title: Impact of Peripheral Intravenous Catheter Gauge on Vessel Size, Blood Flow Velocity and Thrombus Volume Using Three-Dimensional Ultrasound Imaging
Creators: name: Bell, Claudia A
Publisher: name: Griffith University
Year: 2022
Subjects: subject: Peripheral intravenous catheters (PIVCs)
subject: PIVC failure
subject: causative factors
subject: vascular access

description: Background and Aims Peripheral intravenous catheters (PIVCs) are the most commonly used vascular access device for short term medical therapy [1-3]. Despite their ubiquitous use, up to 69% of PIVCs fail before therapy is complete [4-6]. The failure of PIVCs delays treatment, causes discomfort and increases the risk of infection [5]. Reducing the PIVC failure rate by 10% (assuming a 69% failure rate and a 70 AUD replacement cost) would save 210 million AUD per annum, with 30 million PIVCs used annually [7] in Australia. Considering the impact that PIVC failure has on clinical practice and patient outcomes, there is a significant need to improve our understanding of the causative factors of PIVC failure. Firstly, this thesis aimed to develop a vascular access phantom that mimics the ultrasonic nature of a human’s subcutaneous tissue within the antebrachium and various standardised operating procedures that quantify anatomical volumes (blood vessel and artificial thrombus) from a three-dimensional (3D) ultrasound transducer. Secondly, this thesis sought to determine whether inserting 18G or 22G PIVCs affects vessel diameter and volume, blood flow velocity and PIVC-associated thrombosis volume change over five hours. Methods The current thesis was comprised of three parts; 1, 2 and 3. Part 1 developed an in vitro vascular access phantom that mimicked the ultrasonic appearance of the distal cephalic vein with a luminal thrombus. Part 2 quantified the internal luminal volume of various sized silicone rubber microtubes, in addition to artificial thrombi within the silicone tubing, using various three-dimensional (3D) volume rendering methods (Virtual Organ Computer-Aided Analysis (VOCAL), Tomographic Ultrasound Imaging (TUI) area and diameter measurements, and Materialise Interactive Medical Image Control System (MIMICS) software). Part 3 investigated the impact of bilateral insertion of 18G and 22G PIVCs into the distal cephalic veins of volunteers by assessing blood vessel diameter, blood flow velocity, and the occurrence of PIVC-associated thrombosis. Three-dimensional ultrasound (TUI area and MIMICS software) assessed the volume of the vessel lumen and suspected thrombi as there was no significant difference between these two methods. Results Volume rendering of the known internal volumes of silicone tubing demonstrated that VOCAL and MIMICS image analysis more accurately predicted internal volumes than TUI area and diameter measurements. There was no significant difference between MIMICS and TUI area measurement methods for vessel lumen and thrombus volume in silico or in vitro. There were time effects for blood vessel volume (p = 0.004) and blood flow velocity (p = 0.0013), however, no between catheter effects for blood vessel diameter, volume of blood flow velocity (p &gt; 0.05). After five hours, 2/12 22G catheters failed versus 0/12 18G catheters, and eight thrombi were observed with 22G PIVCs whilst only four with 18G. Furthermore, 22G PIVCs tended to have larger thrombi volume (p = 0.07) than those found within an 18G. Conclusion This thesis developed an ultrasound phantom appropriate for assessing 3D vessel and thrombotic measurements. In addition, 3D ultrasonography followed by image analysis using onboard (TUI, VOCAL) and external image analysis software (MIMICS) assessed the accuracy of volumetric scanning for this purpose. This analysis showed that MIMICS software and TUI area measurements were similar in quantifying known artificial volumes. The in vivo results were promising and showed that maintenance flushes of saline through a syringe at clinically relevant flow rates (1mL/sec, 10 mLs total) through narrower bore 22G (versus 18G) catheters might lead to larger thromboses developing, with further studies needed to determine whether an increased thrombotic risk is also evident when using these devices. Future studies will extend cannulation time and include serial 3D assessments to track thrombus evolution over a clinically relevant period of 72 hours. These studies should assist in informing guidelines concerning the most appropriate PIVC to insert and potentially guidance regarding how these catheters should be maintained.