Fluid pump with disposable component

A pump having a disposable fluid contacting portion which defines a fluid inlet and outlet and a fluid path there between. The pump includes a drive portion configured to engage the disposable portion to cause fluid to be moved from the fluid inlet to the fluid outlet. The disposable portion is configured to be selectively coupled to the drive portion. The disposable portion includes a driven membrane which forms a portion of the fluid path, and the drive portion includes a drive membrane. The two membranes are vacuum coupled to each other, whereby movement of the drive membrane causes the driven membrane to move, causing fluid to be pumped through the disposable portion. The pump has particular utility in the medical field for moving fluid from a source to a patient. The pump may include features such as an air-trap, bubble detection, fluid flow controls, and pressure detection.

FIELD OF THE INVENTION

The present invention relates to fluid pumps, especially to medication delivery pumps.

BACKGROUND OF THE INVENTION

A wide variety of medication delivery pumps are known. In general, these pumps are configured to deliver a fluid from a source to a patient under pressure.

In order for the pump to be re-usable, at least the portion of the pump which contacts the fluid must be sterilizable. This is difficult for integral pumps where the pumping mechanism and fluid path are part of a single unit. For this reason, pumps have been developed with have a re-usable pumping unit which cooperates with a fluid path element. In this manner, the fluid path element can be separated from the pumping unit for sterilization and reuse.

These reusable pumps, however, suffer from a number of drawbacks. First, many designs are highly complex, resulting in high costs of manufacture and maintenance costs, and low reliability. In addition, the pumps generally suffer from one or more design issues which result in less than optimum performance. For example, it is desirable for the pump to include a flow sensor, and yet such a feature is often inconsistent with the design of the re-usable pump. Also, these pumps generally have undesirable compliance. “Compliance” is a measure of the volume per unit pressure change in region between intake and outlet of the pump. Many commercial pumps suffer significantly due to undesirable compliance resulting in either significant change to average and instantaneous flow when varying intake and output pressures are experienced.

For example, one re-usable pump design is represented by the IVAC 500 series (550, 570, 580, etc.) linear peristaltic pumps. These pumps use sequentially occluding fingers to peristaltically advance fluid by advancing an occlusion point from the intake end to the outlet end of a second of tubing. Compliance of the tubing governs the sensitivity of average flow to intake pressure. The average flow of these pumps is quite insensitive to output pressure. However, flow uniformity is degraded with increasing output pressure and pump segment compliance.

Other examples of re-usable pumps are the Alaris LVP Module and Asena GP pumps. These are dual chamber pumps using conventional cylindrical tubing together with two active pumping regions and two valves, one above the upper region and the second between the upper and lower pumping region. The net filling volume of the upper pump region defines the cyclic volume pumped and due to the elasticity of this region, variation of intake pressure affects the actual volume delivery. The lower pump region delivers fluid while the upper chamber is filling, resulting in smoothing of flow output. If elevated output pressure exists, when the lower occlude opens, fluid moves retrograde into the upper pump region. When the upper occluder opens, this excess volume moves back into the drip chamber, thus reducing net volume pumped and disturbing uniformity of flow. A second drawback of dual chamber pumps is the likelihood of air being entrained within the pumping chambers. When this occurs, not only is the compliance increased, but the net pumping volume is directly diminished.

SUMMARY OF THE INVENTION

One aspect of the invention is a fluid pump and a method of pumping or moving fluid.

One embodiment of a fluid pump comprises a drive unit and a driven unit. The drive unit comprises a housing, a drive or driving membrane and at least one drive device configured to move the driving membrane between at least a first and a second position. The driven unit is preferably configured as the fluid contacting portion of the pump, and thus comprises a disposable portion of the pump. The driven unit comprises a housing, a fluid path leading from a fluid inlet to a fluid outlet, and at least one driven membrane defining at least a portion of the fluid path.

The driven unit is configured to be selectively coupled to the drive unit so that the driven membrane is coupled to the driving membrane, whereby movement of the driving membrane effectuates movement of the driven membrane, causing fluid to be pumped through the driven unit from the fluid inlet to the fluid outlet. Preferably, the driving and driven membranes are vacuum coupled, such as by applying a vacuum source to a vacuum path or line extending to the interface of the membranes.

The drive unit includes a drive device configured to move the driving membrane. In one embodiment, the driving membrane forms a portion of a boundary of a variable volume fluid chamber. The drive device includes a piston or other member for changing the volume of the chamber. In another embodiment, the driving membrane is moved directly, such as a by one or more actuators.

The pump may include fluid flow controls, such as a fluid inlet and fluid outlet valve or control. The pump may also include such features as an air trap, bubble detector, pressure sensor(s), and fluid line connectors.

