GB2344858A

GB2344858A - Medical liquid hose pump transfer system

Info

Publication number: GB2344858A
Application number: GB9924531A
Authority: GB
Inventors: Juergen Steger; Hans Gerlach
Original assignee: B Braun Melsungen AG
Current assignee: B Braun Melsungen AG
Priority date: 1998-10-17
Filing date: 1999-10-15
Publication date: 2000-06-21
Also published as: ES2156092A1; DE29818577U1; FR2784586A1; JP2000120549A; BR9904731A; ES2156092B1; GB9924531D0

Abstract

An integral portion of a transfer hose 10 is formed as a pump hose 16 having a concertina-like moulded bellows portion 18 defining a chamber 40, either side of which two squeezing portions 34,35 are moved axially relative to each other. The pump hose 16 is inserted into a hose pump 17 having a blocking element V1 provided on a fixed holder 19, and a blocking element V2 on a holder 20 which is movable in the longitudinal direction 21 of the hose 16. The blocking elements V1,V2 are controlled 22 to act as one-way valves by alternately pinching or clamping the squeezing portions 34,35 of the hose 16 whilst the bellows portion 18 is axially extended and contracted between the holders 19,20, enabling a precise volume of fluid to be dispensed during each cycle.

Description

2344858

Title of the invention

A medical liquid transfer system Background of the invention

The present invention refers to a medical liquid transfer system comprising a transfer hose and a hose pump for conveying liquid.

In the field of medicine, liquid transfer systems are employed that include a hose pump or a diaphragm pump. In a hose pump, designed as a peristaltic roller pump or a finger pump, the hose is continually squeezed radially, whereby the liquid in the pump hose is advanced. It is an advantage that the medium to be pumped is exclusively in contact with the pump hose and not with other functional parts of the pump. Therefore, the risk of contamination is low. However, it is disadvantageous that the precision of delivery of such pumps depends substantially on the dimensional accuracy and the operational behavior of the pump hose and that it is variable over time. This results in a comparatively poor precision of delivery of such hose pumps. Moreover, this type of hose pumps is generally not self-priming.

In hose pumps, the pump hose typically is a disposable article discarded after a single use. Not only must the pump hose be placed in the pump, it must also be coupled to connecting hoses, which is disadvantageous because of the time required and the risk of confusion. The flexing movement stresses the hose material to such an extent that special pump hoses, e.g. of silicone, have to be used at the pump to allow for a long service life. On the one hand such special hose elements are expensive, and, on the other hand, they require an additional 2 mounting effort. A flirther disadvantage of known hose pumps lies with the high energy loss due to the flexing movement.

From US 5,718,687, an axially acting hose pump is known comprising a highly elastic pump hose that is axially expanded and squeezed again- At its inlet and at its outlet, the pump hose includes an integrated check valve. Such a pump hose is expensive because of the check valves and the hose fittings, which makes it rather unsuitable for use as a one-way article.

It is an object of the present invention to provide a medical liquid transfer system that acts gently on the medium to pump and is provided with an inexpensive pump hose that may be used as a one-way article.

Summary of the invention

In the present liquid transfer system, the hose pump is an axial pump, wherein two axially spaced portions of the pump hose are moved axially relative to each other. Thereby, the medium to be pumped is displaced in the longitudinal direction of the pump hose and is not squeezed. The volume of the hose is proportional to the stroke of the pump so that the hose pump operates with a high volumetric precision; the precision equals that of a syringe pump. The periodic stretching and stuffing of the hose returns the same exactly to its initial position, prior to each pump stroke. Thus, it is made sure that each pump stroke starts under the same conditions and that no drift of a restoring force occurs. By pushing and pulling the hose exclusively in the axial direction, only little energy is transformed into flexing work. A high percentage of the movement energy is used to convey the medium. Thus the efficiency of the hose pump is high so that i 3 the hose pump is suitable in particular for battery-powered apparatus. The pump hose contains no valves so that it may be produced economically as a one-way article. The valve function is fulfilled by controlled blocking elements that are parts of the hose pump (not the pump hose). This blocking elements are controlled synchronously to the pumping action.

It is another advantage that the hose pump is self-priming. This means that, due to the forced control of the pump volume, the pump is able to draw liquid from a lower to a higher level without requiring a stagnant liquid column. Therefore, the hose pump may be used to draw liquid from a liquid container standing on the floor and to infuse it into a patient.

