Energy-saving anti-free flow portable pump for use with standard PVC IV tubing
The present invention comprises an apparatus for pumping fluid through tubing. The apparatus includes a tubing base having a tubing support surface and a stop platen. The stop platen and the tubing support surface each comprise respective ridges aligned with a direction of fluid flow through the apparatus. The respective ridges are operatively arranged to engage a wall of tubing along a longitudinal axis of the tubing. In some aspects, the respective ridges are arcuate in a plane orthogonal to the direction of flow. In some aspects, the respective ridges are centered with respect to a transverse axis of the tubing and have a respective width less than an outside diameter of the tubing.
This is a continuation-in-part patent application under 35 USC 120, which claims the benefit of U.S. patent application Ser. No. 10/117,515, filed Apr. 5, 2002, entitled, “ENERGY-SAVING ANTI-FREE FLOW PORTABLE PUMP FOR USE WITH STANDARD PVC IV TUBING” and incorporated by reference herein.
FIELD OF THE INVENTIONThis invention relates to a pump for providing fluid for injection into a patient. More specifically it relates to a method and apparatus for an ambulatory infusion pump for pumping liquid through standard intravenous (IV) tubing.
BACKGROUND OF THE INVENTIONInfusion pumps for delivering fluid to a patient are well known in the art. Two general categories of infusion pumps known in the art are ambulatory pumps and large volume parenteral (LVP) pumps. These pumps deliver fluid to a patient through tubing at higher accuracies than gravity drip tubing delivery systems.
LVP pumps are relatively large infusion pumps that can provide a fluid to a patient for 4-6 hours or more on a single battery charge, or indefinitely from an AC power connection. They may operate on standard IV polyvinyl chloride (PVC) tubing. Most available LVP pumps completely collapse the PVC tubing during operation to ensure that there is no free flow to the patient or back flow to the fluid reservoir. This leads to very high power consumption when using standard tubing. Thus, a battery capable of powering the pump for 24 hours is very heavy and bulky. A patient receiving fluid from an LVP pump must stay within reach of a power cord, or push a wheeled stand with the LVP pump and battery mounted on it. In addition, fully collapsing the tubing deforms the tubing. The tubing cross section becomes more elliptical the longer the pump operates on it. Less fluid is discharged from the tubing as the cross section becomes more elliptical, leading to negative flow rate errors. The pump rate accuracy decays proportional to the amount of time an individual tubing set is used to deliver fluid to a patient. An example of an LVP infusion pump is shown in U.S. Pat. No. 4,653,987 (Tsuji et al.).
Ambulatory pumps are smaller infusion pumps that can be attached to a patient's belt, allowing them to move around without a bulky LVP pump. However, there are several drawbacks in comparison to the LVP pump. To reduce the weight to a level where a patient can carry the pump, the size of the battery is reduced considerably. The reduced battery cannot provide the power required to completely collapse standard PVC tubing. Instead, many ambulatory pumps require the use of special dedicated IV sets, or special silicon tubing threaded through a cassette to be inserted into the pump. This specialized equipment increases the cost of using the pumps. Even with special dedicated IV sets or silicon tubing and cassettes, many ambulatory pumps can only provide fluid to a patient for a few hours on a single battery charge. An example of an infusion pump that requires a dedicated IV set is shown in U.S. Pat. No. 5,772,409 (Johnson). An example of an ambulatory infusion pump that requires silicon tubing and cassettes is shown in U.S. Pat. No. 5,791,880 (Wilson).
Another problem with the infusion pumps currently in the art is the danger of free flow of fluid when the tubing is inserted or removed from the pump. An occluder is used to completely collapse the tubing while the tubing is outside the pump. The occluder is disengaged when the tubing is installed in the pump. The tubing is occluded again before the tubing is taken out of the pump. However, there is no means currently in the art to ensure that the tubing is occluded before the tubing is installed into or removed from the pump. Thus, the tubing may accidentally become unoccluded while the tubing is outside the pump, allowing fluid to flow freely to the patient. This overdose of fluid may be harmful or even lethal.
Clearly, then, there is a longfelt need for an ambulatory infusion pump that utilizes standard PVC tubing, operates for approximately 24 hours on one battery charge, and can prevent free flow of fluid into the patient.