One embodiment of a method comprises providing a drive unit and disposable or driven unit and connecting the driven unit with the drive unit so that a driven membrane of the disposable unit is positioned adjacent a driving membrane of the drive unit. The method further comprises vacuum coupling the driven membrane to the driving membrane and moving the driving membrane, whereby the driven membrane is moved therewith, causing fluid to be pumped through the driven unit from a fluid inlet to a fluid outlet.

DETAILED DESCRIPTION OF THE INVENTION

In general, the invention comprises a fluid pump. The pump has particular utility to the medical field, such as for use in pumping medication from a source to a patient. In general, the pump has a first, disposable portion, and a second, drive portion. The disposable portion is preferably configured as the fluid contacting portion and defines a fluid inlet and outlet and a fluid path there between. The drive portion is configured to engage the disposable portion to cause fluid to be moved from the fluid inlet to the fluid outlet. The disposable portion is configured to be selectively coupled to the drive portion. In one embodiment, the disposable portion and the drive portion are vacuum coupled.

The invention will first be described with reference toFIGS. 1-3, which illustrate one embodiment of the invention in a conceptual or basic configuration. As illustrated inFIG. 1, a fluid pump20preferably comprises a driven unit or portion22and a drive unit or portion24. In a preferred embodiment, the driven portion22is configured to be disposable (i.e. used a limited number of times, such as once, in conjunction with the drive portion, and then discarded), and as such is referred to herein as a disposable unit or portion.

In one embodiment, the disposable portion22comprises a housing26which defines a fluid inlet28and a fluid outlet30. The drive portion24similarly comprises a housing32and at least one drive element34. In a preferred embodiment, the disposable portion22and drive portion24are configured to be vacuum coupled. As such, the drive portion24may include a vacuum pathway37.

InFIGS. 1-3, the housings26,32of the disposable portion22and drive portion24of the pump20are illustrated as being generally cylindrical in shape. As detailed herein, the disposable portion22and drive portion24may have a variety of configurations.

Referring toFIG. 2, in one embodiment, the disposable portion22has a top and a bottom. The bottom is configured to mate with a top of the drive portion24of the pump20. The disposable portion22and drive portion24could be configured to mate or connect in other manners or positions, such as in a side-by-side configuration or where the drive portion24is mounted on the disposable portion22.

A fluid pathway is defined from the fluid inlet28to the fluid outlet30of the disposable portion22. Preferably, this fluid pathway is defined by the housing26. In one embodiment, this fluid pathway comprises a pump chamber36, a fluid inlet pathway38leading from the fluid inlet28to the pump chamber36, and a fluid outlet pathway40leading from the pump chamber36to the fluid outlet30. In one embodiment, the fluid inlet and outlet pathways38,40are passages through the housing26.

As illustrated, the pump chamber36comprises a recessed area of the bottom of the housing26of the disposable portion26. In one embodiment, the recessed area is generally dome or hemi-spherical in shape (i.e. having a perimeter which is circular in shape, but varying in diameter along its depth). In addition, the pump20comprises a first or driven membrane42. In one embodiment, the driven membrane42spans or covers the recessed area of the disposable portion22, thus enclosing that portion to form the pump chamber36or otherwise forming at least a portion of the boundary of the pump chamber36. As detailed below, the driven membrane42preferably comprises a flexible and resilient member which is configured to move relative to the housing26of the disposable member22.

The drive element34of the drive portion24is preferably configured to selective move the driven membrane42relative to the housing26of the disposable portion22, thereby changing the volume of the pump chamber36. In this manner, as detailed below, fluid is pumped from the inlet28to the outlet30of the disposable portion22.

As detailed herein, the drive element34may comprise a wide variety of elements or mechanisms. As illustrated inFIG. 2, the drive element34comprises a drive or driving membrane46movable in response to movement of a piston44which is movably located in a portion of the housing32of the drive portion24of the pump20. In this configuration, the driving membrane46is fluid driven. In particular, the driving membrane46is associated with a variable volume fluid chamber48, and preferably comprises a boundary portion thereof. The piston44also defines at least a portion of the chamber48, and in that the piston44is moveable (such as between extended and retracted positions), the volume of the chamber48may be varied. Preferably, the driving membrane46is connected to the housing32of the drive portion24, such as by positioning a periphery of the driving membrane46between a top portion of the housing32and a retainer50selectively coupled to the housing32.

Fluid52is located between a top of the piston44and the driving membrane46. As detailed below, movement of the piston44causes the driving membrane46to move in and out (the range of movement may vary, such as depending upon desired flow rate, wherein the movement may be between convex, concave and/or neutral or flat positions relative to the housing), thus moving the driven membrane42of the disposable portion22of the pump20. As detailed below, one or more mechanisms may be provided for moving the piston44.

