US20050234394A1 - Dual cylinder vacuum pump for medical aspiration system - Google Patents

Abstract

A dual cylinder pump that is used to create a vacuum in an aspiration tube of a medical system. The pump includes a first plunger that moves within a first cylinder and a second plunger that moves within a second cylinder. Movement of the plungers is controlled by a motor assembly. The pump includes valves that control the flow of fluid into and out of the cylinders so that one cylinder is pulling fluid from the aspiration tube while the other cylinder is discharging fluid. The pump housing can be constructed as a cartridge that can be removed and readily sterilized.

Description

REFERENCE TO CROSS-RELATED APPLICATIONS
• This application claims priority to provisional application No. 556,963 filed on Mar. 26, 2004.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a vacuum pump for a medical aspiration system.
• 2. Background Information
• Ophthalmic procedures are typically performed with instruments that have a tip located at the distal end of a handpiece. The handpiece is held by a surgeon who inserts the tip into the inner ocular chamber of an eye. By way of example, the surgeon may remove a cataracteous lens, or reattach a retina with the instrument.
• During a procedure, irrigation fluid is introduced into the eye to maintain the ocular pressure of the anterior chamber. The handpiece tip is coupled to an aspiration system that pulls the irrigation fluid and possibly tissue out of the anterior chamber. The tissue and irrigation fluid flow through an inner channel in the tip.
• The aspiration system includes a pump coupled to an aspiration tube. The aspiration tube is connected to an outlet port of the handpiece. Most aspiration pumps are of the peristaltic type because the pump behavior is predictable. A peristaltic pump essentially pushes the air/fluid within the aspiration tube to create a vacuum pressure within the tube. The operation of a peristaltic pump creates surges in the pressure within the system. Pressure surges can be undesirable when performing delicate procedures such as retinal reattachment.
• Some aspiration systems contain a venturi type pump. Venturi pumps do not creates pressure surges and are thus typically used in delicate ophthalmic procedures. Commercially available venturi pumps require a tank of compressed nitrogen gas. It is generally undesirable to have a pressurized gas tank in an operating environment. Additionally, venturi pumps are energy inefficient in creating a vacuum.
SUMMARY OF THE INVENTION
• A pump for a medical aspiration system. The pump includes a housing with an input port, an output port, a first cylinder and a second cylinder. A motor assembly of the pump moves a first plunger within the first cylinder and a second plunger within a second cylinder. The pump includes valve assemblies that control fluid communication between the input/output ports and the cylinders.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic of an embodiment of a medical system;
• FIG. 2 is an illustration of a dual cylinder pump of the medical system.
DETAILED DESCRIPTION
• Disclosed is a dual cylinder pump that is used to create a vacuum in an aspiration tube of a medical system. The pump includes a first plunger that moves within a first cylinder and a second plunger that moves within a second cylinder. Movement of the plungers is controlled by a motor assembly. The pump includes valves that control the flow of fluid into and out of the cylinders so that one cylinder is pulling fluid from the aspiration tube while the other cylinder is discharging fluid. In this manner the pump is continuously pulling vacuum, thereby preventing vacuum surges found in peristaltic pumps of the prior art. Additionally, the pump is relatively energy efficient and does not require a separate nitrogen tank as required by commercially available venturi pumps of the prior art. The pump can be constructed as a cartridge that can be removed and disposed.
• Referring to the drawings more particularly by reference numbers,FIG. 1 shows an embodiment of amedical system10 of the present invention. Thesystem10 may be used by a surgeon to perform ophthalmic medical procedures such as cataract lens removal, or retina reattachment.
• Thesystem10 may include aninstrument12 that is coupled to anaspiration system14. Theinstrument12 may include atip16 that extends from ahandpiece18 and can be held by a surgeon. Thetip16 can be inserted into the eye of a patient.
• Theaspiration system14 may include an aspiration tube(s)20 that is coupled to theinstrument12. Theaspiration tube20 is connected to avacuum pump22 and acollection canister24. Thevacuum pump22 creates a vacuum pressure within theaspiration tube20 and a flow of fluid from theinstrument12 to thecanister24. Theaspiration system14 can pull emulsified tissue and fluid from theinstrument12 and into the canister29.
