Evaluation of the elastic behaviour of central venous PVC, polyurethane and silicone catheters

Impact of mechanical stress on flexible tubing used for biomedical applications: Characterization of the damages and impact on the patient's health

Flexible tubing is a key part of a lot of medical devices used in hospital, but may be subjected to a lot of various mechanical stresses that can led to the failure or to complications for the patients. The nature and causes of these mechanical stresses were listed for peristaltic pump tubing, infusion set tubing and catheters. Their consequences in term of tubing damages and particular contamination were reported. The impact of the chemical nature of the tubing, of its size and also the impact of various parameters of the clinical acts were reviewed. Last the consequences for the patient's health were discussed.

Folded large-bore central catheter in the right internal jugular vein as shown by ultrasound: a case report

Central venous catheters are used for various purposes in the operating room. Generally, the use of ultrasound to insert a central venous catheter is rapid and minimally complicated. An advanced venous access (AVA) catheter is used to gain access to the pulmonary artery and facilitate fluid resuscitation through the internal jugular vein. The present report describes a case in which ultrasound was used in a 43-year-old man to avoid complications during insertion of an AVA catheter with a relatively large diameter. The sheath of the catheter was so thin that a dilator was essential to prevent it from folding upon insertion. Despite the use of ultrasound guidance, the AVA catheter sheath became folded within the patient’s internal jugular vein. Mechanical complications of central venous catheter insertion are well known, but folding of a large-bore catheter in the internal jugular vein has rarely been reported.

Development, safety and efficacy of a novel circular-irrigated deca-channel mapping and ablation catheter for pulmonary vein isolation

BACKGROUND

Pulmonary vein isolation (PVI), a cornerstone for catheter ablation of atrial fibrillation (AF), remains a complex and time-consuming procedure. Present study introduces a novel, circular-irrigated, deca-channel mapping and ablation catheter (CIDMA), describes the in vitro test results on feasibility, safety, and acute efficacy of the CIDMA catheter.

METHODS

An assembled CIDMA catheter was subjected to a number of in vitro tests. With this catheter, ablation procedures were first performed in a pig's myocardial strips in vitro to determine the effects in unipolar or bipolar configuration.

RESULTS

Three catheters were assembled. The adjustable circular diameter was changed from initial state of 32.41 ± 0.61 mm into controlled state of 28.61 ± 0.47 mm (P = 0.013). In the plastic model, the push-ability, torque-ability, and kink resistance of CIDMA catheter were shown to be satisfactory. In vitro, our findings showed that ablation could produce obvious ablation lesions, and unipolar ablation (at length, width and depth of 5.0 ± 1.3, 4.6 ± 0.7, and 4.2 ± 0.6 mm, respectively) was more effective than bipolar (at length, width and depth of 2.8 ± 0.2, 4.2 ± 0.5, and 2.3 ± 0.4 mm, respectively) (P < 0.01).

CONCLUSIONS

In vitro, our preliminary data suggest that the CIDMA catheter produced optimal ablation lesions, especially in the unipolar ablation mode. Future in vivo animal and clinical studies are warranted to test the efficacy of this catheter in real-world scenario.

A catheter friction tester using balance sensor: Combined evaluation of the effects of mechanical properties of tubing materials and surface coatings

In this study, we introduce a new experimental approach to characterize the forces emerging from simulated catherization. This setup allows for a linear translation of urinary catheters in vertical direction as controlled by an actuator. By employing silicone-based elastomer with a duct of comparable diameter with catheters as urethra model, sliding contacts during the translation of catheters along the duct is generated. A most unique design and operation feature of this setup is that a digital balance was employed as the sensor to detect emerging forces from simulated catherization. Moreover, the possibility to give a variation in environment (ambient air vs. water), clearance, elasticity, and curvature of silicone-based urethra model allows for the detection of forces arising from diverse simulated catherization conditions. Two types of commercially available catheters varying in tubing materials and surface coatings were tested together with their respective uncoated catheter tubing. The first set of testing on the catheter samples showed that this setup can probe the combined effect from flexural strain of bulk tubing materials and slipperiness of surface coatings, both of which are expected to affect the comfort and smooth gliding in clinical catherization. We argue that this new experimental setup can provide unique and valuable information in preclinical friction testing of urinary catheters.

Tensile properties of the rectal and sigmoid colon: a comparative analysis of human and porcine tissue

For many patients, rectal catheters are an effective means to manage bowel incontinence. Unfortunately, the incidence of catheter leakage in these patients remains troublingly high. Matching the mechanical properties of the catheter and the surrounding tissue may improve the catheter seal and reduce leakage. However, little data is available on the mechanical properties of colorectal tissue. Therefore, our group examined the mechanical properties of colorectal tissue obtained from both a common animal model and humans. Uniaxial tension tests were performed to determine the effects of location, orientation, and species (porcine and human) on bowel tissue tensile mechanical properties. Bowel tissue ultimate strength, elongation at failure, and elastic modulus were derived from these tests and statistically analyzed. Ultimate tensile strength (0.58 MPa, 0.87 MPa), elongation at failure (113.19%, 62.81%), and elastic modulus (1.83 MPa, 5.18 MPa) for porcine and human samples respectively exhibited significant differences based on species. Generally, human tissues were stronger and less compliant than their porcine counterparts. Furthermore, harvest site location and testing orientation significantly affected several mechanical properties in porcine derived tissues, but very few in human tissues. The data suggests that porcine colorectal tissue does not accurately model human colorectal tissue mechanical properties. Ultimately, the tensile properties reported herein may be used to help guide the design of next generation rectal catheters with tissue mimetic properties, as well as aid in the development of physical and computer based bowel models.