The driven membrane42and driving membrane46are configured to move with one another. In a preferred embodiment, the drive membrane46and driven membrane46are coupled to one another. Various means may be utilized for this purpose. Preferably, the means allows the disposable portion22of the pump20to be selectively connected to, and disconnected from (such as for connection of another disposable portion) the drive portion24of the pump.

In one embodiment, the driven membrane42and driving membrane46are vacuum coupled. As indicated, a vacuum pathway37is provided for this purpose. The vacuum pathway37preferably leads from a vacuum source to a region adjacent the drive membrane46(and the driven membrane42or the interface of the driven membrane42and driving membrane46when the disposable portion22is connected to the drive portion24of the pump20). As detailed below, a vacuum applied through the pathway37preferably vacuum couples the driven membrane42and driving membrane46.

A method of pumping in accordance with the invention will now be described with reference toFIGS. 3 and 4. In general, activation of the drive element34causes the volume of the pump chamber36to vary, thus causing fluid to be drawn into the fluid inlet28and expelled out the fluid outlet30. In use, a disposable portion22is mounted or connected to a drive portion24. A vacuum is then applied to vacuum couple the driven membrane42to the driving membrane46, such as by connecting the vacuum line37to a vacuum source.

Referring toFIG. 4, when the piston44is moved downwardly, the volume of the fluid chamber increases. This draws the driving membrane46, and thus the driven membrane42coupled thereto, downwardly. This increases the volume of the pump chamber36, causing fluid to be drawn through the fluid inlet28and along the fluid inlet pathway38to the pump chamber36.

As illustrated inFIG. 3, when the piston44is moved upwardly, the volume of the fluid chamber48decreases, causing the fluid pressure to increase, forcing the driving membrane46upwardly or outwardly. This causes the driven membrane42to move inwardly, thus reducing the volume of the pump chamber36. This causes fluid to be displaced from the pump chamber36through the fluid outlet pathway40to the fluid outlet30. In this regard, it is noted that while the pressure of the fluid in the pumping chamber48of the drive portion24of the pump increases (as a result of movement of the piston44reducing the volume of that chamber while the volume of fluid therein remains static), the fluid pressure in the actual fluid pump chamber36may or may not increase, although the volume of that chamber decreases thus causing fluid to be pumped through the pump (for example, the change in fluid pressure in the actual fluid pump chamber may negligible or low when the fluid outflow resistance is relatively low and the overall fluid flow rate through the pump is relatively high).

As detailed below, in one embodiment, means may be provided for selectively controlling the flow of fluid through the driven portion22of the pump. Preferably, this means is configured to prevent the back-flow of fluid from the pump chamber36to the fluid inlet28.

In operation, repeated cycling of the piston44effects pumping which causes a stream or flow of fluid through the pump20.

Another embodiment of the invention is illustrated inFIGS. 5 and 6. This embodiment pump120similarly comprises a first or disposable unit or portion122and a second or drive unit or portion124. As illustrated, in this embodiment, a housing126of the disposable portion122is generally hemispherical in shape, having a domed top surface and (except as detailed below) a generally flat bottom surface. A fluid inlet pathway138leads from a fluid inlet128in the top of the housing126to the bottom of the housing126. Likewise, a fluid outlet pathway140leads from the bottom of the housing126to a fluid outlet130at the top of the housing. In one embodiment, the fluid inlet128and fluid outlet130are located in the same plane, at opposing sides of the housing126.

Once again, a pump chamber136is defined at the bottom of the disposable portion122of the pump120. The pump chamber136is, as illustrated, a somewhat hemi-spherical chamber extending into the bottom of the housing126. A driven membrane142extends over the bottom of the housing126, thus cooperating with the housing126to generally enclose the pump chamber136.

The driven membrane142preferably comprises a flexible and yet resilient member. In one embodiment, as illustrated, the driven membrane142is approximately the same size as the bottom of the housing126of the disposable portion122of the pump120. The driven membrane142may thus be generally circular in shape. The membrane142may be secured to the housing126by a lock ring156. Preferably, the lock ring156is generally ring-shaped, having a central opening158corresponding to the fluid chamber136. The lock ring156preferably engages the housing126such that at least a portion of the periphery of the driven membrane142is positioned there between.

The drive portion124of the pump120again comprises a housing132and a drive element134. In one embodiment, the housing132is generally cylindrical in shape, having a cylindrical outer wall with a top and a bottom. The drive element134comprises a drive or driving membrane146. Means are provided for moving the driving membrane146. In one embodiment, this comprises a piston144and fluid150. In the embodiment illustrated, a piston144is configured to move up and down relative to the housing132of the drive portion124, such as within a chamber defined in an interior area thereof. A variable volume fluid chamber is defined by the housing132, the drive membrane146, and a bellows160and associated mount.

