Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-06-01
2004-01-27
Thanh, LoAn H. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C128S898000
Reexamination Certificate
active
06682519
ABSTRACT:
BACKGROUND OF THE INVENTION
Catheters for the introduction or removal of fluids may be located in various venous locations and cavities throughout the body. Several types of catheters have been developed for fluid transduction applications including multiple lumen catheters, such as a dual lumen catheter in which one lumen introduces fluids and one lumen removes fluids, and multiple catheter assemblies, which comprise multiple, individual, typically single lumen catheters which are inserted through one or more incisions into an area to be catheterized. Examples of multiple catheter assemblies include the Tesio catheter and the SchonCath® catheter.
To insert any catheter into a blood vessel, it is generally necessary to identify the vessel by aspiration with a long hollow needle in accordance with the Seldinger technique. When blood enters a syringe attached to the needle, the syringe is disconnected and a thin guide wire is passed through the needle into the interior of the vessel. The needle is then removed, leaving the guide wire within the vessel. The guide wire projects beyond the surface of the skin.
Once the guide wire is placed within the vessel, a physician may choose to pass a catheter into the vessel directly over the guide wire, and remove the guide wire, leaving the catheter in position within the vessel. Alternatively, a dilator device can be passed over the guide wire to enlarge the hole. A catheter is then passed over the guide wire, and the guide wire and dilator are removed. Although employing a dilator is particularly useful when the catheter to be inserted is significantly larger in diameter than the guide wire, removing a dilator in the manner prescribed by most catheterization methods is associated with increased bleeding and the formation of blood clots at the insertion site.
Double catheter assemblies used for rapid withdrawal and/or infusion of blood and blood components or products and used repeatedly over weeks to months, are usually of a size equal to or larger than 12 French. They may be designed as two assemblies joined together through most of their length or as in the SchonCath® and Tesio double catheter systems designed as two independent catheters with lumens and inserted together either attached at some point or independent in which each lumen has a diameter of usually greater than 6 French. Such retained assemblies are preferably made of soft material to minimize trauma to the vessels during prolonged contact, and are therefore often difficult to insert without bending, kinking or crimping during insertion. When using these retained assemblies, a physician may find it is necessary to use an introducer sheath to facilitate insertion.
An introducer sheath is simply a large, stiff thin-walled tube which serves as a temporary conduit for the permanent catheter which is being placed. The introducer sheath is positioned by placing a dilator device inside of the introducer sheath and passing both the dilator and the introducer sheath together into the vessel. A guide wire, left in the vessel after insertion of the dilator-sheath assembly as described above, and the dilator(s) is (are) then removed, leaving the thin-walled introducer sheath in place. The dilator must be removed in order for the catheter to pass into and through the sheath. When the dilator is removed the sheath is left open with nothing to prevent blood from issuing out nor air from entering in. Thus significant blood loss can occur if there is any delay caused by difficulty in passing the catheter assembly into the sheath. An additional complication is that, with the dilator out, if the patient inspires deeply and creates negative pressure, air is sucked into the central vessels through the open sheath and results in air embolism. Air embolism is a potentially very serious complication and may be fatal.
In the case of a Tesio catheter assembly, an individual catheter, without a hub or an anchoring device, may be passed through the sheath and into the vessel. The sheath is then removed over the catheter. When a connecting means such as a retaining sleeve, or any type of anchoring device such as a Dacron® or other fabric anchoring cuff is permanently attached to the catheter, the sheath must be either larger than the cuff or comprise a tear-away portion which splits into two parts as the sheath is retracted. Even when no cuff is present and a tunneling procedure is commonly not performed, as with a Tesio assembly used for acute catheterization (U.S. Pat. No. 5,776,111), the assembly is so large and flexible that a sheath is often necessary to facilitation insertion. Once inserted, each of the proximal ends of the catheters in the assembly is stabilized, either by means of an anchoring device, subcutaneous tunneling as in chronic catheterization, or by affixing to the patient's skin as in acute catheterization.
Typical anchoring devices for such catheters and other venous and body cavity catheters and shunts involve use of a tissue ingrowth cuff, generally made of a fabric such as Dacron® or the like, fitted on a proximal portion of the catheter for stabilization of the catheter in a single position if the catheter is to be left in that position for a significant length of time. Surrounding tissue cells grow into the fabric stabilizing the catheter in that particular location. In using catheters having a fabric cuff, or other retaining devices or fittings, one stabilizing technique includes creating a subcutaneous tunnel, or similar opening, several centimeters caudal to the insertion site of the catheter for stabilization of the catheter using the cuff or other device. Subcutaneous tunnels and stabilizing devices are typically used, for example, for multi-lumen catheters and for catheter assemblies such as the Tesio and the SchonCath®.
In a typical tunneling procedure, the skin is anesthetized in a linear fashion for a distance of about 6-8 centimeters caudal to the insertion site. If tunneling is used for venous insertion, a second incision is made and a tunneling device such as a trocar is passed into the incision and out through the skin at the point of catheter insertion creating a subcutaneous tunnel. The catheter is attached to the tunneling device and pulled back through the skin tunnel.
For a self-retaining, double catheter assembly, such as a SchonCath®, in which the individual catheters are either permanently or adjustably linked in one location along their length by a retaining sleeve, subcutaneous anchoring is accomplished by positioning the retaining sleeve below the incision site and outside the area to be catheterized. The sleeve renders the assembly self-retaining such that the double tunneling procedure necessary to insert, for example, a Tesio catheter, is optional.
Both an adjustable catheter according to U.S. Pat. No. 5,718,692 and a Tesio catheter permit independent insertion and removal of the individual catheters such that dialysis need not be unnecessarily prolonged. Further, because the individual catheters in these assemblies can be adjusted within the vessel and in relation to one another, a physician is able to optimize catheter placement for a given location on a given patient. The ability to adjust individual catheters within a multiple catheter assembly represents a significant advantage over multiple lumen catheters, since positioning of catheters is particularly important to proper catheter functioning. For example, if the tip of a central venous catheter is not properly located within a vessel, the catheter may cause the condition of cardiac arrhythmia or otherwise inhibit blood flow. If the catheter tip is not properly located within a body cavity there may not be sufficient access to the tip to allow bodily fluid to properly flow through the catheter. Further, the catheter tip may damage a vessel wall and surrounding tissue if not properly placed within the vessel.
In addition to providing more desirable flow characteristics with less vessel damage than multiple lumen catheters, multiple catheter assemblies are generally formed of flexible cat
Maenner Joseph E.
Medical Components Inc.
Monte & McGraw, P.C.
Thanh LoAn H.
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