In a preferred embodiment of the invention, the pump hose comprises an integral portion of the transfer hose, the transfer hose extending from a liquid container, a syringe coupling or a transfer device to a patientside hose coupling. Since there are no particular requirements regarding the mechanical strength of the pump hose, it is possible to realize the pump hose as an integral portion of the overall transfer hose. This means that a transfer hose of 1-2 rn in length has a portion along part of that length that is deformed so as to form the pump hose. This deformation may be a bellows portion or- defined squeezing.portions-. In this portion, wall thickness of the pump hose is reduced by annular expansion so as to achieve the required deformation behavior. Thus, it becomes possible to use a single hose as a transfer hose in the form of a disposable article so that hose couplings and, in particular, the assembling effort required for connecting hose portions can be omitted. Due to the low requirements on the pump hose, the entire transfer hose may be made from a relatively simple and inexpensive material, for example, from PVC. An integral portion of the transfer hose may 4 also be a portion that is made from another material as the remainder of the transfer hose and that is fixedly and permanently connected therewith, e.g. by glueing.

Preferably, a common drive means is provided for the axial movements of the pump hose and the blocking elements. This drive means may be an electric motor. When the axial drive for the pumping movement is a crank drive, the pumping movement is a sinusoidal movement. The switching of the blocking elements is effected at the return point of the axial movement at which the motor does not have to provide any pumping energy. Therefore, the motor may be designed with relatively low power, since the energy consumption of the pumping movement and the energy consumption of the blocking elements occur alternately.

Generally, the present liquid transfer system is suitable for any kind of infusion or transfusion. For example, medical infusion solutions, medication or blood may be pumped. Since the medium is not squeezed but displace, the pump is particularly suitable for blood which is not affected by the pump drive.

The invention ftirther provides the possibility to form a bag to the transfer hose so that the transfer hose and the bag are integral. Due to the ability of the hose pump to selectively convey in either direction, the hose pump may be used to fill the bag by drawing the contents of a supply container into the bag and to subsequently convey the liquid from the bag to the patient.

The hose pump is a volumetric pump with a high suction force. This pump can be used to draw the contents of a pump and to either convey it into another container or to supply it directly to a patient.

The invention further refers to a transfer hose for a medical liquid transfer system, the transfer hose comprising an integrated pump hose having a bellows portion and a respective squeezing portion on either side thereof The material thickness is reduced in the squeezed portions.

The transfer hose of the present invention may be produced by locally heating a hose of a constant cross section over its entire length and by then deforming the hose in the heated portion. This deformation may be effected by means of an exterior mold pressed against the hose wall while generating pneumatic pressure inside the hose. In this manner, the bellows portions and the squeezing portions may be made by blow molding.

Brief description of the drawings

The following is a description of embodiments of the present invention taken in con unction with the drawings.

j In the Figures:

Fig. I is a view of a transfer hose with an integrated pump hose, Figs. la and lb are modified embodiments of the proximal end of the transfer hose, 6 Fig. 2 is a lateral view of the hose pump, Fig. 3 is a front view of the cam drive.

partly in section, Fig. 4 illustrates a top plan view on the hose pump, Fig. 5 is an enlarged representation of the detail V of Fig. 3, Fig. 6 is a longitudinal section through the pump hose, and Fig. 7 shows an embodiment with two fixed holders.

Detailed description of the preferred embodiments

Fig. I is a schematic representation of a liquid transfer system. It comprises a transfer hose 10 that is continuously made from a uniform material and has a generally constant cross section. The distal end of the transfer hose 10 is provided with a hose coupling 11 in the form of a Luer lock connector closed by a closure cap 12 threaded thereon. The hose coupling may be connected to a catheter, a cannula or another instrument leading into a patient's body.

The proximal end of the transfer hose 10 is provided with a drip chamber 13 having a puncturing thorn 14 which, in the present case, is enclosed by a removable protective cap 15. The piercing thorn 15 may be used to pierce the elastomer stopper of a bottle so as to let the contents of the bottle flow out. Together with the hose coupling 11 and the drip chamber 13 with the piercing thorn 14, 7 the transfer hose 10 forms an integral liquid transfer system designed as a oneway unit for disposal after use.

Along the transfer hose 10, a portion thereof is formed as a pump hose 16 which is inserted into a hose pump 17 so that becomes part of this hose pump. The pump hose 16 is an integral part of the transfer hose 10, hence, it is made of the same material as the other portions of the transfer hose. As will be described below, this material is deformed to form the pump hose 16. The pump hose may be a hose portion glued into the transfer hose 10. It is a fixed and permanent part of the transfer hose.