• Thesystem10 may include acontroller26 that is connected to theinstrument12 and thevacuum pump22. Thesystem10 may further have a control device such as afoot pedal28 that is connected to thecontroller26. The surgeon can control theinstrument12 and/or thepump22 thru thefoot pedal28. Thecontroller26 may include a processor, memory, etc. (not shown) that can operate thepump22 in synchronization with theinstrument12. Although thefoot pedal28 is shown as being connected to thecontroller26, thefoot pedal28 may be connected directly to thepump22 and/orinstrument12.
• FIG. 2 shows an embodiment of thevacuum pump22. Thepump22 may include ahousing30 that has afirst cylinder32 and asecond cylinder34. Thehousing30 also includes aninput port36 and anoutput port38. Theinput port36 includeschannels40 and42 in fluid communication with the first32 andsecond cylinders34, respectively.
• Thepump22 may have afirst valve assembly44 that controls the flow of fluid between thecylinders32 and34 and amanifold tube46. Themanifold tube46 is connected to theaspiration tube20 of theaspiration system14. Thefirst valve assembly44 may include afirst input valve48 that controls the flow of fluid into thefirst cylinder32 and asecond input valve50 that controls the flow of fluid into thesecond cylinder34.
• Thepump22 may further have asecond valve assembly52 that controls the flow of fluid between thecylinders32 and34 andoutlet lines54 and56 of the output port. Thesecond valve assembly52 may include afirst output valve58 that controls the flow of fluid from thefirst cylinder32 and asecond output valve60 that controls the flow of fluid from thesecond cylinder34. Thevalves48,50,58 and60 may be controlled actuators or motors that are connected to and controlled by thecontroller26 shown inFIG. 1.
• Thepump22 may includepressure transducers62 and64 that sense the pressure within the first32 and second34 cylinders, respectively. The pressure transducers62 and64 can be connected to thecontroller26 shown inFIG. 1, and provide pressure feedback information that can be used in a feedback control loop of thepump22.
• Thepump22 includes afirst plunger66 that moves within thefirst cylinder32 and asecond plunger68 that moves within thesecond cylinder34. Theplungers66 and68 are moved by amotor assembly70. Themotor assembly70 may include afirst motor72 that moves thefirst plunger66 and asecond motor74 that moves thesecond plunger68. Themotors72 and74 may move theplungers66 and68 out of phase relative to each other. By way of example, theplungers66 and68 may move 180 degrees out of phase relative to each other. Themotors72 and74 may be connected to thecontroller26 which controls the timing and phase of theplungers66 and68. Although two motors are shown and described, it is to be understood that the plungers could be coupled to a single motor.
• Themotors72 and74 may be attached to theplungers66 and68 bycouplers76 and78. Thecouplers76 and68 may be of the quick disconnect type so that theplungers66 and68, andhousing30 can be detached from themotor assembly70. This allows thehousing30 andplungers66 and68 to be packaged as a cartridge that can be detached after a medical procedure. Theplungers66 and68 may be of the syringe type that can be readily discarded and replaced. Thehousing30 can be sterilized for reuse in thesystem10. The valve actuators and pressure transducers may also be attached to thehousing30 in a sealed and readily detachable manner so that these components do not have to be sterilized after each procedure.
• Thecontroller26 may control themotors72 and74 and thevalve assemblies44 and52 in the following manner. Thefirst input valve48 may be opened to provide fluid communication between themanifold tube46 and thefirst cylinder32. Thesecond input valve50 is closed. Thefirst motor72 may pull thefirst plunger66 in a direction indicated by the arrow. Movement of theplunger66 pulls fluid into thefirst cylinder32.
• When thefirst plunger66 reaches an end of travel thefirst input valve48 is closed and thesecond input valve50 is opened. Thesecond motor74 then pulls thesecond plunger68 to draw fluid into thesecond cylinder34. During this second plunger movement thefirst motor72 pushes thefirst plunger66. Thefirst output valve58 is opened so that the fluid within thefirst cylinder32 is pushed out of thepump22. The motors and valves are operated so that one of the cylinders is pulling in fluid while the other cylinder is pushing out fluid. In this manner a continuous vacuum is created in the aspiration tube. There are not sudden surges as found in prior art peristaltic pumps.
• To maintain a continuous vacuum level, thesecond plunger68 may begin to pull a vacuum incylinder34 as thefirst plunger66 nears the end of travel incylinder32.Valve50 may be closed during movement of the second plunger until thetransducers62 and64 sense the same pressure whereinvalve50 is opened andvalve48 is closed.
• While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
• For example, althoughmultiple values48,50,58 and60 are shown and described, it is to be understood that thepump22 may have other value arrangements. By way of example thepump22 may have a single four-way valve.

