Estimating risk of encapsulating peritoneal sclerosis accounting for the competing risk of death

Background

Risk of encapsulating peritoneal sclerosis (EPS) is strongly associated with the duration of peritoneal dialysis (PD), such that patients who have been on PD for some time may consider elective transfer to haemodialysis to mitigate the risk of EPS. There is a need to determine this risk to better inform clinical decision making, but previous studies have not allowed for the competing risk of death.

Methods

This study included new adult PD patients in Australia and New Zealand (ANZ; 1990–2010) or Scotland (2000–08) followed until 2012. Age, time on PD, primary renal disease, gender, data set and diabetic status were evaluated as predictors at the start of PD, then at 3 and 5 years after starting PD using flexible parametric competing risks models.

Results

In 17 396 patients (16 162 ANZ, 1234 Scotland), EPS was observed in 99 (0.57%) patients, less frequently in ANZ patients (n = 65; 0.4%) than in Scottish patients (n = 34; 2.8%). The estimated risk of EPS was much lower when the competing risk of death was taken into account (1 Kaplan–Meier = 0.0126, cumulative incidence function = 0.0054). Strong predictors of EPS included age, primary renal disease and time on PD. The risk of EPS was reasonably discriminated at the start of PD (C-statistic = 0.74–0.79) and this improved at 3 and 5 years after starting PD (C-statistic = 0.81–0.92).

Conclusions

EPS risk estimates are lower when calculated using competing risk of death analyses. A patient’s estimated risk of EPS is country-specific and can be predicted using age, primary renal disease and duration of PD.

Peritoneal Cavity Lymphatics

Lymphatic drainage of particulate matters from the peritoneal cavity occurs mainly from lacunae located in the diaphragm. These are a triple-layered structure consisting of mesothelium, a loose network of connective tissue and endothelium. Absorption of particles may occur via gap junctions, through the cells or via vesicles.

Whole blood can be removed fairly rapidly from the peritoneal cavity. Respiration plays an important role in the absorption of particles through lymphatics. Intra-abdominal pressure and posture are other factors which influence lymphatic flow rate in the peritoneal cavity. Little is known about the influence of drugs on lymphatic flow rate from the peritoneal cavity.

Adequacy Targets Can be Met in Anuric Patients by Automated Peritoneal Dialysis: Baseline Data from Eapos

♦ Objective

Conventional continuous ambulatory peritoneal dialysis (CAPD) in patients without residual renal function and with high solute transport is associated with worse clinical outcomes. Automated peritoneal dialysis (APD) has the potential to improve both solute clearance and ultrafiltration in these circumstances, but its efficacy as a treatment modality is unknown. The European Automated Peritoneal Dialysis Outcomes Study (EAPOS) is a 2-year, prospective, European multi-center study designed to determine APD feasibility and clinical outcomes in anuric patients. The present article describes the baseline data for patients recruited into the study.

♦ Design

All PD patients treated in the participating centers were screened for inclusion criteria [urinary output < 100 mL/24 h, or residual renal function (RRF) < 1 mL/min, or both]. After enrollment, changes were made to the dialysis prescription to achieve a weekly creatinine clearance above 60 L per 1.73 m2 and an ultrafiltration rate above 750 mL in 24 hours.

♦ Setting

The study is being conducted in 26 dialysis centers in 13 European countries.

♦ Baseline Data Collection

The information collected includes patient demographics, dialysis prescription, achieved weekly creatinine clearance, and 24-hour ultra-filtration (UF).

♦ Results

The study enrolled 177 anuric patients. Median dialysis duration before enrollment was 22.5 months (range: 0 – 285 months). Mean solute transport measured as the dialysate-to-plasma ratio of creatinine (D/PCr) was 0.74 ± 0.12. Patients received APD for a median of 9.0 hours overnight (range: 7 – 12 hours) using a median of 11.0 L of fluid (range: 6 – 28.75 L). Median daytime volume was 4.0 L (range: 0.0 – 9.0 L). Tidal dialysis was used in 26 patients, and icodextrin in 86 patients. At baseline, before treatment optimization, the weekly mean total creatinine clearance was 65.2 ± 14.4 L/1.73 m2, with 105 patients (60%) achieving the target of more than 60 L/1.73 m2. At baseline, 81% of patients with high transport, 69% with high-average transport, and 40% with low-average transport met the target. At baseline, 70% of patients with a body surface area (BSA) below 1.7 m2, 60% with a BSA of 1.7 – 2.0 m2, and 56% with a BSA above 2.0 m2 achieved 60 L/1.73 m2 weekly. Median UF was 1090 mL/24 h, and 75% of patients achieved the UF target of more than 750 mL/24 h.

