Measuring intradialytic hypotension to improve quality of care

Association of frequent intradialytic hypotension with the clinical outcomes of patients on hemodialysis: a prospective cohort study

Intradialytic hypotension (IDH) is a common complication of hemodialysis (HD), but there is no consensus on its definition. In 2015, Flythe proposed a definition of IDH (Definition 1 in this study): nadir systolic blood pressure (SBP) <90 mmHg during hemodialysis for patients with pre-dialysis SBP <159 mmHg, and nadir SBP <100 mmHg during hemodialysis for patients with pre-dialysis SBP ≥160 mmHg. This prospective observational cohort study investigated the association of frequent IDH based on Definition 1 with clinical outcomes and compared Definition 1 with a commonly used definition (nadir SBP <90 mmHg during hemodialysis, Definition 2). The incidence of IDH was observed over a 3-month exposure assessment period. Patients with IDH events ≥30% were classified as 'frequent IDH'; the others were 'infrequent IDH'. All-cause mortality, cardiovascular mortality, and all-cause hospitalization events were followed up for 36 months. This study enrolled 163 HD patients. The incidence of IDH was 11.1% according to Definition 1 and 10.5% according to Definition 2. The Kaplan-Meier curves showed that frequent IDH patients had higher risks of all-cause mortality (p = 0.009, Definition 1; p = 0.002, Definition 2) and cardiovascular mortality (p = 0.021, Definition 1). Multivariable Cox regression analysis indicated that frequent IDH was independently associated with a higher risk of all-cause mortality (Model 1: HR = 2.553, 95%CI 1.334-4.886, p = 0.005; Model 2: HR = 2.406, 95%CI 1.253-4.621, p = 0.008). In conclusion, HD patients classified as frequent IDH are at a greater risk of all-cause mortality. This highlights the significance of acknowledging and proactively managing frequent IDH within the HD patients.

Prediction of intradialytic hypotension using pre-dialysis features-a deep learning-based artificial intelligence model

BACKGROUND

Intradialytic hypotension (IDH) is a serious complication of hemodialysis (HD) that is associated with increased risks of cardiovascular morbidity and mortality. However, its accurate prediction remains a clinical challenge. The aim of this study was to develop a deep learning-based artificial intelligence (AI) model to predict IDH using pre-dialysis features.

METHODS

Data from 2007 patients with 943 220 HD sessions at seven university hospitals were used. The performance of the deep learning model was compared with three machine learning models (logistic regression, random forest and XGBoost).

RESULTS

IDH occurred in 5.39% of all studied HD sessions. A lower pre-dialysis blood pressure (BP), and a higher ultrafiltration (UF) target rate and interdialytic weight gain in IDH sessions compared with non-IDH sessions, and the occurrence of IDH in previous sessions was more frequent among IDH sessions compared with non-IDH sessions. Matthews correlation coefficient and macro-averaged F1 score were used to evaluate both positive and negative prediction performances. Both values were similar in logistic regression, random forest, XGBoost and deep learning models, developed with data from a single session. When combining data from the previous three sessions, the prediction performance of the deep learning model improved and became superior to that of other models. The common top-ranked features for IDH prediction were mean systolic BP (SBP) during the previous session, UF target rate, pre-dialysis SBP, and IDH experience during the previous session.

CONCLUSIONS

Our AI model predicts IDH accurately, suggesting it as a reliable tool for HD treatment.

Diagnosis and treatment of hypertension in dialysis patients: a systematic review