As illustrated, the bellows160is located between a top mount162aand a bottom mount162b, the bottom mount162bbeing connected to or otherwise configured to move with the piston144. In one embodiment, the bottom mount162bmight simply comprise the head of the piston144and the top mount162amight comprise a portion of the housing132. The bellows160comprises an accordion-like expandable and contractable member, whereby expansion and contraction of the bellows160via movement of the piston144causes the volume of the fluid chamber to change (thus changing the pressure of the fluid therein and the location of the driving membrane146).

The pump120is configured so that the driving membrane146engages the driven membrane142. In the embodiment illustrated, where the driven membrane142is inset from the bottom of the lock ring156, the driving membrane146may be located outwardly of the top of the housing132of the drive portion124. As illustrated, the housing132includes a flange or mount164which extends upwardly from the remainder of the top portion of the housing132. The driving membrane146extends across this mount164. Preferably, the mount164is sized to fit within the opening158of the lock ring156so that: (1) a seal is defined between the mount164and lock ring156; and (2) the driving membrane146and driven membrane142engage one another.

As indicated above, means are preferably provided for selectively coupling the driving and driven membranes so that they move with one another, and yet which allows the disposable portion122of the pump120to be removed from the drive portion124in a manner allowing the drive portion124to be re-used with another disposable portion122. In one embodiment, this means comprises a vacuum seal created by a vacuum device or source (not shown) via a vacuum line137. The vacuum line137leads from the vacuum device or source to an interface between the driven membrane142and the driving membrane146. As illustrated, the vacuum line137extends through the lock ring156(such as comprising a passage formed therein), and leading to the opening158therein. The vacuum line137may terminate at a sloping or recessed portion of the lock ring158at a point below the driven membrane142. As detailed below, this permits air to be drawn from the space between the driving membrane146and driven membrane142, thus vacuum coupling the two membranes to one another.

Preferably, the pump120is configured to control the flow of fluid between the fluid inlet pathway138and the fluid chamber136, and the fluid chamber136and the fluid outlet pathway140. In particular, it is desired that the pump120be configured so that when fluid is drawn into the fluid chamber136, it is drawn through the fluid inlet pathway138, and not backwardly through the fluid outlet pathway140. Likewise, when fluid is pumped out of the fluid chamber136, it is preferably delivered through the fluid outlet pathway140, and not back to the fluid inlet through the fluid inlet pathway138.

In one embodiment, one or more valves or other fluid flow controls are provided for this purpose. As illustrated inFIG. 5, the pump120includes a fluid inlet valve or control and a fluid outlet valve or control. In a preferred embodiment, the inlet and outlet valves take advantage of the driven membrane142, and in particular, cause utilize the membrane142to selectively open and close fluid paths leading to and from the fluid chamber136. In the embodiment illustrated, a portion of the driven membrane142can selectively be moved so as to open or close the end of the fluid intake pathway138at the bottom of the housing126of the disposable portion122. Likewise, a portion of the driven membrane142can be moved so as to open or close the end of the fluid outlet pathway140at the bottom of the housing126.

In the embodiment illustrated, a mechanism is provided for selectively moving the portions of the driven membrane142between the fluid pathway opening and closing positions. In a preferred embodiment, this mechanism comprises one or more actuators.

As illustrated, an inlet actuator168is configured to move between extended and retracted positions (or up and down as illustrated in the figures), thereby moving the driven membrane142up and down in the region of the fluid inlet pathway138. As illustrated, the inlet actuator168is push-rod type element having a nose or end configured to engage the driven membrane142. In order to permit the inlet actuator168to engage the driven membrane142, a passage172is located in the lock ring156in alignment with the fluid inlet pathway138.

The inlet actuator168is configured to move up and down, such as by a driving mechanism described in more detail below. In a first or up position, the nose of the inlet actuator168presses the driven membrane142against the bottom of the housing126of the disposable portion122of the pump120at the point where the fluid inlet pathway138intersects the bottom of the housing126, thereby closing it. At this time, fluid is generally prevented from flowing between the fluid chamber136and the fluid inlet pathway138.

When the inlet actuator168is in a second or down position, the driven membrane142preferably moves to a position in which it no longer blocks the fluid inlet pathway138, as illustrated inFIG. 5. To provide sufficient space for downward movement of the driven membrane142, the top surface of the lock ring156may be recessed at the location corresponding to the fluid inlet pathway, as illustrated.

When the fluid inlet pathway138is open, a fluid path is preferably defined between it and the fluid chamber136. As illustrated, a fluid entry174may be defined for this purpose. The fluid entry174may comprise a path or channel defined in the bottom of the housing126which extends from the fluid chamber136to the space above the driven membrane142in the location of the fluid inlet pathway138.

