Manual bolus volume estimation

Abstract

The syringe pump includes a plunger driver head that selectively applies force to the syringe. The drive arm includes an elongated plunger tube. The drive arm is coupled to the plunger driver head, such that movement of the elongated plunger tube corresponds to movement of the syringe plunger along the first central longitudinal axis. The potentiometer generates a signal proportional to the insertion distance of the rod inside the elongated plunger tube. The syringe pump records the signal from the potentiometer when delivery of infusion fluid by the syringe pump is paused and when delivery resumes. The syringe pump detects information about the syringe and accesses an electronic system to determine information about the syringe, enabling it to calculate the volume of a manual bolus from the syringe while delivery of infusion fluid from the syringe pump was paused.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 433,679, filed December 19, 2022, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates generally to medical devices and, more particularly, to calculating an estimate of a manual bolus administered while a syringe pump is on. [Background technology]

[0003] In the field of drug delivery devices, including so-called "syringe pumps," a syringe is typically mechanically driven under the control of a computer or digital processor, or microprocessor (collectively "processor") to deliver a prescribed volume or dose of a drug, fluid, fluid-like substance, or medication (hereinafter collectively referred to as "infusate") to a patient at a controlled rate through an infusion line or tubing in fluid communication with the syringe. Syringe pumps typically include a motor that rotates a lead screw. The lead screw, in turn, activates a plunger driver that pushes forward a plunger within the barrel of a syringe removably mounted within the pump. In this manner, pushing the plunger forward forces the infusate out of the syringe, into the infusion line or tubing, and into the patient, typically intravenously. Examples of syringe pumps are disclosed in U.S. Pat. No. 4,978,335, entitled "Infusion Pump with Bar Code Input to Computer," U.S. Pat. No. 8,182,461, entitled "Syringe Pump Rapid Occlusion Detection System," U.S. Pat. No. 8,209,060, entitled "Updating Syringe Profiles for a Syringe Pump," and WO 2016 / 183342, entitled "High Accuracy Syringe Pumps." As used throughout this disclosure, the term "syringe pump" is generally intended to relate to any device that applies a controllable force acting on a syringe to direct infusion fluid outward therefrom.

[0004] Syringe pumps are used to control the delivery of infusion fluids to a patient, including, but not limited to, therapeutic agents, nutrients, drugs, such as antibiotics, blood and blood products, coagulants, and painkillers, as well as other fluids. The devices can be used to introduce the infusion fluid into the patient's body using any of several routes, such as, for example, intravenous, subcutaneous, intra-arterial, or epidural.

[0005] It is sometimes desirable to remove the syringe from the syringe pump, manually administer a bolus to the patient, reinsert the syringe into the syringe pump, and resume delivery of infusate by the syringe pump. In this regard, a bolus or loading dose (!loading dose!) can represent the maximum volume that can be rapidly delivered to the patient. For example, an anesthesiologist may wish to deliver a manual bolus dose of propofol to a patient by either unlatching the plunger driver head of the syringe pump and manually advancing the plunger driver head to administer a bolus dose of propofol from the syringe, or by completely removing the syringe from the pump and manually depressing the syringe plunger to deliver the bolus. Currently, the volume of a manually delivered bolus is visually estimated and manually recorded by the clinician (provided the clinician remembers to record the visually estimated volume delivered with acceptable accuracy and does not fail before recording it). The need to manually deliver a bolus may be to infuse at a faster rate than can be supplied by a syringe pump, or to initiate the bolus more quickly without the time delay introduced by programming the bolus. While programmed infusions can currently be automatically captured electronically into the patient record, manual boluses, because they occur outside of pump-based infusions, cannot. Thus, there is a long-felt need to improve the accuracy and reliability of estimating and recording manual bolus administration by reducing or eliminating the visual estimation and subsequent manual data entry of administered manual bolus volume and time.

[0006] Therefore, it would be useful and advantageous to provide an apparatus and method for a syringe pump that calculates an estimate of the volume of a manual bolus administered while the syringe pump is not injecting, and records and transmits such data to an electronic records management system, such as a Pharmacy Management System, an Electronic Medical Records (EMR) system, an Electronic Health Records (EHR) system, or a Hospital Information System (HIS) (collectively, "electronic systems"). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 4,978,335 [Patent Document 2] U.S. Patent No. 8,182,461 [Patent Document 3] U.S. Patent No. 8,209,060 [Patent Document 4] International Publication No. 2016 / 183342 Summary of the Invention

[0008] The present disclosure describes a novel and inventive apparatus and method for a syringe pump that calculates the volume of a manual bolus while the delivery of infusate by the syringe pump is paused.

[0009] In the context of a syringe pump, infusate delivery from a syringe is typically directly proportional to the movement of the syringe's plunger head. Accordingly, embodiments described herein disclose devices and methods for measuring the position of the plunger head when infusate delivery by the syringe pump is paused and when infusate delivery by the syringe pump is resumed again. If, upon resumption of infusate delivery by the syringe pump, the plunger head position has been advanced relative to the time delivery was paused, an estimate of the manual bolus volume imparted during administration of the manual bolus from a syringe temporarily removed from the syringe pump can be calculated and recorded by the syringe pump and / or by an electronic system.

