Vascular access sheath

Details Vascular access sheath Vascular access sheath

2000-10-06

2003-01-21

Hayes, Michael J. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06508790

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a permanent or semipermanent hemodialysis access sheath and an adapter for a hemodialysis catheter.
2. Description of Related Art
Hemodialysis is a procedure for removing metabolic waste products or toxic substances from the bloodstream by dialysis. Dialysis, in terms of hemofiltration, is the process of separating elements in a solution by convective transport of solute through ultrafiltration across a semipermeable membrane down a concentration gradient. Convective solute transport depends on the movement of dissolved substances concomitant with fluid flow through a filtering membrane.
Hemodialysis requires extracorporeal circulation of the blood. Blood is removed from the patient via a suitable access and pumped to the membrane unit. Dialyzed blood is returned to the patient through tubing that incorporates an air embolus protector.
Typically, long-term access to the circulation is provided by subcutaneous arteriovenous fistulas. Temporary access to the circulation may be achieved by inserting single- or double-lumen catheters into the subclavian or femoral veins. Most subclavian catheters are useful for hemodialysis over 2 to 6 weeks when strict skin care protocols are followed and the use of the catheter is limited to hemodialysis and hemofiltration procedures. Some designs are made of silicone rubber and have a subcutaneous fabric cuff. The latter has a longer life span and may be used for chronic hemodialysis in those patients for whom it is impossible to create a conventional access.
Current chronic type hemodialysis access catheters are placed in a large central vein usually in patients who have exhausted all other means of hemodialysis access or who are awaiting maturation of an A-V fistula. These catheters have a limited life span from many causes, chiefly fibrin sheath development and thrombosis. They are also prone to malfunction because of suboptimal positioning. Once these catheters fail, they must be surgically removed and surgically replaced in another vein. Over time, the venous access sites become exhausted.
Both catheters and sheaths have been the subjects of previous patents. U.S. Design Pat. No. 384,411 shows an ornamental design for a double lumen catheter with a guidewire retainer. U.S. Pat. No. 3,595,230 discloses a catheter placement unit which includes a catheter shield, catheter and needle for use in venipuncture. U.S. Pat. No. 4,913,704 discloses a disposable indwelling catheter placement unit which includes a plastic catheter and a plastic sheath having a slit. U.S. Pat. No. 5,676,656 shows a control forward introducer needle and catheter assembly. U.S. Pat. No. 5,697,914 shows a control forward and flashback forward one hand introducer needle and catheter assembly for use when introducing fluid intravenously.
U.S. Patent Nos. 4,551,137 and 4,634,433 describe a flexible sheath which maintains the sterility of the exposed portion of an indwelling catheter. U.S. Pat. No. 4,619,643 shows a double lumen catheter for use in hemodialysis. U.S. Pat. No. 5,250,038 shows a multiple lumen vascular access introducer sheath having a main lumen for introducing another device, and a secondary lumen having a significantly smaller cross-sectional area for infusion of small doses of medication. U.S. Pat. No. 5,256,150 discloses a large-diameter expandable sheath for use in introducing a catheter into a vessel. U.S. Pat. Nos. 5,599,305 and 5,843,031 disclose a large-diameter introducer sheath which has a hemostasis valve and removable steering mechanism. U.S. Pat. No. 5,779,681 discloses a stiff tubular catheter segment which is designed to remain outside the body. None of the above patents for catheters and sheathes disclose hubs or flanges for holding a sheath to a catheter for long term use and replacement, nor do they provide for permanent placement of a sheath or a catheter in a venous cavity.
U.S. Pat. No. 4,392,853 issued to Muto on Jul. 12, 1983 discloses a sterile assembly for protecting and fastening an indwelling device such as an elongated catheter or pacer lead in an incision. The invention of Muto utilizes a clamp to hold a length of an indwelling device, such as a catheter, in place. The clamp is secured external to the body near the incision. No provision is made for removing the indwelling device and replacing the indwelling device without removing the clamp and reinserting the entire apparatus again.
U.S. Pat. No. 4,547,194 issued to Moorehead on Oct. 15, 1985 discloses an apparatus and method which includes a catheter and a hub, and a method for inserting, extending and repairing the exposed (external) end of the catheter. The hub is connected to the exposed end of an indwelling pliant catheter tube in order to facilitate extending the catheter with additional lengths. The invention of Moorehead does not provide for the removal and replacement of an indwelling catheter nor does it provide an apparatus to secure the catheter in place.
U.S. Pat. Nos. 4,643,711 and 4,772,268, issued to Bates on Feb. 17, 1987 and Sep. 20, 1988 respectively, disclose a dual lumen hemodialysis catheter which includes a tube having circular external cross section that is rotatably received within a fitting. The fitting is designed to be attached to the patient by sutures or the like. The catheter is kept from moving longitudinally relative to the fitting but is allowed to freely rotate. The invention of Bates does not provide an easily replaceable catheter since the fitting must be removed in order to replace the catheter.
U.S. Pat. No. 5,106,368 issued to Uldall et al. on Apr. 21, 1992 discloses a dual lumen catheter, for providing extra-corporeal treatment such as hemodialysis, which is percutaneously inserted for either short-term or long-term vascular access. A ring-like grommet moveable along the proximal segment of the catheter anchors the catheter to the surrounding tissue via a flange extending from the grommet. Sutures are utilized to hold the grommet in to place. The grommet can be released by pulling on it or by dissecting it out; there is no bleeding associated with the release of the grommet. The catheter is left in place. There is no provision in the invention of Uldall et al. for the insertion and maintenance of a sheath in place instead of fixing the catheter in place. To replace the catheter, the supraclavicular incision must be reopened and the subcutaneous sutures anchoring the grommet in place must be removed.
U.S. Pat. Nos. 5,474,534 and 5,681,288, issued to Schlitt on Dec. 12, 1995 and Oct. 28, 1997 respectively, disclose an indwelling catheter having a tab which can be rotated against the skin and taped into place with a strip of adhesive tape. The tab is utilized in inserting the catheter into a subcutaneous vein, artery or other blood vessel, and then the tab serves to prevent the catheter from rotating or moving longitudinally once secured into place. Specifically, the catheter of Schlitt is designed to introduce liquids directly into the blood stream. The catheter of Schlitt is not designed to be left in place long term nor is a sheath utilized for removing and replacing the catheter.
U.S. Pat. No. 5,672,158 issued to Okada et al. on Sep. 30, 1997 shows a catheter introducer which allows a dilator section and a sheath section to be readily engaged with and disengaged from each other. The catheter introducer has a sheath, a sheath hub, a dilator, and a dilator hub. The dilator hub includes a flange to cover the end of the sheath hub. The catheter introducer of Okada et al. is specifically intended to introduce a catheter into a blood vessel such as for angiography. The invention is particularly designed to prevent the relative rotation and axial displacement of the dilator with respect to the sheath during introduction of a catheter. The sheath is not designed to remain in place long term. The significance of the invention of Okada et al. is on the means of engaging the dilator and the sheath in order to prevent undesirable movement of the sheathe relative t

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