Ingemar Davidson

Effect of clopidogrel on early failure of arteriovenous fistulas for hemodialysis: a randomized controlled trial.

CONTEXT The arteriovenous fistula is the preferred type of vascular access for hemodialysis because of lower thrombosis and infection rates and lower health care expenditures compared with synthetic grafts or central venous catheters. Early failure of fistulas due to thrombosis or inadequate maturation is a barrier to increasing the prevalence of fistulas among patients treated with hemodialysis. Small, inconclusive trials have suggested that antiplatelet agents may reduce thrombosis of new fistulas. OBJECTIVE To determine whether clopidogrel reduces early failure of hemodialysis fistulas. DESIGN, SETTING, AND PARTICIPANTS Randomized, double-blind, placebo-controlled trial conducted at 9 US centers composed of academic and community nephrology practices in 2003-2007. Eight hundred seventy-seven participants with end-stage renal disease or advanced chronic kidney disease were followed up until 150 to 180 days after fistula creation or 30 days after initiation of dialysis, whichever occurred later. INTERVENTION Participants were randomly assigned to receive clopidogrel (300-mg loading dose followed by daily dose of 75 mg; n = 441) or placebo (n = 436) for 6 weeks starting within 1 day after fistula creation. MAIN OUTCOME MEASURES The primary outcome was fistula thrombosis, determined by physical examination at 6 weeks. The secondary outcome was failure of the fistula to become suitable for dialysis. Suitability was defined as use of the fistula at a dialysis machine blood pump rate of 300 mL/min or more during 8 of 12 dialysis sessions. RESULTS Enrollment was stopped after 877 participants were randomized based on a stopping rule for intervention efficacy. Fistula thrombosis occurred in 53 (12.2%) participants assigned to clopidogrel compared with 84 (19.5%) participants assigned to placebo (relative risk, 0.63; 95% confidence interval, 0.46-0.97; P = .018). Failure to attain suitability for dialysis did not differ between the clopidogrel and placebo groups (61.8% vs 59.5%, respectively; relative risk, 1.05; 95% confidence interval, 0.94-1.17; P = .40). CONCLUSION Clopidogrel reduces the frequency of early thrombosis of new arteriovenous fistulas but does not increase the proportion of fistulas that become suitable for dialysis. Trial Registration clinicaltrials.gov Identifier: NCT00067119.

Effect of Dipyridamole plus Aspirin on Hemodialysis Graft Patency

BACKGROUND Arteriovenous graft stenosis leading to thrombosis is a major cause of complications in patients undergoing hemodialysis. Procedural interventions may restore patency but are costly. Although there is no proven pharmacologic therapy, dipyridamole may be promising because of its known vascular antiproliferative activity. METHODS We conducted a randomized, double-blind, placebo-controlled trial of extended-release dipyridamole, at a dose of 200 mg, and aspirin, at a dose of 25 mg, given twice daily after the placement of a new arteriovenous graft until the primary outcome, loss of primary unassisted patency (i.e., patency without thrombosis or requirement for intervention), was reached. Secondary outcomes were cumulative graft failure and death. Primary and secondary outcomes were analyzed with the use of a Cox proportional-hazards regression with adjustment for prespecified covariates. RESULTS At 13 centers in the United States, 649 patients were randomly assigned to receive dipyridamole plus aspirin (321 patients) or placebo (328 patients) over a period of 4.5 years, with 6 additional months of follow-up. The incidence of primary unassisted patency at 1 year was 23% (95% confidence interval [CI], 18 to 28) in the placebo group and 28% (95% CI, 23 to 34) in the dipyridamole-aspirin group, an absolute difference of 5 percentage points. Treatment with dipyridamole plus aspirin significantly prolonged the duration of primary unassisted patency (hazard ratio, 0.82; 95% CI, 0.68 to 0.98; P=0.03) and inhibited stenosis. The incidences of cumulative graft failure, death, the composite of graft failure or death, and serious adverse events (including bleeding) did not differ significantly between study groups. CONCLUSIONS Treatment with dipyridamole plus aspirin had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts. (ClinicalTrials.gov number, NCT00067119.)

Use of Aspirin Associates with Longer Primary Patency of Hemodialysis Grafts

Extended-release dipyridamole plus low-dose aspirin (ERDP/ASA) prolongs primary unassisted graft patency of newly created hemodialysis arteriovenous grafts, but the individual contributions of each component are unknown. Here, we analyzed whether use of aspirin at baseline associated with primary unassisted graft patency among participants in a randomized trial that compared ERDP/ASA and placebo in newly created grafts. We used Cox proportional hazards regression, adjusting for prespecified baseline comorbidities and covariates. Of all participants, 43% reported use of aspirin at baseline; of these, 82% remained on nonstudy aspirin (i.e., excluding ERDP/ASA) at 1 year. After 1 year of follow-up, the incidence of primary unassisted patency among participants using aspirin at baseline was 30% (95% CI: 24 to 35%) and among those not using aspirin was 23% (95% CI: 18 to 27%). Use of aspirin at baseline associated with a dose-dependent prolongation of primary unassisted graft patency that approached statistical significance (adjusted HR, 0.83; 95% CI: 0.68 to 1.01; P=0.06). Use of aspirin at baseline did not associate with prolongation of cumulative graft patency or participant survival. In conclusion, use of aspirin associates with a trend toward longer primary unassisted patency of newly placed hemodialysis grafts similar to that observed for ERDP/ASA.

