WO2018060822A1

WO2018060822A1 - System and method for a syringe infusion pump that prevents an accidental bolus upon installation of the syringe

Info

Publication number: WO2018060822A1
Application number: PCT/IB2017/055758
Authority: WO
Inventors: Donald Alan FORRER; Francis Patrick O'NEILL; Christopher J. Page
Original assignee: Koninklijke Philips N.V.
Priority date: 2016-09-29
Filing date: 2017-09-22
Publication date: 2018-04-05

Abstract

A syringe infusion pump (10) includes a barrel clamp (32) configured to hold an associated syringe (26) having a syringe tube axis. A plunger drive arm (36) has a hollow collar (34) arranged coaxially with a plunger (28) of the syringe and has an inner diameter that is greater than a diameter of the plunger of the syringe held by the barrel clamp. A drive motor (38) is connected to operate the plunger drive arm to move the hollow collar along the direction of the syringe tube axis of the syringe held by the barrel clamp. A sensor (40) is disposed on the hollow collar. The sensor is configured to detect entry of the plunger of the syringe held by the barrel clamp into the hollow collar. The drive motor is configured to stop moving the hollow collar in response to the sensor detecting entry of the plunger of the syringe into the hollow collar. A plunger clamp (46) is disposed on the hollow collar and operable to clamp onto a sidewall (30) of the plunger of the syringe held by the barrel clamp.

Description

SYSTEM AND METHOD FOR A SYRINGE INFUSION PUMP THAT PREVENTS AN ACCIDENTAL BOLUS UPON INSTALLATION OF THE SYRINGE

FIELD The following relates generally to the medical infusion arts, infusion pump arts, and related arts.

BACKGROUND

A syringe infusion pump provides medicine or other therapeutic fluids to a patient. A syringe pump employs a syringe including a cylindrical tube or "barrel" with a nozzle, and a plunger that is pushed into the barrel to expel the therapeutic fluid out the nozzle. Such a syringe can be used manually in conjunction with an intravascular needle attached directly to the nozzle - the nurse or other medical professional inserts the needle into a vein (or, in some cases, an artery) and proceeds to push the plunger to deliver the intravenous injection. Such a manual approach is convenient, but does not provide high precision delivery, especially when a continuous flow is desired.

A syringe pump provides for precise continuous delivery using a syringe. In a typical design, a screw is turned at a constant rotational rate and pushes on the end of the plunger to deliver the continuous flow. To use, the syringe is carefully mounted to the syringe infusion pump and then typically manually loaded for infusion. Automated loading is also known, in which the screw or other piston is operated by the motor until a contact sensor detects contact with the end of the syringe plunger.

Improvements disclosed herein address the foregoing and other disadvantages of existing infusion pump systems, methods, and the like.

BRIEF SUMMARY

In accordance with one illustrative example, a syringe infusion pump includes a barrel clamp configured to hold an associated syringe having a syringe tube axis. A plunger drive arm has a hollow collar arranged coaxially with a plunger of the syringe and has an inner diameter that is greater than a diameter of the plunger of the syringe held by the barrel clamp. A drive motor is connected to operate the plunger drive arm to move the hollow collar along the direction of the syringe tube axis of the syringe held by the barrel clamp. A sensor is disposed on the hollow collar. The sensor is configured to detect entry of the plunger of the syringe held by the barrel clamp into the hollow collar. The drive motor is configured to stop moving the hollow collar in response to the sensor detecting entry of the plunger of the syringe into the hollow collar. A plunger clamp is disposed on the hollow collar and operable to clamp onto a sidewall of the plunger of the syringe held by the barrel clamp.

In accordance with another illustrative example, a method of loading a syringe in an infusion pump includes: loading the syringe in a barrel clamp of the infusion pump; with a plunger drive motor, moving a hollow collar mounted on a plunger drive arm over a plunger of the syringe such that the plunger is received within a hollow portion of the hollow collar without the hollow collar contacting the plunger; with a sensor , detecting entry of the plunger into the hollow portion of the hollow collar; with at least one processor, stopping movement of the hollow collar in response to the detecting; and with a plunger clamp, clamping the hollow collar onto a sidewall of the plunger.

