Hemodynamic Effects of Peritoneal Dialysis

Evaluation and outcomes of a 5-year assisted peritoneal dialysis program

BACKGROUND

In 2016, Peritoneal Dialysis Assist (PDA) was implemented in British Columbia, Canada, as a pilot program to allow patients with physical, cognitive and social impairments to access an independent dialysis modality. This is a presentation of the usage and 5-year clinical outcomes of our provincial assisted peritoneal dialysis (PD) program.

METHODS

Patients who utilised long-term or respite PDA services in British Columbia, Canada, from 2016 to 2021 were included in this program evaluation. Incident and prevalent patient numbers were characterised annually as well as indications for PDA and patient demographics both annually and over time. Outcomes of interest included death, transfer to haemodialysis, transplantation and cessation of the PDA program but retention on PD.

RESULTS

Three hundred twenty-two total patients received services through the PDA program. The percentage of PD patients supported by long-term PDA service has grown to 11.2% in the most recent year. Patients spend a median of 13.6 (95% CI: 11.0, 16.1) months on long-term PDA, prolonging overall patient duration on PD by a little over a year. Of the patients who exited the long-term PDA program, 73 (37.4%) were able to utilise the service until they died.

CONCLUSION

PDA is an accessible, patient-centric service with clear and standardised referral criteria. Through the implementation of a local PDA program, patients have accessed PD and may have extended their PD life span, through avoidance of in-centre haemodialysis, by over 13 months during this 5-year study period. A significant proportion of patients on long-term PDA were able to use their preferred kidney replacement modality at home until they reached end of life.

Peritoneal dialysis for acute kidney injury: back on the front-line

Peritoneal dialysis (PD) for acute kidney injury (AKI) has been available for nearly 80 years and has been through periods of use and disuse largely determined by availability of other modalities of kidney replacement therapy and the relative enthusiasm of clinicians. In the past 10 years there has been a resurgence in the use of acute PD globally, facilitated by promotion of PD for AKI in lower resource countries by nephrology organizations effected through the Saving Young Lives program and collaborations with the World Health Organisation, the development of guidelines standardizing prescribing practices and finally the COVID-19 pandemic. This review highlights the history of PD for AKI and looks at misconceptions about efficacy as well as the available evidence demonstrating that acute PD is a safe and lifesaving therapy with comparable outcomes to other modalities of treatment.

Cardiorenal syndrome in the pediatric population: A systematic review

The concept of cardiorenal syndrome (CRS) is derived from the crosstalk between the heart and kidneys in pathological conditions. Despite the rising importance of CRS, there is a paucity of information on the understanding of its pathophysiology and management, increasing both morbidity and mortality for patients. This review summarizes the existing conceptual pathophysiology of different types of CRS and delves into the associated therapeutic modalities with a focus on pediatric cases. Prospective or retrospective observational studies, comparative studies, case reports, case-control, and cross-sectional studies that include pediatric patients with CRS were included in this review. Literature was searched using PubMed, EMBASE, and Google Scholar with keywords including "cardio-renal syndrome, type," "reno-cardio syndrome," "children," "acute kidney injury," and "acute decompensated heart failure" from January 2000 to January 2021. A total of 14 pediatric studies were ultimately included and analyzed, comprising a combined population of 3608 children of which 32% had CRS. Of the 14 studies, 57% were based on type 1 CRS, 14% on types 2 and 3 CRS, and 7% were on types 4 and 5 CRS. The majority of included studies were prospective cohort, although a wide spectrum was observed in terms of patient age, comorbidities, etiologies, and treatment strategies. Commonly observed comorbidities in CRS type 1 were hematologic, oncologic, cardiology-related side effects, muscular dystrophy, and pneumonia/bronchiolitis. CRS, particularly type 1, is prevalent in children and has a significant risk of mortality. The current treatment regimen primarily involves diuretics, extracorporeal fluid removal, and treatment of underlying etiologies and comorbidities.

Simple, high-throughput measurement of gut-derived short-chain fatty acids in clinically relevant biofluids using gas chromatography-mass spectrometry

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A high-throughput assay for measurement of short-chain fatty acids in biofluids.

