Infusion system with deformation and / or compliance compensation

Abstract

An infusion system includes an infusion device including a driver and an infusion set coupled to the driver, a sensor assembly including a sensor coupled to the infusion device, and a controller coupled to the driver and the sensor assembly. The controller is configured to actuate the driver according to a desired flow, receive a signal from the sensor, determine a deformation and / or a volume change of the infusion set based on the signal, determine a correction based on the deformation and / or volume change of the infusion set, and apply the correction to the driver.

Description

FLU23-02 PRO (9600-0005)INFUSION SYSTEM WITH DEFORMATION AND / OR COMPLIANCE COMPENSATIONTECHNICAL FIELD

[0001] The present disclosure is generally directed to infusion systems and methods with deformation compensation, compliance compensation, or both. For example, the present disclosure is directed to infusion systems in the form of a syringe pump incorporating a controller providing a method of compensating for plunger / pusher device deformation and / or syringe compliance.BACKGROUND

[0002] One type of infusion device commonly used for delivering a medical fluid, for example a medication or a nutritional fluid, is a syringe pump. The syringe pump includes a syringe having a barrel that is loaded with the medical fluid. The syringe pump also includes a pusher device that cooperates with a plunger received in the barrel of the syringe to move the medical fluid out of the barrel and into an infusion line connected to the barrel of the syringe. The pusher device typically is connected to an electromechanical drive system that causes the pusher device to move, and thus the plunger to move.

[0003] The process of applying a force to the plunger and causing the medical fluid to exit the syringe can cause changes to the components of the system, including the syringe pump and associated syringe. In this context, it is common to discuss the compliance of the components of the syringe pump (or related infusion set), and in particular the components of the syringe. Compliance may be referred to as a measurement of the degree to which a component deformsunder force. When referencing a syringe pump, one may refer to the compliance of the syringe body (i.e. , barrel) as well as the deformation of the plunger (or more appropriately, the pusher device with which the plunger is in contact).

[0004] The changes to the components of the infusion system can have an effect on the operation of the system. The changes may affect the delivery of the medical fluid by the system. The changes may also affect the detection of different states of the system, such as whether an occlusion has occurred in the system, such as in the infusion line or set. Consequently, device improvements have been considered, both hardware and software, to address specific effects caused by these changes to the components of the infusion system.SUMMARY

[0005] According to an aspect, an infusion system includes an infusion device including a driver and an infusion set coupled to the driver, a sensor assembly including a sensor coupled to the infusion device, and a controller coupled to the driver and the sensor assembly. The controller is configured to actuate the driver according to a desired flow, receive a signal from the sensor, determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.

[0006] According to another aspect, an infusion system includes an infusion device including a syringe including a barrel and a plunger, and a pusher device in engagement with the plunger, a sensor assembly including a sensor disposed between the plunger and the pusher device, and a controller coupled to thepusher device and the sensor assembly. The controller is configured to displace the pusher device a distance according to a desired flow, receive a signal from the sensor, determine a deformation of the pusher device based on the signal, optionally determine a volume change of the syringe based on the signal, determine a distance correction for the distance based on the deformation of the pusher device and optionally the volume change of the syringe, and apply the distance correction to the distance.

[0007] According to a further aspect, an infusion system includes an infusion device including a driver and an infusion set coupled to the driver, the infusion set having a downstream tube section, a sensor assembly including a sensor coupled to the downstream tube section, and a controller coupled to the driver and the sensor assembly. The controller is configured to actuate the driver according to a desired flow, receive a signal from the sensor, determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The disclosure will be more fully understood from the following description taken in conjunction with the accompanying drawings. Some of the figures may have been simplified by the omission of selected elements for the purpose of more clearly showing other elements. Such omissions of elements in some figures are not necessarily indicative of the presence or absence of particular elements in any of the exemplary embodiments, except as may beexplicitly delineated in the corresponding written description. None of the drawings is necessarily to scale.