The outlet actuator170is generally similar to and operates similar to the inlet actuator168. As illustrated, the outlet actuator170is configured to engage the driven membrane142in the location of the intersection of the fluid outlet pathway140and the bottom of the housing126. The outlet actuator170extends through a passage176in the lock ring156. A fluid exit178, comprising a path or channel defined in the housing126, preferably extends from the fluid chamber136to the space above the driven membrane142in the location of the fluid outlet pathway140.

Preferably, the inlet and outlet actuators170are associated with the drive portion124of the pump. A drive mechanism is provided for effectuating movement of the inlet and outlet actuator168,170.

FIG. 6illustrates the pump120with the disposable portion122mounted to the drive portion124for operation. As illustrated, the bottom of the lock ring156rests upon the top of the drive portion124. The flange164of the drive portion124extends into the opening158of the lock ring156, so that the driving membrane146is positioned adjacent the driven membrane142. When a vacuum is applied through the vacuum line137, the driving membrane146and driven membrane142are vacuum coupled so that they move in unison.

FIGS. 7A and 7Badditionally illustrate the disposable portion122and drive portion124of the pump120.FIG. 7Ais a bottom view of the disposable portion122or the pump120. This figure illustrates the generally circular shape of the bottom of the housing126thereof, as well as the dome-shaped pump chamber136. Further illustrated are the fluid inlet and outlet pathways138,140. Also illustrated are the fluid entry174and fluid exit178.

FIG. 7Bis top view of the housing132of the drive portion124of the pump120. This figure further illustrates the inlet actuator168, outlet actuator170, and driven membrane146.

Additional aspects of the invention, including a method of pumping, will be described with reference primarily toFIG. 6.FIG. 6is an assembled view of the pump120detailed above. In particular, as illustrated, the disposable portion122has been connected to or mated with the drive portion124. At this time, the bottom of the lock ring156rests upon the top of the housing134of the drive portion124. The upwardly extending flange164of the housing134extends into the opening158in the lock ring156, whereby the driving membrane146is located adjacent to, or touches, the driven membrane142.

In operation, a vacuum is applied to the vacuum line137to evacuate air from the space between the drive and driven membranes146,142. In this manner, the two membranes are vacuum coupled and move with one another. A fluid source is connected to the pump120, such as by connecting a fluid line leading from a fluid source to the fluid inlet128of the pump120. Preferably, a similar fluid line is coupled to the fluid outlet130of the pump120, whereby fluid may be delivered to a desired location, such as a patient.

Fluid is drawn into the pump chamber136from the fluid inlet128of the pump, through the fluid inlet pathway138. In order to permit fluid to flow to the chamber, the inlet actuator168is moved to a downward or retracted position, thus allowing the driven membrane142to move away from the opening of the fluid inlet pathway138. At that time, fluid may flow from the fluid inlet pathway138through the fluid entry174to the pump chamber136. Inlet fluid flow is induced by downward movement of the driven membrane142, as effectuated by downward movement of the driving membrane146by downward movement of the piston144.

When fluid is being drawn into the fluid chamber136, fluid is preferably prevented from flowing through the fluid exit178. In particular, the outlet actuator170is moved to its raised position, forcing the driven membrane142over the opening to the fluid outlet pathway140. This prevents fluid from being drawn backwardly through the pump from the fluid outlet140towards the fluid chamber136.

Fluid is forced out of the pump chamber136by upward movement of the piston144. As the piston144moves upwardly, it reduces the volume of the variable volume fluid chamber. This increases fluid pressure, forcing the driving membrane146upwardly, which in turn forcing the driven membrane142upwardly. This reduces the volume of the pump chamber136. Fluid is permitted to flow through the fluid exit178by retraction of the outlet actuator170. At that time, a fluid path is established from the fluid exit178to the fluid outlet pathway140to the fluid outlet130of the pump120. In order to prevent fluid from being delivered backwardly to the fluid inlet128, inlet actuator168is moved upwardly to close the fluid inlet pathway138.

This process is then repeated. In particular, the piston144begins moving downwardly to again increase the volume of the pump chamber136. The inlet actuator168is moved downwardly to permit the flow of fluid from the fluid inlet128to the pump chamber136. The outlet actuator170is moved upwardly to prevent fluid from being drawn backwardly in the direction of the fluid outlet130to the pump chamber136.

FIGS. 8A and 8Billustrate another embodiment of a disposable unit portion222of a pump20. As illustrated, the disposable portion222has a housing226having a top223aand a bottom223b. In use, the bottom223bof the housing226would be placed against or mounted to a driving or pumping portion or unit, in similar fashion to that detailed above.

