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.

Salvage of angioplasty failures and complications in hemodialysis arteriovenous access using the FLUENCY Plus Stent Graft: technical and 180-day patency results.

PURPOSE: To review technical and 180-day clinical outcomes when stent grafts were used to treat dysfunctional arteriovenous (AV) hemodialysis access circuits. MATERIALS AND METHODS: The FLUENCY Plus Stent Graft (Bard Peripheral Vascular, Tempe, Arizona) was used to salvage percutaneous transluminal angioplasty (PTA) technical failures and complications in AV access circuits over 2 years. There were 106 patients treated with 138 stent grafts. Indications for stent graft use included residual stenosis after PTA (n = 81), extravasation after PTA (n = 22), early recurrent stenosis (n = 14), pseudoaneurysms (n = 4), and "other" (n = 4). Data were retrospectively analyzed for complications and outcomes. RESULTS: Technical success was achieved in all patients, and clinical success was achieved in 104 (98%) of 106 patients. At 180 days, postintervention primary patency (PIPP) was 47%, and postintervention secondary patency (PISP) was 79%. PIPP was 62% for autogenous fistulas (AVFs) and 35% for prosthetic grafts (AVGs) (P = .010). The 180-day PIPP for stent grafts 9-10 mm in diameter was 63% versus 38% for stent grafts 6-8 mm in diameter (P = .012). Implants that did not cross the elbow had a 180-day PIPP of 47% compared with 25% for implants across the elbow (P = .032). Technical complications were periprocedure AVG thromboses (n = 2), intraprocedural stent graft dislodgment (n = 1), venospasm (n = 2), and contrast agent-related hives (n = 1). One patient returned at 2 months with an infected AVG and stent graft in the outflow vein. CONCLUSIONS: The FLUENCY Plus Stent Graft was effective for maintenance of hemodialysis access circuit patency and was comparable or better than historical outcomes for PTA and bare stents. Factors that favored improved patency included larger diameter devices, use in AVFs, and avoiding placement across the elbow joint.

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.

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.

Simulation training for vascular access interventions.

Training and learning in the field of access for dialysis, including peritoneal and hemodialysis and access for oncologic patients, is well suited for the use of simulators, simulated case learning, and root cause analysis of adverse outcomes and team training. Simulators range over a wide spectrum from simple suture learning devices, inexpensive systems for venous puncture simulation, such as a turkey breast or leg with a pressurized tunneled rubber or graft conduit, to sophisticated computer designed simulators to teach interventional procedures such as vascular access angiogram, balloon angioplasty and stent placing. Team training capitalizes on the principles used in aviation, known as Crew Resource Management (CRM) or Human Factor (HF). The objectives of team training are to improve communication and leadership skills, to use checklists to prevent errors, to promote a change in the attitudes towards vascular access from learning through mistakes in a non-punitive environment, to impacting positively the employee performance and to increase staff retention by making the workplace safer, more efficient and user-friendly.

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.)

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.