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A simple, time efficient liquid–liquid extraction protocol with no derivatization.

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Recommend use of lithium heparin plasma or clotting activator serum collection.

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Clinical applicability demonstrated by measurement of kidney disease patient samples.

Introduction

The quantitative measurement of circulating gut bacteria-derived metabolites has increased in recent years due to their associations with health and disease. While much of the previous attention has been placed on metabolites considered as deleterious to health, a shift to the investigation of short-chain fatty acids (SCFAs) as potential health promotors has been observed.

Objectives

To develop a simple, high-throughput and quantitative assay to measure gut-derived SCFAs in clinically relevant biofluids using gas chromatography-mass spectrometry (GC–MS).

Methods

A short (7.5 min) GC–MS assay was optimized for measurement of seven straight- and branched-chain SCFAs and their deuterated isotopes using a wax-based column for analysis without prior derivatization. The assay was validated using routine criteria to assess precision, accuracy, matrix effects, recovery, and extraction reproducibility. Assay applicability was tested in cohorts of healthy individuals and kidney disease patients.

Results

The assay was demonstrated to be precise, accurate and reproducible with acceptable levels of matrix effect and analyte recovery. Lower limits of detection and quantitation were in the low ng/mL range. An investigation into different blood collection tube chemistries demonstrated that lithium heparin plasma and serum clotting activator tubes are recommended for use in future cross-study comparisons. Kidney disease patient analyses demonstrated variable differences across SCFAs when comparing hemodialysis to earlier stages of chronic kidney disease, demonstrating the suitability of the assay for translation to clinical analyses.

Conclusion

The assay has been validated and identified as reliable for use in larger-scale studies for the analysis of SCFAs in human plasma and serum.

Managing heart failure in dialysis patients

The heart and the kidney are intimately connected. They communicate in a bidirectional manner through a variety of pathways, forming an interdependent relationship. Recognition of this co-dependency is crucial in managing patients with cardiorenal syndrome, as we begin to realise the inevitability of disease progression to both organs; and an approach that focuses treatment on one organ may result in worsening outcome on the other organ. When faced with patients with deteriorating cardiac disease, nephrologists tend to focus on stabilisation of cardiac function and accept the heart disease to be unmodifiable. Likewise, cardiac patients with persistent kidney failure are presented with a poor renal prognosis and prepared for kidney transplantation. Adopting a cardio-protective approach in combination with dialysis optimisation raises hope for a more positive outcome with evidence of cardiac and renal recovery in some patients.

Comparison of Cardiovascular Outcomes by Dialysis Modality: A Systematic Review and Meta-Analysis

Debates exist regarding the merit of starting one dialysis modality over the other for improved cardiovascular outcomes. Five previously published prospective and retrospective cohort studies have reported inconsistent conclusions on this topic. The aim of this systematic review and meta-analysis is to evaluate the influence initiation of hemodialysis (HD) vs peritoneal dialysis (PD) may have on the relative risk (RR) of subsequent development of adverse cardiovascular events (ACVE) in patients with end-stage renal disease (ESRD). Of the 518 records identified, 5 cohort studies, assessing a total of 47,062 patients were included in the meta-analysis. With regard to the subsequent development of ACVE following initiation on the different dialysis modalities, the pooled RR was found to be non-significant. Peritoneal dialysis is a suitable and cost-effective alternative to HD for ESRD patients at risk of cardiovascular disease.

The systemic microcirculation in dialysis populations

In a rapidly expanding population of patients with chronic kidney disease, including 2 million people requiring renal replacement therapy, cardiovascular mortality is 15 times greater than the general population. In addition to traditional cardiovascular risk factors, more poorly defined risks related to uremia and its treatments appear to contribute to this exaggerated risk. In this context, the microcirculation may play an important early role in cardiovascular disease associated with chronic kidney disease. Experimentally, the uremic environment and dialysis have been linked to multiple pathways causing microvascular dysfunction. Coronary microvascular dysfunction is reflected in remote and more easily studied vascular beds such as the skin. There is increasing evidence for a correlation between systemic microvascular dysfunction and adverse cardiovascular outcomes. Systemic microcirculatory changes have not been extensively investigated across the spectrum of chronic kidney disease. Recent advances in non-invasive techniques studying the microcirculation in vivo in man are increasing the data available particularly in patients on hemodialysis. Here, we review current knowledge of the systemic microcirculation in dialysis populations, explore whether non-invasive techniques to study its function could be used to detect early stage cardiovascular disease, address challenges faced in studying this patient cohort and identify potential future avenues for research.

