Patent Application
20130150811
The present invention relates generally to an implantable port for fluid access to a site within a human body. More specifically, the invention relates to an implantable port with a reservoir, a needle-penetrable septum for access to the reservoir, and a stem with multiple cylindrical lumens in fluid communication with the reservoir.
Ports are commonly implanted in humans for fluid access to a site within the body. Ports generally include a reservoir, a needle-penetrable septum for access to the reservoir, and a stem for connecting a catheter to the port and transmitting fluid between the reservoir and a target site within the body. The outside of the stem can be shaped to accept a catheter, and a locking mechanism is typically used to secure the catheter to the stem. The distal end of the catheter can be advanced to a target site within the body. The target site can vary depending on the type of treatment being administered.
Treatments such as antibiotics, chemotherapy, pain medicine, and nutrition are commonly infused transdermally into the port reservoir, and delivered to the target site. For example, a syringe containing a treatment fluid can be connected to a hypodermic needle for infusing treatment through the port. Once the needle fully penetrates the skin and the septum, there is fluid access between the port reservoir and the syringe. Treatment fluid can then be infused into the reservoir, through a lumen in the stem, through the lumen in the catheter, and delivered to the target site. The port can also be used for aspirating fluid transdermally from the target site to an external container. For example, a syringe can be used to create negative pressure in the reservoir and the attached catheter. As a result, fluid near the tip of the catheter will flow through the catheter, through the stem, into the reservoir, through the hollow opening in the needle tip, and into the syringe. Huber style needles are commonly employed for establishing transdermal fluid access to a port reservoir.
Ports with high flow rates are desirable for numerous treatments. For example, during contrast enhanced computed tomography scans, it is desirable to inject contrast media to the target site at a high flow rate to facilitate improved imaging contrast and clarity. Alternatively, for apheresis and dialysis applications, infusion and aspiration of fluid must occur at high flow rates for proper treatment.
In a single reservoir port, the stem is typically a tubular shaped stem made of the same material as the port body. Common port body and stem materials include plastic, stainless steel or titanium. Various techniques are used to create a fluid channel or lumen through the center of the stem, often depending on the composition of the stem. For example, for a plastic stem, cylindrical and non-cylindrical lumens can easily be created using molding and manipulation techniques commonly known in the art. In one technique, a metal insert shaped to the desired dimensions of the lumen is embedded into the stem during molding. Once the molding process is complete, the metal insert is removed, creating a lumen characterized by the shape of the metal insert. For stem compositions that are harder to shape, such as metals, a small drill bit can be used to drill a cylindrical lumen longitudinally through the center of the stem. With drilling techniques, a lumen having a maximum cylindrical cross-sectional area can be formed by simply selecting a drill bit of appropriate diameter.
Dual reservoir port designs increase flexibility in treatment options available to the patient. Dual reservoir ports typically use opposing D-shaped stems to realize the largest cross-sectional area, while maintaining an overall circular shape capable of accepting a catheter lumen. The opposing D-shaped stem also maintains structural integrity while maintaining the separation of flows. Ideally, to maintain a high flow rate, the D-shaped stem would also have D-shaped lumen. For stems made of plastic, a D-shaped lumen can easily be created using cost-effective molding and manipulation techniques known in the art. However, for non-plastic materials that are difficult to mold and manipulate, such as metals, it is difficult to shape a non-cylindrical lumen. Manufacturing a non-cylindrical lumen in a small metal component can also be expensive and often cost prohibitive. For example, a process known as wire electric discharge machining can be used for forming non-cylindrical lumens in metals such as titanium. The wire electric discharge machining process requires the design and maintenance of special electrodes, which can dramatically increase manufacturing costs. Because of the cost and complexity involved with manufacturing non-cylindrical lumens in materials such as metals, the drilling technique as described above is often replicated in D-shaped stems, and a drill bit is used to create a cylindrical lumen of maximum diameter. Nonetheless, a cylindrical lumen of maximum diameter in a D-shaped stem has a limited flow rate, and the need remains for a cost effective way of increasing flow rates in a D-shaped stem to accommodate high flow treatments.
The present invention is directed to a port stem for an implantable port having fluid access to a site within a human body.
In one embodiment, an implantable port for fluid access to a site within a human body includes a reservoir, a needle-penetrable septum for access to the reservoir, and a stem. The stem has a plurality of cylindrical lumens extending longitudinally therethrough in fluid communication with the reservoir.
In another embodiment, an implantable dual reservoir port for fluid access to a site within a human body includes a first and second reservoir, a first needle-penetrable septum for access to at least one of the first and second reservoir, and a first and second stem. The first stem has a first plurality of cylindrical lumens extending longitudinally therethrough in fluid communication with the first reservoir, and the second stem has a second plurality of cylindrical lumens extending longitudinally therethrough in fluid communication with the second reservoir.
In another embodiment, a method for manufacturing a D-shaped stem for an implantable port includes forming the D-shaped stem, where the stem includes a proximal end and a distal end. Multiple lumens are drilled longitudinally through the stem, and the lumens extend from the proximal end to the distal end of the stem.
The foregoing purposes and features, as well as other purposes and features, will become apparent with reference to the description and accompanying figures below, which are included to provide an understanding of the invention and constitute a part of the specification, in which like numerals represent like elements, and in which:
The present invention can be understood more readily by reference to the following detailed description, the examples included therein, and to the Figures and their following description. The drawings, which are not necessarily to scale, depict selected preferred embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. The skilled artisan will readily appreciate that the devices and methods described herein are merely examples and that variations can be made without departing from the spirit and scope of the invention. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
Referring now in detail to the drawings, in which like reference numerals indicate like parts or elements throughout the several views, in various embodiments, presented herein is a high-flow port stem.
A flow simulator was used to compare the flow rate of a D-shaped stem having a single maximum diameter lumen with the flow rate of an equivalent D-shaped stem having two smaller offset lumens. The diameter of the single maximum lumen was 0.038 inches, and the diameter of each offset lumen in the two lumen design was 0.032 inches. For equivalent pressure, fluid viscosity and stem length, the two lumen design resulted in a flow rate improvement factor of approximately 3.26 times the flow rate of the single maximum lumen. An additional advantage of the two lumen design is a lower pressure drop across the stem. A simulation using 11.8 cP contrast media at a flow rate of 5 ml/s resulted in a pressure drop of 304 mmHg measured across the stem for the single maximum lumen design, and a pressure drop of 167 mmHg measured across the stem for the two offset lumen design, representing an approximately 45% improvement. Lower pressure levels provide a clinical advantage in both blood conveyance and contrast media injections by maximizing injector performance, minimizing the possibility of patient injury, lowering pressure levels in the port assembly and lessening strain on the catheter shaft.
