In this article, we will discuss how port catheters work, the benefits and risks of port catheters. Discover their advantages and disadvantages, what type of complications you may expect from them, and the history of port-a-cath, also known as chemoport.
A port catheter is a totally implantable vascular access device (TIVAD) designed to provide repeated access to the vascular system for the delivery of medication, intravenous fluids, parenteral nutrition solutions, and blood products. The port catheter is surgically placed completely under the skin and left implanted.
Uses of Port Catheters:
The device, most commonly referred to as a port-a-cath or chemoport, has an intended purpose of making it easier to deliver medications directly into the patient’s bloodstream. Due to the relative ease of access there has been an exponential increase in the number of devices implanted into patients every year. While there were somewhere in the neighborhood of 80,000 devices implanted into patients in the United States in 2013, that number had quintupled to roughly 400,000 port-a-caths implanted in 2018.
History of Port Catheters:
The most significant adoption of these devices occurred after the first power injection port, manufactured by Becton Dickinson subsidiary, C.R. Bard, received a 510(k) ‘substantially equivalent to legally marketed device’ FDA approval for the PowerPort™ in 2006. All port catheters sold in the US today received approval via the 510(k) process as opposed to the more rigorous testing required for an original device to receive full Pre Market Approval (PMA) by the Food and Drug Administration.
The port catheter, first approved for use by the FDA in 1981, is a system consisting of two primary components: an injection port and a polyurethane or silicone catheter. The injection port has a raised center, or “septum,” where the needle is inserted for delivery of the medication or blood transfusion. The medication or blood is carried from the port into the bloodstream through a small, flexible tube, called a catheter, that is inserted into a blood vessel.
Port Catheters’ Uses:
The port-a-cath is “indicated for patient therapies requiring repeated access to the vascular system. The port system can be used for infusion of medications, I.V. fluids, parenteral nutrition solutions, blood products, and for the withdrawal of blood samples.”
Port Catheters’ Features:
According to manufacturers’ marketing materials, the polyurethane catheter “has less propensity for surface biodegradation, making it more resistant to environmental stress cracking.” The polyurethane or silicone comprising the catheter in the port-a-cath is comprised of a polymeric mixture of the thermoplastic and barium sulfate, a soft metal compound which is visible in certain radiologic studies (most commonly a lineogram).
Port Catheters’ Risks:
Barium sulfate is known to contribute to reduction of the mechanical integrity of polyurethane/silicone en vivo as the particles of barium sulfate dissociate from the surface of the catheter over time, leaving microfractures and other alterations of the polymeric structure and degrading the mechanical properties of the catheter.
The mechanical integrity of a barium sulfate-impregnated polyurethane is affected by the concentration of barium sulfate as well as the homogeneity of the modified polymer. The manufacturing process in constructing in a significant portion of the implanted catheters involve too high a concentration of barium sulfate particles, leading to improperly high viscosity of the raw polyurethane or silicone before polymerization and causing improper mixing of barium sulfate particles within the polymer matrix.
This improper mixing of the barium sulfate and polymer, as noted in numerous studies over the past forty years, can lead to pockets of barium sulfate and entrapped air being distributed through the catheter body and on the inner and outer surfaces of the catheter tube. This defect in the manufacturing process led to a heterogeneous modified polymer which led to an irregular catheter surface replete with fissures, pits and cracks. In addition to the degradation of the structural integrity which can lead to the catheter tube breaking apart and fragments passing through the blood stream into the heart or lungs, the roughened catheter surface also leads to the collection and proliferation of biofilm and fibrinous blood products, thereby drastically increasing the risk of infection and thromboembolism.
Current Port Catheter Studies:
Numerous studies have concluded that the surface degradation and resulting risk of fracture, infection and thromboembolism can be greatly reduced or avoided with design modifications to encapsulate the radiopaque compound or by using a different polymer formulation. Unfortunately, to this point, there are very few devices on the market which have added this additional safety measure to the catheter tube to reduce the extraordinarily high rates of complication, infection, blood clotting, and mechanical failure experienced by patients with these devices implanted.
Strategies for catheter manufacturing quality control must be implemented to minimize these defects and associated health risks. Further research and development in catheter materials and manufacturing processes are also necessary to improve catheter safety and efficacy. To see more research articles, visit our Science & Research page.