[0010] In an embodiment of the novel and inventive subject matter of the present disclosure, a syringe pump detects that one of its control features, for example, a field or button defined within a graphical user interface, is touched or pressed to cause a pause in the syringe pump's infusion delivery. The syringe pump then records a first signal (e.g., a voltage or frequency signal) from a linear potentiometer within the syringe pump at that time. The first signal corresponds to a first position of the syringe pump's plunger driver. After the manual bolus is administered, the syringe pump operator reinserts the syringe into the syringe pump, slides the plunger driver forward, and touches a field or button defined on the graphical user interface to resume the infusion. The syringe pump then records a second signal from the linear potentiometer at which time the syringe pump's infusion delivery resumes. The second signal corresponds to a second position of the syringe pump's plunger driver. The syringe pump then calculates the distance the plunger driver of the syringe pump has been moved forward in response to the first and second signals of the linear potentiometer, and further calculates the displaced volume by multiplying the distance the plunger driver has been moved forward by the internal cross-sectional area of ​​the syringe in use.

[0011] In one embodiment, the syringe pump can detect a characteristic of the syringe, such as an RFID tag or barcode portion of the syringe. For example, the RFID tag or barcode can include information about the syringe's starting or initial volume. The syringe pump can additionally or alternatively access information about the syringe, such as via an electronic system, including the syringe's inner diameter or volume per unit of syringe plunger displacement. Additionally or alternatively, the syringe pump can calculate an estimate of the manual bolus volume and record the manual bolus volume. In one embodiment, the syringe pump transmits its calculation of the bolus volume delivered for each distance the plunger drive arm is advanced during the pause and the subsequent calculation of the volume displaced to the electronic system to estimate and record the manual bolus volume. In one embodiment, the syringe pump displays a message on a user interface asking the syringe pump operator to confirm that a manual bolus was administered during the pause of the syringe pump's infusion fluid delivery. In one embodiment, the syringe pump can prompt the operator to confirm the calculated manual bolus volume and / or dosage when confirming delivery of the manual bolus. In particular, the pump can prompt for confirmation that the manual bolus has been delivered, at which point the calculated bolus volume can also be presented or displayed for confirmation, allowing the operator to visually recognize the specific volume that will be recorded. If the operator confirms that the manual bolus has been delivered, that estimate is recorded by the syringe pump or electronic system.

[0012] In other embodiments, the volume of a manually delivered bolus may be determined or closely approximated by alternative means of identifying the linear position of the syringe plunger, for example, by optical or other detection means.

[0013] In other embodiments, the volume of a manually delivered loading or induction dose may be captured by the pump, typically the volume of a bolus delivered at the beginning of an infusion prior to placing the syringe in the syringe pump. In this embodiment, the volume of the loading dose may be calculated and recorded by considering the initial volume included on the syringe label or recorded in an RFID tag on the syringe and the post-bolus volume calculated based on the syringe plunger position when loading the syringe into the pump. Alternatively, the loading dose may be delivered by the clinician manually pushing the plunger assembly forward with the syringe placed in the pump, in which case the linear position before and after the manual loading dose may be determined in the same manner as a manual bolus during an infusion.

[0014] An embodiment may include a syringe pump including a pump housing and a drive assembly. The drive assembly is slidably movable horizontally to extend and retract relative to the pump housing and includes a plunger drive head, a drive arm, a lead screw, a motor, and a linear potentiometer. The plunger drive head has a surface structure that selectively and forcibly applies a force to a thumb press of a syringe plunger along a first central longitudinal axis when the syringe is installed in the syringe pump. The syringe is configured to contain an infusion solution and includes a barrel and a plunger slidably residing within the barrel and configured to together define the first central longitudinal axis. The drive arm includes an elongated plunger tube having a second longitudinal axis generally parallel to the first central longitudinal axis. The drive arm is coupled to the plunger drive head such that movement of the elongated plunger tube corresponds to a generally equal and parallel movement of the syringe plunger along the first central longitudinal axis. The lead screw is operatively coupled to the drive arm, and the motor is operatively coupled to the lead screw for governing movement of the lead screw, and consequently the drive arm, when the pump is operating to expel infusion fluid from the syringe. The linear potentiometer generates a signal (e.g., voltage or frequency) output proportional to the insertion distance of the rod inside the elongated plunger tube.

[0015] Apparatus and methods for calculating an estimate of the volume of a manual bolus administered while syringe pump delivery of infusion fluid is paused are illustrated by way of example, and not by way of limitation, in the figures identified below. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a front perspective view of a syringe pump according to one embodiment. [Figure 2] FIG. 2 is a rear perspective view of the syringe pump of FIG. 1 according to one embodiment, allowing for viewing of the internal components of the drive assembly that are generally obstructed by the syringe pump housing. [Figure 3] FIG. 3 is a partial perspective view of a syringe pump drive assembly according to one embodiment. [Figure 4] FIG. 4 is a partial perspective view of a syringe pump drive assembly according to one embodiment. [Figure 5] FIG. 5 is a partial side view of a syringe pump drive assembly according to one embodiment. [Figure 6] FIG. 6 is an example of a linear potentiometer for use in a syringe pump drive assembly according to one embodiment. [Figure 7] FIG. 7 is a flowchart of a method for calculating and recording an estimate of the volume of a manual bolus administered while delivery of infusate by a syringe pump is paused, according to one embodiment. [Figure 8] FIG. 8 is a flowchart of a method for calculating and recording an estimate of the volume of manual loading delivery to be administered before reducing to a lower maintenance delivery of infusate by a syringe pump, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] The devices and methods described in further detail by example herein calculate and record an estimate of the volume of a manual bolus administered from a syringe while delivery of infusate by the syringe pump is paused, such as when a manual bolus is administered to a patient by a clinician after the syringe has been removed from the pump. This can be accomplished by removing the syringe from the syringe pump, manually advancing the syringe plunger, reinserting the syringe into the syringe pump, and resuming delivery of infusate by the syringe pump. Such functionality can provide advantages not contemplated by existing syringe pump systems, and such advantages are illustrated by example herein.