In accordance with another illustrative example, a syringe infusion pump includes a barrel clamp configured to hold an associated syringe having a syringe tube axis. A plunger drive arm has a hollow collar arranged coaxially with a plunger of the syringe and has an inner diameter that is greater than a diameter of the plunger of the syringe held by the barrel clamp. A drive motor is connected to operate the plunger drive arm to move the hollow collar along the direction of the syringe tube axis of the syringe held by the barrel clamp. A sensor is disposed on the hollow collar. The sensor is configured to detect entry of the plunger of the syringe held by the barrel clamp into the hollow collar. The drive motor is configured to stop moving the hollow collar in response to the sensor detecting entry of the plunger of the syringe into the hollow collar. A plunger clamp is disposed on the hollow collar and operable to clamp onto a sidewall of the plunger of the syringe held by the barrel clamp. When the sensor detects entry of the plunger of the syringe into the hollow collar, at least one electronic processor is programmed to prevent operation of the drive motor to prevent movement of the hollow collar into contact with the plunger. One advantage resides in controlling the speed at which medication is delivered to a patient from a syringe.

Another advantage resides in reducing an accidental bolus to a patient.

Another advantage resides in preventing an accidental bolus to a patient during loading of a syringe pump.

Another advantage resides in providing for loading a syringe into an infusion pump without causing accidental depression of a syringe plunger.

Another advantage resides in providing a syringe pump with automatic engagement of the syringe plunger, in which a failure of the engagement mechanism does not produce an accidental bolus and for which the mechanism failure is visually evident.

Further advantages of the present disclosure will be appreciated to those of ordinary skill in the art upon reading and understand the following detailed description. It will be appreciated that a given embodiment may provide none, one, two, or more of these advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIGURES 1-8 diagrammatically illustrates different views of medical device in accordance with one aspect.

FIGURE 9 diagrammatically illustrates a syringe loading method suitably performed using the medical device of FIGURE 1.

FIGURES 10A-10D diagrammatically illustrates the operations of the method of FIGURE 9.

DETAILED DESCRD7TION

One of the most significant issues encountered during the manual loading of the infusion pump is the risk of inadvertently infusing a bolus. A bolus is a rapid infusion of a medicine and can be given purposely by a doctor or clinician when necessary. Accidental bolus infusion can be harmful to the patient.

The following relates to infusion pumps, and more particularly to syringe pumps. In this type of pump, the medicine is loaded into a syringe having a plunger. The syringe is then loaded into the syringe pump which holds the syringe fixed and has a piston that drives the plunger at a slow programmed rate so as to deliver a continuous infusion at a (typically relatively low) flow rate. Tubing connects the outlet end of the syringe to the patient. Loading can be done automatically or, in some automated designs, the piston is programmed to be brought into contact with the end of the syringe plunger by action of the motor, and has a contact sensor to detect when the piston engages the end of the plunger.

There is a problem with existing syringe pumps, in that if a malfunction occurs and piston/plunger engagement is not detected then the piston will continue to move toward the (missed) engagement, thereby pushing the plunger and delivering a high-flow dose (i.e., bolus) of the medication. The same problem can arise if the contact sensor works properly but the interlock that stops the drive motor in response to sensor contact fails. Depending upon the medication and other factors, this accidental bolus delivery can be highly detrimental to the patient.

The following discloses a solution to this problem. Instead of a solid piston head, the piston has a collar whose inner diameter (ID) is larger than the diameter of the plunger. As the piston moves toward the collar it therefore does not directly engage the end of the plunger, but instead the end of the plunger passes into the ID of the collar. An optical detector (e.g. a semiconductor laser or LED disposed in the collar that illuminates a photodiode or other optical detector located across the ID from the laser or LED) detects the plunger end as it blocks the laser/LED beam from reaching the detector. Upon detection of this blocked light signal further automatic movement of the piston ceases. The user then turns the collar to operate an iris or other gripping mechanism that extends inward from the collar to grip the end of the plunger from the sides to complete the piston/plunger engagement.