SUMMARY OF THE INVENTIONThe present invention comprises an apparatus for pumping fluid through tubing. The apparatus includes a tubing base having a tubing support surface and a stop platen. The stop platen and the tubing support surface each comprise respective ridges aligned with a direction of fluid flow through the apparatus. The respective ridges are operatively arranged to engage a wall of tubing along a longitudinal axis of the tubing. In some aspects, the respective ridges are arcuate in a plane orthogonal to the direction of flow. In some aspects, the respective ridges are centered with respect to a transverse axis of the tubing and have a respective width less than an outside diameter of the tubing.
The stop platen is arranged to be moved to a position closest to the tubing base and when the stop platen is in this position, the tubing is formed in first and second lobes. The lobes form passages through said first tubing. In some aspects, the lobes are symmetrical with respect to the longitudinal axis.
The present invention also includes a method for pumping fluid through tubing.
A general object of the present invention is to provide an ambulatory pump that utilizes standard PVC tubing.
Another object of the present invention is to provide an ambulatory pump with high accuracy, preferably better than ±5% accuracy.
It is a further object to provide an ambulatory pump that can deliver fluid to a patient at a relatively high volume flow rate, for example 125 ml/hour, for at least 24 hours.
It is yet another object to provide an ambulatory pump that prevents the free flow of fluid into the patient when the tubing is installed and removed.
These and other objects, features and advantages of the present invention will become readily apparent to those having ordinary skill in the art upon a reading of the following detailed description of the invention in view of the drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGSThe nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:
It should be appreciated that, in the detailed description of the invention which follows, like reference numbers on different drawing views are intended to identify identical structural elements of the invention in the respective views.
A first embodiment of the present invention is shown in
Cam 36 drives pump platen 25 from a first position to a second position as shaft 38 rotates. The first position is shown in
In one embodiment, the platens are spring loaded, to allow the platens to be overdriven. This ensures tubing 21 is occluded by the occlusion platens or partially occluded by the stop platen, regardless of the dimension of tubing 21. This improves the accuracy of the pump when using tubing of varying dimensions. Otherwise expensive, complicated measurement devices are needed to ensure that the tubing is deflected the appropriate amount by each platen. Springs 52, shown in
As shown in
In an embodiment, pump assembly 50 is mounted in cabinet 70, as shown in
Free flow of fluid through the tubing is prevented with the present apparatus as follows.
To remove the tubing from cabinet 70, occluder 80 is again inserted in keyhole 73. This forces tubing 21 to first end 81, occluding the tubing. Door 78 opens, as shown in
Although two pump platens are shown in
In some aspects, platen 130 includes insert 143, which slides into the main body of platen 130. The use of insert 143 allows the main body of 130 and the insert to be made of different materials. For example, a plastic may have desirable characteristics with respect to the interaction of the platen with the cams, but may lack the structural strength needed for the protrusion. Likewise, a metal may have the strength characteristics desired for the protrusion but may lack the characteristics desirable for interaction with the cams. Thus, the main body can be made of the plastic and the insert can be made of the metal.
Platen 102 includes a concavity 164. In some aspects, stop platen 152 is disposed within concavity 164. That is, platen 152 forms a part of concavity 164. In some aspects, concavity 164 is parallel to a longitudinal axis 166 (shown in end view) for tubing 154. In general, axis 166 is parallel to the direction of fluid flow in device 100. Concavity 164 holds tubing 154. In some aspects, concavity 164 is shaped so that tubing 154 does not shift in a direction substantially parallel to axis 162.
In some aspects, support plate 150 includes ridge/protrusion 168. In general, ridge 168 is the portion of plate 150 which engages tubing 154 and towards which stop platen 152 pushes to occlude the tubing as shown in
Concavity 164 includes surfaces 174 and 176. Stop platen 152 is located between surfaces 174 and 176. In some aspects, surfaces 156, 174, and 176 form a continuous surface within concavity 164. In some aspects, surfaces 174 and 176 are symmetrical with respect to longitudinal axis 166 and axis 172. In some aspects, stop platen 152 is symmetrical with respect to axis 172. In some aspects at least a portion of surfaces 174 and 176 are arranged to engage tubing 154 when the tubing is pressed between platen 102 and plate 150. Stop platen 152 and ridge 168 are configured so that when the tubing is engaged by platen 152 and ridge 168, for example, as shown in
Tubing 154 includes an inner surface 178. Device 100 is arranged to compress tubing 154 between stop platen 152 and ridge 168 by moving pump platen 102 from the position shown in
Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, and these modifications are intended to be within the spirit and scope of the invention as claimed.