The pump hose 16 has a bellows portion 18 of alternating portions of larger and smaller diameter, forming a concertina-like structure. -On both sides of the bellows portion 18, controlled blocking elements VI und V2 engage the pump hose. These blocking elements are valves or squeezing elements that can squeeze the pump hose and shut it at this location. Moreover, the blocking elements fix the hose in the longitudinal direction. The blocking element V I is provided at a fixed holder 19 that is mounted stationarily on the hose pump 16. The movable holder 20 may be moved under control along the longitudinal direction of the pump hose 16 as indicated by the arrow 2 1.

When the holder 20 is moved away from the holder 19, the blocking element V I is closed and the blocking element V2 is open. Thus, liquid flows into the pump hose 16 from the inlet side 10a of the transfer hose. At the end of the traveling movement of the holder, the blocking element V2 is closed and the blocking element V1 is opened. Then, the pumping stroke is performed, the holder 20 being moved towards the holder 19. Here, the contents of the pump hose 16 is 8 transferred into the outlet portion 1 Ob of the transfer hose 10. At the end of this movement, the blocking element V I is closed again and the blocking element V2 is opened. Such, a precisely defined liquid volume is conveyed with each pump stroke. The blocking elements V1 and V2 are controlled by a common control means 22 synchronously, with the movement of the holder 20.

Referring now to Figs. 2-5, the hose pump 17 comprises a guide track consisting of two parallel rails 23, 24. On the one hand, the fixed holder 19 is mounted at a fixed position along this guide track, while, on the other hand, the movable holder 20 may be displaced along the same. The movable holder 20 is displaced longitudinally by a crank drive 25 comprising a crank disc 26 and a connecting rod 27 eccentrically engaging the crank disc and being connected with the holder 20. Upon rotation of the crank disc 26, the holder 20 is displaced linearly first towards the holder 19 and then in the opposite direction, the linear movement of the holder 20 being a sinusoidal movement over time. The one end of the pump hose 16 is fixed to the holder 19, while the other end of the pump hose 16 is fixed to the holder 20. Again, the pump hose 16 is a part of the transfer hose. The bellows portion 18 is located between the holders 19 and 20.

A control shaft 28 extends in parallel to the guide rails 23, 24. The control shaft 28 is designed as a splined shaft with a longitudinally extending cross-shaped profile and through which the holders 19 and 20 pass. Seated on the crossshaped profile is a longitudinally displaceable cam disc 29 that is a part of the holder 20. A corresponding cam disc 29 is also provided in the holder 19.

i 9 The connecting rod drive 25 is driven by a motor 32 through a gearing 33. Through a gearing 3 1, the motor 32 also drives the control shaft 28 for the blocking elements V1 and V2.

The control means comprises microprocessor control electronics causing a linearization of the volume/stroke characteristics of the pump system by transforming the sinusoidal movement of the holder 20 into a movement that provides a delivery rate that is substantially constant over time. This is achieved by driving the motor 32, designed as a step motor, according to a table in a ROM that linearizes the sinusoidal movement.

The pump hose 16 has two squeezing portions 34, 35 on which the blocking elements VI, V2 act. The squeezing elements 34, 35 are inserted into the holders 19, 20, which are subsequently closed so that the ends of the pump hose 16 or of the pump portion forming the pump hose are fixed to the respective holder 19 or 20.

Figs. 3 and 5 illustrate the control of the blocking element V I by means of the cam disc 29 driven by the control shaft 28. The circumference of the cam disc 29 is engaged by a cam follower 36 pressed against the cam disc 28 by a spring 37. The cam follower 36 comprises a slide 38 displaceable transverse to the pump hose 16. The circumferential surface of the cam disc 29 has a cam structure moving the slide 39 between a closed position and an open position.

Assume, the conveying direction in Fig. 2 is from left to right. In this case, the blocking element V I opens and the blocking element V2 is closed if the holder 20 is approximate the holder 19. This state prevails as the holder 20 is shifted to the right and the pumping chamber 40 within the pump hose 16 is filled up with liquid. Upon reaching the extreme right position of the holder 20, the blocking element V1 is closed and the blocking element V2 opens. As the holder 20 subsequently approaches the holder 19, the liquid is expelled from the pumping chamber 40 in the conveying direction.