As illustrated, the disposable portion222again has a fluid inlet228and fluid outlet230. In this embodiment, the disposable portion222defines a bubble trapping chamber280(the purpose of which is to catch air in the fluid and prevent it from reaching the pump chamber and being pumped through the pump) and a pump chamber236. A fluid inlet pathway238extends from the fluid inlet228to the bubble trapping chamber280, thereon to the pump chamber236. A fluid outlet pathway240extends from the pump chamber236to the fluid outlet230.

In the embodiment illustrated, the housing226is generally rectangular in peripheral shape. In one embodiment, various of the fluid pathways and/or chambers may be defined by raised or recessed areas. For example, when viewing the bottom of the disposable portion222as inFIG. 8A, the pump chamber236may appear as a depression in the housing226. This depression, however, may be defined at least in part by a raised portion extending outwardly from the top of the housing226, as illustrated inFIG. 8B.

FIG. 8Cillustrates yet another embodiment of a disposable unit or portion322of a pump in accordance with the present invention. This embodiment disposable portion322is illustrated conceptually to illustrate various features which the disposable portion322may incorporate.

Once again, this embodiment disposable portion322includes a housing326. The housing326defines a fluid inlet328and a fluid outlet330. The disposable portion322further includes an air trap380, a bubble detector382and a flow stop384, as well as the pump chamber336(as defined by the housing326and a driven membrane342in cooperation with the housing326).

As indicated above, the air trap380is preferably configured to trap air in the fluid which is drawn into the pump. Air which is trapped in the air trap380may be expelled manually or automatically, such as through a port or valve to the exterior of the housing326of the disposable portion322.

The bubble detector382is preferably configured to detect bubbles in the fluid. The detector382is preferably located along an upward fluid outlet path, to avoid “floating” bubble false alarms. The bubble detector382may comprise a chamber having a reflective side wall and transmitter/receiver.

In one embodiment, the disposable portion322may also comprise a fluid pressure sensor. The sensor may be configured to detect fluid inlet and/or outlet pressure.

As indicated above, in various embodiments, one or more drive mechanisms or devices may be provided for moving the various elements of the pump. For example, referring to the embodiment pump120illustrated inFIGS. 5 and 6, the inlet and outlet actuators168,170and the piston144may be selectively moved in order to effectuate operation of the pump120. Various embodiments of drive mechanisms will now be described with reference toFIGS. 9A-9D.

FIG. 9Aillustrates a cam-type drive mechanism434. As illustrated, a drive member486is configured to move cam elements corresponding to each of the members to be driven. In the embodiment illustrated, corresponding to a pump configuration such as that illustrated inFIGS. 5 and 6, where there is an inlet actuator468, an outlet actuator470, and a piston444. As illustrated, a first cam member488ais associated with the inlet actuator468, a second cam member488bis associated with the piston444(though it could be configured to directly engage the bellows), and a third cam member488cis associated with the outlet actuator470. The cam members488a,488b,488care configured to be moved by the drive member486in a desired path. As illustrated, each cam member has a pin which engages a track in the drive member486. The pin corresponding to each cam member may be offset from a central axis, whereby the path of the periphery of the cam member is non-circular. Each of the inlet actuator468, outlet actuator470and piston444are configured to follow those respective paths, whereby they may be moved up and down. Of course, the movement is timed so that, for example, the pump220illustrated inFIGS. 5 and 6operates as described.

Though not shown, one or more drives may be provided for moving the drive member486. Such drives may have a variety of configurations and be powered in a variety of manners, such as mechanically or electrically.

The drive mechanism is preferably associated with the drive portion of the pump of the invention. In one embodiment, the drive mechanism may be connected to the drive portion, such as an in a manner permitting the drive mechanism and drive portions to be separated. In another embodiment, the drive mechanism is preferably integral with the drive portion, such as being located in a lower portion of the housing thereof.

FIG. 9Billustrates a solenoid drive mechanism534. As illustrated, a first drive588ain the form of an electrically powered solenoid is provided. The first drive588apreferably moves a drive rod, which in turn drives or moves the inlet actuator568. Likewise, a third drive588cis in the form of an electrically powered solenoid. The third drive588cpreferably also includes a drive rod. That drive rod moves the outlet actuator570. Lastly, in one embodiment, a second drive588bhas the form of a stepper motor, and is configured to move or drive the piston544.

In general, the solenoids comprising the first and third drives588a,cmay be configured to move their associated drives between extended and retracted positions. Preferably, those positions correspond to the extended and retracted positions of the inlet actuator568and outlet actuator570.

In a preferred embodiment, the second drive588bhas the form of a linear stepper motor in order to allow the piston544to be moved to various positions (such as a retracted and a plurality of extended positions between the retracted and a maximum extended position). In this manner, the position of the piston444may be selectively controlled (such as for controlling the pumping volume and cycle time, as detailed below).

FIGS. 9C and 9Dillustrate yet another embodiment of a drive mechanism634. In this embodiment, the drive mechanism634is configured to directly drive the drive or driving membrane, rather than drive that membrane indirectly, such as via fluid associated with a variable volume chamber.

