WO2001026713A1

WO2001026713A1 - Single needle vascular access for home hemodialysis

Info

Publication number: WO2001026713A1
Application number: PCT/US2000/026253
Authority: WO
Inventors: Frank R. Prosl; Hans-Dietrich Polaschegg; Robert J. Mercier
Original assignee: Biolink Corporation
Priority date: 1999-10-12
Filing date: 2000-10-12
Publication date: 2001-04-19
Also published as: AU1071101A; WO2001026713A9

Abstract

A port for single needle hemodialysis with alternating inflow and outflow of blood fluids, the port comprising an adaptation of a dual needle dual lumen port known commercially as Dialock & Trade;. This invention comprises two inlet ports (11A, 11B) connected to a single outlet port (12) to be connected to the patient's vascular system. The adaptation preserves the smooth and non-obstructed flow of the two-needle Dialock & Trade;.

Description

SINGLE NEEDLE VASCULAR ACCESS FOR HOME HEMODIALYSIS

The present invention relates generally to apparatus that allows access to the vascular system of a human or veterinary patient 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 implanted access of single-lumen construct and a mating needle apparatus.

BACKGROUND OF THE INVENTION Kidney failure, technically known as end-stage-renal-disease (ESRD), is a scourge. Diabetes patients who do not succumb to stroke or other deleterious effects of that

disease very frequently develop ESRD. Other pathological conditions lead to ESRD as well.

The ultimate treatment for ESRD would be successful kidney transplant. However, the availability of donor kidneys for transplant is such that only a small fraction of patients in need at any one time can receive a transplant. Without some treatment, ESRD leads to death.

Hemodialysis, the process of artificially removing deleterious metabolic byproducts and water from the blood and adjusting blood chemistry, is really the only treatment available for ESRD

patients who are not able to receive a transplanted kidney.

Typically hemodialysis is administered in multi-hour sessions in a dedicated clinic preferably three times per week. Patients are attended by nurses or technicians and by

physicians to assure effective treatment and safety. (As noted below, loss of fluid connection can in some circumstances result in the patient bleeding out.) Traditionally access to the

patient's vascular system for fluid exchange was by one of three methods: indwelling catheters, arterio-venous (AV) fistulas, and PTFE grafts. In recent years there has been much motivation to replace these somewhat crude methods with subcutaneous ports. Initially developed ports had serious shortcomings, principally in two areas. First, such ports typically used rubber or polymer septums that are penetrated in use by needles for fluid exchange. Repeated penetration eventually breaks down the septum. Second, such ports typically have had corners, barriers, and other irregularities in the flow path. The fluid flowing through such devices is blood, which is very susceptible to clotting in such an environment.

Accordingly, novel ports avoiding these limitations have been developed. Prosl, et al., U.S. Patent No. 6,013,058, issued January 11, 2000; Prosl, U.S. Patent No. 5,954,691, issued September 21, 1999; Estabrook, et al., U.S. Patent No. 5,911,706, issued June 15, 1999; and Prosl, U. S. Patent Application No. 09/083,078, filed May 21, 1998, all of which are incorporated herein by reference as though fully set forth in this application, describe an implanted port having smooth, relatively straight flow paths such that the device avoids giving rise to clotting. Such a port is accessed by a pair of needles that penetrate the skin, enter the port, and reversibly lock therein so as to create a flow path which can support the high flow rates necessary for dialysis without triggering clotting. This existing port apparatus only accommodates the conventional system of hemodialysis, which requires one conduit for flow of blood from the patient's vascular system, comprising part of a closed circuit in which blood flows through the hemodialysis machine, and also comprising a second conduit for return of blood to the patient. This system necessitates that the patient come to the dialysis clinic and be connected to the machine for an extended period, and practically speaking the maximum number of feasible sessions is about three per week.

