Modelling catheter-vein biomechanical interactions during an intravenous procedure

A multi-asperity adhesive contact model for catheter and vascular artery contact in endovascular surgery

Contact behaviors of medical devices, such as guidewires and catheters, are critical in endovascular surgeries. In this work, a new method to predict adhesive contact force between catheter and vascular artery is presented. Multi-asperity adhesion on the surface of vascular artery, deformation of asperity and deformation of vascular substrate are all considered. The single asperity behavior is described with Johnson-Kendall-Roberts (JKR) contact model. The multi-asperity behavior is based on Greenwood-Williamson (GW) asperity model. Vascular substrate is considered as elastic bulk substrate and its deformation is determined with Hertzian pressure from asperity on a circular region on the elastic half space. The model shows that the deformation of vascular substrate accounts for the majority of the total contact deformation and significantly affects the predicted contact force. The model is verified with published experimental data. The comparison shows that the model produces very accurate prediction of contact force between catheter and vascular artery when the contact force is compressive. Parametric analysis based on asperity topography is carried out. The analysis shows that the diameter of the circular region of the interface between asperity and vascular substrate has more significant effect on the estimation of contact force than the radius of asperity. Further validation of prediction accuracy of the model under experiment is needed.

Novel Design of Peripheral Infusion Catheter Improves the Kinetics of Intravenous Drug Release

Short peripheral catheters are ubiquitous in today's healthcare environment, enabling effective and direct delivery of fluids and medications intravenously. A commonly associated complication of their use is thrombophlebitis-thrombus formation-involved inflammation of the vein wall. A novel design of a very short peripheral catheter showed promising results in a pig model in reducing the mechanical irritation to the vein wall. Here, the kinetics of drug release through the novel catheter was compared to a standard commercial catheter using experimental and computational models. In a good agreement, in vitro and in silico models reveal the superiority of the novel catheter design with faster washout time, favorable spatial distribution within the vein, and substantially lower wall shear stress. We submit therefore that the novel design has an improved drug removal profile compared to the conventional catheter and can potentially reduce chemical irritation to the vein wall and minimize the risk for thrombophlebitis. CLINICAL RELEVANCE: Short peripheral catheters are ubiquitous in today's healthcare environment, allowing effective and direct delivery of fluids and medications intravenously. It is well known, however, that prolonged exposure to an irritant drug may lead to its absorption in the endothelial layer lining the vein wall, promoting among other, thrombophlebitis that may lead to increased morbidity, delayed treatment, and prolonged hospitalization. There have been multiple calls to consider low infusion rates with various infusion protocols and to place the catheter tip as central as possible to promote faster drug clearance and reduce the potential vessel damage, but the requisite device had not been available, and the short peripheral catheter is still, and for decades, the standard of care. Towards this end, we recently introduced a novel very short peripheral catheter design, and here, we demonstrate using experimental and computational models its favorable spatial and temporal drug-releasing profiles compared with the standard catheter. The clinically potential relevance is underscore both by the more efficient perfusion of IV drugs and lower irritation to the vein wall at the site of injection. Graphical abstract.

Mechanism of pulsatile flushing technique for saline injection via a peripheral intravenous catheter

BACKGROUND

The underlying mechanism of pulsatile flushing technique has not been fully elucidated, and the partial understanding of the mechanism has been confined to hydrodynamic simulation, ignoring the dynamic interaction among the catheter, blood vessel, blood stream, and saline.

METHODS

The peripheral intravenous catheter and vein models and their internal flow fields were assessed using a commercial software. The parameters of both fluid and structural mechanics were calculated and compared in the push and pause phase. The effect of different flushing volumes per bolus before each pause (0.5, 1.0, 1.5, and 2.0 mL) were compared, respectively corresponding to group (A, B, C and D).

FINDINGS

In groups C and D, the wall shear stress value (≥2 Pa) and enhanced shear rates (peaks up to 10,000 s^-1) were higher in the vessel wall near the catheter tip, which may be at risk of vascular endothelial injury. Furthermore, extraluminal flushing might be attributed to the recirculation of jet from the catheter outlet. The vortices of all groups faded away in an extremely short period (≤0.1 s) if the push was suddenly discontinued. Finally, overlarge displacement of the catheter tip in groups C and D (0.91 and 1.1 mm, respectively) caused the peripheral intravenous catheters to angle with the venous wall.

INTERPRETATION

The pulsatile flushing technique can facilitate intra- and extraluminal flushing of peripheral intravenous catheters. Furthermore, an insufficient volume per bolus can lead to inefficient flushing, and an overdose of single push may cause mechanical endothelial injury.