[0009] Fig. 1 is a schematic view of an embodiment of an infusion system including an infusion device (in the form of a syringe pump), an infusion line or set, and a sensor assembly.

[0010] Fig. 2 is an enlarged, perspective view of an embodiment of an infusion system in accordance with the schematic of Fig. 1 .

[0011] Fig. 3 is a flowchart of a method of operating the embodiment of the infusion system according to Fig. 1 and / or 2.

[0012] Fig. 4 is a flowchart of a variant of the method of Fig. 3 of operating the embodiment of the infusion system according to Fig. 1 and / or 2.

[0013] Fig. 5 is a schematic view of an embodiment of an infusion system including an infusion device (in the form of a volumetric pump), an infusion line or set, and a sensor assembly.

[0014] Fig. 6 is a flow chart of a method of operating the embodiment of the infusion system according to Fig. 5.DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0015] A detailed description of an infusion devices and methods in accordance with the present disclosure is set forth below. It should be understood that the description below of specific devices and methods is intended to be exemplary, and not exhaustive of all possible variations or applications. Thus, the scope of the disclosure is not intended to be limiting, and should be understood toencompass all variations or embodiments that would occur to persons of ordinary skill.

[0016] Fig. 1 shows a schematic view of an embodiment of an infusion system, while Fig. 2 shows a perspective view of an embodiment of an infusion system consistent with the schematic of Fig. 1 . Consequently, both systems will be referred to as the infusion system 100, and similar components will be indicated with the same reference numerals. The infusion system 100 includes equipment generally grouped into an infusion device, or pump, 102, an infusion line or set 104, and a sensor assembly 106.

[0017] As will be explained below with reference to Fig. 2, the pump 102 may include a housing, and certain aspects of the infusion set and / or the sensor assembly may be connected to or mounted on the housing. Further, the pump 102 may include a controller, and the controller may be coupled to the sensor assembly 106 to receive signals therefrom. Consequently, the description of the system 100 as a pump 102, set 104, and sensor assembly 106 does not require a physical separation of elements, unless specifically stated. Indeed, aspects may be identified with the pump 102, the set 104, or both. Reference to a pump 102, set 104 and sensor assembly 106 herein is for ease of discussion.

[0018] As illustrated in Figs. 1 and 2, the pump 102 includes a syringe 110 with a barrel 112 having an outlet end 114. The syringe 110 also includes a plunger 116 with a first end 118 (or plunger head) disposed outside the barrel 112, and a second end 120 with a piston 122 that is disposed within the barrel 112 (see Fig.1 ). The second end 120 and the piston 122 are moveable within the barrel 112 in the direction towards and away from the outlet end 114.

[0019] The pump 102 also includes a pusher device 124, which may be described as part of a driver of the pump 102. As illustrated, the pusher device 124 is in engagement with (e.g., abuts) the first end 118 of the plunger 116. The movement of the pusher device 124 in a first direction causes the piston 122 to be moved along the barrel 112 in the direction of the outlet end 114 (see arrow A, Fig. 1 ). The movement of the pusher device 124 in a second direction causes the piston 122 to be moved along the barrel 112 in an opposite direction away from the outlet end 114.

[0020] As also illustrated in Figs. 1 and 2, the infusion set 104 includes an infusion line 130 having a first end 132 in communication with or coupled to the outlet end (or connector) 114 of the barrel 112. The line 130 also has a second end 134. The second end 134 is connected to a container or to a patient (not shown). The line 130 may be made of flexible tubing of a material such as a polyvinylchloride (PVC).

[0021] As illustrated in Figs. 1 and 2, the sensor assembly 106 includes a first sensor 140 disposed between the first end 118 of the plunger 116 and the pusher device 124. In a general sense, the sensor 140 is coupled to the infusion device, or pump, 102.