[0018] In an example embodiment of an apparatus and method for calculating and recording an estimate of the volume of a manual bolus administered to a patient by a clinician, the above functionality is achieved by a syringe pump including a drive assembly or “drive train” having a linear potentiometer and configuration enabling the corresponding capabilities. This arrangement embodiment contemplates improved documentation of the volume of infusate the patient received immediately following administration of the manual bolus and the total volume of infusate administered to the patient at the time delivery of infusate by the syringe pump was discontinued. Such documentation is an improvement over conventional or other known processes in which a clinician visually estimates the volume of an administered manual bolus and manually records it. During certain medical procedures and patient responses, a clinician may not have adequate opportunity to accurately record their estimate, potentially resulting in errors in later recall of the administered volume. This arrangement embodiment also contemplates reducing or eliminating the risk of human error, such as a manual bolus not being entered into an electronic system database due to human forgetfulness, human incompetence, or lost documentation.

[0019] Generally, accuracy and control of infusate delivery are two desirable aspects of effective operation for a syringe pump. Based on fundamental features of its design, the syringe is intended to provide infusion delivery that is directly proportional to the movement of the drive arm. FIG. 1 shows an example embodiment of a syringe pump 10 configured for precise infusion control. The syringe pump 10 includes a housing 12 configured to receive a syringe 20 having a barrel 30 and a plunger 40 with a plunger tip 50 and a thumb press 60. The illustrated housing 12 is generally box-shaped and encloses the internal drive components of the pump 10 and provides a structure for externally receiving the syringe 20. The syringe 20 is typically prescribed by a pharmacist or other qualified clinician. Its internal diameter or delivery volume per unit length can be entered into an electronic system. As an added safeguard, the syringe may have a feature detectable by the syringe pump, such as a bar code or RFID tag, to enable the syringe pump to verify that the correct syringe has actually been loaded into the syringe pump. The syringe 20 is configured to contain a medication or other infusion fluid to be delivered to a patient from the syringe pump 10. Specifically, the syringe pump 10 is configured to act on the syringe 20 by a plunger driver head 70 that selectively and forcibly applies force, such as against the thumb press 60 of the plunger 40. Movement of the plunger driver head 70 is generally controlled by a drive assembly 100 that enables its slidable movement to extend and retract horizontally relative to the housing 12. The barrel 30 and plunger 40 together define a central longitudinal axis 80 of the syringe 20.

[0020] Syringe pump 10 also includes software (not explicitly shown) and display means, which in one embodiment may be provided by suitable computing components (not explicitly shown) and a display screen or graphical user interface 90, located, for example, on the front of syringe pump 10 in FIG. 1 . A user may use interface 90 to effectively observe and control pump 10 or otherwise interact with the programming and operation of pump 10. In some embodiments, such pump programming operations may interact with an infusate delivery "engine" that determines the volume of infusate delivered from syringe 20 based in part on sensor data, such as from a distance sensor, among other pump information and parameters.

[0021] For purposes of this disclosure, the term “engine” may be defined as a real-world device, component, or arrangement of components implemented using hardware, or as a combination of hardware and software, such as a processor system and a set of specific program instructions that, while executing, adapt or prompt the engine to implement specific functions that transform the processor system into an application-specific device. An engine may also be implemented as a combination of the two, with certain functions performed solely by hardware and other functions performed by a combination of software-controlled hardware. In particular implementations, at least some, and possibly all, of an engine may include one or more computer processors that run an operating system, system programs, and application programs, while an engine may also be implemented using multitasking, multithreading, distributed (e.g., cluster, peer-peer, cloud) processing, or other such techniques, as appropriate. Furthermore, an engine may itself be composed of multiple sub-engines, each of which, collectively or individually, may be considered an engine.

[0022] 2-5, with continued reference to FIG. 1, various partial views of an embodiment of a drive assembly 100 of a syringe pump 10 are shown. The drive assembly 100 of the pump 10 includes a plunger drive head 70, a linear potentiometer 110, a plunger tube 120, a lead screw 130, a lead screw housing 140, a gear 150, and a motor 160. Generally, the drive assembly 100 is supported between a first support plate 170 and a second support plate 180, each located on either side of the housing 12. A plunger head drive arm 190 extends through the second support plate 180. The plunger head drive arm 190 generally refers to the combination of elongated components extending across the drive assembly 100 and may include, for example, the plunger tube 120 and the lead screw housing 140. The plunger tube 120 may comprise a hollow tube that extends across the top of the plunger head drive arm 190, but in some embodiments may be formed integrally with the lead screw housing 140.