Claims
1. An apparatus for pumping fluid through tubing comprising:
- a tubing base having a tubing support surface; and,
- a stop platen, said stop platen comprising a first ridge aligned with a direction of fluid flow through said apparatus.
2. The apparatus recited in claim 1 wherein said first ridge is arcuate in a first plane orthogonal to said direction of flow.
3. The apparatus recited in claim 1 further comprising a first tubing with a wall, said first tubing comprising a first longitudinal axis aligned with said direction of flow; and,
- wherein said first ridge is operatively arranged to engage said wall of said first tubing along said first longitudinal axis.
4. The apparatus recited in claim 3 wherein said first tubing comprises a first outside diameter, said first ridge comprises a first width, and said first width is less than said first outside diameter.
5. The apparatus recited in claim 3 wherein said tubing support surface further comprises a second ridge aligned with said direction of fluid flow.
6. The apparatus recited in claim 5 wherein said second ridge is operatively arranged to engage said wall of said first tubing along said first longitudinal axis.
7. The apparatus recited in claim 5 wherein said second ridge is arcuate in a second plane orthogonal to said direction of flow.
8. The apparatus recited in claim 5 wherein said first tubing comprises a second outside diameter, said second ridge comprises a second width, and said second width is less than said second outside diameter.
9. The apparatus recited in claim 3 wherein said first tubing comprises a transverse axis and said first ridge is centered with respect to said transverse axis; and,
- wherein said stop platen is arranged to be moved to a first position closest to said tubing base and where in said first position, said second ridge is centered with respect to said transverse axis.
10. The apparatus recited in claim 9 wherein said first and second ridges are symmetrical with respect to said transverse axis.
11. The apparatus recited in claim 3 wherein said first tubing comprises an inside wall with first and second segments; and,
- wherein said stop platen is arranged to be moved to a second position closest to said tubing base and where in said second position, said first and second segments are in contact and said first tubing is formed in first and second lobes, said lobes forming passages through said first tubing.
12. The apparatus recited in claim 11 wherein said first and second lobes are symmetrical with respect to said first longitudinal axis.
13. The apparatus recited in claim 1 further comprising a second tubing, said second tubing comprising a second longitudinal axis aligned with said direction of flow; and, said apparatus further comprising:
- a pump platen, said pump platen comprising a concavity parallel to said second longitudinal axis, said concavity arranged to hold said second tubing, and said concavity comprising said stop platen.
14. A method for pumping fluid through tubing comprising:
- supporting a tubing on a tubing support surface; and,
- engaging a wall of said tubing with a first ridge on a stop platen, said engaging along a longitudinal axis of said tubing.
15. The method recited in claim 14 wherein said tubing support surface further comprises a second ridge; and, said method further comprising:
- aligning said second ridge with said longitudinal axis.
16. The apparatus recited in claim 15 wherein said first and second ridges are arcuate in a plane orthogonal to said longitudinal axis.
17. The method recited in claim 15 wherein said tubing comprises an outside diameter, said first and second ridges comprise respective widths, and said respective widths are each less than said outside diameter.
18. The method recited in claim 15 wherein said tubing comprises a transverse axis; and, said method further comprising:
- centering said first ridge with respect to said transverse axis; and,
- moving said stop platen to a position closest to said tubing base, where in said position, said second ridge is centered with respect to said transverse axis.
19. The apparatus recited in claim 18 further comprising:
- holding said tubing in a concavity, said concavity parallel to said longitudinal axis;
- disposing said stop platen in said concavity; and,
- forming said tubing into first and second lobes.
20. The method recited in claim 19 wherein said first and second lobes are symmetrical with respect to said longitudinal axis.
Type: Application
Filed: May 17, 2005
Publication Date: Sep 29, 2005
Inventors: Kenneth Corwin (Rochester, NY), Roger Hungerford (Medina, NY), Yuriy Shvetsov (Medina, NY), Michael Wollowitz (Chatham, NY)
Application Number: 11/131,058