Development of a Method to Assess the Impact of Saline Infusion on Venous Physiology and Injury in Humans

Abstract

Background and Aims: Peripherally inserted catheters (PIVCs) are one of the most commonly utilised invasive device globally [1-3]. However, despite the frequent usage of PIVCs, up to 69% [4-8] of these devices fail (unplanned removal) before the completion of therapy. Failure of PIVCs can delay treatment, cause discomfort (due to the requirement for new cannula insertion) as well as increase the risk of infection [9]. Reducing the failure rate of PIVCs by 10% (assuming a 69% failure rate and a $70 replacement fee) would also save AUD 210 million per annum, given that approximately 30 million PIVC's are used annually [2] in Australia. Considering the impact of PIVC failure on clinical practice and patient outcomes, there is a significant need to improve our understanding of the determinants of PIVC failure. The current thesis aimed to develop a method that measures the velocity of saline infusion by measuring the pressure within the infusion line. Secondly, this thesis sought to determine whether high, yet clinically relevant infusion rates (i.e. 1.5 mL/s), result in vascular damage. Methods: The current thesis was comprised of three main parts; part 1, 2 and 3. Part 1 developed a software application using LabVIEW to assess real-time infusion flow rates from a pressure transducer. Part 2 identified the relationship between pressure and flow rate in an in vitro and in vivo system. Part 3 investigated the impact of high (1.5 mL/s) and low (0.1 mL/s) infusion flow rates on platelet activation, haemolysis, and plasma concentrations of single-stranded deoxyribonucleic acid (ssDNA). Results: A second-order polynomial relationship existed between pressure and flow rate; with the pressure increase being proportional to the flow rate squared. The pressure values within the 22G PIVC were significantly greater than that of the 18G PIVC at the same flow rate, in both the in vitro and in vivo experiments. No significant increase was observed in blood platelet activation, haemolysis and plasma ssDNA concentration at the highest flow rate tested (1.5mL/s) when compared to the lowest flow rate tested in vivo (0.1mL/s) or between either catheter gauge (18/22G). Conclusion: This study aimed to develop a software application that could measure real-time infusion flow rates and assess the implication of clinically relevant flow rates on the vasculature. There was a significant relationship between pressure and flow rate, and as a result, the Infusion Pressure-Rate (IPR) application was able to determine the infusion flow rate accurately. Unfortunately, due to COVID-19, the study was prematurely ended with a small number of participants for the in vivo section. As a result, no significance was observed in the platelet activation, haemolysis and plasma ssDNA concentrations between catheter gauge (18 and 22G) and flow rate (0.1 and 1.5 mL/s); however, this study was successful as several methods were developed and refined. Future studies will be able to use the application to monitor the flow rate at which clinicians flush.