In patients with end-stage renal disease (ESRD) undergoing dialysis, hypertension is common but often inadequately controlled. The prevalence of hypertension varies widely among studies because of differences in the definition of hypertension and the methods of used to measure blood pressure (BP), i.e., peri-dialysis or ambulatory BP monitoring (ABPM). Recently, ABPM has become the gold standard for diagnosing hypertension in dialysis patients. Home BP monitoring can also be a good alternative to ABPM, emphasizing BP measurement outside the hemodialysis (HD) unit. One thing for sure is pre- and post-dialysis BP measurements should not be used alone to diagnose and manage hypertension in dialysis patients. The exact target of BP and the relationship between BP and all-cause mortality or cause-specific mortality are unclear in this population. Many observational studies with HD cohorts have almost universally reported a U-shaped or even an L-shaped association between BP and all-cause mortality, but most of these data are based on the BP measured in HD units. Some data with ABPM have shown a linear association between BP and mortality even in HD patients, similar to the general population. Supporting this, the results of meta-analysis have shown a clear benefit of BP reduction in HD patients. Therefore, further research is needed to determine the optimal target BP in the dialysis population, and for now, an individualized approach is appropriate, with particular emphasis on avoiding excessively low BP. Maintaining euvolemia is of paramount importance for BP control in dialysis patients. Patient heterogeneity and the lack of comparative evidence preclude the recommendation of one class of medication over another for all patients. Recently, however, β-blockers could be considered as a first-line therapy in dialysis patients, as they can reduce sympathetic overactivity and left ventricular hypertrophy, which contribute to the high incidence of arrhythmias and sudden cardiac death. Several studies with mineralocorticoid receptor antagonists have also reported promising results in reducing mortality in dialysis patients. However, safety issues such as hyperkalemia or hypotension should be further evaluated before their use.

Low dialysate sodium in children and young adults on maintenance hemodialysis: a prospective, randomized, crossover study

BACKGROUND

The optimal dialysate sodium concentration (dNa) in children on hemodialysis (HD) is unknown. The aim of this study was to compare the effect on interdialytic weight gain (IDWG) and blood pressure (BP) of a low (135 mmol/l) and standard dNa (138 mmol/l) in children and young adults on maintenance HD.

METHODS

This prospective single-blind randomized crossover study consisted of a randomized sequence of two phases: "standard dNa" of 138 mmol/L and "low dNa" of 135 mmol/L. Each phase lasted 4 weeks. Inclusion criteria were age < 25 years, hypertension, pre-HD serum Na (sNa) ≥ 130 mmol/L, and occurrence of symptoms in less than 25% of sessions. Primary outcomes were pre-HD systolic and diastolic BP and IDWG.

RESULTS

Fifteen patients were recruited, mean age 17.8 ± 4.4 years. Pre-HD SBP and DBP were not different between the two treatments. Mean IDWG was significantly lower with low dNa than with standard dNa: 2.12 ± 1.39% vs. 2.77 ± 1.53%, respectively (p = 0.008). The first-hour refill index (a volume index based on blood-volume monitoring) was significantly lower with dNa 135 mmol/L (p = 0.018). The mean Na gradient (dNa-sNa) was - 2.53 ± 2.4 mmol/L with dNa 135 mmol/L and 0.17 ± 2.8 mmol/L with dNa 138 mmol/L (p = 0.0001). The incidence of symptomatic sessions was similar (1.0% vs. 1.0%).

CONCLUSIONS

In a selected population of hypertensive pediatric and young adult HD patients, a dNa of 135 mmol/L was associated with a significant reduction of IDWG compared with a dNa of 138 mmol/L. Furthermore, long-term studies are needed to investigate the effect of lowering dNa on BP. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

The time of onset of intradialytic hypotension during a hemodialysis session associates with clinical parameters and mortality

Intradialytic hypotension (IDH) is a common complication of hemodialysis, but there is no data about the time of onset during treatment. Here we describe the incidence of IDH throughout hemodialysis and associations of time of hypotension with clinical parameters and survival by analyzing data from 21 dialysis clinics in the United States to include 785682 treatments from 4348 patients. IDH was defined as a systolic blood pressure of 90 mmHg or under while IDH incidence was calculated in 30-minute intervals throughout the hemodialysis session. Associations of time of IDH with clinical and treatment parameters were explored using logistic regression and with survival using Cox-regression. Sensitivity analysis considered further IDH definitions. IDH occurred in 12% of sessions at a median time interval of 120-149 minutes. There was no notable change in IDH incidence across hemodialysis intervals (range: 2.6-3.2 episodes per 100 session-intervals). Relative blood volume and ultrafiltration volume did not notably associate with IDH in the first 90 minutes but did thereafter. Associations between central venous but not arterial oxygen saturation and IDH were present throughout hemodialysis. Patients prone to IDH early as compared to late in a session had worse survival. Sensitivity analyses suggested IDH definition affects time of onset but other analyses were comparable. Thus, our study highlights the incidence of IDH during the early part of hemodialysis which, when compared to later episodes, associates with clinical parameters and mortality.

