JPS631061B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for controlling fluid flow from a fluid source to a patient. More particularly, the present invention relates to devices for delivering precise amounts of fluid from a fluid source to a patient over an extended period of time at a preselected flow rate.

As human knowledge advances, medical procedures have become increasingly complex. For example, it has become increasingly clear to medical professionals that patients need to receive precise amounts of fluid into their venous flow over time at preselected flow rates. When a patient receives fluid at a reduced flow rate, their ability to recover is hampered. However, when a patient receives fluid at a greater than preselected flow rate, they often become poisoned by the drug in the fluid.

Devices have recently been provided that allow controlled amounts of fluid to be introduced into a patient at selected flow rates. for example,
This type of device was introduced in October 1976 as an “IV pump”.
No. 3,985,133 issued to Jon J. Jenkins et al. and assigned to the assignee of this application. One cassette is included in this device. The cassette includes a chamber having a generally constant cross section and a piston reciprocatable in both directions within the chamber. The displacement and flow rate of the piston is precisely controlled by the device to introduce fluid into the patient at a predetermined rate.

In the device disclosed and claimed in US Pat. No. 3,985,133, the piston includes a pair of lands and a recess therebetween. A lubricating fluid is stored in the recess and lubricates the piston as it reciprocates. Lubricating the piston often ensures a sustained and efficient reciprocating motion of the piston. However, the recess can sometimes dry out after some reciprocation of the piston. This sometimes causes the piston to become stuck within the chamber. This sticking is exacerbated by expansion of the lands as a result of heat generation as they move within the chamber without lubricant. This blocks the pump and prevents venous fluid from being properly transferred to the patient.

The present invention improves the cassette-type infusion device that ensures proper transfer of intravenous fluid to the patient. The invention includes a chamber having a generally constant cross section;
It also includes a piston that reciprocates in a specific direction within the chamber. The piston may be made of a resilient material and may include a pair of lands spaced from each other in a particular direction. The chamber, together with the lands and the piston, defines a recess in the space between the lands. A lubricating fluid is placed in this recess to perform a lubricating action.

A device for reciprocating the piston within the chamber is operatively associated with the piston. Fluid, such as intravenous fluid, enters the chamber during one reciprocation of the piston device and exits the chamber during another reciprocation of the piston device. One of the lands is positioned adjacent to the venous fluid stored in the chamber, and the other land is isolated from the venous fluid stored in the chamber. A device providing an auxiliary reservoir of lubricating fluid is movable with the piston and is positioned in adjacent relationship with one of the lands. Such an auxiliary reservoir may be adjacent to a land isolated from the fluid within the chamber. Such devices are porous and the lubricating fluid may be located within the pores. The auxiliary reservoir device is flexible and has an outer diameter larger than the outer diameter of the land to facilitate wiping action between the device and the chamber. The auxiliary reservoir may be in the form of relatively thin porous packing made of a suitable material such as polyurethane.

In one embodiment of the invention, a total of 10
The cassette-type infusion device shown generally is adapted for use with a positive displacement pump shown at 12. Positive displacement pump 12 is disclosed in U.S. Patent No. 3985133 to Jon J. Jenkins et al.
The structure may be similar to the pump disclosed and claimed in the US Pat. However, it will be appreciated that other pumps may be used, and in fact any device capable of delivering fluid from a fluid source to a patient may be used. It will also be appreciated that cassette-type injectors other than the cassette-type injector disclosed and claimed in U.S. Pat. No. 3,985,133 may be used.

The cassette-type infusion device 10 is disposable. Thus, after being used to deliver fluid from a fluid source to a patient, the cassette can be discarded and replaced with another cassette-type infusion device. This eliminates the need to disinfect the cassette infusion device after use. Additionally, the cassette infusion device is operatively positioned relative to the pump such that fluid passes only through the cassette infusion device and not through the pump. This allows the pump to be replaced with another cassette injector without the need to disinfect the pump.

Cassette infusion device 10 includes a chamber 14 made of a suitable material, preferably transparent, such as glass or plastic. The chamber has a generally constant cross-sectional area along its length and is preferably cylindrical. A conduit 16 is provided at one end of the pump. Conduit 16 has a pair of conduits 18 at one end.
and 20 branches. Conduit 18 is a fluid source 22
The conduit 20 extends from the patient 24 to the patient 24 .
The conduit includes a rotatable two-position valve 26 which in one position operates to direct venous fluid from the fluid source 22 to the chamber and in a second position operates to direct fluid from the chamber 14 to the patient. Works to send to. Valve 26 is operated by pump 12.

Plunger 30 is disposed within chamber 14;
It is movable axially within the chamber. Plunger 30 includes a detent 32, which in combination with a corresponding detent on the pump provides reciprocating movement of plunger 30 by the pump. A piston 34 is located at the end of plunger 30 adjacent conduit 16 and may be made of a suitably resilient material such as butyl rubber. The piston 34 has a pair of axially spaced lands 36 and 38 which, together with the chamber 14, form a recess 4.
0. A suitable lubricating oil 42, such as silicone oil, may be placed in the recess. The silicone oil 42 may be of the Dow 360 type and has a volume within the recess 40 of approximately 25 to 150 microliters.