In this way, if the optical detector fails or for some other reason the piston fails to stop its movement, no bolus will be delivered. Rather, the plunger will simply continue to pass through the ID of the collar. This also provides an unmistakable indication of the failure, as the nurse will observe the end of the plunger sticking out of the collar.

The prevention of an accidental bolus during syringe loading of an infusion pump is thus achieved by: (1) a hands free mechanism that grasps the syringe flange on the sides of the syringe plunger; (2) a hollow plunger mechanism; and (3) an algorithm that integrates the syringe motor step function with the bolus detection sensor to control the pressure and speed of syringe mounting.

It will be appreciated that FIGURES 1-8 show multiple views of an infusion pump 10. Therefore, the following will describe features interchangeable between FIGURES 1-8. It will also be appreciated that features already identified in any of FIGURES 1-8 may not be identified again in subsequent figures, for clarity.

With reference now to FIGURES 1-8, the syringe infusion pump 10 is described. The illustrative syringe infusion pump 10 includes a housing 12 with a power source (or power converter, e.g. converting 110 Vac to a device drive power, not shown), and at least one electronic processor 18. The at least one processor 18 is programmed to control operations of the syringe infusion pump 10, as described in more detail below. The syringe infusion pump 10 optionally also includes a display 20 configured to display details of operations of the medical device 10, and/or a keypad 22 or other user input device, e.g. disposed adjacent the display 20. The illustrative keypad 22 includes a plurality of keys 24, but other input devices such as knobs, dials, or so forth are contemplated.

The infusion pump 10 includes components for holding and securing an associated syringe 26 that contains medication. As shown in FIGURE 1, the syringe 26 includes a cylindrical hollow barrel 27 and a plunger 28 with at least one sidewall 30 sized to slide into the inner diameter (ID) of the syringe barrel 27. For example, the plunger 28 can be circular and thus the plunger includes a single, circular sidewall 30. However, the plunger 28 can be any other suitable shape (e.g., square) such that the plunger includes multiple sidewalls 30. (In this case, the end of the plunger is circular with an O-ring, gasket, or the like to seal against the ID of the barrel). The plunger 28, being circular, includes a diameter Di (shown in FIGURE 2). The syringe 26 defines syringe tube axis A (FIGURE 1). As best shown in FIGURE 2, to secure the syringe 26 to the infusion pump 10, the infusion pump includes a barrel clamp 32 that is configured to hold the barrel 27 of the syringe 26 in place against (or partly or wholly within) the housing 12 when installed in the infusion pump. The barrel clamp 32 can be rotated to allow the syringe 26 to be placed in the infusion pump 10, and then rotated again to secure the syringe to the infusion pump. A hollow collar 34 is configured to engage a portion of the syringe 26. To do so, a hollow portion 35 of the hollow collar 34 is attached to a plunger drive arm 36. The plunger drive arm 36 is connected to a drive motor 38 disposed within the housing 12. The drive motor 38 (indicated diagrammatically in the drawings, and may be embodied as a stepper motor or the like) is configured to operate the plunger drive arm 36 to move it linearly along the direction of the syringe tube axis A of the syringe 26 when the syringe is held by the barrel clamp 28.

The hollow collar 34 is positioned on an end of the plunger drive arm 36 such that the hollow collar is arranged coaxially with the plunger 28. The hollow collar 34 includes an inner diameter D₂ that is greater than the diameter Di of the plunger 28. As a result, the hollow collar 34 is configured to fit over the plunger 28 so that during movement of the drive arm 36, the hollow collar 34 is configured to push the plunger 28 to deliver the medication in the barrel 27 of the syringe 26 to the patient, as described in more detail below.