Effect of a Supervised Peridialytic Exercise Program on Serum Asymmetric Dimethylarginine in Maintenance Hemodialysis Patients

End-stage renal disease (ESRD) patients treated with maintenance haemodialysis (MHD) have alarmingly high atherosclerotic cardiovascular disease morbidity and mortality. Nitric oxide (NO) is the principal endogenous antiatherosclerotic molecule. Increased asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor, was strongly implicated in endothelial dysfunction, premature atherosclerosis, vascular events, and mortality. Regular physical exercise effectively decreased serum ADMA in several patient cohorts, but this potential benefit has not been specifically explored among MHD patients. Forty-four middle-aged ESRD patients treated with thrice-weekly MHD for ≥6 months completed a 6-months regimen of peridialytic lower limb exercise comprising predialytic 10–12 stretching cycles and 20–30 minutes of intradialytic pedaling cycles. Before and after the study, predialytic haemoglobin, serum ADMA, urea, creatinine, calcium, phosphorus, and C-reactive protein (CRP) were measured. Dialysis adequacy was assessed by single-pool Kt/V. The average total physical activity (PA) level was assessed by the International Physical Activity Questionnaire (IPAQ). P values <0.05 denoted a statistical significance. The overall level of PA, on both categorical and continuous scales, has significantly increased after application of the exercise program. However, S. ADMA increased from a median of 2375 to 3000 ng/mL (P=0.016). Thirty-one patients sustained an increase in S. ADMA (ADMA_Inc), whereas 13 patients had a declining or stable S. ADMA (ADMA_Dec). Compared with ADMA_Inc, ADMA_Dec patients had significantly higher Kt/V (P=0.02), higher grade of the basal general PA level (P=0.017), and significantly fewer intradialytic hypotension episodes (IDHs) (P=0.019). The increase in the S. ADMA and the poststudy S. ADMA level had statistically significant positive correlations with the number of IDHs (r = 0.401, P=0.007 and r = 0.305, P=0.044, respectively). A 6-month program of combined aerobic and resistance peridialytic exercise failed to reduce S. ADMA in most MHD patients studied. A modest S. ADMA decline, however, occurred in patients with higher basal PA levels, higher Kt/V, and less IDHs. A potential exercise benefit may be promoted by a multidisciplinary approach targeting increased PA, improved dialysis efficiency, and prevention of IDHs.

Predictive modeling of blood pressure during hemodialysis: a comparison of linear model, random forest, support vector regression, XGBoost, LASSO regression and ensemble method

BACKGROUND

Intradialytic hypotension (IDH) is commonly occurred and links to higher mortality among patients undergoing hemodialysis (HD). Its early prediction and prevention will dramatically improve the quality of life. However, predicting the occurrence of IDH clinically is not simple. The aims of this study are to develop an intelligent system with capability of predicting blood pressure (BP) during HD, and to further compare different machine learning algorithms for next systolic BP (SBP) prediction.

METHODS

This study presented comprehensive comparisons among linear regression model, least absolute shrinkage and selection operator (LASSO), tree-based ensemble machine learning models (random forest [RF] and extreme gradient boosting [XGBoost]), and support vector regression to predict the BP during HD treatment based on 200 and 48 maintenance HD patients containing a total of 7,180 and 2,065 BP records for the training and test dataset, respectively. Ensemble method also was computed to obtain better predictive performance. We compared the developed models based on R², root mean square error (RMSE) and mean absolute error (MAE).