Experience has shown, however, that daily dialysis provides improved clinical results for ESRD patients as compared with twice or three times a week dialysis in a clinic. In addition, simpler and therefore less expensive machines have in recent years become available and are eminently useful for daily dialysis These can be used at home, so that the patient can self-dialize

A key requirement of this approach is safety If the patient is hydraulically connected to a standard dialysis machine, the blood fluid circuit is a closed loop of one way flow In the event of unnoticed dislodgment of the venous catheter connection, the patient can bleed to death Thus the patient must be attended by medical staff to minimize the possibility of such a catastrophic event The need for attendance precludes the use of unassisted self- dialysis and therefore rules out home dialysis There is also risk of air leakage into the system which in adverse circumstances could result in introduction of an air bolus into the patient's vascular system

About twenty years ago a procedure for single needle dialysis was developed This procedure involves only one fluid connection to the patient's vascular system In this approach, a fixed volume of blood, perhaps 100 or 200 milliliters, is withdrawn from the patient in the arterial segment of the cycle through the single hydraulic connection and cleaned in the dialysis machine The clean blood is then returned to the patient in the venous segment of the cycle through the same single hydraulic connection This sequence is repeated a large number of times until the concentration of waste substances in the patient's blood is reduced to a clinically appropriate level A more detailed description of this process is contained in Drukker, Parsons and Maker, Replacement Of Renal Function By Dialysis, C Jacobs, C M Kjellstrand, K M Koch, and J F Winchester, 4^th Ed (Kluwer Academic Publishers, Dordrecht/Boston/London 1996), at pp 340-43 [Hereinafter "Drukker "]

The single needle dialysis procedure is inherently safe if a single needle dislodgment fault occurs during dialysis In this case the patient does not bleed nor can air be introduced into the patient's vascular system In addition, for the same effective blood flow the catheter will occupy less space inside the patient's blood vessel, thereby lowering the likely rate of stenosis in that vessel Moreover, a single puncture per session instead of two punctures for conventional dialysis produces less trauma to the patient's skin.

The principal limitation of home dialysis using two way sequential flow through a single hydraulic connection to the patient's vascular system is vascular access In the existing mode of single needle dialysis, as described in Drukker, access to the patient's vascular system is through an AV fistula or graft or in acute cases through a central venous catheter. In these forms of access, loss of blood because of rupture or inadvertent removal of needles or connectors is still a safety concern The probability of catastrophic failure is diminshed but not so much as to permit widespread use of home dialysis Accordingly, there is an unfulfilled need for a method of access to the patient's vascular system which lessens the danger of the patient bleeding out sufficiently that home dialysis can become a widely accepted practice.

SUMMARY OF THE INVENTION The invention disclosed in this application is a port for single needle dialysis with alternating inflow and outflow of blood fluids, the port comprising an adaptation of a dual needle dual lumen port known commercially as the Dialock™ This invention comprises two inlet ports connected to a single outlet port to be connected to the patient's vascular system The adaptation preserves the smooth and non-obstructed flow of the two-needle Dialock™

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a photograph of the Dialock™ single needle port with catheter attached

Figure 2 is a fluid system diagram of single needle home dialysis using the Dialock™ single needle port DESCRIPTION OF THE PREFERRED EMBODIMENTS As noted above with respect to previously filed and issued patent applications, one of the current inventors and others have developed a new type of hemodialysis access port, called the Dialock™ vascular access port, for two-catheter use with standard closed circuit continuous flow hemodialysis machines The Dialock™ has the significant advantage of smooth flow, which minimizes clotting and hemolyis The inventors herein have determined that the Dialock™ port can be modified without loss of the necessary smooth flow performance so as to involve only a single catheter inserted into the vascular system A photograph of a prototype of this system is shown in Figure 1 Figure 2 shows a schematic diagram of the single needle home hemodialysis system using the Dialock™ port The customary Dialock™ 10 hemodialysis port has been modified so that both inlet channels 11A and 11B flow into a single outlet catheter implanted in the patient's vascular system 12 In accessing the Dialock™ access device, the patient (or the professional assisting the patient) inserts the access needle 13 into only one of the access channels 11A or 11B The access needle 13 is connected at the proximal end to a Y-connector and valve arrangement 14 (see Drukker for details) The Y-connector and valve arrangement 14 is in turn connected to a withdrawn blood, or arterial, flow conduit 15 and to a return blood, or venous, flow conduit 16 In accordance with the scheme described in Drukker, blood is alternately withdrawn from the patient in increments, for example possibly 100 ml, cycled through the dialysis machine for cleaning and thence into a compliance vessel, where cleaned blood is accumulated Upon accumulation of a unit of cleaned blood, the system is switched, including switching the Y-connector and valve arrangement 14, to "return" and the cleaned blood is pumped back into the patient's vascular system via the return blood conduit 16 This cycle is repeated as many times as is necessary to achieve a clinically desirable or ordered state of the patient's blood At that state the dialysis machine is turned off and the needle disconnected from the Dialock' access device The Fresenius Corporation owns proprietary technology for a simple single needle dialysis machine, which technology can also be retrofitted into current dialysis machines These dialyzers can sense air leaks into the system and blood leaks from the system The advantages of this system for home dialysis comprise at least the following the patient can easily learn to self-access using device landmarks and tactile feedback, a positive (felt) mechanical stop determines the proper needle position, the Dialock™ is robust and virtually impossible to damage during needle accessing, and a Dialock™ can be placed in a number of body locations to optimize self-access capability In addition, the patient can safely perform hemodialysis without help or supervision Because either a heparin catheter lock or Biolink Corporation's proprietary Catheter Lock Solution is used, bleeding after needle withdrawal is minimal The retaining force, due simply to the geometry and to the locking of the needle in the Dialock™ access device, is high, thereby minimizing accidental or inadvertent disconnection Even in the event of unintentional needle removal, the Dialock™ seals automatically, limiting the The Dialock™ also provides lower vulnerability to mishap because the needle and blood flow line lies roughly parallel to the skin In addition, the Dialock™ has a relatively low infection rate, 2 7 episodes per 1000 days, with heparin as the catheter lock and an extremely low infection rate, 0 6 episodes per 1000 days, with Biolink' s proprietary Catheter Lock Solution Also perhaps the most significant advantage of the Dialock™ single needle modified access port is the saving of wear and tear on the patient's skin The single needle scheme in itself requires only half as many punctures per session as closed circuit two needle dialysis On the other hand, dialysis will probably occur twice as often, so that this advantage is most likely offset However, the Dialock™ system offers the advantage of being able to cycle between needle connections A and B, Fig 2 11A and llB This system will allow alternating puncture sites, resulting in only, for example 3 punctures per week in the same skin area instead of 6 punctures. Clinical studies strongly suggest that patient skin will withstand this level of puncturing long term.

