Assessment of flow instabilities in in‐vitro stenotic arteriovenous grafts using an equivalent astable multivibrator

Review of Experimental Modelling in Vascular Access for Hemodialysis

“…Principle Quantity Measurement type pressure sensor [37,17,18,4,6,39,38,11,10,26] various pressure bulk, instantaneous, ≥ kHz flow sensor [35,37,17,18,6,39,38,11,10,26] various flow rate bulk, instantaneous, ≥ kHz LDV [35] optical velocity point, instantaneous, ≥ kHz VDUS [22,21] acoustic velocity point, average * , O(10) Hz PIV [4,19,12,2,27,15,28,3] optical velocity grid of points, instantaneous, O(10) Hz UIV [20] acoustic velocity grid of points, instantaneous, O(10 − 1000) Hz PLIF [3] optical concentration 2D plane, instantaneous, O(10) Hz CDUS [22,21] acoustic velocity 2D plane, average * , O(10) Hz Different methods exist to measure bulk pressure and flow rate, including Pitot tube-type and piezo-electric pressure sensors, and paddle wheel or ultrasoundbased flow rate sensors (for more information, see e.g. [36]).…”

“…Similar to an AVF, AVGs are generally placed in the upper limbs and can also be positioned in the lower limbs. The use of experimental modelling to verify a computational model is also seen in the case of AVGs [38,11,10,26]. However, in this case experimental modelling is also used as a tool on its own [15,39,38,22,21].…”

“…Finally, in the papers by Chen et al [11,10], and Lin et al [26], the cardiovascular system is modelled as an electrical circuit (figure 6). The idea behind this is that flow instabilities induced by an artificially created vascular access induce vibrations in the elastic vessel wall, and that the flow resistance and vessel compliance affect the rise time, amplitude and time interval of the transverse vibration pressure associated with these vessel wall vibrations.…”

“…Paper Geometry Material Heise et al [15] Straight and Cuffed PTFE Van Tricht et al [39] Straight and Tapered PTFE Van Tricht [38] Straight PTFE Kokkalis et al [22,21] Straight and Spiral ePTFE Chen et al [11,10] Electrical Circuit Silcone Tubes Lin et al [26] ---Data not available Water-glycerol (58-42%) -500 [39] Water-glycerol (60-40%) 933, 2800 500-1500 [38] Water-glycerol (60-40%) -500, 1000, 1500 [22,21] Water-glycerol (91-9%) 570, 850, 1140, 1420, 1700 240, 360, 480, 600, 720 [11,10] Water-glycerol -600-1000 [26] ----Data not available…”

Bilateral photoplethysmography for peripheral arterial disease screening in haemodialysis patients using astable multivibrator and machine learning classifier

“…Non-invasive PPG measurements can obtain variations in blood flow volume in in vivo examinations. We, therefore, propose an astable multivibrator [11,24] to model BPW parameters, including the pulse duration (duty ratio, D), RT, and amplitude. Bilateral differences in time constants, = (R × C), and the Ds of dexter-tosinister PPG signals are used to identify the normal condition and degrees of PAD, comparing them with the bilateral timing differences and the degree of stenosis (DOS) [24], as shown in Fig.…”