Patient-Specific Computational Modeling of Upper Extremity Arteriovenous Fistula Creation: Its Feasibility to Support Clinical Decision-Making

<div><h3>Introduction</h3><p>Inadequate flow enhancement on the one hand, and excessive flow enhancement on the other hand, remain frequent complications of arteriovenous fistula (AVF) creation, and hamper hemodialysis therapy in patients with end-stage renal disease. In an effort to reduce these, a patient-specific computational model, capable of predicting postoperative flow, has been developed. The purpose of this study was to determine the accuracy of the patient-specific model and to investigate its feasibility to support decision-making in AVF surgery.</p> <h3>Methods</h3><p>Patient-specific pulse wave propagation models were created for 25 patients awaiting AVF creation. Model input parameters were obtained from clinical measurements and literature. For every patient, a radiocephalic AVF, a brachiocephalic AVF, and a brachiobasilic AVF configuration were simulated and analyzed for their postoperative flow. The most distal configuration with a predicted flow between 400 and 1500 ml/min was considered the preferred location for AVF surgery. The suggestion of the model was compared to the choice of an experienced vascular surgeon. Furthermore, predicted flows were compared to measured postoperative flows.</p> <h3>Results</h3><p>Taken into account the confidence interval (25^th and 75^th percentile interval), overlap between predicted and measured postoperative flows was observed in 70% of the patients. Differentiation between upper and lower arm configuration was similar in 76% of the patients, whereas discrimination between two upper arm AVF configurations was more difficult. In 3 patients the surgeon created an upper arm AVF, while model based predictions allowed for lower arm AVF creation, thereby preserving proximal vessels. In one patient early thrombosis in a radiocephalic AVF was observed which might have been indicated by the low predicted postoperative flow.</p> <h3>Conclusions</h3><p>Postoperative flow can be predicted relatively accurately for multiple AVF configurations by using computational modeling. This model may therefore be considered a valuable additional tool in the preoperative work-up of patients awaiting AVF creation.</p> </div

Patient safety in dialysis access: education and research.

Today, a growing activity to improve patient safety in all domains of medicine is reality. This chapter deals with patient safety research in general, but is also about strategies to implement this evidence in the daily clinical work treating patients on dialysis. Good clinical research practice has been well established for some years. In the domain of dialysis access, further basic, clinical, epidemiological and health service research will be important to further improve patient safety as a whole

Preoperative computer simulation for planning of vascular access surgery in hemodialysis patients

Introduction: The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients. Unfortunately, 20-40% of all constructed AVFs fail to mature (FTM), and are therefore not usable for hemodialysis. AVF maturation importantly depends on postoperative blood volume flow. Predicting patient-specific immediate postoperative flow could therefore support surgical planning. A computational model predicting blood volume flow is available, but the effect of blood flow predictions on the clinical endpoint of maturation (at least 500 mL/min blood volume flow, diameter of the venous cannulation segment &gt;= 4 mm) remains undetermined.Methods: A multicenter randomized clinical trial will be conducted in which 372 patients will be randomized (1:1 allocation ratio) between conventional healthcare and computational model-aided decision making. All patients are extensively examined using duplex ultrasonography (DUS) during preoperative assessment (12 venous and 11 arterial diameter measurements; 3 arterial volume flow measurements). The computational model will predict patient-specific immediate postoperative blood volume flows based on this DUS examination. Using these predictions, the preferred AVF configuration is recommended for the individual patient (radiocephalic, brachiocephalic, or brachiobasilic). The primary endpoint is FTM rate at six weeks in both groups, secondary endpoints include AVF functionality and patency rates at 6 and 12 months postoperatively.</p

Buttonhole needling of haemodialysis arteriovenous fistulae results in less complications and interventions compared to the rope-ladder technique

BACKGROUND: The rope-ladder puncture technique, with cannulation along the whole length of the vessel traject, has been very common in haemodialysis patients with autogenous arterio-venous fistula (AVF). Today's dialysis population with AVF may exhibit difficult cannulation, because of a short vein length or a complicated cannulation route. An alternative needling possibility is the buttonhole (BH) technique, which inserts needles at exactly the same location during every dialysis session. The present study was conducted to investigate the effect of both cannulation techniques on the incidence of vascular access (VA) complications. METHODS: A total of 75 prevalent haemodialysis patients with autogenous AVF using the BH technique were compared with 70 patients using the rope-ladder technique. The following parameters were registered: haematoma occurrence, redness, swelling, aneurysm formation, the use of sharp or dull needles, miscannulations, and interventions. Needling pain and fear of puncture were assessed using a verbal rating scale (VRS). The duration of the follow-up was 9 months. RESULTS: Patients in the BH group had more unsuccessful cannulations, compared with the rope-ladder method (P < 0.0001), but the frequency of haematoma (P < 0.0001) and aneurysm formation (P < 0.0001) was less. In addition, intervention such as angioplasty (P < 0.0001) was higher in patients using the rope-ladder technique. A negative outcome of the BH technique was the higher incidence of access infections compared to the rope-ladder method. CONCLUSION: This study showed that the BH method is a valuable technique with few complications like haematoma, aneurysm formation and the need for interventions. However, the infections induced by the BH method should not be underestimated. This underlines the importance of an aseptic and correct technique of the buttonhole procedure