RESULTS

We found that RF (R²=0.95, RMSE=6.64, MAE=4.90) and XGBoost (R²=1.00, RMSE=1.83, MAE=1.29) had comparable predictive performance on the training dataset. However, RF (R²=0.49, RMSE=16.24, MAE=12.14) had more accurate than XGBoost (R²=0.41, RMSE=17.65, MAE=13.47) on testing dataset. Among these models, the ensemble method (R²=0.50, RMSE=16.01, MAE=11.97) had the best performance on testing dataset for next SBP prediction.

CONCLUSIONS

We compared five machine learning and an ensemble method for next SBP prediction. Among all studied algorithms, the RF and the ensemble method have the better predictive performance. The prediction models using ensemble method for intradialytic BP profiling may be able to assist the HD staff or physicians in individualized care and prompt intervention for patients' safety and improve care of HD patients.

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.

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.

Intermittent pneumatic compression in patients with ESRD. A systematic review

INTRODUCTION

Patients with end-stage renal disease (ESRD) experience frequent hemodialysis (HD) complications. Intradialytic hypotension (IDH) is a common complication presenting in approximately between 20 and 50% of HD sessions. Available interventions such as volume replacement or vasoactive medications are associated with significant side effects. Intermittent pneumatic compression (IPC) has been proposed as a feasible intervention for the prevention of IDH, treatment of peripheral arterial disease and venous ulcers. These devices apply intermittent pressure to the legs improving arterial blood flow, mobilization of pooled blood with an increase in venous return increasing the effective circulatory volume. Our goal was to identify the published clinical evidence on whether IPC has a circulatory benefit and is it well-tolerated among patients receiving HD.

METHODS

We conducted a systematic review to identify studies assessing the efficacy and safety of IPC in patients with ESRD. Our primary outcome was IDH. Secondary outcomes such as HD comfort, ultrafiltration volume, and physical activity were collected. No restrictions where used and we included all observational and interventional studies. Two reviewers performed screening and study quality assessment.

FINDINGS

We included seven studies. Out of the seven studies, five addressed IDH, and the rest were included for secondary outcomes such as physical capacity and HD comfort. In one randomized crossover trial comparing exercise against IPC, 21 patients were randomized to 3 different arms (no intervention, cycling, IPC) a decrease in the rates of IDH with IPC was described (43%, 38%, and 24% respectively P = 0.014). The smaller studies corroborated these results. All studies where at high risk of bias.

DISCUSSION

IPC might offer significant benefits for patients undergoing HD not limited to prevention of IDH but also improvement of hemodialysis comfort and physical capacity. However, our results should be interpreted in the context of its limitations.

Blood volume analysis as a guide for dry weight determination in chronic hemodialysis patients: a crossover study

BACKGROUND

Volume overload and depletion both lead to high morbidity and mortality. Achieving euvolemia is a challenge in patients with end stage kidney disease on hemodialysis (HD). Blood volume analysis (BVA) uses radiolabeled albumin to determine intravascular blood volume (BV). The measured BV is compared to an ideal BV (validated in healthy controls). We hypothesized that BVA could be used in HD to evaluate the adequacy of the current clinically prescribed "estimated dry weight" (EDW) and to titrate EDW in order to improve overall volume status. We were also interested in the reproducibility of BVA results in end stage kidney disease.

METHODS

Twelve adults on chronic HD were recruited; 10 completed the study. BVA (Daxor, New York, NY, USA) was used to measure BV at baseline. EDW was kept the same if the patient was deemed to be euvolemic by BVA otherwise, the prescribed EDW was changed with the aim that measured BV would match ideal BV. A second BVA measurement was done 1-3 months later in order to measure BV again.

RESULTS

Based on BVA, 6/10 patients were euvolemic at baseline and 5/10 were euvolemic at the second measurement. When comparing patients who had their prescribed EDW changed after the initial BVA to those who did not, both groups had similar differences between measured and ideal BV (P = 0.75). BV values were unchanged at the second measurement (P = 0.34) and there was no linear correlation between BV change and weight change (r² = 0.08).