As illustrated, this drive mechanism634comprises multiple actuators. Preferably, the actuators are nested. In particular, in one embodiment, the drive mechanism634comprises a first actuator590a, a second actuator590b, and a third actuator590c. The first actuator590ais located or housed at least partially within the second actuator590b, which in turn is located or housed at least partially within the third actuator590c.

In one embodiment, the first, second and third actuators590a,590b,590care generally conical in shape, having a first or top end and a second or bottom end, the first end being smaller in dimension than the second end. Preferably, the actuators are sized to permit their relative and at least partial independent movement, i.e. to permit the first actuator590ato move within the second actuator590b, to permit the second actuator590bto move with respect to the first and third actuators590a,590c, and to permit the third actuator590cto move relative to the second actuator590b.

In a preferred embodiment, the actuators can be moved between at least extended and retracted positions, and preferably one or more positions there between. When used with a pump such as that illustrated inFIGS. 5 and 6, the extended and retracted positions may correspond to raised or upper, and retracted or lower, positions.

The drive mechanism includes a driving device configured to move the actuators. In one embodiment, each of the actuators defines a passage592a,592b,592cthrough the second or bottom end thereof. A cam-type drive shaft594extends there through. Rotation or other movement of the shaft594preferably effectuates movement of the actuators590a,590b,590c. In one embodiment, the shaft594defines a plurality of cams thereon, at least one cam corresponding to each of the actuators and configured to move the corresponding actuator in a specific pattern. Of course, other means might be provided for moving the actuators, such as solenoids, linear stepper motors or other mechanical or electromechanical drives.

Of course, the drive might have fewer than three or more than three actuators. Further, the shape of those actuators might vary. Preferably, however, each actuator is configured to engage and move a portion of the drive membrane.

A particular advantage of this embodiment drive mechanism is that movement of the drive membrane is effected without the need for a variable volume chamber or fluid. Instead, movement of the membrane is effected directly.

In addition, an advantage of multiple actuators is that the amount of force applied to the drive membrane may be closely controlled by controlling how many of the actuators are moved and the extent of their movement. In this manner, movement of the driven membrane may be closely controlled, thus allowing the fluid flow characteristics to be carefully controlled. In addition, the actuators590a,590b,590cmay selectively be moved in the forward or reverse (up or down) directions, again allowing significant control over pumping.

The pump and method of pumping or moving fluid may have numerous other embodiments in accordance with the invention.

In one embodiment, the pump of the invention has two main portions: a fluid contacting portion, which is referred to herein as a disposable unit or portion, and a drive portion. However, the pump may have more than two portions. For example, the pump may have three portions, such as a disposable fluid-contacting portion, an actuating portion (such as including the inlet actuator, outlet actuator and piston), and a drive portion (such as containing solenoids and stepper motors or a cam drive or the like).

Preferably, the drive portion of the pump is computer controlled, whereby the displaced volume of the pump chamber may be controlled. For example, a computer may be utilized to control the multiple actuators590a,590b,590cof the embodiment pump illustrated inFIG. 9Dor the stepper motor588billustrated inFIG. 9B, whereby the change in volume of the pump chamber of the pump may be varied over time in a controlled manner.

The pump may be constructed from a variety of materials and in a variety of manners. In a preferred embodiment, the disposable portion is constructed to be disposable, i.e. preferably to have a low cost. For example, the disposable may be constructed of a thermo-plastic material and, as detailed herein, have a simple configuration (such as the sole moving part comprising the driven membrane).

As indicated herein, the pump may be configured to include a number of features, such as an air trap, a bubble sensor, a flow rate sensor, one or more pressure sensors, a flow stop, or combinations thereof. The configurations of these features may vary. For example, various types of pressure sensors may be utilized as part of the pump. Such sensors may be utilized, for example, to measure intake, outlet and, in the case of fluid actuator, the fluid pressure. In the latter case, the intake and output pressures may be inferred from the fluid actuator pressure, eliminating the need for secondary sensors. In one embodiment, the pump may include a vacuum pressure sensor. Such a sensor may be utilized to detect or determine the pressure within the vacuum line(s). The sensor could be associated with or comprise a switch, such as coupled to the vacuum source, for causing the source to be activated when the pump is turned on and/or to be activated in the event vacuum pressure falls below a minimum level.

As indicated above, various drive devices or mechanisms may be utilized to actuate the pump. Various embodiments have been described and illustrated herein, but others are possible.

The portions of the pump, such as the housings of the disposable portion and drive portion, may have a variety of shapes and sizes. The shapes and sizes of the portions may vary depending on various design criteria.