Claims

CLAIMS 1 A reversible flow hemodialysis access system for access to a human or animal patient's vascular system for high fluid flow rate exchange of blood between the vascular system and an external processing apparatus preferably at a volumetric flow rate in excess of 250 ml/minute, and comprising, in combination,

(a) a needle assembly comprising a lumen defined by an interior surface and constructed and arranged for puncturing the skin of the patient and for carrying blood therethrouqh at a flow rate consistent with high blood flow requirement of the blood exchange process,

(b) a subcutaneously implantable access device permitting fluid connection to a vessel or space within a patient's body, the device comprising

(i) at least two substantially straight-through flow channel structures each having an interior surface and a distal end and a proximal end with reference to the patient's skin puncture site and constructed and arranged for insertion of the needle through the proximal end of the channel and withdrawal of the needle therefrom, (ii) a smooth non-obstructive connector joining the at least two substantially straight- through flow channel structures into one substantially straight-through flow channel structure such that quasilaminar flow of blood is maintained, said one straight-through flow channel structure having a proximal end at the point of juncture and a distal end away from the patient's skin puncture,

(iii) a seal arranged within each of the substantially straight-through flow channels and movable between first and second positions, where said seal, in said first position, with said needle not inserted through said seal, prevents fluids from passing said seal and, in said second position, with said needle inserted through said seal, allows fluids to pass through said needle and emerge substantially at said channel distal end, and where blood flowpath transitions between said needle interior surface and said channel interior surface are substantially continuous and smooth when said means for sealing is in said second position, and (iv) structure for joining said channel distal end to a catheter that extends to an internal vessel of the body, and wherein such joining is continuous and smooth along said interior surfaces of the channel and catheter

2 An access system as defined in claim 1 further comprising

(c) a catheter constructed and arranged for implantation between said device at a proximal catheter end and to or into a patient blood vessel at a distal catheter end, and

(d) means for attaching the catheter to the surrounding patient tissue, said attachment allowing movement of the catheter's proximal end and of said device

3 Apparatus as defined in claim 1 wherein said needle has a lumen and disposed along a first axis, said needle matingly corresponding to the inner surface and having a wall thickness of approximately 0 1 mm,

an obturator that is disposed within the needle along the first axis and matingly inserted into the lumen of said needle, said needle and obturator designed to provide an assembly with a pointed end constructed for opening said means for sealing, and

means defining an access channel external to the patient communicating with the lumen of said needle, when it is inserted into the patient and through said means for sealing and wherein said access channel is disposed at an acute angle from said needle first axis.