[0023] The plunger driver head 70 is shown in FIG. 3 as a plate-like or generally oval, disk-like component attached to one end of the plunger head driver arm 190 near one edge of its surface. Also referring to FIG. 1, the opposite edge of the plunger driver head 70 provides a surface structure 200 (as identified in FIG. 3) for selectively engaging the thumb press 60 of the syringe 20 and applying a forcing force along the longitudinal axis 80. This surface structure 200 may simply comprise a generally flat surface of the plunger driver head 70, or it may include various protruding or recessed areas for providing engagement with the thumb press 60 when the syringe 20 is installed in the pump 10. Although not shown, the driver head 70 may include one or more thumb press capture components or "flippers" that releasably engage a thumb press flange or other captureable surface of the syringe. Thus, the plunger drive head 70 can controllably push the thumb press 60, and thus the plunger 40, within the barrel 30 of the syringe 20 in response to rotation by the lead screw 130, which in turn pulls the plunger drive head 70 toward the housing 10. The rotation of the lead screw 130 is thus controlled by rotational motion imparted by a motor 160, which drives a gear 150 that engages the lead screw 130 to enable the rotational motion.

[0024] As best visually shown in FIGS. 2-4 , the linear potentiometer 110 extends between the first support plate 170 and the plunger tube 120. Specifically, in this embodiment, the linear potentiometer 110 is fixed at one end to the first support plate 170 and extends at the opposite end into an opening 202 in the plunger tube 120 of the plunger head drive arm 190. The elongated plunger tube 120 has a longitudinal axis 204 passing through its center that is generally parallel to the longitudinal axis 80 (e.g., as shown in FIG. 2 ) and aligned with the longitudinal axis of the linear potentiometer 110. Furthermore, when installed in the syringe pump 10, the linear potentiometer 110 is oriented substantially parallel to the central longitudinal axis 80 of the syringe 20. Similarly, in this exemplary embodiment (e.g., as shown in FIG. 3 ), the lead screw 130 and the motor 160 are fixed to the first support plate 170. Lead screw 130 is oriented substantially parallel to central longitudinal axis 80 of syringe 20 and linear potentiometer 110. The embodiment uses linear potentiometer 110, which is a high-precision type of linear potentiometer that is specially integrated into syringe pump 10.

[0025] In certain embodiments, the linear potentiometer 110 includes, for example, an inner wound coil that conducts current in a clockwise direction and an outer wound coil that conducts current in a counterclockwise direction. For example, possible linear potentiometers that can be used in embodiments of the proposed syringe pump include the Distributed Impedance Sensor Technology (DIST) sensor and related technology manufactured by LRT Sensors LLC. of Huntingdon Valley, Pennsylvania. In such an embodiment, as shown in FIG. 6 , the linear potentiometer 110 can be a sensor including a double coil 210 wound on a circular, non-conductive fiberglass rod 220. The wire is wound around the first coil as a spiral with a large pitch. At the end of the rod 220, the pitch is reversed, and a second coil as a returning spiral is superimposed on the first coil. One end of the rod 220 includes an electronic device 230 including a transistor connected to the spiral wire assembly resulting from the first and second coils, generating a resonant circuit and oscillation. The opposite end of the rod 220 comprises a rod tip 232, which is the portion of the rod 220 that is first shielded by the plunger tube 120 during pumping.

[0026] This configuration results in two coils in series, one with a generally clockwise current flow and the other with a generally counterclockwise current flow. When energized, the resulting magnetic fields in the coils are generally parallel to the sensor but in opposite directions, thus canceling each other. The electric fields from the currents are generally perpendicular to the rod 220 and therefore additive. This provides an electromagnetic field outside the coils, which is predominantly electrical. As a result, the exemplary linear potentiometer 110 discussed does not require magnets or magnetic materials in various embodiments. The potentiometer 110 is generally insensitive to external magnetic fields, which may allow satisfactory operation in environments experiencing high magnetic fields.

[0027] The frequency of a circuit including a DIST sensor is determined by the inductance and capacitance of the spiral wire assembly. Operating the circuit at its resonant frequency typically results in a very stable output. The assembly's inductance is low and constant due to the relatively small number of turns in the first and second coils, but the ratio of capacitance to inductance is higher than in an inductive sensor and is based on the interaction of the sensor's strong electric field with any nearby conductive surfaces. Therefore, one way to significantly change the capacitance and resonant frequency of the sensing element is to cover the coil and rod with a conductive structure. In an embodiment of the syringe pump 10 including a DIST sensor, the spiral wire assembly and rod 220 are partially and slidably covered by an elongated plunger tube 120 made of a conductive material. Even a 1 MHz change in resonant frequency can result as the plunger tube 120 moves on the potentiometer 110. The frequency change is linear with respect to the movement of the plunger tube 120. These changes can be transmitted and converted into a digital signal for further processing as required.

[0028] A DIST sensor used as a linear potentiometer 110 is advantageous because it is a relatively simple device requiring only a single wire for power and information transmission. The digital output frequency can be "piggybacked" or carried on or in conjunction with a DC power supply, thereby requiring only one wire and allowing the receiver to be located remotely. This wire provides great flexibility in locating the signal analysis electronics, due in part to the large length of the signal wire. Generally, using only one wire minimizes problems. Thus, the DIST sensor is a simple, economical, and compact device useful for making accurate linear measurements using only a single wire for power and signal.

