Dilating Insertion Device

Abstract

The goal of this Thesis is to reduce the patient's discomfort during hemodialysis by achieving improved vascular access using a novel insertion device with a dilating diameter. High measures of discomfort are associated during achieving vascular access during hemodialysis therapy. The vascular access devices require large gauge sizes (14/15G) compared to the entry veins to achieve the high blood flow rates (BFRs) needed for an efficient dialysis. These large gauge sizes result in a moderate to severe pain experience for most dialysis patients during insertion. Moreover, the entered vein needs to be surgically prepared before it is able to withstand the used BFRs. A now commonly used technique to prepare the vein, is the creation of an Arteriovenous fistula (AVF). Although less than the techniques used in the past, an AVF can come with complications. An AVF can cause more narrow access veins due to maturation problems, which results in a higher chance of a miss hit and unnecessary trauma.

To reduce patients' discomfort associated with achieving vascular access, a design process was set up in order to reduce both the experienced pain as the possibility of miss hits. The size of the access device was said to be a major cause for both problems. Accordingly, there seems to be a need for a smaller insertion gauge without lowering the BFR. Based on this, a novel insertion device with a dilating diameter was designed.

A patent study was conducted of existing solutions for the design obstacles. The solutions found were combined with novel ideas not found during the patent study and consolidated in a morphological overview. This was used as a tool to choose and elaborate four concepts based on two dilation solutions: a dilating spiral and a slide-on dilator.

To validate the concepts two proof-of-principle experiments were executed for every dilation solution, resulting in four experiments in total. A difference in insertion force for adding a slide-on dilator compared to the conventional straight needles was measured. The slide-on dilator was found to produce a higher insertion force than the currently used needle and was therefore rated as more painful than the currently used insertion methods. As the dilating spiral is a new design, its working principle itself had to be proven during the experiment. The results showed how a dilating spiral, as designed in the concepts, is able to create sufficient dilation force.

The experimental results were used to rate the set-up criteria and choose one final concept. The concept was constructed and assembled, after which the design was validated by means of 3D printed parts and a larger scaled dilating spiral. The evaluation was incorporated into the final design, which in turn has been evaluated after it was assembled. All parts but the Spiral-Dilator were 3D-printed on a scale 1:1 and work well together. The device fits well in one's hand, feels naturally and is easy to handle. The Spiral-Dilator was created on a larger scale. Testing made clear that a twisting motion was necessary to let the spiral stay in shape during the slide back of its holder. To do so, the Slide Container has to be altered to enable the Dilation Slide slide back in a twisting motion. A final version of the Spiral-Dilator was not created and will be necessary for a definite confirmation of the working principle. Nonetheless, the Dilating Insertion Device (DID) has shown to be promising, it adds accuracy and in potential reduce experienced pain to the insertion for vascular access.