♦ Conclusion

This baseline analysis of anuric patients recruited into the EAPOS study demonstrates that a high proportion of anuric patients on APD can achieve dialysis and ultrafiltration targets using a variety of regimes. This 2-year follow-up study aims to optimize APD prescription to reach predefined clearance and ultrafiltration targets, and to observe the resulting clinical outcomes.

A Randomized, Single-Blind, Crossover Trial of Recovery Time in High-Flux Hemodialysis and Hemodiafiltration

Background

The choice between hemodiafiltration (HDF) or high-flux hemodialysis (HD) to treat end-stage kidney disease remains a matter of debate. The duration of recovery time after treatment has been associated with mortality, affects quality of life, and may therefore be important in informing patient choice. We aimed to establish whether recovery time is influenced by treatment with HDF or HD.

Study Design

Randomized patient-blinded crossover trial.

Settings & Participants

100 patients with end-stage kidney disease were enrolled from 2 satellite dialysis units in Glasgow, United Kingdom.

Intervention

8 weeks of HD followed by 8 weeks of online postdilution HDF or vice versa.

Outcomes

Posttreatment recovery time, symptomatic hypotension events, dialysis circuit clotting events, and biochemical parameters.

Measurements

Patient-reported recovery time in minutes, incidence of adverse events during treatments, hematology and biochemistry results, quality-of-life questionnaire.

Results

There was no overall difference in recovery time between treatments (medians for HDF vs HD of 47.5 [IQR, 0-240] vs 30 [IQR, 0-210] minutes, respectively; P = 0.9). During HDF treatment, there were significant increases in rates of symptomatic hypotension (8.0% in HDF vs 5.3% in HD; relative risk [RR], 1.52; 95% CI, 1.2-1.9; P < 0.001) and intradialytic tendency to clotting (1.8% in HDF vs 0.7% in HD; RR, 2.7; 95% CI, 1.5-5.0; P = 0.002). Serum albumin level was significantly lower during HDF (3.2 vs 3.3 g/dL; P < 0.001). Health-related quality-of-life scores were equivalent.

Limitations

Single center; mean achieved HDF convection volume, 20.6 L.

Conclusions

Patients blinded to whether they were receiving HD or HDF in a randomized controlled crossover study reported similar posttreatment recovery times and health-related quality-of-life scores.

Extracorporeal treatment for barbiturate poisoning: recommendations from the EXTRIP Workgroup

The EXTRIP (Extracorporeal Treatments in Poisoning) Workgroup conducted a systematic review of barbiturate poisoning using a standardized evidence-based process to provide recommendations on the use of extracorporeal treatment (ECTR) in patients with barbiturate poisoning. The authors reviewed all articles, extracted data, summarized key findings, and proposed structured voting statements following a predetermined format. A 2-round modified Delphi method was used to reach a consensus on voting statements, and the RAND/UCLA Appropriateness Method was used to quantify disagreement. 617 articles met the search inclusion criteria. Data for 538 patients were abstracted and evaluated. Only case reports, case series, and nonrandomized observational studies were identified, yielding a low quality of evidence for all recommendations. Using established criteria, the workgroup deemed that long-acting barbiturates are dialyzable and short-acting barbiturates are moderately dialyzable. Four key recommendations were made. (1) The use of ECTR should be restricted to cases of severe long-acting barbiturate poisoning. (2) The indications for ECTR in this setting are the presence of prolonged coma, respiratory depression necessitating mechanical ventilation, shock, persistent toxicity, or increasing or persistently elevated serum barbiturate concentrations despite treatment with multiple-dose activated charcoal. (3) Intermittent hemodialysis is the preferred mode of ECTR, and multiple-dose activated charcoal treatment should be continued during ECTR. (4) Cessation of ECTR is indicated when clinical improvement is apparent. This report provides detailed descriptions of the rationale for all recommendations. In summary, patients with long-acting barbiturate poisoning should be treated with ECTR provided at least one of the specific criteria in the first recommendation is present.