[0029] DIST sensors do not need to use extremely thin wires as other sensor structures, but can instead use heavy wires, which are generally designed to maximize capacitance. A more robust wire is advantageous because heavy wire wound on a flexible rod can withstand extremely high levels of shock and vibration, overcoming the susceptibility of other sensors to these disturbances.

[0030] In some embodiments, a conventional linear potentiometer can be used in place of the DIST sensor. The resistance to current flowing through a conventional linear potentiometer in a syringe pump is an indication of the position of the plunger rod drive arm, and the resulting voltage output is an indication of its linear position. An example of a commercial pump incorporating such a conventional linear potentiometer is the MEDFUSION 4000 syringe pump manufactured by Smiths Medical ASD Inc.

[0031] 4 and 5 further illustrate partial views of an embodiment of syringe pump drive assembly 100, in which the structural relationships and arrangement of components that enable the effective use of a type of linear potentiometer, such as potentiometer 110, can be more fully appreciated. Specifically, in these embodiments, linear potentiometer 110 and plunger tube 120 are axially aligned with one another. Furthermore, linear potentiometer 110 and plunger tube 120 are positioned vertically above lead screw 130. Thus, the respective axes of rod 220 of linear potentiometer 110, elongated plunger tube 120, and lead screw 130 are generally parallel to one another and project outwardly in a generally vertical orientation from the generally planar surface of first support plate 170.

[0032] 3, the linear potentiometer 110 can be a DIST sensor that generates a frequency output proportional to the insertion distance 236 of the sensor (i.e., rod 220) inside a metal or aluminum tube, such as the plunger tube 120. This insertion distance 236 of the sensor can be understood to represent the covered length of the rod 220 extending between the opening 202 of the plunger tube 120 and the position of the rod tip 232 within the plunger tube 120. This insertion distance 236 of the sensor (i.e., rod 220) determines the frequency output. Thus, as the position of the plunger tube 120 changes as it slides with the drive arm 190—e.g., relative to the plate 170—its frequency output also changes. This frequency can be measured to within 1 Hz in various embodiments. The corresponding change in the distance of plunger travel for such a 1 Hz measurement is, in certain embodiments, approximately 1 micron. Such a level of accuracy allows for detection of displacement to within 1 micron, whereas previously known syringe pumps are only capable of resolution to within about 500 microns. In other embodiments, a conventional linear potentiometer may be used in place of the DIST sensor.

[0033] It should therefore be understood that, generally, the linear potentiometer and associated electronics and processing hardware / software of the injectate delivery engine, as described or otherwise discussed herein with respect to syringe pump 10, enable the determination of the specific position of the plunger relative to the barrel of a syringe installed in pump 10. In certain embodiments, the linear potentiometer may include position sensing technology similar to that described in U.S. Pat. No. 7,216,054 to Pchelnikov et al. and U.S. Pat. No. 8,692,541 to Nyce et al. Accordingly, a linear potentiometer 110, such as that embodied in the DIST sensor described above, is incorporated into the structure of drive assembly 100 of syringe pump 10. The architecture must be constructed to support a configuration whose frequency output is proportional to the displacement of linear potentiometer 110 inside plunger tube 120. As shown in FIGS. 2-5 , some embodiments configure the lead screws 130, which drive the movement of the thumb press 60 and, therefore, the plunger 40, to be generally parallel, such that movement of the plunger 40 directly corresponds to movement of the potentiometer 110, resulting in detection of a frequency output signal. Thus, movement of the plunger 40 along the longitudinal axis 80 causes the plunger tube 120 to move a substantially equal distance in the same direction. Additionally, the linear potentiometer 110 is positioned such that it is rigidly coupled at its end to a first support plate 170. The lead screw 130 is coupled to a stepper motor 160 via a gear 150, which may be housed in a gearbox (not shown). The lead screw 130, as well as the lead screw housing 140, drive the plunger tube 120 relative to the linear potentiometer 110. Both the plunger tube 120 and the lead screw housing 140 comprise components of a plunger head drive arm 190. Thus, motor 160 is operatively coupled to lead screw 130 and controls the movement of lead screw 130 and therefore drive arm 190 .

[0034] As a result, injectate delivery and determination occurs when the plunger head drive arm 190 acts to advance the plunger 40 within the syringe 20. The drive arm 190 causes the linear potentiometer 110 to sense the current position of the drive arm 190, for example, by measuring a frequency or voltage output as previously described. In this manner, the known position of the drive arm 190 is used to determine the position of the plunger tip 50, allowing the software to accurately provide useful information regarding the pump's delivery of injectate from the syringe.

[0035] A display screen or graphical user interface 90 can provide infusion fluid delivery information and control of the syringe pump 10. The interface 90 can include, for example, suitable touchscreen or LCD technology. Examples of touchscreen devices are generally disclosed in U.S. Patent Application Publication No. 2006 / 0097991, entitled "Multipoint Touchscreen," and U.S. Patent Application Publication No. 2011 / 0193788, entitled "Graphical Objects that Respond to Touch or Motion Input." Examples of new and inventive infusion pump technology employing touchscreen devices are disclosed in U.S. Patent Application Publication No. 5,485,408, entitled "Pump Simulation Apparatus," and U.S. Patent Application Publication No. 2009 / 0270810, entitled "Security Features for a Medical Infusion Pump."

[0036] It will also be recognized and understood that the types, components, dimensions, fabrication processes, and other details and parameters of the foregoing embodiments may be substituted or supplemented as desired.