Catheter-Related Central Venous Thrombosis: The Development of a Nationwide Consensus Paper in Italy

Catheter-related central venous thrombosis is a serious complication in patients who need long-term venous access. Though scientific data and clinical experience are steadily increasing, many uncertainties still exist about several aspects of this complication, including etiology, pathogenesis, diagnosis, management, and prevention of this complication. The GAVeCeLT (the Italian Study Group for Long Term Central Venous Access) promoted a nationwide consensus, and 12 experts reviewed systematically all the available literature. A preliminary document was presented and discussed during a specific Consensus Meeting, in front of a panel of more than 80 experts (representing different health professions and disciplines). This led to a prefinal document, which was presented to more than 800 health professionals. After peer review by an external board of experts, the final document was prepared. In this article, methodology and results of the consensus are presented.

Flow characteristics of peripherally inserted central catheters

PURPOSE

Clinical applications of peripherally inserted central catheters (PICCs) are limited by the relatively small lumina and long lengths of these devices. Quantitative analysis of the flow capabilities of a variety of PICCs was performed to aid in deciding which patients should have a PICC and in selecting the appropriate catheter.

MATERIALS AND METHODS

Sixteen different PICCs from six manufacturers were infused at flow rates of 25-270 mL/h. Infusions were performed with distilled water, normal saline, total parenteral nutrition solution, intralipids, and blood. Flow versus pressure curves were generated for each PICC and infusate. Additional catheter data recorded included the working length, outer diameter (OD), and inner diameter (ID) of the PICCs.

RESULTS

Because of the thin wall construction of polyurethane catheters, PICCs made from polyurethane showed much better flow rates than silicone PICCs of a comparable OD. The measured ODs of the PICCs were 4-6 F, whereas the IDs ranged from 0.012 to 0.032 inch. Because of the small ID of some PICCs, infusing blood or intralipids is not practical.

CONCLUSION

There is significant variability in the flow capabilities of available PICCs. Many of the PICCs require pressures greater than those that can be generated by commercially available infusion pumps. Matching PICC characteristics to the desired application will avoid many of the clinical problems currently encountered with PICCs.

Selection of vascular access devices and nursing care

OBJECTIVE

To provide an overview of the patient selection criteria for a vascular access device (VAD) and its maintenance care.

CONCLUSIONS

The availability of different types of devices had led to confusion on the part of many health care professionals as to which device is the best for their purpose. Selecting the appropriate VAD is an interdisciplinary decision based on patient characteristics, type of therapy, support system availability, and cost. Numerous controversial issues surround the care of VADs, and research results have not yet resolved these practice issues. Although various procedures are used throughout the country, it can be reasonably concluded that the fundamental requirement for successful maintenance of a VAD is strict adherence to established care protocols.

IMPLICATIONS FOR NURSING PRACTICE

Assessment of the need for a VAD is an ongoing process. Nurses are in a perfect position to assess the factors that precede device selection, including the frequency of access, type of intravenous therapy, and the condition of the patient's peripheral veins. The vast array of devices demands specialized knowledge in selecting the appropriate VAD, providing correct care, and evaluating the device once inserted or implanted.

Hydropneumomediastinum and bilateral hydropneumothorax as delayed complications of central venous catheterization

A case of hydropneumomediastinum and bilateral hydropneumothorax from a central venous catheter is described. The complication is related to the position of the catheter after placement through the left internal jugular vein. Proper placement of a central venous line into the superior vena cava is essential to avoid this serious complication.

Long-term central venous catheters: issues for care

Long-term central venous catheters allow the safe administration of chemotherapy, blood and blood products, total parenteral nutrition, fluids, and other medications. Despite their benefits, the risk of certain complications (e.g., fibrin sleeve and mural thrombus formation, infection, catheter occlusion, extravasation, and catheter malposition) exist for every person who has a catheter. Thus, preventative measures, recognition of early signs and symptoms of complications, and adequate care of utmost importance.

Fracturing and stretching of angioplasty balloon catheters under bending with tension

Eight catheters from five manufacturers have been subjected to tests which combined bending and tension. Three failure mechanisms have been identified. These included separation of the balloon from its proximal attachment to the shaft, fracture of the shaft at its junction with the balloon, and undue ductility of the shaft. It is concluded that good catheter design should ensure that there is no sudden change in stiffness along the length of the catheter, and that the optimum relationship of ductility to stiffness has not yet been defined for catheters. Recommendations relating to these characteristics could be included in the British Standards relating to angioplasty balloon catheters.