Decreased cerebral blood flow and improved cognitive function in patients with end-stage renal disease after peritoneal dialysis: An arterial spin-labelling study

OBJECTIVES

The aim of this study was to evaluate the relationship between cognitive impairment and brain perfusion using arterial spin labelling (ASL) in end-stage renal disease (ESRD) patients undergoing PD.

METHODS

ESRD patients undergoing PD were recruited. Laboratory screening, neuropsychological tests and ASL magnetic resonance imaging (MRI) were conducted prior to and after 6 months of PD. Age- and sex-matched normal subjects without ESRD served as the control group. Comparisons of regional CBF between ESRD patients before or after undergoing PD and normal controls were performed. Correlations between biochemical, neuropsychological and CBF data were also conducted to evaluate the relationships.

RESULTS

ESRD patients showed poor performance in many of the neuropsychological tests; PD improved cognition in some domains. Pre-PD patients had higher mean CBF than post-PD patients and normal controls, but no significant difference was found between the normal controls and post-PD patients. Negative correlations were observed pre-PD (regional CBF in left hippocampus vs. perseverative responses, r = -0.662, p = 0.014), post-PD (mean CBF vs. haemoglobin level, r = -0.766, p = 0.002), and before and after PD (change in CBF in the left putamen vs. change in haematocrit percentage, r = -0.808, p = 0.001).

CONCLUSION

Before PD, ESRD patients had increased cerebral perfusion that was related to poorer executive function, especially in the left hippocampus. Post-PD patients performed better in some cognitive test domains than pre-PD patients. The degree of anaemia, i.e., haemoglobin level or haematocrit percentage, might predict cognitive impairment in PD patients.

KEY POINTS

• In this study, ESRD patients before PD had cerebral hyperperfusion that was related to poorer executive function. • Post-PD patients performed better in some cognitive test domains than pre-PD patients did. • The degree of anaemia might predict cognitive impairment in PD patients.

Effectiveness and Safety of Peritoneal Dialysis Treatment in Patients with Refractory Congestive Heart Failure due to Chronic Cardiorenal Syndrome

Aims

To evaluate the effectiveness and safety of peritoneal dialysis (PD) in treating refractory congestive heart failure (RCHF) with cardiorenal syndrome (CRS).

Methods

A total of 36 patients with RCHF were divided into type 2 CRS group (group A) and non-type 2 CRS group (group B) according to the patients' clinical presentations and the ratio of serum urea to creatinine and urinary analyses in this prospective study. All patients were followed up till death or discontinuation of PD. Data were collected for analysis, including patient survival time on PD, technique failure, changes of heart function, and complications associated with PD treatment and hospitalization.

Results

There were 27 deaths and 9 patients quitting PD program after a follow-up for 73 months with an average PD time of 22.8 ± 18.2 months. A significant longer PD time was found in group B as compared with that in group A (29.0 ± 19.4 versus 13.1 ± 10.6 months, p = 0.003). Kaplan–Meier curves showed a higher survival probability in group B than that in group A (p < 0.001). Multivariate regression demonstrated that type 2 CRS was an independent risk factor for short survival time on PD. The benefit of PD on the improvement of survival and LVEF was limited to group B patients, but absent from group A patients. The impairment of exercise tolerance indicated by NYHA classification was markedly improved by PD for both groups. The technique survival was high, and the hospital readmission was evidently decreased for both group A and group B patients.

Conclusions

Our data suggest that PD is a safe and feasible palliative treatment for RCHF with type 2 CRS, though the long-term survival could not be expected for patients with the type 2 CRS. Registration ID Number is ChiCTR1800015910.

