Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-05-25
2003-04-08
Nguyen, Anhtuan T. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S272000
Reexamination Certificate
active
06544214
ABSTRACT:
BACKGROUND OF THE INVENTION
In the field of hemodialysis and other forms of blood processing, the various techniques for gaining access to the blood stream of a patient have exhibited significant, known, technical disadvantages.
In response to this, a new technology for blood access has been developed by Vasca Inc. of Topsfield, Mass., involving an implantable port chamber in the body of a patient which is used in a manner described in PCT Publications WO98/31416 and WO99/03527, as well as in other references. Specifically, an implanted port is implanted within the skin of the patient, with a preformed needle track or “tract” extending from the entrance of the port through the tissue and through the skin. Thus, repeated penetration of the needle or tissue “tract” by an access cannula can take place without cutting of tissue, since cells similar to scar tissue form around the walls of the tissue tract, providing a result similar to the tissue track passing through earlobes in the case of pierced ears.
A Vasca or other type of implanted port communicates with a body lumen, typically a vein of the patient, but desirably with a valve that normally closes the flow path between the implanted port and the vein of the patient. When access to the blood stream is desired, (or access to another body lumen), a needle penetrates the preformed tissue “tract” and passes into the entrance of the port, pushing open the closure valve and thus providing access to the blood stream through the port.
It has been found to be usually desirable to also provide a flush treatment of the port interior and the tissue track leading to the skin.
This is accomplished in the prior art with a thin needle, thinner than the access needle that opens the port valve to gain access for extracorporeal blood flow, so that the thin needle enters the implanted port through the preformed tissue track without pushing open the valve. Then, flushing/disinfectant solution may pass into the port through the thin needle, with the flushing solution flowing outwardly through the tissue track along the exterior of the thin needle, to provide antibacterial flushing of the implanted port and tissue track.
The tissue track is preferably formed by a sharp needle, so that, when closed and not containing a needle, it is of the cross-sectional shape of a slit, and preferably a crescent-shaped slit, and not a round hole like a pierced ear. This provides natural sealing without substantial bleeding, after the tissue track has formed its scar tissue wall, especially in the circumstance where the tissue track leads to an implanted, valved port so that little or no blood backflow occurs when needles are withdrawn from the tissue track.
It has been found to be generally desirable for the disinfection procedure using a narrow needle to be used with every procedure of access to the tissue track. Thus it is desirable for the disinfecting needle and a needle that facilitates the dilation and stretching of the tissue track for receiving of blood access needle to work together in concert.
While dull access needles have been taught for use with preformed tissue tracks, clinical experiences show to the present that only certain types of dull access needles have been able to access such tracks, which are also called “buttonholes”. Needles that have too steep a bevelled tip angle, or no bevel at all with a perpendicular, flush end, generally cannot spread apart the freshly formed tissue track after a few days of nonuse, and cannot be used to gain entry unless a trocar is used in conjunction with them. However, trocars are expensive, and are difficult to place in non-gapped relation to the overlying cannula. If a gap occurs, the resulting incision can be painful when it tears tissue along the needle track. Nevertheless, the use of dull needles is highly desirable in view of laws that are going into place in the various states of the United States and perhaps elsewhere, mandating the use of either dull needles or guarded needles, to avoid accidental needle stick.
Thus, it would be desirable for a dull, safe needle to be used to pre-dilate the buttonhole so that a subsequent dull, safe, large-port access cannula, for example a dialysis flow cannula, can be inserted without a trocar. It would be beneficial if such a predilation needle can serve as a disinfecting needle as well, so that two functions may take place: a pre-dilation of the tissue track so that a blunt, larger needle can penetrate the track, and also providing of effective antimicrobial flushing for reduction of infection in the tissue track.
By this invention, such a needle or cannula, and a method of use, is provided to address the above disadvantages and technical issues.
DESCRIPTION OF THE INVENTION
By this invention, a cannula set has a first cannula for entry at least partially into an implantable artificial port through a preformed needle track through the skin of a patient, for fluid flow access in either direction. The implantable port has a flow conduit for connection with a body lumen such as a vein of a patient, plus a closure member (valve) for blocking flow between the port and the body lumen. This may comprise a moveable clamp which opens and closes a flexible tubing which typically is grafted at one end to a vein of a patient and which connects with the lumen of the implantable port at the other end. The closure member is normally closed by spring action or alternatively closures such as that disclosed by ports of Ensminger, Prosl and others, which closures are openable by insertion of a properly-sized and shaped cannula into the port.
The first cannula of this invention has a proximal end which maybe is connected to a hub, a proximal portion adjacent to the proximal end, and a distal portion. The distal portion of the first cannula is of insufficient size to open the closure member when inserted into the port, for example by being of insufficient length, or of insufficient outer diameter, to actuate the closure member.
The proximal portion of the first cannula may be of larger outer diameter than the distal portion, and is proportioned to dilate the tissue surrounding the preformed needle track leading to the implanted port, to facilitate subsequent advancement of a larger diameter fluid flow cannula through the needle track after withdrawing the first cannula.
Thus, the first cannula may be passed through the needle track to engage the implanted port with the distal cannula portion without causing the closure member of the port to be opened. Flushing/disinfectant solution may then be passed into the system through the first cannula, with the result that the flushing solution flows outwardly from the port through the port interior and the needle track outside of the first cannula, to provide a disinfection and flushing of both the interior of the implanted port and the needle track, for suppression of infection. Simultaneously, the proximal portion of the first cannula stretches the tissue surrounding the preformed needle track so that, upon withdrawal, it becomes a easier matter to insert a larger, second cannula through the needle track into engagement with the implanted port. This larger, second cannula is of sufficient size to cause opening of the closure member, so that the interior of the implantable port enters into fluid flow contact with the body lumen, particularly a vein of the patient. Thus, a relatively large diameter flow access path is provided through the port and the second cannula between the patient body lumen and the exterior. In the case of hemodialysis, this permits access to the venous system of the patient, so that blood can be withdrawn from the patient, passed through a blood processing apparatus such as a hemodialyzer, hemofiltration device, or the like, and then returned again to the patient, typically by means of a second implanted port and cannula system.
Preferably, especially for purposes of hemodialysis, hemofiltration, and the like, the first cannula may be at least 15 mm. in length. Also, the proximal portion of the first cannula, typically
DSU Medical Corporation
Ellis Garrettson
Lam Ann Y
Nguyen Anhtuan T.
Shaw Seyfarth
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