CONCLUSIONS

This pilot study is the first longitudinal measurement of BVA in HD patients. It revealed that changing weight did not proportionally change intravascular BV. BV remained stable for 1-3 months. BVA may not be helpful in clinically stable HD patients but studies on patients with hemodynamic instability and uncertain volume status are needed.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02717533), first registered February 4, 2015.

Implementation of an Algorithm Utilizing Saline Versus Albumin for the Treatment of Intradialytic Hypotension

Background: Intradialytic hypotension (IDH) is the most commonly reported complication of hemodialysis (HD) treatment. At our institution, dialysis patients often have both 25% albumin and normal saline ordered as rescue options for management of IDH, without specification of which agent to use first. Objective: The purpose of this study was to determine the effect of an algorithm for IDH management. Methods: A retrospective study was conducted in HD patients who experienced IDH. The primary end point was to evaluate albumin use. Secondary end points included albumin costs, study fluid use per dialysis session, compliance with algorithm, efficacy of hypotension reversal to mean arterial pressure (MAP) ⩾60 mm Hg, percentage of target ultrafiltration achieved, time required to restore systolic blood pressure ⩾90 mm Hg, blood pressure post–study fluids, IDH treatment failure rate, and early termination of dialysis as a result of persistent IDH. Results: Implementation of the algorithm was observed in 94% of patients (n = 90). Total albumin use was significantly reduced from 11 400 to 4700 mL in the pre– (n = 90) and post–algorithm implementation group (n = 90; P < 0.001). The associated total cost of albumin was reduced by 59% ($10 534 vs $4343; P < 0.001). No statistical differences were observed between the 2 groups regarding efficacy of hypotension reversal to MAP ⩾60 mm Hg, early HD termination, or treatment failure rates (all P = 0.99). Conclusion and Relevance: Implementation of an evidence-based, standardized algorithm and pharmacy education to nursing staff can result in a reduction in albumin use and its associated drug costs for IDH management without compromising efficacy of IDH reversal.

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.

Intradialytic hypotension

PURPOSE OF REVIEW

This review focuses on recent advances in our understanding of intradialytic hypotension (IDH) and measures that may reduce its frequency.

RECENT FINDINGS

The frequency and severity of IDH predict the risk for adverse clinical outcomes. The highest mortality risks associated with IDH were observed when the intradialytic systolic blood pressure (SBP) nadirs were <90 and <100 mmHg and the predialysis SBP were ≤159 mmHg or ≥160 mmHg, respectively. Interdialytic weight gain (IDWG) ≥3 kg occurs more frequently among patients with IDH. Prolonged and possibly more frequent dialysis, use of biofeedback devices, dialysate cooling and limiting sodium loading are useful measures to reduce the frequency of IDH.

SUMMARY

Frequent IDH is associated with high IDWGs and a poor prognosis. Studies on prolonged dialysis, biofeedback devices and cooled dialysate have yielded promising results. Intradialytic relative blood volume monitoring devices have been investigated in preventing IDH but results are mixed. Administration of a sodium/hydrogen exchange isoform 3 inhibitor increases stool sodium but has not been shown to decrease IDWG. IDH continues to be a significant dialysis complication deserving of further investigation.

BP in Dialysis: Results of a Pilot Study

The optimal BP target for patients receiving hemodialysis is unknown. We randomized 126 hypertensive patients on hemodialysis to a standardized predialysis systolic BP of 110-140 mmHg (intensive arm) or 155-165 mmHg (standard arm). The primary objectives were to assess feasibility and safety and inform the design of a full-scale trial. A secondary objective was to assess changes in left ventricular mass. Median follow-up was 365 days. In the standard arm, the 2-week moving average systolic BP did not change significantly during the intervention period, but in the intensive arm, systolic BP decreased from 160 mmHg at baseline to 143 mmHg at 4.5 months. From months 4-12, the mean separation in systolic BP between arms was 12.9 mmHg. Four deaths occurred in the intensive arm and one death occurred in the standard arm. The incidence rate ratios for the intensive compared with the standard arm (95% confidence intervals) were 1.18 (0.40 to 3.33), 1.61 (0.87 to 2.97), and 3.09 (0.96 to 8.78) for major adverse cardiovascular events, hospitalizations, and vascular access thrombosis, respectively. The intensive and standard arms had similar median changes (95% confidence intervals) in left ventricular mass of -0.84 (-17.1 to 10.0) g and 1.4 (-11.6 to 10.4) g, respectively. Although we identified a possible safety signal, the small size and short duration of the trial prevent definitive conclusions. Considering the high risk for major adverse cardiovascular events in patients receiving hemodialysis, a full-scale trial is needed to assess potential benefits of intensive hypertension control in this population.