With every stroke of the pump, an exactly defined volume is conveyed. Due to the continuous circumferential ribs, the bellows portion has a great dimensional stability so that it is not susceptible to collapsing. Therefore, the pump may also be used to aspire.

Fig. 6 illustrates the pump hose 16 separately. The drawing shows the bellows portion 18 formed by sinusoidally extending circumferential corrugations of the hose wall. The two squeezing portions 34 and 3 5 are arranged at a short distance from the bellows portion 18. In these squeezing portions, the hose diameter is enlarged, whereby the wall thickness is reduced. The wall thickness is also reduced in the bellows portion 18 because of the increase in the hose length. As an alternative to the embodiment illustrated, the squeezing portions may also be flattened.

In the embodiment of Fig. 6, the pump hose 16 also is an integral part of the transfer hose 10. The pump hose is shaped by plasticizing the material of the transfer hose 10 by local heating. In an exterior mold, having the intended contour of the pump hose 16 as its inner contour, the hose is inflated or pressurized from inside so that the outer wall abuts the mold and, simultaneously, the above mentioned reduced wall thickness is achieved. Thereafter, the hose shape thus obtained is solidified by cooling. The hose needs no cutting. The pumping 11 portion of the transfer hose 10 thus produced only has to be inserted into the hose pump 17. No mounting is required.

In the embodiment of Fig. I a, the drip chamber of Fig. 1 has been replaced by a syringe coupling 41 in the shape of a Luer lock connector joined to the transfer hose 10. This syringe coupling serves to connect the system to a syringe filled with the liquid to be pumped. In this manner, an infusion, for example, may be made from a syringe (as in a conventional syringe pump), by withdrawing the liquid from the syringe using the hose pump 17 and transferring it to the patient.

Another possibility is illustrated in Fig. lb. Here, the liquid container is a bag 42 fixedly connected with the transfer hose 10 and preferably formed integrally therewith. This bag 42 may contain the liquid to be pumped. Yet, it is also possible to initially have an empty bag that is filled by operating the hose pump in the reverse mode. When the bag is filled, it may be emptied in the forward mode.

In the embodiment of Fig. 7, a pump hose 16 with -a bellows portion 18 is arranged between a fixed holder 19 and a linearly displaceable holder 20. To prevent the movement of the holder 20 from causing any movement of the supply hose outside the pump, a second bellows 44 is connected to the inlet of the holder 20, which is fixedly connected with a fixed holder 45 to which the external supply hose is connected. The holder 45 includes no valve. The bellows 44 forms a length compensating conduit. A hose loop may be used instead of the bellows. The holders 19 and 20 correspond to those of the first embodiment. They each include a controlled squeezing valve.

Claims

What is claimed is:

1 - A medical liquid transfer system comprising at least one transfer hose (10) and a hose pump (17), the hose pump (17) being arranged as an axial pump axially moving two spaced apart portions of a pump hose (16) relative to each other, wherein the hose pump (17) includes controlled blocking elements (V 1, V2) that alternately squeeze squeezing portions (34, 35) of the pump hose (16).

2. The liquid transfer system of claim 1, characterized in that the pump hose (16) is an integral portion of the transfer hose ( 10), the transfer hose ( 10) extending from a liquid container, a syringe coupling or a transfer device (13, 14) to a distal hose coupling (11).

3. The liquid transfer system of claim 1 or 2, characterized in that the pump hose (16) has a bellows portion (18).

4. The liquid transfer system of one of claims 1-3, characterized in that the hose pump (17) comprises a fixed holder (19) and a holder (20) periodically movable relative to the former, and that both holders (19, 20) comprise controlled blocking elements (V 1, V2) for squeezing a squeezing region (34, 3 5) of the pump hose (16).

5. The liquid transfer system of one of claims 1-4, characterized in that a common drive is provided for the axial movements of the pump hose (16) and the blocking elements (13, 14).

i

6. The liquid transfer system of one of claims 1-5, characterized in that the transfer hose (10) has an integrally formed bag (42) as the liquid container.

7. The liquid transfer system of one of claims 1-6, characterized by a compensating conduit (44) connected at one end with a movable holder (20) of the hose pump (17) and with a fixed holder (45) at the other end.

8. A transfer hose for a medical liquid system of claims 1-7, comprising an integrated pump hose (16) with a bellows portion (18) and a respective squeezing portion (34, 35) on either side thereof