Guidelines for reporting case studies on extracorporeal treatments in poisonings: methodology

A literature review performed by the EXtracorporeal TReatments In Poisoning (EXTRIP) workgroup highlighted deficiencies in the existing literature, especially the reporting of case studies. Although general reporting guidelines exist for case studies, there are none in the specific field of extracorporeal treatments in toxicology. Our goal was to construct and propose a checklist that systematically outlines the minimum essential items to be reported in a case study of poisoned patients undergoing extracorporeal treatments. Through a modified two-round Delphi technique, panelists (mostly chosen from the EXTRIP workgroup) were asked to vote on the pertinence of a set of items to identify those considered minimally essential for reporting complete and accurate case reports. Furthermore, independent raters validated the clarity of each selected items between each round of voting. All case reports containing data on extracorporeal treatments in poisoning published in Medline in 2011 were reviewed during the external validation rounds. Twenty-one panelists (20 from the EXTRIP workgroup and an invited expert on pharmacology reporting guidelines) participated in the modified Delphi technique. This group included journal editors and experts in nephrology, clinical toxicology, critical care medicine, emergency medicine, and clinical pharmacology. Three independent raters participated in the validation rounds. Panelists voted on a total of 144 items in the first round and 137 items in the second round, with response rates of 96.3% and 98.3%, respectively. Twenty case reports were evaluated at each validation round and the independent raters' response rate was 99.6% and 98.8% per validation round. The final checklist consists of 114 items considered essential for case study reporting. This methodology of alternate voting and external validation rounds was useful in developing the first reporting guideline for case studies in the field of extracorporeal treatments in poisoning. We believe that this guideline will improve the completeness and transparency of published case reports and that the systematic aggregation of information from case reports may provide early signals of effectiveness and/or harm, thereby improving healthcare decision-making.

The EXTRIP (EXtracorporeal TReatments In Poisoning) workgroup: guideline methodology

Extracorporeal treatments (ECTRs), such as hemodialysis and hemoperfusion, are used in poisoning despite a lack of controlled human trials demonstrating efficacy. To provide uniform recommendations, the EXTRIP group was formed as an international collaboration among recognized experts from nephrology, clinical toxicology, critical care, or pharmacology and supported by over 30 professional societies. For every poison, the clinical benefit of ECTR is weighed against associated complications, alternative therapies, and costs. Rigorous methodology, using the AGREE instrument, was developed and ratified. Methods rely on evidence appraisal and, in the absence of robust studies, on a thorough and transparent process of consensus statements. Twenty-four poisons were chosen according to their frequency, available evidence, and relevance. A systematic literature search was performed in order to retrieve all original publications regardless of language. Data were extracted on a standardized instrument. Quality of the evidence was assessed by GRADE as: High = A, Moderate = B, Low = C, Very Low = D. For every poison, dialyzability was assessed and clinical effect of ECTR summarized. All pertinent documents were submitted to the workgroup with a list of statements for vote (general statement, indications, timing, ECTR choice). A modified Delphi method with two voting rounds was used, between which deliberation was required. Each statement was voted on a Likert scale (1-9) to establish the strength of recommendation. This approach will permit the production of the first important practice guidelines on this topic.

Precipitating factors and patient outcomes in acute kidney injury treated with renal replacement therapy

Acute kidney injury (AKI) is not uncommon in acute hospital admissions. AKI treated with renal replacement therapy (RRT) has a wide spectrum of causes and the mortality rate at 90 days, approaches 50%. This study was performed to analyse the identifiable causes and outcomes of all cases of AKI treated with RRT in the Glasgow Royal Infirmary (GRI) renal wards during 2007. This study identified 65 cases of AKI treated with RRT from the GRI renal unit electronic patient record (EPR). Causes of AKI, modality of RRT and patient outcomes were retrieved from the EPR and discharge letters. The main outcome measures were the mortality rate and the percentage of patients still receiving RRT at 90 days. More than one precipitating factor was identified in half of the cases of dialysis-dependent AKI. Sepsis, hypovolaemia and nephrotoxic drugs were the main contributory factors and were observed in 52%, 40% and 23% of the cases, respectively. The mortality rate was 29% at 90 days. This study shows that the aetiology of AKI is often multifactorial and the 90-day mortality rate of AKI treated with RRT is still high.