[0037] It should be appreciated and understood that during administration of infusion fluid by a clinician to a patient, the clinician can pause delivery of infusion fluid by the syringe pump, remove the syringe from the syringe pump, manually advance the syringe plunger to administer a “manual bolus,” reinsert the syringe into the syringe pump, and cause the syringe pump to resume delivery of infusion fluid. An estimate of the manual bolus volume provided during administration of a manual bolus from a syringe 20 temporarily removed from the syringe pump 10 can be calculated and recorded by the syringe pump 10. The syringe pump 10 detects that one of its control features, for example, a field or button defined within the graphical user interface 90, has been touched or pressed to pause delivery of infusion fluid by the syringe pump. The syringe pump then records, for example, the frequency or voltage signal from the linear potentiometer 110 at that time. After the manual bolus is administered, the operator of syringe pump 10 reinserts syringe 20 into syringe pump 10, slides plunger head drive arm 190 forward, and touches a field or button defined on graphical user interface 90 to resume syringe pump delivery of infusate. Syringe pump 10 records the signal from linear potentiometer 110 at the time syringe pump delivery of infusate resumes. Syringe pump 10 then calculates the distance plunger head drive arm 190 was moved forward while syringe pump 10 delivery of infusate was paused.

[0038] The syringe pump 10 can detect a characteristic of the syringe 20, such as an RFID tag or barcode portion of the syringe 20, access information about the syringe 20 through the electronic system, including the internal diameter of the syringe 20 or the volume per unit of plunger displacement, calculate an estimate of the manual bolus volume, and record the estimate of the manual bolus volume. In one embodiment, the syringe pump 10 then transmits the information to the electronic system for recording. In one embodiment, the syringe pump 10 does not need to detect a characteristic of the syringe 20, but rather transmits a calculation of the distance the plunger drive arm 190 was advanced during the pause to the electronic system, which calculates and records the estimate of the manual bolus volume.

[0039] In one embodiment, syringe pump 10 displays a message on interface 90 asking the operator of syringe pump 10 to confirm that a manual bolus was administered during the pause in syringe pump delivery of infusate. In one embodiment, the confirmation includes presenting the calculated volume and / or dose to the clinician. If and only if the operator confirms that a manual bolus was administered, is the manual bolus estimate recorded.

[0040] Referring now to FIG. 7, an example of the operation of a syringe pump system is shown, including a method for calculating and recording a manual bolus estimate. In FIG. 7, an embodiment is disclosed, described by a flowchart of a method 300 for calculating and recording a manual bolus estimate. First, at 310, a syringe pump, such as pump 10, is provided, including a pump housing 12 and a drive assembly 100 that slidably extends and retracts relative to the pump housing 12. Drive assembly 100 includes a plunger drive head 70, a drive arm 190, a lead screw 130, a motor 160, and a linear potentiometer 130. Further, at 310, the method includes receiving a syringe 20 filled with a total volume of infusion fluid into syringe pump 10.

[0041] At 320, the method also includes starting delivery of infusion fluid by syringe pump 10. At 330, the method further includes pausing delivery of infusion fluid by syringe pump 10.

[0042] At 340, the method further includes resuming delivery of infusion fluid by syringe pump 10. At 350, syringe pump 10 calculates the distance the plunger rod drive arm was advanced while delivery of infusion fluid by syringe pump 10 was paused by comparing the signal from linear potentiometer 110 at the time delivery of infusion fluid by syringe pump 10 was paused with the signal from linear potentiometer 110 at the time delivery of infusion fluid by syringe pump 10 was resumed.

[0043] At 360, the syringe pump 10 or the electronic system determines a characteristic of the syringe indicating its internal diameter or volume per unit of syringe plunger displacement. At 370, the syringe pump 10, the electronic system, or both calculates an estimate of the volume of the manual bolus (e.g., to be administered by a clinician to a patient). At 380, the syringe pump 10, the electronic system, or both record the estimate of the volume of the manual bolus.

[0044] 8, an example of the operation of a syringe pump system is shown, including a method for calculating and recording an estimate of a manual loading dose or induction dose ("loading dose"). A loading dose of infusate may be administered without relying on the pump for administration when, for example, it is necessary or desirable to infuse an initial, higher dose of infusate relatively quickly at the beginning of the patient infusion process, followed by a decrease to a maintenance delivery of a lower infusate.

[0045] 8 discloses an embodiment described by a flowchart of a method 800 for calculating and recording a loaded dose estimate. First, at 810, a syringe pump such as pump 10 is provided, including a pump housing 12 and a drive assembly 100 that slidably extends and retracts relative to the pump housing 12. Drive assembly 100 includes a plunger drive head 70, a drive arm 190, a lead screw 130, a motor 160, and a linear potentiometer 130. Further, at 810, the method includes receiving a syringe 20 filled with a total volume of infusion fluid into syringe pump 10.

[0046] At 820, the method also includes initiating delivery of the loading dose, for example, by disengaging syringe 20 from plunger driver head 70 and manually advancing the plunger of syringe 20 in response to the intended loading dose volume or amount or an observed patient response. At 830, the method further includes terminating delivery of the loading dose.

