Indwelling catheter valve

Details Indwelling catheter valve Indwelling catheter valve

1999-01-29

2001-02-20

Chambers, A. Michael (Department: 3753)

Valves and valve actuation

With correlated flow path

Valve operated by joining flow path sections

C604S256000, C604S905000

Reexamination Certificate

active

06189859

ABSTRACT:

This invention relates to a valve. This invention relates particularly to a valve used in a catheter for administering fluid intravenously to a patient and for drawing body fluid from a patient. The invention also extends to a valve insert for use in the valve and a resilient element for use in the valve.
When medicament needs to be administered intravenously to a patient on a regular basis, it is a common medical procedure to insert an indwelling catheter into a blood vessel of a patient. This obviates the need to puncture the patient's skin each time medicament needs to be administered.
The indwelling catheter naturally includes a fitting or valve which stops the flow of blood out of a patient's blood vessel through the catheter while at the same time permitting intermittent access to the venous site for the purposes described above. Such fittings or valves are known in the art as intermittent caps.
Several known prior art intermittent caps suffer from the disadvantage that they have relatively large flow paths which are open to contamination and it is difficult to sterilise these flow paths each time medicament is administered.
Another known valve is disclosed in U.S. Pat. No. 5,065,783 granted to Ogle the entire contents of which are specifically incorporated herein by reference. Ogle discloses a valve housing having a cannula disposed therein and movable between open and closed positions. The cannula has opposed first and second sharp ends and first and second flexible elastomeric sleeves extending around respectively the first and second sharp ends. Each sleeve is attached to the cannula at a point intermediate the ends thereof and the closed end of the sleeve is free to move axially relative to the cannula. In the closed position each of the sleeves extend around respectively the first and second sharp ends of the cannula acting as a barrier to liquid flow therethrough. When a syringe nozzle is inserted into the valve housing, the first and second sleeves, are moved relative to the cannula to the open position where the sharp ends of the cannula pierce and penetrate the sleeves. This enables fluid to flow through the valve housing from the inlet to the outlet and also in a reverse direction from the outlet to the inlet.
However a shortcoming of this valve is that it only provides limited resistance to unwanted reverse or back flow through the valve when there is no syringe nozzle inserted in the valve housing. Fluid pressure in the reverse direction may force the sharp end of the cannula on the patient side ie proximate the outlet to pierce the adjacent sleeve and possibly open the cannula to fluid flow. It would obviously be advantageous if a valve could be provided which had substantially increased resistance to back or reverse flow.
In this specification the term cannula shall be given a broad meaning and shall be interpreted to include members of the same general type as the cannula described in the Ogle patent above. It shall not be limited to a tube fitted with a trocar for insertion into the body.
While it is convenient in this specification to refer to the inlet and outlet of the housing and the inlet and outlet of the cannula, it is to be clearly understood that the valve can be used to pass fluids therethrough in both directions. In essence the function of the valve is to provide a closure for the catheter flow path which flowpath can be opened as and when required by the insertion of a syringe nozzle into the housing. Such syringe can then be used to inject medicament into a patient or to withdraw a body fluid sample, eg blood sample from the patient. Injected medicament passes through the valve in a forward direction from inlet to outlet whereas a blood sample flows in a reverse direction through the valve.
It is an object of this invention to provide a valve which is suitable for use in an indwelling catheter and also which resists unwanted fluid flow in a reverse direction when subjected to back pressure.
According to a first aspect of this invention there is provided a valve housing having an inlet and an outlet and defining a passage from said inlet to said outlet;
an elongate cannula within the passage of the housing having an inlet towards one end thereof and an outlet towards an opposed end thereof, and defining a flow path from said inlet to said outlet;
a seal comprising a body defining an opening through which the outlet end of the cannula is passed, said body sealingly engaging each of the cannula and the housing, and said cannula being displaceable relative to said seal between a closed position in which the cannula outlet is upstream of said seal and an open position in which the cannula outlet is downstream of said seal placing the cannula outlet in fluid communication with the housing outlet; and
biasing means biasing the cannula to the closed position.
Typically the body of the seal is of resilient material and said resilient material urges radially inwardly against the cannula which is passed through said opening in the seal.
Preferably the biasing means comprises a sleeve of resilient material extending around the cannula, one end of which is attached to an intermediate point on the cannula and the other end of which urges against the seal, said sleeve being loaded under compression in a longitudinal direction.
Advantageously said seal and said sleeve are formed by an integral body of resilient material, eg a single unitary body.
Further advantageously the outlet end of the cannula is rounded to ease its sliding displacement in the passage and said outlet is spaced axially inwardly of the outlet end of the cannula.
Typically said seal has one surface in sealing engagement with the cannula, and a further surface in sealing engagement with the housing.
Advantageously said one surface extends substantially in the longitudinal direction of the cannula and said further surface extends transversely to said one surface.
Typically said housing defines a seat extending transversely to the longitudinal axis of the housing and said further surface sealingly engages said seat.
Advantageously said seat includes a projection projecting outwardly proud of the remainder of the seat, to enhance the sealing of the seal to the housing.
In a preferred form said projection tapers inwardly in a direction axially outwardly away from the seat to a sharp point and said projection extends circumferentially around the cannula. In a preferred form the projection forms a substantially annular knife-edge seal.
Typically the valve includes a further sleeve of resilient material having a closed end and an opposed open end, said closed end extending circumferentially around the inlet end of the cannula and said open end being attached to a further intermediate point on the cannula.
Preferably the inlet end of the cannula is sharp to enable the end to penetrate the closed end of the further sleeve.
Advantageously said one and further sleeves are made of elastomeric material. Further advantageously each of said one and further sleeves has a plurality of circumferentially extending zones of increased thickness located at spaced intervals along the length of the sleeve.
Preferably the valve also includes means for guiding axial displacement of the cannula relative to the housing between said open and closed positions. Preferably said guide means includes at least one guide formation on the cannula received within a complementary internal guide formation defined by the housing.
In a preferred form said guide formation comprises a radially outwardly projecting flange-like formation disposed intermediate the ends of the cannula, and said complementary internal guide formation is defined by a complementary configuration of a longitudinal section of the passage of the housing.
Advantageously the housing further includes stop formations for defining respectively said open and closed positions of the cannula and for limiting movement of the cannula to movement between said open and closed positions. In a preferred form said stop formations engage the radially outwardly pro

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