A prospective observational study of catheter-related bacteraemia and thrombosis in a haemodialysis cohort: univariate and multivariate analyses of risk association

BACKGROUND

Central venous catheterization is a fundamental component in delivering haemodialysis yet is associated with significantly higher complication rates than other methods of vascular access. In this study, we report results of univariate and multivariate analyses designed to identify and quantify independent risk association for catheterization type, clinical variables and laboratory variables with regard to the development of catheter-related bacteraemia (CRB) and catheter failure due to poor haemodialysis flow.

METHODS

A 2-year prospective study of all incident haemodialysis vascular access catheter insertions was conducted. Laboratory and clinical variables were recorded at catheter insertion, and the clinical course was followed up to the point of catheter removal. CRB and catheter failure due to poor flow were recorded as outcome events. Univariate and multivariate analyses were used to test for association between clinical and laboratory variables and outcome.

RESULTS

Forty-four thousand five hundred seventy-six catheter days were accumulated over the study period. Multivariate analysis demonstrated an independent association between non-tunnelled catheterization procedures and adverse outcomes compared with tunnelled central venous catheter insertions. Elevated modified Charlson comorbidity score was independently associated with the development of CRBc. Elevated C-reactive protein and low haemodialysis blood pump flow were independently associated with catheter failure due to poor flow.

CONCLUSIONS

The data demonstrate that tunnelled central venous catheter insertions have an association with lower complication rates than non-tunnelled central venous catheter insertions that is independent of whether patients have acute or chronic renal failure, or high levels of comorbidity.

Long-term vascular access for hemodialysis using silicon dual-lumen catheters with guidewire replacement of catheters for technique salvage

Difficulties in creating vascular access in patients on hemodialysis are encountered in most dialysis centers. This is usually due to a lack of suitable peripheral vessels due to previous access surgery in patients on long-term hemodialysis, but also may be seen in some patients de novo, particularly diabetics and patients with peripheral vascular disease. Surgical techniques used to overcome this problem vary depending on patient characteristics and, to a certain extent, on local expertise/preference. We report our experience of using silicon dual-lumen hemodialysis catheters over a 3-year period; during this time, 54 catheters were inserted into 32 hemodialysis patients. The indication for this procedure in 52 catheters (31 patients) was either exhausted vascular access or obvious difficulty identifying a suitable peripheral blood vessel. Of the catheters inserted, 20 were placed into subclavian veins by primary insertion (ie, patients did not have existing subclavian catheter); 34 were replaced over a guidewire (a procedure used to allow technique salvage). The catheter survival rate was 72.7% at 90 days and 48.7% at 1 year. Corresponding rates at 90 days and 1 year for technique survival were 93.3% and 81.8%, respectively. The mean catheter and technique survival was 387 (95% confidence intervals [CIs], 273, 502) and 844 (95% CIs, 684, 1,005) days, respectively. Poor flow accounted for 70.4% of catheter failures and, despite 18 episodes of catheter-related sepsis, no catheters were lost due to infection. Factors identified as leading to reduced catheter survival were left-sided placement and catheter tip placement in the superior vena cava (as opposed to right atrial placement). We did not observe poorer survival or increased sepsis in catheters replaced over a guidewire, and would advocate this technique as a means of salvage in this group of patients.

Sclerosing peritonitis occurring in a hemodialysis patient

The pathogenesis of sclerosing peritonitis is poorly understood. In patients with end-stage renal failure, it has been described in association with continuous ambulatory peritoneal dialysis (CAPD), although it has not been described in patients treated exclusively by hemodialysis. We present a case of sclerosing peritonitis occurring in a 47-year-old man who was treated solely by hemodialysis. Additionally, the patient was diagnosed as having "nephrogenic ascites" 5 years before developing sclerosing peritonitis, and we discuss a possible link between these two conditions.