Evaluation of A 12-Month Pilot of Long-Term and Temporary Assisted Peritoneal Dialysis

Background

Peritoneal dialysis (PD) is challenging for patients with functional limitations, and assisted PD can support these patients, but previous reports of assisted PD have not examined the role of temporary assisted PD and had difficulty identifying adequate comparator cohorts.

Methods

Peritoneal Dialysis Assist (PDA), a 12-month pilot of long-term and temporary assisted PD was completed in multiple PD centers in British Columbia, Canada. Continuous cycler PD (CCPD) patients were identified for PDA by standardized criteria, and service could be long-term or temporary/respite. The PDA program provided daily assistance with cycler dismantle and setup, but patients remained responsible for cycler connections and treatment decisions. Outcomes were compared against both the general CCPD population and patients who met PDA criteria but were not enrolled (PDA-eligible).

Results

Fifty-three PDA patients had an 88% 1-year death- and transplant-censored technique survival that was similar to the general CCPD cohort (84%) and PDA-eligible cohort (86%). The PDA cohort had lower peritonitis rates (0.18 episodes/patient-year vs 0.22 and 0.36, respectively), but higher hospitalization (55% vs 34% and 35%, respectively). Long-term PDA cost approximately CDN$15,000/year in addition to existing dialysis costs. A total of 8/11 respite PDA patients (73%) returned to self-care PD after a median PDA use of 29 days, which costs $1,250/patient.

Conclusions

Peritoneal Dialysis Assist provides effective support to functionally-limited CCPD patients and yields acceptable clinical outcomes. The program costs less than transfer to HD or long-term care, which represents cost minimization for failing self-care PD patients. Respite PDA provides effective temporary support; most patients returned to self-care PD and service was cost-effective compared with alternatives of hospitalization or transfer to HD.

Plasma free metanephrine and normetanephrine levels are increased in patients with chronic kidney disease

OBJECTIVE

Patients with impaired renal function, particularly those on dialysis, frequently exhibit high blood pressure and hemodynamic instability, which often lead to pheochromocytoma assessment. Our objective was to assess plasma free metanephrine (MN) and normetanephrine (NMN) in chronic kidney disease patients (CKD) with or without dialysis.

METHODS

In this prospective observational study we performed enzyme-linked immunosorbent assays (ELISAs) to evaluate plasma free MN and NMN in 48 CKD patients (15 with stage 3-5 CKD without dialysis, 26 on hemodialysis [HD], and 7 continuous ambulatory peritoneal dialysis [CAPD]), 30 patients with histologically proven pheochromocytoma, and 43 hypertensive patients. Adrenal masses were ruled out by abdominal computed tomography (CT) scans in all CKD and control hypertensive patients.

RESULTS

All 3 CKD groups (HD, CAPD, and CKD without dialysis) had significantly higher plasma free MN and NMN levels than the control hypertensive group (P<.0055). HD and CAPD patients had significantly lower plasma free NMN (P<.0055), but free MN levels were not significantly different than those observed in pheochromocytoma patients. In patients with HD, CAPD, and CKD without dialysis, plasma free MN and NMN were higher than manufacturer's upper limits of normal in 57.7% and 28.5%, 13.3% and 61.5%, and 85.7% and 26.6%, respectively. Regression models showed that the number of dialysis years was significantly correlated with plasma free MN (r = 0.615, P<.001) but not free NMN.

CONCLUSION

Plasma free MN and NMN levels are frequently elevated in CKD patients, particularly in those on dialysis. Plasma free MN levels significantly overlap with the range in pheochromocytoma patients and correlate with the number of years on dialysis.