An extended Kalman filter with inequality constraints for real-time detection of intradialytic hypotension

Intradialytic hypotension (IDH) is the most common complication of hemodialysis, affecting 15-50% of all dialysis sessions. Previously, we had presented a non-invasive Polyvinylidene Fluoride (PVDF) based sensor in the form of a ring to measure vascular tone and we showed that the morphology of the signal can be utilized to predict IDH. This paper presents an approach for analyzing the PVDF signal using extended Kalman filter (EKF) and a synthetic model that has previously been used to model the ECG signal with Gaussian functions. Moreover, a novel approach for incorporating state inequality constraints into the EKF process using a gradient projection method is introduced. The taut string algorithm was first used to estimate the outline of the signal and remove it to highlight the reflection waves. Then, the EKF was used to characterize the morphology of the signal using Gaussian functions. The amplitudes of the Gaussian functions were used as features to train a classifier. The results indicated that the PPV and NPV for the prediction were 83.33% and 100%, respectively.

Peter WL, Ephraim PL, McDermott A, Herzog CA, Crews DC, Scialla JJ, Tangri N, Miskulin DC, Michels WM, Jaar BG, Zager PG, Meyer KB, Wu AW, Boulware LE. Antihypertensive medications and risk of death and hospitalizations in US hemodialysis patients: Evidence from a cohort study to inform hypertension treatment practices

Antihypertensive medications are commonly prescribed to hemodialysis patients but the optimal regimens to prevent morbidity and mortality are unknown. The goal of our study was to compare the association of routinely prescribed antihypertensive regimens with outcomes in US hemodialysis patients.We used 2 datasets for our analysis. Our primary cohort (US Renal Data System [USRDS]) included adult patients initiating in-center hemodialysis from July 1, 2006 to June 30, 2008 (n = 33,005) with follow-up through December 31, 2009. Our secondary cohort included adult patients from Dialysis Clinic, Inc. (DCI), a national not-for-profit dialysis provider, initiating in-center hemodialysis from January 1, 2003 to June 30, 2008 (n = 11,291) with follow-up through December 31, 2008. We linked the USRDS cohort with Medicare part D prescriptions-fill data and the DCI cohort with USRDS data. Unique aspect of USRDS cohort was pharmacy prescription-fill data and for DCI cohort was detailed clinical data, including blood pressure, weight, and ultrafiltration. We classified prescribed antihypertensives into the following mutually exclusive regimens: β-blockers, renin-angiotensin system blocking drugs-containing regimens without a β-blocker (RAS), β-blocker + RAS, and others. We used marginal structural models accounting for time-updated comorbidities to quantify each regimen's association with mortality (both cohorts) and cardiovascular hospitalization (DCI-Medicare Subcohort).In the USRDS and DCI cohorts there were 9655 (29%) and 3200 (28%) deaths, respectively. In both cohorts, RAS compared to β-blockers regimens were associated with lower risk of death; (hazard ratio [HR]) (95% confidence interval [CI]) for all-cause mortality, (0.90 [0.82-0.97] in USRDS and 0.87 [0.76-0.98] in DCI) and cardiovascular mortality (0.84 [0.75-0.95] in USRDS and 0.88 [0.71-1.07] in DCI). There was no association between antihypertensive regimens and the risk of cardiovascular hospitalizations.In hemodialysis patients undergoing routine care, renin-angiotensin system blocking drugs-containing regimens were associated with a lower risk of death compared with β-blockers-containing regimens but there was no association with cardiovascular hospitalizations. Pragmatic clinical trials are needed to specifically examine the effectiveness of these commonly used antihypertensive regimens in dialysis patients.