Atrial natriuretic factor improves renal function and lowers systolic blood pressure in renal allograft recipients treated with cyclosporin A

OBJECTIVE

Atrial natriuretic factor (ANF) has several properties which suggest that it may ameliorate cyclosporin A nephrotoxicity. We therefore investigated the response to a pharmacological dose of ANF in renal transplant recipients treated with cyclosporin A.

DESIGN

A single-blind randomized crossover design comparing the renal and haemodynamic effects of D-glucose (placebo) with ANF.

METHODS

Seven patients with stable renal function following renal transplantation were studied under maximal water diuresis. Glomerular filtration rate and effective renal plasma flow were estimated from clearances of inulin and para-aminohippurate, respectively.

RESULTS

Plasma ANF levels increased significantly in association with increased diuresis and natriuresis. Glomerular filtration rate was unchanged after placebo but increased significantly after ANF fusion. Likewise, effective renal plasma flow increased significantly with ANF infusion. There was a significant fall in systolic blood pressure, with no apparent change in heart rate and diastolic blood pressure.

CONCLUSIONS

These results suggest that ANF may have beneficial effects in protecting against cyclosporin A-induced nephrotoxicity and hypertension.

Role of lymphatics in peritoneal dialysis

There is a renewed interest in understanding the precise role of lymphatics in the ultrafiltration kinetics during peritoneal dialysis. In the normal state, lymphatics draining the peritoneal cavity are the principal means of removal of intraperitoneal isosmotic fluid and macromolecules. During a hypertonic peritoneal dialysis exchange, after peak intraperitoneal volume is achieved, fluid removal proceeds at an almost linear rate, causing intraperitoneal fluid volume to reduce. The isosmotic fluid removal from the peritoneal cavity could occur through the microcirculatory capillaries or through the lymphatic capillaries draining the peritoneal cavity. Animal and human studies suggest that this fluid loss occurs primarily through lymphatics. The two indirect methods of lymph flow measurements, plasma appearance and peritoneal disappearance of tracer colloid, show conflicting results. Although direct measurement of lymph flow rates through cannulation of mediastinal lymph vessels in animals suggests a significant flow through the lymph channels in response to intraperitoneal fluid instillation, lymph flow modification at the lymph node level may prevent use of this technique to assess the precise role played by lymphatics in fluid kinetics during peritoneal dialysis. By analogy with ascites and by extrapolation from previous studies of drain volumes after infusion of isotonic and hypertonic solutions, the average daily lymph absorption rate during CAPD may be predicted to be at least 1 liter per day.

Non-renal indications for peritoneal dialysis

Peritoneal dialysis is rarely indicated for conditions other than end-stage renal failure. Patients with refractory congestive cardiac failure, who are awaiting cardiac transplantation or have potentially reversible cardiac disease, appear to benefit from CAPD. The prognosis of patients with fulminant hepatic failure or severe acute pancreatitis has not yet been shown to improve with the addition of peritoneal dialysis to standard supportive treatment. Isolated reports have suggested that patients with hypothermia, hyperthermia, dialysis-associated ascites and drug poisonings may be treated successfully with peritoneal dialysis. The above indications are encountered infrequently and renal failure remains the only major indication for commencing patients on peritoneal dialysis.

The kinetics of ultrafiltration during peritoneal dialysis: the role of lymphatics

Net ultrafiltration was measured directly during hypertonic peritoneal dialysis exchanges in rats. Simultaneously, lymphatic absorption was measured by monitoring the disappearance of albumin in the instilled dialysis solution from the peritoneal cavity. The albumin method for measuring lymphatic absorption was also tested in rats absorbing Lactated Ringer's solution from the peritoneal cavity where absorption rate could also be measured directly. The findings suggest the following: 1.) lymphatic absorption rate is similar with both hypertonic dialysis solutions and Lactated Ringer's solution; 2.) lymphatic absorption is substantial and net ultrafiltration is well below true transcapillary ultrafiltration; and 3.) in our model, lymphatic absorption occurs at a relatively constant rate over six hours of dwell time.

Acute oliguric renal failure secondary to lymphomatous infiltration of the kidneys

A case of lymphomatous infiltration of the kidneys presenting as acute oliguric renal failure of unknown cause is described. Renal biopsy was required to establish the diagnosis. Combined chemotherapy (MOPP) produced significant improvement in renal function.