frailty) were used to estimate associations between facility practices reported by medical directors in response to the DOPPS Medical Directors Survey and all-cause and cardiovascular mortality and hospitalization, and cardiovascular events, adjusting for country, age, sex, dialysis vintage, predialysis systolic BP, cardiovascular comorbidities, diabetes, body mass index, smoking, residual kidney function, dialysis adequacy, and vascular access type.

RESULTS

Of ten facility practices tested (chosen a priori), having a protocol that specifies how often to assess dry weight in most patients was associated with lower all-cause (hazard ratio [HR], 0.78; 99% confidence interval [99% CI], 0.64 to 0.94) and cardiovascular mortality (HR, 0.72; 99% CI, 0.55 to 0.95). Routine orthostatic BP measurement to assess dry weight was associated with lower all-cause hospitalization (HR, 0.86; 99% CI, 0.77 to 0.97) and cardiovascular events (HR, 0.85; 99% CI, 0.73 to 0.98). Routine use of lower dialysate temperature to limit or prevent intradialytic hypotension was associated with lower cardiovascular mortality (HR, 0.76; 99% CI, 0.58 to 0.98). Routine use of an online volume indicator to assess dry weight was associated with higher all-cause hospitalization (HR, 1.19; 99% CI, 1.02 to 1.38). Routine use of sodium modeling/profiling to limit or prevent intradialytic hypotension was associated with higher all-cause mortality (HR, 1.36; 99% CI, 1.14 to 1.63), cardiovascular mortality (HR, 1.34; 99% CI, 1.04 to 1.73), and cardiovascular events (HR, 1.21; 99% CI, 1.03 to 1.43).

CONCLUSIONS

Hemodialysis facility practices relating to the management of fluid volume and intradialytic hypotension are associated with patient outcomes.

Predicting intradialytic hypotension using heart rate variability

This study aimed to identify whether a new method using heart rate variability (HRV) could predict intradialytic hypotension (IDH) for one month in advance for patients undergoing prevalent hemodialysis. A total 71 patients were enrolled, and baseline clinical characteristics and laboratory results were collected when HRV was measured, then, the frequency of IDH was collected during the observation period. HRV parameters included heart rate, R-R interval, the standard deviation of N-N interval, the square root of the mean squared differences of successive NN intervals, very low frequency, low frequency, high frequency, total power, and low frequency/high frequency ratio. During the one-month observation period, 28 patients experienced 85 cases of IDH (10.0% of a total 852 dialysis sessions). Among the clinical and laboratory parameters, ultrafiltration rate, prior history of diabetes, coronary artery disease, or congestive heart failure, age, intact parathyroid hormone level, and history of antihypertensive drug use were integrated into the multivariate model, referred to as a basic model, which showed significant ability to predict IDH (the area-under-curve [AUC], 0.726; p = 0.002). In HRV parameters, changes between the early and middle phases of hemodialysis (referred to Δ) were identified as significant independent variables. New models were built from the combination of Δ values with the basic model. Among them, a model with the highest AUC value (AUC, 804; p < 0.001) was compared to the basic model and demonstrated improved performance when HRV parameters were used (p = 0.049). Based on our results, it is possible that future IDH might be predicted more accurately using HRV.

Prognostic value of pre-dialysis blood pressure and risk threshold on clinical outcomes in hemodialysis patients: The Q-Cohort Study

The influence of pre-dialysis blood pressure (BP) on the prognosis of hemodialysis (HD) patients is still inconclusive.A total of 3436 HD patients were prospectively followed up for 4 years. The patients were divided into quintiles of pre-dialysis systolic BP (SBP) and diastolic BP (DBP) levels [mm Hg]: Quintile 1 (Q1), SBP <134, DBP <66; Q2, SBP 134 to 147, DBP 66 to 72; Q3, SBP 148 to 158, DBP 73 to 79; Q4, SBP 159 to 171, DBP 80 to 85; Q5, SBP ≥172, DBP ≥86. The association between the pre-dialysis BP and outcomes were examined using a Cox proportional hazards model.During a 4-year follow-up period, 564 (16.4%) patients died of any cause and 590 (17.2%) developed cardiovascular (CV) events. The lowest level of pre-dialysis SBP group (Q1) showed a significantly increased risk of all-cause mortality (hazard ratio [HR] 1.83, 95% confidence interval [CI] 1.40-2.39) and the highest group (Q5) significantly increased risk of CV events (HR 1.31, 95% CI 1.02-1.68) compared with the reference group (Q3), respectively. The highest level of pre-dialysis DBP group was significantly associated with increased risk for both all-cause mortality and CV events. Restricted cubic spline analysis for BP and outcomes suggested the optimal pre-dialysis BP value associated with the lowest risk of outcomes was SBP 152 mm Hg for all-cause mortality, SBP 143 mm Hg for CV events, and DBP 68 mm Hg for all-cause mortality.Our results suggested that pre-dialysis BP was independently associated with all-cause mortality and CV events among Japanese HD patients.

Novel Insights into the Pathogenesis and Prevention of Intradialytic Hypotension

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of haemodialysis (HD) and associated with adverse outcomes, especially when a nadir definition (systolic blood pressure <90 mm Hg) is used. The pathogenesis of IDH is directly linked to the discontinuous nature of the HD treatment, in combination with patient-related factors such as age, diabetes mellitus and cardiac failure.

SUMMARY

Although the decline in blood volume due to removal of fluid by ultrafiltration is the prime mover, thermally induced reflex vasodilation compromises the haemodynamic response to hypovolemia. Recent studies have stressed the relevance of changes in tissue perfusion during HD, which may translate in long-term organ damage. Monitoring changes in tissue perfusion, for which emerging evidence becomes available, appears to have great promise in the fine-tuning of the dialysis procedure. Key Messages: While it is unlikely that IDH can be completely prevented, reduction in inter-dialytic weight gain, prevention of an increase in core temperature by adjusting the dialysate temperature and more frequent or prolonged dialysis treatment remain cornerstones in providing a more comfortable and safe treatment.