Cerebral blood flow changes in hemodialysis and peritoneal dialysis patients: an arterial-spin labeling MR imaging

We used arterial-spin labeling (ASL) MR imaging, a non-invasive technique to evaluate cerebral blood flow (CBF) changes in patients with end-stage renal disease (ESRD) undergoing peritoneal dialysis (PD) and hemodialysis (HD), and nondialysis ESRD patients compared with healthy cohort. Ninety seven ESRD patients including 32 PD patients (20 male, 12 female; mean age 33 ± 8 years), 33 HD patients (22 male, 11 female; mean age 33 ± 8 years) and 32 nondialysis patients (20 male, 12 female; mean age 35 ± 7 years) and 31 age- and gender-matched healthy controls (20 male, 11 female; mean age 32 ± 8 years) were included in this study. All subjects underwent ASL MR imaging, neuropsychologic tests, and ESRD patients underwent laboratory testing. CBF values were compared among PD, HD, nondialysis patients and control groups. Correlation analysis and multiple regression analysis were performed to investigate the association between CBF values and hemoglobin, neuropsychologic test results, serum creatinine, urea levels, disease duration, and dialysis duration. Elevated CBFs of whole brain region, gray matter, and white matter were found in all ESRD patient groups compared with healthy controls (all P < 0.001). However, compared with non-dialysis ESRD patients, both PD and HD patients had widespread regional CBF decline mainly in bilateral frontal and anterior cingulate cortices. There were no differences for CBF between PD and HD patient groups. Negative correlations were observed between mean CBFs of whole brain region, gray matter, and white matter and the hemoglobin level in all ESRD patients. Multiple linear regression showed elevated CBF of multiple brain areas correlated with some neuropsychological tests in ESRD patients (all P < 0.001, AlphaSim corrected), but the association was not present or shrank after adjusting hemoglobin level. This study found that mean CBF was predominantly increased in patients with ESRD, which correlated with their hemoglobin level and neurocognitive disorders. There were no differences of CBF change and cognitive function between PD and HD ESRD patients with long-term treatment. The degree of anemia may be a predominant risk factor for cognitive impairment in these ESRD patients.

Successful Management of Recurrent Colon Ulcer in Hemodialysis Patient after Conversion to Peritoneal Dialysis

Lower gastrointestinal complications often develop in end stage renal disease patients, and among the more problematic is recurrent colon ulcer. The exact pathogenesis of this condition is not known and there were no specific therapeutic modalities concerning this type of disease entity. We report, with a literature review, a case of recurrent colon ulcer with intermittent hematochezia in an end stage renal disease patient on long term hemodialysis that improved after conversion to peritoneal dialysis.

Reverse Epidemiology of Blood Pressure in Peritoneal Dialysis Associated with Dynamic Deterioration of Left Ventricular Function

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BACKGROUND

Reverse epidemiology of blood pressure (BP) in end-stage kidney disease (ESKD) is manifested as higher mortality at lower blood pressure. We hypothesize that this phenomenon is partially mediated by deterioration of cardiac structure and function. ♦

METHODS

Seventy-seven prevalent ESKD patients starting renal replacement therapy on peritoneal dialysis (PD) from 2007 to 2012 were evaluated for the primary outcome of all-cause mortality. Longitudinal data were obtained from 1,930 patient-encounters including monthly clinic BP and serial echocardiograms. Generalized linear mixed models using data from the last observation moving backward, and time-to-event analysis using time-varying Cox-survival models to estimate mortality risk at different blood pressure categories were applied. ♦

RESULTS

There were 39 males (50.6%). Mean age was 51 years (standard deviation [SD] = 15). During follow-up, 20 patients (25%) died. As compared to systolic blood pressure (SBP) of 140-159 mmHg, unadjusted risk of mortality was 7.3 (95% confidence interval [CI]: 1.5-35.7, p = 0.008) at level < 120 mmHg. Systolic BP trended down to an average of 117 mmHg prior to death in non-survivors as compared to 141 mmHg in survivors (p < 0.05). In non-survivors, percentage with concentric left ventricular hypertrophy (LVH) decreased by 20% at the expense of a 20% reciprocal increase in eccentric hypertrophy associated with a 30% increase in percentage with low ejection fraction (EF) (< 50%). After adjusting for EF, risk of mortality at SBP < 120 mmHg attenuated to 3.4 (95% CI: 0.7-17.7, p = 0.14). ♦

CONCLUSION

We conclude that higher mortality associated with lower BP may be mediated in part by worsening heart function in ESKD patients receiving PD.