Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-01-08
2003-01-14
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S174000, C604S905000
Reexamination Certificate
active
06506182
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to apparatus that allows access to the vascular system of a human (or other animal), particularly for the high-volume fluid flow required in hemodialysis, plasmapheresis and other fluid exchange therapies. More particularly, the present invention relates to a septum-less, subcutaneously-implantable access device of single or dual-lumen construct, and mating needle apparatus.
BACKGROUND OF THE INVENTION
There exists a class of devices for accessing fluid spaces and vessels within a human (or animal) body that are generally referred to as “ports”. Herein, “vessel” is defined as any conduit carrying a fluid within the patient's body. These prior art port devices generally comprise a chamber having an access opening sealed by means of a septum and having an egress from a second location leading to a catheter which is disposed within a fluid space or vessel. The septum allows a hollow needle (or “cannula”) to pass into the port's chamber, but then closes when the needle is removed, thereby preventing fluid leakage from within the bodily fluid space or vessel and also preventing anything from entering or exiting the port's chamber. These port devices are usually implantable below the skin so as to prevent infection, other contamination and mishandling.
Prior art ports are designed for relatively infrequent use, perhaps once a week, and, importantly, for fluid flow rates of 50 milliliters per minute or less, as is common during chemotherapeutic treatment. Modification of these prior art port devices for hemodialysis, plasmapheresis and other fluid exchange therapies, which require much greater flow rates, by simply enlarging the device components, poses several serious drawbacks that effectively limit use in such high-volume applications.
First, the prior art port's septum degrades quickly due to the larger gauge needles necessary to accommodate the higher flow rates required in hemodialysis. Repeated puncturing of the septum by these large needles produces numerous free-floating septum fragments that can find their way into the patient's circulatory system. Accordingly, the useful life of the port device is substantially shortened, thereby defeating one of the purposes of using an implantable subcutaneous access device.
Second, the prior art port's flow path has several stagnation points where clots may form, and the port is also not completely flushable or easily cleaned, thereby providing breeding grounds for infection, once contaminated, or a build-up of material which may adversely affect function.
Third, the prior art port's flow path is not streamlined and contains flow path obstructions, sharp corners, and abrupt changes in flow area and flow direction. This tends to increase the shear stress and turbulences experienced by blood flowing through the port device due to the significantly higher flow rates required in hemodialysis, thereby increasing erythrocyte damage and platelet activation. Also, the prior art port's tortuous flow path increases the flow path resistance and the pressure drop through the port device; such effects can increase air release and foaming, thereby causing the dialysis machine's safety alarms to activate.
A general limitation in all relevant prior art port devices is the lack of a streamlined flow path. Without such streamlining, stagnant volumes exist where clots may form and shear stress is higher, tending towards erythrocytic damage. Such locations cannot be flushed or easily cleaned. Blood residue remaining in the devices after flushing may clot and may provide breeding grounds for infection, once contaminated. In addition, pressure drops and abrupt flow direction changes may damage blood components.
The present invention is also useful for other liquid or fluid (including gases) transfer purposes into and out of human and animal bodies, including the transfer of externally-prepared solutions for cleaning, flushing, dialysis, chemical agent delivery, transfusions, blood donation, insufflation, wound drainage, etc.
Accordingly, it is a principal object of this invention to overcome the above-illustrated inadequacies and problems of extant devices by providing a totally implantable access means suitable for repeated use in applications (e.g., hemodialysis) with blood flow rates of 250 milliliters per minute or more, yet with low pressure drops along the flow path.
It is another principal object of the present invention to optimize fluid flow, in hemodialysis particularly, and in other applications referred to generally, above.
It is another object of this invention to provide a substantially laminar flowstream.
It is yet another object of this invention to minimize flow discontinuities and to substantially match the internal diameters of the injecting needle (or cannula) and the receiving catheter, and a related object is to bring the exit end of the needle (or cannula) and the entrance end of the catheter into close proximity.
It is a further object of this invention to provide access means where the flow path is streamlined and provides substantially no stagnation points and no flow discontinuities, and also to provide an apparatus where the entire flowstream is flushable.
It is a further object of the present invention to minimize internal fluid collection zones or stagnant volumes in such an access device.
It is a still further object of this invention to have lower clotting, stenosis and infection rates than with synthetic grafts.
It is yet another object of this invention to have lower infection and lumen clotting rates than with percutaneous catheters.
It is a still further object of this invention to provide apparatus suitable for single and dual-lumen catheter systems.
It is yet another object of this invention to provide an access device that is less painful during needle (or cannula) insertion and more accommodating during dialysis for the patient.
It is a further object of the present invention to minimize irritation and other adverse effects associated with intermittent skin punctures over a course of days, months or years of repetitive subcutaneous access.
It is a further object of this invention to secure the needle (or cannula) within the access device during the dialysis session.
It is a further object of the present invention to enhance the access device so as to more effectively lock in a needle (or cannula) to the access device in order to avoid inadvertent separation, yet allow ease of deliberate release of the needle (or cannula).
It is a further object of the present invention to provide ease of manufacture and assembly of such an access device consistent with enhanced locking.
A further object of the present invention is to establish economy of the lock devices for disposability.
It is a further object of the present invention to provide enhanced needle (or cannula) and obturator handling external to a patient via hub devices coordinated with the structure and functions of the locking devices.
It is another object of the present invention, when using dual-lumen catheters, to secure both needles (or cannulas) to each other.
And another object of the present invention is to provide improved needle (or cannula) and obturator assemblies.
It is also an object of the present invention to accommodate multiples of the foregoing objects together.
SUMMARY OF THE INVENTION
The foregoing objects are met by a single subcutaneously-implantable device for accessing a vessel within a patient's body, or a ganged pair of such devices or separate such devices, each device including (a) access guidance means having an entrance and a passageway for receiving a needle (or cannula) and accommodating a locking means for the needle (or cannula), (b) flexible locking means, (c) needle guidance means of sufficient hardness to prevent scoring or chipping, (d) valve means for allowing access to a vessel when a needle (or cannula) is inserted into the device and preventing fluid flow through the device when the needle (or cannula) is withdrawn
Estabrook Brian K.
Smith Paul J.
Biolink Corporation
Casler Brian L.
Pandiscio & Pandiscio
Thanh LoAn H.
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