Preventing peripheral intravenous catheter failure by reducing mechanical irritation

Peripheral intravenous catheter failure is a significant concern in the clinical setting. We investigated the effectiveness of care protocols, including an ultrasonographic “pre-scan” for selecting a large-diameter vein before catheterization, a “post-scan” for confirming the catheter tip position after catheterization with ultrasonography, and the use of a flexible polyurethane catheter to reduce the mechanical irritation that contributes to the incidence of catheter failure. This intervention study was a non-randomized controlled trial to investigate the effectiveness of the abovementioned care protocols, the effects of which were compared to the outcomes in the control group, which received conventional care. For both groups, participants were selected from patients in two wards at the University of Tokyo in Japan between July and November 2017. Inverse probability score-based weighted methods (IPW) using propensity score were used to estimate the effectiveness of care protocols. The primary outcome was catheter failure, which was defined as accidental and unplanned catheter removal. We used Kaplan-Meier survival curves to compare rates of time until catheter failure. We analysed 189 and 233 catheters in the intervention and control groups, respectively. In the control group, 68 catheters (29.2%) were determined to have failed, whereas, in the intervention group, only 21 catheters (11.1%) failed. There was a significant difference between each group regarding the ratio of catheter failure adjusted according to IPW (p = 0.003). The relative risk reduction of the intervention for catheter failure was 0.60 (95% CI: 0.47–0.71). Care protocols, including assessment of vein diameter, vein depth, and catheter tip location using ultrasound examination for reducing mechanical irritation is a promising method to reduce catheter failure incidence.

Novel short peripheral catheter design for prevention of thrombophlebitis

Essentials Phlebitis is one of the most frequent complications related to short peripheral catheters (SPC). A new SPC design, aimed for minimizing mechanical phlebitis, was tested in vivo in swine. MRI analysis revealed 40% less inflammation with the new SPC design compared to commercial SPC. The results confirm that our SPC biomechanical design approach can minimize phlebitis rates. SUMMARY: Background Short peripheral catheters (SPCs) are the most common intravenous device in today's medical practice. Short peripheral catheter thrombophlebitis (SPCT) occurs in up to 80% of hospitalized patients. Symptoms appear on average 3 days after catheter insertion and can lead to extended hospitalization and increased related costs. Here we introduce a novel SPC, named very short peripheral catheter (VSPC), that was designed to minimize biomechanical irritation and improve blood flow. Objective The goal was to test the performance of the novel catheter in vivo for reduction of thrombophlebitis. Methods Very short peripheral catheter prototypes were inserted into swine ear veins (n = 12). Verification of the catheter conformation in situ and blood perfusion was performed using Echo-Doppler. The SPCT development rate was measured using magnetic resonance imaging (MRI), 4 and 12 days after catheter insertion, and analyzed by means of edema and inflammation intensities. Blind histopathology analysis was performed on the veins postmortem. Clinically available SPC was used as a reference. Results Operation of the VSPC devices did not require any special skills over those used for the clinically available SPC. Echo-Doppler imaging confirmed that in contrast to the traditional SPC, the VSPC avoided contact with the vein wall and allowed better blood perfusion. The MRI analysis revealed 2-fold inflammation and edema rates (~80%) in the veins cannulated with the commercial SPC, whereas rates of only ~40% were seen with the novel VSPC. A similar trend was noticed in the histopathology analysis. Conclusions The results indicate that the novel catheter design significantly reduced SPCT rates and demonstrated proof of concept for our biomechanical approach.

Mechanical Compression Effects on the Secretion of vWF and IL-8 by Cultured Human Vein Endothelium

Short peripheral catheters are ubiquitous in today's healthcare environment enabling effective delivery of fluids and medications directly into a patient's vasculature. However, complications related to their use, such as short peripheral catheter thrombophlebitis (SPCT), affect up to 80% of hospitalized patients. While indwelling within the vein, the catheters exert prolonged constant pressure upon the endothelium which can trigger inflammation processes. We have developed and studied an in-vitro model of cultured endothelial cells subjected to mechanical compression of modular self-designed weights, and explored their inflammatory response by quantification of two key biomarkers- vWF and IL-8. Evaluation was performed by ELISA immunoassay and processing of vWF-labeled immunofluorescence images. We found that application of weights correspond to 272 Pa yielded increased release of vWF and IL-8 up to 150% and 250% respectively, comparing to the exertion of 136 Pa. Analyses of the immunofluorescence images revealed significantly longer and more extracellular vWF-strings as well as higher intensity stained-pixels in cells exposed to elevated pressures. The release of both factors found to be significantly dependent on the extent of the exerted pressure. The research shed a light on the relationship between induced mechanical compression and the pathogenesis of SPCT. Minimizing, let alone eliminating the contact between the catheter and the vein wall will mitigate the pressure acting on the endothelium, thereby reducing the secretion of inflammatory factors and lessen the incidence of SPCT.

Quantitative T2 mapping for detection and quantification of thrombophlebitis in a rabbit model

Short peripheral catheter thrombophlebitis (SPCT), a sterile inflammation of the vein wall, is the most common complication associated with short peripheral catheters (SPCs) and affects up to 80% of hospitalized patients receiving IV therapy. Extensive research efforts have been devoted for improvement and optimization of the catheter material, but means for examination of any novel design are limited, inaccurate and require costly comprehensive pre-clinical and clinical trials. Therefore, there is a conclusive need for a reliable quantitative method for evaluation of SPCT, in particular for research purposes examining the thrombophlebitis-related symptoms of any novel catheter design. In this study, we developed for the first time a quantitative MRI based tool for evaluation of SPCT. The extent and severity of SPCT caused by two different commercially available SPCs with known predisposition for thrombophlebitis, were studied in a rabbit model. MRI analysis was consistent with the standardized pathology evaluation and showed remarkable difference in the percent of edema between the experimental groups. These differences were in line with previous studies and provide evidence that this type of analysis may be useful for future assessment of SPCT in vivo. As a non-invasive method, it may constitute a cost effective solution for examination of new catheters and other medical devices, thereby reducing the need for animal sacrifice.