As shown in FIGURES 3 and 4, the hollow collar 34 includes a sensor 40 disposed on the hollow portion 35 thereof. The sensor 40 is configured to detect entry of the plunger 28 into the hollow collar 34 when the syringe 26 is held by the barrel clamp 32. When the sensor 40 detects entry of the plunger 28 into the hollow portion 35 of the hollow collar 34 (i.e., by virtue of the diameter D₂ of the hollow collar 34 being greater than the diameter Di of the plunger 28), the drive motor 38 is responsively configured to stop movement of the hollow collar by preventing further movement of the plunger drive arm 36 (i.e., so that the plunger does engage a portion of the hollow collar). To do so, the illustrative sensor 40 includes an optical detector 42 and a light source 44 configured to transmit light to the optical detector. The optical detector 42 and the light source 40 are arranged such that entry of the plunger 28 of the syringe 26, upon entering into the hollow collar 36, blocks light from the light source from reaching the optical detector. In this manner, the at least one processor 18 is configured to stop operation of the drive motor 38 so that the hollow collar 34 is prevented from further movement towards the plunger 28. This is merely an illustrative sensor, and other sensor designs are contemplated, e.g. a hair trigger contact sensor extending inwardly into the hollow portion 35 of the collar 34 to physically contact the sidewall of the plunger 28.

The use of the hollow collar 34 operates as a fail-safe to prevent accidental infusion of the medication in the syringe 26 to the patient. In the event of a failure of the sensor 40, or in the event of a failure of the interlock response to the triggering of the sensor 40, the drive motor 38 may continue to operate to as to drive the drive arm 36 so that the hollow collar 34 continues to move towards the syringe 26, even after the plunger 28 has entered the hollow portion 35 of the hollow collar. As shown in FIGURE 5, the plunger 28 extends out of the hollow collar 34 when this occurs. No force is applied to the plunger 28 in this circumstance, and hence no accidental bolus is delivered to the patient. (By contrast, with a conventional piston that contacts the top of the plunger, such a failure of the contact sensor and/or interlock circuitry can result in the piston continuing to drive the plunger into the barrel of the syringe, thus delivering an accidental bolus to the patient).

As shown in FIGURE 6, the hollow collar 34 also includes a plunger clamp 46 disposed on the hollow portion 35 thereof. The plunger clamp 46 is operable to clamp onto the sidewall 30 of the plunger 28 when the syringe 26 is held by the barrel clamp 32. To do so, the plunger clamp 46 includes an iris 48 that extends inward into the hollow portion 35 of the hollow collar 34. The iris 48 is configured to grip the sidewall of the plunger 28 when the syringe 26 is being held by the barrel clamp 32. Other clamping mechanisms beside the illustrative iris are contemplated, e.g. clamping arms or fingers or the like.

The iris 48 includes a handle 50 that is manually operable to close the iris 48 to clamp onto the sidewall 30 of the plunger 28 when the syringe 26 is held by the barrel clamp 32. In one example, a user manually rotates the handle 50 to clamp the iris 48 onto the sidewall 30. In another example, the sensor 40 is configured to automatically cause rotation of the handle 50 (e.g., with the drive motor 38, or a separate collar motor (not shown)) or activation of some other clamp actuator to clamp the iris 48 onto the sidewall 30. The handle 50 optionally includes a notch 52 or other indicator configured to indicate when the iris 48 is or is not clamped onto the sidewall 30. For example, as shown in FIGURE 7, when the iris 48 is not clamped onto the sidewall 30, the notch 52 is in a "top" position relative to the handle 50. When the iris 48 is clamped onto the sidewall 30, as shown in FIGURE 8, the handle 50 has been rotated and therefore the notch 52 is in a "side" position relative to the handle.

When the plunger clamp 46 is clamped onto the sidewall 30 of the plunger 28 when the syringe 26 held by the barrel clamp 32, the drive motor 38 is operable to move the hollow collar 36 and the clamped plunger to deliver infusion fluid contained in the barrel 27 of the syringe at a controlled flow rate. To do so, the at least one processor 18 is programmed to determine a speed value of the hollow collar 34 as the hollow collar moves towards the plunger 28. The at least one processor 18 is also programmed to determine a pressure value generated when the hollow collar 34 engages a head of the plunger 28. From the determined speed and pressure, the at least one processor 18 is configured to control the engagement of the hollow collar 34 and the plunger 28, and therefore control the speed at which medication is dispensed from the barrel 27 of the syringe 26 to the patient. To do so, the at least one processor 18 is programmed to compare the measured speed and pressure values and compare them with corresponding speed and pressure threshold values that are programmed into the at least one processor. If the determined speed and pressure values are greater than the corresponding threshold values, then the at least one processor 18 is programmed to cause the drive motor 38 to output less power, thereby slowing the speed of the drive arm 36 and the hollow collar 34 towards the plunger 28, and also decreasing the pressure of the hollow collar onto the plunger. Advantageously, an accidental Bolus to the patient can be prevented.