[0047] At 840, the method further includes initiating a maintenance delivery of the lower infusate by syringe pump 10, thereby re-engaging the plunger of syringe 20 with plunger drive head 70. At 850, syringe pump 10 calculates the distance the plunger rod drive arm has advanced since delivery of the load dose by comparing the signal from linear potentiometer 110 at the time just prior to delivery of the load dose with the signal from linear potentiometer 110 at the time the maintenance delivery of the lower infusate was initiated.

[0048] At 860, the syringe pump 10 or the electronic system determines a characteristic of the syringe indicating its internal diameter or volume per unit of syringe plunger displacement. At 870, the syringe pump 10, the electronic system, or both calculates an estimate of the volume of the loaded dose. At 880, the syringe pump 10, the electronic system, or both record the estimate of the volume of the loaded dose.

[0049] In one embodiment, rather than removing the syringe from the pump to manually deliver the loading dose, the clinician may leave the syringe loaded in the pump and manually deliver the loading dose by manually depressing the pump plunger drive head 70 (FIG. 1) which delivers the loading dose to the patient, and simultaneously depressing the forward-mounted syringe plunger 40 into the barrel 30.

[0050] Although not specifically illustrated, it should be appreciated and understood that the processes described by way of example with reference to Figures 7 and 8 may be provided alternatively or in any suitable combination with one another to advantageously provide for efficient estimation and / or recording of specific infusate delivery to a patient.

[0051] It should also be appreciated and understood that the subject matter herein is suitable for and can accommodate a variety of infusion measurements or parameters depending on the particular clinical need. For example, a manual bolus or loading dose may be characterized as a volume (e.g., 5 mL) or as a dose (e.g., 5 mg).

[0052] Regardless of the particular embodiment, it should be appreciated and understood that embodiments of devices, systems, and methods relating to syringe pumps that estimate and record manual bolus volume provide convenience and efficiency and reduce the likelihood that the manual bolus volume will not be recorded accurately or at all.

[0053] Although reference is made herein to manual bolus administration to a patient, it should also be recognized and understood that embodiments of the devices, systems, and methods, as exemplary described or otherwise discussed herein, may be useful in virtually any situation where a syringe is removed from a syringe pump and the syringe plunger is manually advanced before reinstalling the syringe in the pump. Such a situation may be, for example, when air is found in the syringe and needs to be quickly expelled, or when a "flush" of infusion fluid is desired through tubing connected to the syringe.

[0054] Furthermore, it should be recognized and understood that in some situations, a manual bolus may be delivered while the pump is infusing or paused. For example, an anesthesiologist may prescribe a continuous infusion of propofol, but the patient receiving the infusion begins to prematurely recover from the anesthetic effect. In such a situation, the anesthesiologist may preemptively prescribe the administration of a "top-up" bolus to adequately maintain the patient under the effects of anesthesia. The devices, systems, and methods described by example or otherwise discussed herein can advantageously provide for the estimation and recording of such a "top-up" bolus.

[0055] Furthermore, it should be recognized and understood that information exchange or code recognition may be advantageously used in the devices, systems, and methods described by example or otherwise discussed herein. For example, an information exchange or code recognition system, such as an RFID or barcode (as described above), or a QR code, may be useful in situations where a syringe has been completely removed from a pump and the operator is unsure or desires positive confirmation as to whether the same syringe has been reinserted into the pump. An information exchange or code recognition system (e.g., the RFID, barcode, QR code described above) may be on or associated with the syringe to help confirm that the syringe has not been accidentally swapped with another syringe of a similar brand or volume, or with another syringe containing a different medication, or with another syringe containing the same medication at a different concentration.

[0056] While the syringe pump device, system, and method for estimating and recording manual bolus volume have been particularly shown and described with reference to the accompanying drawings and specification, it should be understood that other modifications thereto are possible, and all are intended to be within the true spirit and scope of the novel and inventive device, system, and method described herein. Accordingly, the configuration and components of various features may be modified or varied depending on the particular embodiment. For example, additional steps may be included to various method steps described by example or otherwise discussed herein, such as a step in which the syringe pump displays a message asking the syringe pump operator to confirm that the manual bolus has been administered.

[0057] It should also be understood that, in general, any suitable alternatives may be used to provide the new and inventive apparatus, systems, and methods for syringe pumps for estimating and recording manual bolus volume described by example or otherwise contemplated herein. The composition, size, and strength of the various components of the apparatus, systems, and methods for syringe pumps for estimating and recording manual bolus volume described by example or otherwise contemplated herein are all matters of engineering choice depending on their intended use.

[0058] Accordingly, these and various other changes or modifications in form and detail may also be made without departing from the true spirit and scope of the syringe pump related devices, systems, and methods for estimating and recording manual bolus volume.

Claims

1. A syringe pump, the syringe pump comprising: A pump housing; a drive assembly that slidably extends and retracts relative to the pump housing, the drive assembly comprising: a plunger drive head having a surface structure that selectively applies a force to a syringe along a first central longitudinal axis when the syringe is installed in the syringe pump, the syringe being configured to contain an infusion fluid and including a barrel and a plunger that define the first central longitudinal axis; a drive arm including an elongated plunger tube having a second longitudinal axis generally parallel to the first central longitudinal axis, the drive arm being coupled to the plunger drive head such that movement of the elongated plunger tube corresponds to movement of the syringe plunger along the substantially equal and substantially parallel first central longitudinal axis; a lead screw operatively coupled to said drive arm; a motor operatively coupled to the lead screw for movement of the lead screw and the drive arm; a potentiometer, said potentiometer generating a signal proportional to the insertion distance of a rod inside said elongated plunger tube; a control feature used by an operator of the syringe pump to pause delivery of the infusion fluid by the syringe pump; a control feature used by the operator of the syringe pump to resume delivery of the infusion fluid by the syringe pump; and a drive assembly comprising a processor that calculates a distance the drive arm is advanced while delivery of the infusion fluid by the syringe pump is paused.