Claims (20)

1. A pump for a medical aspiration system, comprising:

a housing that has an input port, an output port, a first cylinder and a second cylinder;

a first plunger that moves within said first cylinder;

a second plunger that moves within said second cylinder;

a motor assembly that moves said first and second plungers within said first and second cylinders, respectively; and,

a valve assembly that controls fluid communication between said first and second cylinders, and said input and output ports.

2. The pump ofclaim 1, wherein said motor assembly includes a first motor connected to said first plunger by a first coupler and a second motor connected to said second plunger by a second coupler.

3. The pump ofclaim 1, wherein said first and second plungers move out of phase relative to each other.

4. The pump ofclaim 1, wherein said valve assembly includes a first input valve that controls fluid communication between said input port and said first cylinder and a second input valve that controls fluid communication between input port and said second cylinder.

5. The pump ofclaim 1, wherein said valve assembly includes a first output valve that controls fluid communication between said first cylinder and said output port and a second output valve that controls fluid communication between said second cylinder and said output port.

6. A medical system, comprising:

an instrument;

an aspiration tube coupled to said handpiece;

a pump coupled to said aspiration tube, said pump including;

a housing that has an input port coupled to said aspiration tube, an output port coupled to said aspiration tube, a first cylinder and a second cylinder;

a first plunger that moves within said first cylinder;

a second plunger that moves within said second cylinder;

a motor assembly that moves said first and second plungers within said first and second cylinders, respectively;

a valve assembly that controls fluid communication between said first and second cylinders, and said input and output ports; and,

a control device coupled to said pump.

7. The system ofclaim 6, wherein said motor assembly includes a first motor connected to said first plunger by a first coupler and a second motor connected to said second plunger by a second coupler.

8. The system ofclaim 6, wherein said first and second plungers move out of phase relative to each other.

9. The system ofclaim 6, wherein said valve assembly includes a first input valve that controls fluid communication between said input port and said first cylinder and a second input valve that controls fluid communication between input port and said second cylinder.

10. The system ofclaim 6, wherein said valve assembly includes a first output valve that controls fluid communication between said first cylinder and said output port and a second output valve that controls fluid communication between said second cylinder and said output port.

11. The system ofclaim 6, wherein said control device includes a foot pedal.

12. The system ofclaim 11, further comprising a controller coupled to said foot pedal and said pump.

13. A method for creating a vacuum pressure within an aspiration tube of a medical system, comprising:

moving a first plunger within a first cylinder of a housing and moving a second plunger within a second cylinder of the housing; and,

switching at least one valve to create fluid communication between an input port of the housing and the first and second cylinders and a fluid communication between an output port of the housing and the first and second cylinders, so that movement of the first and second plungers create a vacuum within an aspiration tube coupled to the input port.

14. The method ofclaim 13, wherein the first and second plungers move out of phase with each other.

15. The method ofclaim 13, wherein the first plunger is moved by a first motor and the second plunger is moved by a second motor.

16. The method ofclaim 13, wherein the vacuum pressure irrigates fluid from an eye.

17. A pump cartridge that can be connected to an aspiration tube of a medical system and a motor assembly of a pump, comprising:

a housing that has an input port that can be connected to the aspiration tube, an output port, a first cylinder and a second cylinder;

a first plunger that moves within said first cylinder and can be connected to said motor assembly;

a second plunger that moves within said second cylinder and can be connected to said motor assembly; and

a valve assembly that controls fluid communication between said first and second cylinders, and said input and output ports.

18. The pump cartridge ofclaim 17, wherein said first and second plungers move out of phase relative to each other.

19. The pump cartridge ofclaim 17, wherein said valve assembly includes a first input valve that controls fluid communication between said input port and said first cylinder and a second input valve that controls fluid communication between input port and said second cylinder.

20. The pump cartridge ofclaim 17, wherein said valve assembly includes a first output valve that controls fluid communication between said first cylinder and said output port and a second output valve that controls fluid communication between said second cylinder and said output port.

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