Use of ultrasound by registered nurses-a systematic literature review

BACKGROUND

In Western Australia (WA), most stable patients undergoing haemodialysis receive treatment in a satellite setting where no doctors are on-site during treatment hours, so nurses must make critical decisions about fluid removal. Some patients regularly experience adverse events during dialysis (intradialytic), often due to excessive ultrafiltration goals, with intradialytic hypotension being particularly challenging. Ultrasound of the inferior vena cava has been previously demonstrated being a rapid and non-invasive method for volume assessment on haemodialysis patients, thus could hold valuable information for the treating nurse.

AIM

This paper examines the existing literature in regards to the use of ultrasound measurements of the inferior vena cava in patients on haemodialysis for objective assessment of their intravascular volume status by renal nurses.

METHOD

A systematic literature review was performed within medical and nursing databases including CINAHL Plus with Full Text, SCOPUS, Web of Science and MEDLINE.

RESULTS

Renal nurses are conscious of the significance of intradialytic hypotension and have only limited options for its prevention. Ultrasound of the inferior vena cava could add another objective dimension for intravascular volume assessment and prevention of intradialytic hypotension, but to date renal nurses have not been using this technique.

CONCLUSIONS

Ultrasound of the inferior vena cava has the potential to assist in defining the ultrafiltration goal for that particular dialysis session, thus reducing the risk of intradialytic hypotension. Additionally, it has potential to change current renal nursing practice when added to clinical nursing assessment methods. Further studies are required to validate this assessment tool carried out by a renal nurse compared with a skilled ultrasonographer.

Relationship between Interdialytic Weight Gain and Blood Pressure in Pediatric Patients on Chronic Hemodialysis

Overhydration is reported to be the main cause of hypertension (HTN) as well as to have no association with HTN in hemodialysis (HD) population. This is the first report of the relationship between interdialytic weight gain (IDWG) and pre-HD blood pressure (BP) in pediatric patients in relation to residual urine output (RUO). We studied 170 HD sessions and interdialytic periods performed during a 12-week period in 5 patients [age 4–17 years, weight 20.8–66 kg, 3 anuric (102 HD sessions), and 2 nonanuric (68 HD sessions)]. BP is presented as systolic BP index (SBPI) and diastolic BP index (DBPI), calculated as systolic or diastolic BP/95th percentile for age, height, and gender. IDWG did not differ (P > 0.05) between anuric and nonanuric pts. There was a positive but not significant correlation between IDWG and both pre-HD SBPI (r = 0.833, P = 0.080) and pre-HD DBPI (r = 0.841, P = 0.074). Pre-HD SBPI (1.01 ± 0.12 versus 1.13 ± 0.18) and DBPI (0.92 ± 0.16 versus 1.01 ± 0.24) were higher in nonanuric patents (P < 0.001 and P < 0.01, resp.). Pre-HD HTN may not be solely related to IDWG and therapies beyond fluid removal may be needed. Individualized approach to HTN management is necessary in pediatric dialysis population.

Effect of the decrease in dialysate sodium in pediatric patients on chronic hemodialysis

Optimal dialysate sodium (dNa) is unknown, with both higher and lower values suggested in adult studies to improve outcomes. Similar studies in pediatric hemodialysis (HD) population are missing. This is the first report of the effect of two constant dNa concentrations in pediatric patients on chronic HD. 480 standard HD sessions and interdialytic periods were studied in 5 patients (age 4-17 years, weight 20.8-66 kg) during a period of 6-11 months per patient. dNa was 140 mEq/L during the first half, and 138 mEq/L during the second half of the study period for each patient. Lowering dNa was associated with improved preHD hypertension, decreased interdialytic weight gain, decreased need for ultrafiltration, lower sodium gradient and was well tolerated despite lack of concordance with predialysis sNa, that was variable. Further studies are needed to verify our findings and to investigate if an even lower dNa may be more beneficial in the pediatric HD population.