Risk factors associated with peritoneal dialysis catheter survival: a 9-year single-center study in 315 patients.

Purpose To review the peritoneal dialysis (PD) catheter outcomes at our center and assess factors affecting catheter survival. Methods We carried out a retrospective study on 315 patients who had their first PD catheter placed between January 2001 and September 2009 at the UT Southwestern/DaVita Peritoneal Dialysis Clinic at Dallas, Texas. Medical records were reviewed for demographic and clinical information of the patients. The primary end point of the study was PD catheter failure, defined as removal of a dysfunctional PD catheter due to catheter-related complications. Catheter survival was estimated using the Kaplan-Meier method. Cox proportional hazard regression model was used to identify factors that are independently associated with catheter survival. Results The mean age of the patients was 49.7 ± 29 yrs. The study population included 54.6% females, 42.5% African American, 27.9% Caucasian and 22.9% Hispanic patients. Diabetes was the primary etiology of end-stage renal disease in 43.2% of patients. More than 90% of patients had one or more co-morbidities, and 57.5% had previous abdominal surgery. The mean BMI for the group was 28.6 ± 13.8 kg/m2. Less than a quarter of the patients (24.1%) had non-infectious/mechanical catheter problems. Overall PD catheter survival rates over 12, 24 and 36 months were 92.9%, 91.9% and 91.1%, respectively. PD catheter-related non-infectious problem was the only independent variable that was significantly associated with catheter survival (hazard ratio 22.467; 95% CI 6.665–75.732). No significant association was observed between the PD catheter survival and other risk factors including age, body mass index (BMI), diabetic status, co-morbidities, previous abdominal surgeries or infections. Conclusions Our study shows an excellent 3-yr PD catheter survival (91.1%). Only PD catheter-related non-infectious problems are significantly associated with catheter failure. Other factors such as age, gender, race, BMI, diabetic status, co-morbidities, previous abdominal surgeries, peritoneal infections or exit site/tunnel infections were not found to affect the PD catheter survival and should not be considered barriers to PD initiation.

Expanded polytetrafluoroethylene-covered stent treatment of angioplasty-related extravasation during hemodialysis access intervention: technical and 180-day patency.

PURPOSE To review technical and patency results with expanded polytetrafluoroethylene (ePTFE)-covered stents for treatment of venous rupture encountered during percutaneous hemodialysis intervention. MATERIALS AND METHODS The Fluency covered stent is a tracheobronchial device that was used in an off-label manner to treat percutaneous transluminal angioplasty (PTA)-induced rupture in hemodialysis circuits. Data were retrospectively reviewed for all patients treated with the stent in 2004-2005 at two medical centers for PTA-related rupture. RESULTS From a database of 106 procedures, 21 patients (21 procedures) were treated with the ePTFE-covered stent for PTA-related extravasation. Nine patients had arteriovenous (AV) grafts and 12 had AV fistulas. Five extravasations followed angioplasty as part of an AV graft declotting procedure. Location of extravasation was the outflow or cannulation venous segment (n = 11), cephalic arch (n = 3), AV graft venous anastomosis (n = 6), and intragraft (n = 1). All procedures were technically successful at halting extravasation and preserving vascular access. There were no known complications, and all patients underwent a successful first dialysis session. Twenty of the 21 circuits remained patent beyond the first week after intervention. The 180-day primary circuit patency rate was 20% and the 180-day cumulative circuit patency rate was 65%. CONCLUSIONS In 21 patients, the ePTFE-covered stent successfully treated PTA-induced rupture with no need for acute secondary procedures such as thrombolysis or surgery. There was no instance of pseudoaneurysm formation or delayed bleeding. The ePTFE-covered stent offers advantages compared to prolonged PTA or bare stents when attempting to preserve hemodialysis access after PTA-induced rupture.

A patient centered decision making dialysis access algorithm

Much controversy surrounds the establishment of proper planning, placement and management (the best practice pattern) of dialysis access. These include the dialysis type and modality selection, timing of access placement and who places the access. The lack of and the difficulty of performing randomized studies with multiple confounding factors, in an extremely heterogeneous and rapidly changing ESRD population demographics, only partly explains the dialysis access conundrum. Add to this the rapidly developing and competing technologies, the wide spectrum of the professional experience, bias and socio-economic forces to make the ESRD problems as multivariate and complex as life itself. This overview describes a dialysis access algorithm approach to the patient needing renal replacement therapy, considering long-term improved patient outcome as the ultimate objective.

