Trial design {8}
This is a prospective, multicenter cluster randomized controlled trial.All centers use the same types of medical devices (catheters and puncture needles) and have an ultrasound machine available on site. The number of daily punctures varies from 13 to 40 depending on the center. A center effect will be sought.Only two centers have a lower number of patients and punctures, but they are still comparable. We therefore propose to match the centers according to number of patients and punctures per day. We grouped the centers into pairs according to the criteria of number of AVF punctures per day, number of nurses, before randomization.The different experimental and control groups will move forward in pairs (e.g., center A of the experimental group, center A of the control group).The trial design is described in Fig. Trial design