In a preferred embodiment, the pump includes fluid flow controls to control the flow of fluid there through. As indicated, the fluid flow controls may comprise one or more actuated valves. Other types of fluid flow controls than specifically illustrated herein might be utilized. For example, the actuators might be configured to extend directly into and out of inlet and outlet fluid paths to selectively obscure them.

In a preferred embodiment, the disposable portion of the pump has a single driven membrane. This single membrane is used as a pump member and as a valving member for the intake and outlet fluid paths. The disposable portion might utilize more than one membrane, however, such as a first membrane at the pump chamber, a second in conjunction with the fluid inlet path for serving as the inlet control valve, and a third in conjunction with the fluid outlet path for serving as the outlet control valve.

In one embodiment, the driven membrane may be separated from the disposable portion. In this embodiment, after the disposable portion is used, the driven membrane might be thrown away and the remainder of the disposable portion might be sterilized for reuse. After sterilization, a new driven membrane would be associated with the disposable portion.

In one embodiment, the driving membrane is moved by fluid. As described above and illustrated herein, movement of a piston may change the volume of a chamber containing fluid, which chamber is bounded in at least one area by the driving membrane. In one embodiment, such as illustrated inFIG. 1, the piston itself may bound a portion of the chamber, whereby movement of the piston directly changes the volume of the chamber. In another embodiment, as illustrated inFIG. 4, the piston may move a boundary of the chamber. In that embodiment, the piston moves a portion of the chamber bounded by a bellows. Of course, the driving membrane might be moved in other manners. For example, fluid might be pumped into the chamber or be released from the chamber to change the fluid volume therein. The driving membrane may also be moved directly.

In the preferred embodiment, the driving and driven membranes comprise relatively thin, flexible members. The material from which the membranes are constructed may vary. Further, the membranes may have forms other than generally constant thickness material bodies, but may comprise other members which are sufficient resilient to move up and down in response to applied forces.

In one embodiment, the disposable portion might be configured with integral external fluid lines or fluid connectors for mating with external devices (such as a fluid source or line).

In one embodiment, the driving membrane is indirectly driven, such as by fluid located in a variable volume chamber. In other embodiments, however, the driving membrane may be directly driven.

In one embodiment, the air trap is configured with a sensor to detect or determine when a predetermined amount (such as a maximum amount) of air is contained therein. When such a level or amount of air is sensed, the air may be expelled from the air trap, such as back to a fluid source drip chamber. This may be accomplished by operation of a solenoid or linear actuator, preferably while the inlet valve is closed to avoid any interruption of fluid flow to the patient.

Various aspects of the invention will now be appreciated. First, one aspect of the invention is a fluid pump having at least two portions, a portion which is configured to contact the fluid to be pumped, and another portion. Preferably, the pump has a first portion comprising the pumping or drive portion, and a second fluid contacting portion which can be selectively connected to or disconnected from the drive portion. Advantageously, this allows the fluid-contacting portion to be disposed of after use, or sterilized after use, while the remaining portion of the pump, such as the pumping portion, can be re-used with a new fluid-contacting portion or a sterilized fluid-contacting portion of the pump.

In one embodiment, the fluid-contacting portion of the pump is configured to be “disposable.” In particular, the design of that portion of the pump is configured to be simple, whereby it may be relatively inexpensive to manufacture. This allows that portion to be cheaply replaced (avoiding the costs and steps associated with having to sterilize for reuse). In one embodiment, the disposable may be constructed at least partly of a plastic material for this purpose, such as in a molding process.

Another aspect of the invention is a multi-piece pump where pumping is facilitated through the use of one or more engaging membranes or diaphragms or other flexible members. Preferably, these members are configured to move in unison via a vacuum coupling. The vacuum coupling has the advantage that it is a simple and inexpensive coupling configuration. For example, such a configuration avoids the need for complex mechanical connections of elements as is common in pump drives. In addition, the vacuum coupling provides a simple way of disconnecting the pump portions, in that there is no need to disconnect particular linkages or elements.

Advantageously, the pump of the invention can be configured to be highly compliant. Further, fluid flow rates or volumes, and pressure, may be very closely controlled using the pump of the invention.

A significant benefit of the pump of the invention is the highly elastic membrane of the disposable portion of the pump. This feature minimizes the dimensional accuracy required of the disposable portion, thus reducing significantly the complexity and cost of manufacture, and thus ultimate cost of the disposable portion.

A significant benefit of the vacuum coupling is that the coupling enables the pump to pump against negative output pressures and to aspire fluid from containers lower than the pump (functions which would not otherwise be possible—i.e. the advantages of the disposable portion detailed above are realized or enabled by the vacuum coupling).

Another feature and advantage of the invention is a pre-pump chamber which assists in trapping and eliminating air bubbles which may form in the fluid itself or travel into to the pump from the fluid source.