Virtual Reality: Emerging Role of Simulation Training in Vascular Access

Evolving new technologies in vascular access mandate increased attention to patient safety; an often overlooked yet valuable training tool is simulation. For the end-stage renal disease patient, simulation tools are effective for all aspects of creating access for peritoneal dialysis and hemodialysis. Based on aviation principles, known as crew resource management, we place equal emphasis on team training as individual training to improve interactions between team members and systems, cumulating in improved safety. Simulation allows for environmental control and standardized procedures, letting the trainee practice and correct mistakes without harm to patients, compared with traditional patient-based training. Vascular access simulators range from suture devices, to pressurized tunneled conduits for needle cannulation, to computer-based interventional simulators. Simulation training includes simulated case learning, root cause analysis of adverse outcomes, and continual update and refinement of concepts. Implementation of effective human to complex systems interaction in end-stage renal disease patients involves a change in institutional culture. Three concepts discussed in this article are as follows: (1) the need for user-friendly systems and technology to enhance performance, (2) the necessity for members to both train and work together as a team, and (3) the team assigned to use the system must test and practice it to a proficient level before safely using the system on patients.

Optimal Choice of Dialysis Access for Chronic Kidney Disease Patients: Developing a Life Plan for Dialysis Access

Patient-focused dialysis modality and access selection requires a coordinated teamwork approach that emphasizes chronic kidney disease care to be a continuum of care. Individualized and detailed patient history and examination are the mainstays of dialysis modality and access selection. Preoperative vessel mapping by duplex Doppler ultrasonography can be a useful supplementary investigation to the history and physical examination to determine the optimal dialysis access type and site. Dialysis access modality and choice considers many patient factors that can be aided by a clinical risk score, asking key clinical questions, surgical expert opinion, and a multidisciplinary approach to individualized patient care. In many situations, a lifelong access utilization strategy prioritizes peritoneal dialysis as the first dialysis modality followed by appropriately planned hemodialysis. The goal of an integrated patient-focused approach is to achieve complication-free access to help patients achieve their life goals on and off dialysis.

Peritoneal dialysis access: open versus laparoscopic surgical techniques

Aim To outline pros and cons with the open and laparoscopic techniques when placing peritoneal dialysis (PD) catheters. Background Controversy exists regarding which technique, the open and laparoscopic, if any, is superior to the other. In addition, there is the question of which approach is best in rescuing malfunctioning PD catheters. Results Rather than promoting one doctrine fits all, philosophically, doing the right thing for the patient by specific criteria is ethically the better model. These specific selection criteria include patient characteristics, the teams skills and knowledge and institutional resources and commitment. Also, the sophistication of a PD unit for training and monitoring of patients is crucial for successful outcomes. Open paramedian and two laparoscopic approaches are described in detail, outlining advantages and disadvantages of each, with suggestions when one method is preferred. Conclusions In general, the laparoscopic technique is associated with longer operative times, higher costs and the need to utilize general anesthesia. It is, however, the preferred method when rescuing malfunctioning catheters and may increase the PD patient population in patients with previous abdominal surgeries. The dialysis access surgeon should be familiar with both open and laparoscopic techniques and appropriately choose the ideal method based upon the individual patient and institutional resources.

Arteriovenous access ischemic steal (AVAIS) in haemodialysis: a consensus from the Charing Cross Vascular Access Masterclass 2016

Arteriovenous access ischaemic steal (AVAIS) is a serious and not infrequent complication of vascular access. Pathophysiology is key to diagnosis, investigation and management. Ischaemia distal to an AV access is due to multiple factors. Clinical steal is not simply blood diversion but pressure changes within the adapted vasculature with distal hypoperfusion and resultant poor perfusion pressures in the distal extremity. Reversal of flow within the artery distal to the AV access may be seen but this is not associated with ischaemia in most cases. Terminology is varied and it is suggested that arteriovenous access ischemic steal (AVAIS) is the preferred term. In all cases AVAIS should be carefully classified on clinical symptoms as these determine management options and allow standardisation for studies. Diabetes and peripheral arterial occlusive disease are risk factors but a ‘high risk patient’ profile is not clear and definitive vascular access should not be automatically avoided in these patient groups. Multiple treatment modalities have been described and their use should be directed by appropriate assessment, investigation and treatment of the underlying pathophysiology. Comparison of treatment options is difficult as published studies are heavily biased. Whilst no single technique is suitable for all cases of AVAIS there are some that suit particular scenarios and mild AVAIS may benefit from observation whilst more severe steal mandates surgical intervention.