With reference now to FIGURE 9, a method 100 of loading a syringe 26 in an infusion pump 10 is shown. It will be appreciated that the operational steps of the method 100 are shown in FIGURES 10A-10D. At step 102, the syringe 26 is loaded in a barrel clamp 32 of the infusion pump 10. As shown in FIGURE 10A, the barrel clamp 32 can be rotated to allow the syringe 26 to be placed in the infusion pump 10, and then rotated again to secure the syringe to the infusion pump. At step 104, a hollow collar 34 mounted on a plunger drive arm 36 is moved, with a plunger drive motor 38, over a plunger 28 of the syringe 26 such that the plunger is received within a hollow portion 35 of the hollow collar without the hollow collar contacting the plunger (FIGURE 10B) At step 106, entry of the plunger 28 into the hollow portion 35 of the hollow collar 34 is detected with a sensor 40 (FIGURE IOC). At step 108, movement of the hollow collar 34 is stopped in response to the detected entry with at least one processor 18. At step 110, the hollow collar 34 is clamped onto a sidewall 30 of the plunger 28 with a plunger clamp 46 (FIGURE 10D).

It will be appreciated that the illustrative data processing or data interfacing components of the syringe infusion pump 10 may be embodied as a non-transitory storage medium storing instructions executable by an electronic processor (e.g. the at least one electronic processor 18) to perform the disclosed operations. The non-transitory storage medium may, for example, comprise a hard disk drive, RAID, or other magnetic storage medium; a solid state drive, flash drive, electronically erasable read-only memory (EEROM) or other electronic memory; an optical disk or other optical storage; various combinations thereof; or so forth.

The disclosure has been described with reference to the preferred embodiments.

Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be constructed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

CLAIMS:

1. A syringe infusion pump (10), comprising:

a barrel clamp (32) configured to hold an associated syringe (26) having a syringe tube axis;

a plunger drive arm (36) having a hollow collar (34) arranged coaxially with a plunger (28) of the syringe and having an inner diameter that is greater than a diameter of the plunger of the syringe held by the barrel clamp;

a drive motor (38) connected to operate the plunger drive arm to move the hollow collar along the direction of the syringe tube axis of the syringe held by the barrel clamp;

a sensor (40) disposed on the hollow collar, the sensor being configured to detect entry of the plunger of the syringe held by the barrel clamp into the hollow collar, wherein the drive motor is configured to stop moving the hollow collar in response to the sensor detecting entry of the plunger of the syringe into the hollow collar; and

a plunger clamp (46) disposed on the hollow collar and operable to clamp onto a sidewall (30) of the plunger of the syringe held by the barrel clamp.

2. The infusion pump (10) according to claim 1, wherein the sensor (40) comprises: an optical detector (42); and

a light source (44) configured to transmit light to the optical detector; wherein the optical detector and the light source are arranged such that entry of the plunger (28) of the syringe (26) into the hollow collar (34) blocks light from the light source from reaching the optical detector.

3. The infusion pump (10) according to claim 2, wherein, when the light transmitted from the light source (44) to the optical detector (42) is blocked by the plunger (28), at least one electronic processor (18) is programmed to prevent operation of the drive motor (38) to prevent movement of the hollow collar (34) into contact with the plunger.

4. The infusion pump (10) according to any one of claims 1-3, wherein the plunger clamp (46) comprises:

an iris (48) operable to extend inward from the hollow collar (34) into a hollow portion (35) of the hollow collar to grip the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32).