A packing 46 made of a suitable flexible material such as polyurethane foam is positioned adjacent the land 38 against the collar 48 of the plunger 30. The packing 46 is porous and its pores are filled with a lubricating fluid 50 that preferably corresponds to the lubricating fluid 42. The packing 4
6 has an outer diameter larger than the outer diameter of lands 36 and 38, so that the packing
During the zero reciprocating movement, the surface of the chamber 14 will be wiped. In effect, the packing 46 serves as an auxiliary reservoir for lubricating fluid.

Positive displacement pump 10 includes a step motor (not shown) that operates to advance piston 34 intermittently at regular intervals. During movement of the piston away from conduit 16, a vacuum is created in chamber 14 and venous fluid flows into the chamber from fluid source 22. During movement of the piston toward conduit 16, venous fluid is transferred from chamber 14 to the patient.

While the piston 34 advances toward the conduit, the land 36 is lubricated by the fluid 42 within the recess 40 and the fluid into the vein within the chamber. However, the lands 36 tend to wipe the walls of the chamber 14 and remove lubricant during movement of the piston 34 toward the conduit 16. Land 38 is also lubricated by fluid within recess 40 during similar movement of piston 34.

While piston 34 moves away from conduit 16,
Land 38 is at the leading end of the piston. Land 38 tends to be lubricated by fluid 42 within recess 40 during this movement of the piston. land 3
6 also tends to be lubricated by the fluid 42 in the recess 40 during this movement of the piston.

As can be seen from the above description, lands 36 and 38 tend to be lubricated by fluid 42 within recess 40 during reciprocating movement of piston 34. Although there is only a certain amount of fluid 42 within recess 40, this amount is sufficient to lubricate lands 36 and 38 in most cases even for the maximum period of time that a cassette 12 injector can be used before being discarded. has been found to be sufficient to maintain the

Sometimes the fluid 42 in the recess 40 is emptied before use of the cassette injector is completed. This is a problem. For example, during movement of piston 34 toward conduit 16, fluid into the vein within chamber 14 tends to lubricate land 36. However, land 36 attempts to wipe away this fluid. This wiping action is completed by land 38 which is separated from land 36 by a drying area. As a result, land 38 is not lubricated during movement away from conduit 16. This is Land 38
tends to stick to the chamber 14 during movement away from the conduit. This sticking tends to be exacerbated by expansion of the land 38 relative to the piston as a result of heat generation from the land 38 moving along the chamber without lubrication. As a result, the pump becomes blocked.

Packing 46 helps extend the reciprocating life of piston 34. It moves between lands 36 and 38 during piston movement away from conduit 16.
It precedes this movement and acts to wipe the chamber 14 during this movement. This brushing action lubricates chamber 14 prior to movement of lands 36 and 38 and prevents land 38 from sticking to the chamber. The flexibility of the packing 46 and the oversized construction of the packing facilitate lubrication of the packing. Thus, the operational life of the cassette infusion device 12 is considerably extended. Indeed, by including packing 46 as an auxiliary reservoir for lubricating fluid, the amount of fluid in recess 40 can be reduced and the operational life of cassette infusion device 12 can be further maintained to the desired limit. .

Although this application has described and illustrated specific embodiments,
It will be obvious to those skilled in the art that the principles involved are capable of many other embodiments. Accordingly, the invention is limited only by the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a schematic exploded perspective view of a pump and a cassette-type infusion device that cooperates with the pump to introduce fluid into a patient; FIG. 2 is an enlarged cross-sectional view of the cassette-type infusion device shown in FIG. 1; FIG. 3 is a further enlarged sectional view of the piston included in the cassette-type infusion device. In the figure, 10...cassette type infusion device, 12
...Displacement pump, 14...Chamber, 26...
Two-position valve, 36, 38...land, 40...recess, 46...packing.

Claims (1)

Claims: 1. A vertically placed cassette infusion device for controlling fluid flow between a fluid source and a patient, comprising: a chamber having walls of generally constant cross-sectional area; , movable in the vertical direction,
a plunger member that receives fluid into the chamber when moved downwardly and transfers fluid from the chamber when moved upwardly; a piston device disposed at one end of the plunger member that connects a recessed wall with the wall; a piston device having a land at the lower end that engages the chamber during reciprocating movement of the plunger member, the piston device having a lubricating fluid in the space between the recessed wall and the wall of the chamber; A porous packing member is supported by the plunger member below the land at a position slightly away from the bottom of the land, and a lubricating fluid is present in the many holes, so that when the packing member moves upward, a porous packing member is supported by the plunger member. and a packing member adapted to allow lubricating fluid to flow between the recessed wall and the wall of the chamber. 2. In the cassette-type infusion device according to claim 1, the porous packing member has an outer dimension larger than the land of the piston device, and has a property of deflecting during reciprocating movement of the plunger member. An infusion device characterized by: 3. The cassette-type infusion device according to claim 2, wherein the packing member is made of porous polyurethane and the lubricating fluid is silicone oil. 4. The cassette-type infusion device according to claim 3, wherein the piston device is made of butyl rubber.