2. 2. The syringe pump of claim 1, wherein the syringe pump detects information about the syringe that identifies characteristics of the syringe, including internal diameter or volume per unit of syringe plunger displacement, and calculates the volume of a manual bolus performed while delivery of the infusion fluid by the syringe pump is paused.

3. 3. The syringe pump of claim 2, wherein the syringe pump records the volume of the manual bolus given while delivery of the infusion fluid by the syringe pump is paused.

4. 3. The syringe pump of claim 2, wherein the syringe pump transmits the volume of the manual bolus given while delivery of the infusion fluid by the syringe pump is paused to an electronic system.

5. 3. The syringe pump of claim 2, wherein the syringe pump transmits to an electronic system the distance the drive arm was advanced while delivery of the infusion fluid by the syringe pump was paused, and the electronic system calculates the volume of the manual bolus administered while delivery of the infusion fluid by the syringe pump was paused.

6. 1. A method for calculating the volume of a manual bolus performed while delivery of infusion fluid by a syringe pump is paused, the method comprising: A syringe pump is provided, the syringe pump comprising: A pump housing; a drive assembly that slidably extends and retracts relative to the pump housing, the drive assembly comprising: a plunger drive head having a surface structure that selectively applies a force to a syringe along a first central longitudinal axis when the syringe is installed in the syringe pump, the syringe being configured to contain an infusion fluid and including a barrel and a plunger that define the first central longitudinal axis; a drive arm including an elongated plunger tube having a second longitudinal axis substantially parallel to the first central longitudinal axis, the drive arm being coupled to the plunger drive head such that movement of the elongated plunger tube corresponds to movement of the syringe plunger along the substantially equal and parallel first central longitudinal axis; a lead screw operatively coupled to said drive arm; a motor operatively coupled to the lead screw for movement of the lead screw and the drive arm; a potentiometer, said potentiometer generating a signal proportional to the insertion distance of a rod inside said elongated plunger tube; a control feature used by an operator of the syringe pump to pause delivery of the infusion fluid by the syringe pump; a control feature used by the operator of the syringe pump to resume delivery of the infusion fluid by the syringe pump; and a drive assembly comprising a processor that calculates a distance the drive arm has advanced while delivery of the infusion fluid by the syringe pump is paused; and calculating the distance the drive arm was advanced while delivery of the infusion fluid by the syringe pump was paused.

7. 7. The method of claim 6, wherein the syringe pump detects information about the syringe that identifies characteristics of the syringe, including internal diameter or volume per unit of syringe plunger displacement, and calculates the volume of the manual bolus performed while delivery of the infusion fluid by the syringe pump was paused.

8. 8. The method of claim 7, wherein the syringe pump records the volume of the manual bolus given while delivery of the infusion fluid by the syringe pump is paused.

9. 7. The method of claim 6, wherein the syringe pump transmits to an electronic system the volume of the manual bolus given while delivery of the infusion fluid by the syringe pump is paused.

10. 8. The method of claim 7, wherein the syringe pump transmits to an electronic system the distance the drive arm was advanced while delivery of the infusion fluid by the syringe pump was paused, and the electronic system calculates the volume of the manual bolus administered while delivery of the infusion fluid by the syringe pump was paused.

11. A syringe pump, comprising: A drive assembly, the drive assembly comprising: a plunger drive head configured to apply a force to a syringe when the syringe is installed in the syringe pump, the syringe being configured to contain an infusion fluid and including a barrel and a plunger defining a first central longitudinal axis; and a drive assembly comprising: a drive arm including an elongated plunger tube having a second longitudinal axis, the drive arm coupled to the plunger drive head such that movement of the elongated plunger tube corresponds to movement of the syringe plunger along the first central longitudinal axis that is substantially equal and substantially parallel; a control feature used by an operator of the syringe pump to pause and resume delivery of the infusion fluid by the syringe pump; a processor that calculates a distance the drive arm is advanced while delivery of the infusion fluid by the syringe pump is paused.

12. The syringe pump comprises: a lead screw operatively coupled to the drive arm; and 12. The syringe pump of claim 11, further comprising a motor operatively coupled to the lead screw for movement of the lead screw and the drive arm.

13. The syringe pump comprises:

13. The syringe pump of claim 12, further comprising a potentiometer that generates a signal proportional to a distance of insertion of a rod inside the elongated plunger tube.

14. A syringe pump as described in claim 13, wherein the syringe pump is configured to record the signal from the potentiometer at the time delivery of the injection fluid is paused.

15. A syringe pump as described in claim 14, wherein the syringe pump is configured to record the signal from the potentiometer at the time delivery of the injection fluid is resumed.

16. A syringe pump as described in claim 15, wherein the control feature is configured to display a message on a user interface requesting the operator to confirm that a manual bolus has been administered while delivery of the infusion fluid has been paused.

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