5. The infusion pump (10) according to claim 4, wherein the plunger clamp (46) further includes a handle (50) that is manually operable to close the iris (48) to clamp onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32).

6. The infusion pump (10) according to any one of claims 1-5, wherein, with the plunger clamp (46) being clamped onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32), the drive motor (38) is operable to move the hollow collar (34) and the clamped plunger to deliver infusion fluid contained in the syringe at a controlled flow rate.

7. The infusion pump (10) according to claim 6, wherein the at least one processor (18) programmed to determine a speed of the hollow collar (34) as the hollow collar moves towards the plunger (28), and a pressure generated when the hollow collar engages the plunger.

8. A method of loading a syringe (26) in an infusion pump (10), the method comprising: loading the syringe (26) in a barrel clamp (32) of the infusion pump (10);

with a plunger drive motor (38), moving a hollow collar (34) mounted on a plunger drive arm (36) over a plunger (28) of the syringe such that the plunger is received within a hollow portion (35) of the hollow collar without the hollow collar contacting the plunger;

with a sensor (40), detecting entry of the plunger into the hollow portion of the hollow collar; with at least one processor (18), stopping movement of the hollow collar in response to the detecting; and

with a plunger clamp (46), clamping the hollow collar onto a sidewall (30) of the plunger.

9. The method according to claim 8, further including:

with an optical detector (42) and a light source (44) of the sensor (40), blocking light from the light source from reaching the optical detector upon entry of the plunger (28) into the hollow collar (34).

10. The method according to claim 9, further including:

with the at least one processor (18), when the light transmitted from the light source (44) to the optical detector (42) is blocked by the plunger (28), preventing operation of the drive motor (38) to prevent movement of the hollow collar (34) into contact with the plunger (28).

11. The method according to any one of claims 8-10, further including

with an iris (48) of the plunger clamp (46), gripping the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32).

12. The method (XX) according to claim 11, further including:

with a handle (50) of the plunger clamp (46), closing the iris (48) to clamp onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32).

13. The method according to any one of claims 8-12, further including:

when the plunger clamp (46) is clamped onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32), moving, with the drive motor (38), the hollow collar (34) and the clamped plunger to deliver infusion fluid contained in the syringe (26) at a controlled flow rate.

14. The method according to claim 13, further including: with the at least one processor (18), determining a speed of the hollow collar (34) as the hollow collar moves towards the plunger (26), and a pressure generated when the hollow collar engages the plunger.

15. A syringe infusion pump (10), comprising:

a plunger clamp (46) disposed on the hollow collar and operable to clamp onto a sidewall (30) of the plunger of the syringe held by the barrel clamp;

wherein, when the sensor detects entry of the plunger of the syringe into the hollow collar, at least one electronic processor (18) is programmed to prevent operation of the drive motor to prevent movement of the hollow collar into contact with the plunger.

16. The infusion pump (10) according to claim 15, wherein the sensor (40) comprises: an optical detector (42); and

17. The infusion pump (10) according to claim 16, wherein, when the light transmitted from the light source (44) to the optical detector (42) is blocked by the plunger (28), at least one electronic processor (18) is programmed to prevent operation of the drive motor (38) to prevent movement of the hollow collar (34) into contact with the plunger.

18. The infusion pump (10) according to any one of claims 15-17, wherein the plunger clamp (46) comprises:

an iris (48) operable to extend inward from the hollow collar (34) into a hollow portion (35) of the hollow collar to grip the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32); and

a handle (50) that is manually operable to close the iris (48) to clamp onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32).

19 The infusion pump (10) according to any one of claims 15-18, wherein, with the plunger clamp (46) being clamped onto the sidewall (30) of the plunger (28) of the syringe (26) held by the barrel clamp (32), the drive motor (38) is operable to move the hollow collar (34) and the clamped plunger to deliver infusion fluid contained in the syringe at a controlled flow rate.

20. The infusion pump (10) according to claim 19, wherein the at least one processor (18) programmed to determine a speed of the hollow collar (34) as the hollow collar moves towards the plunger (28), and a pressure generated when the hollow collar engages the plunger.