[0022] As illustrated in Fig. 1 , the pump 102 also includes a controller 144 coupled (i.e. , directly or indirectly connected) to the sensor assembly 106, and thus to the first sensor 140. The controller 144 may receive signals from thesensor assembly 106, and use the signals received to control the operation of the pusher device 124. The controller 144 also may receive the signals from the sensor assembly 106, and activate one or more output devices to inform or to alert a user to a condition or state, e.g., a condition of the pump 102 or fluid flowing through the line 130. The controller 144 may include for example a processor and memory (or storage device), electrical circuits, or a combination of a processor and memory and electrical circuits.

[0023] For example, in operation, the controller 144 may receive a signal from the first sensor 140 (which may be a force sensor or a pressure sensor), and may use that input to determine a force applied to the plunger 116 (or more correctly, by the plunger 116 to the pusher device 124) or a pressure of the fluid in the syringe 110 / infusion set or line 104. In addition, the controller 144 may receive a signal from the first sensor 140, and may use that input as part of a control algorithm to deliver fluid from the syringe 110 at a specified fluid flow rate. The fluid may be a medical fluid, for example a medication or a nutritional fluid for the parenteral feeding of a patient.

[0024] As a general example, the controller 144 may be coupled to the pusher device 124 and the sensor assembly 106. The controller 144 may be configured to displace the pusher device 124 a distance according to a desired flow from the syringe 110. The controller 144 may also be configured to receive a signal from the sensor 140, to determine a deformation of the plunger 116 (or as will be recognized, more correctly, a deformation of the pusher device 124 as the plunger 116 may be more stiff than the pusher device 124, or some combination ofdeformations thereof) based on the signal, optionally determine a volume change of the syringe 110 (and potentially line 130) based on the signal, and to determine a distance correction for the distance based on the deformation of the pusher device 124 and the optional volume change of the syringe 110. Further, the controller 144 may be configured to apply the distance correction to the distance.

[0025] As an example, the controller 144 may determine from the signal that the force applied by the syringe 110 on the pusher device 124 is 5 daN. The controller 144 may use this force value to determine that the pusher device 124 will deflect 0.83 mm, for example by consulting a lookup table or by calculating the amount based on the force and the stiffness of the pusher device 124. Based on this deflection, the controller 144 may further determine that the pusher device 124 has deviated from the desired distance (necessary to provide the desired flow from the syringe 110). As such, the controller 114 may determine that the plunger 116 must be moved a further 0.83 mm to achieve the displacement of the plunger 116 to deliver the desired flow.

[0026] In addition, the controller 144 may determine from the signal that the force applied by the syringe corresponds to a certain pressure for the fluid. In this regard, reference is made to US Pub. No. 2018 / 0311434, which reference is incorporated by reference in its entirety herein. The controller 144 may also determine that the syringe 110 and / or infusion line or set 104 has a particular compliance, for example by consulting a lookup table organized according to particular syringe brands and models. With this information, the controller 144 may determine that under this pressure and with this compliance data, the infusedvolume is below (if positive pressure) or above (if negative pressure) the desired volume to be infused. With information concerning the syringe size, the variation in infused volume can be converted into a displacement necessary to deliver the desired amount of medical fluid.

[0027] The controller 144 may then combine the displacement necessary to compensate for the pusher device deflection or deformation with the displacement necessary to deliver the desired amount of medical fluid. This correction may then be applied by the controller 144 to the displacement of the pusher device 124 to achieve the desired flow, for example by controlling the pusher device 124 to move an additional amount according to the correction by operating the drive connected to the pusher device 124.

[0028] The controller 144 controlling the operation of the infusion device 102, and in particular the pusher device 124, according to such a compensation method may provide one or more of the following benefits. The above infusion system 100 with the controller 144 operating under this compensation method may avoid the need to administer a bolus (sized according to syringe characteristics) to overcome initial “sticking” of the syringe. Furthermore, while this active compensation method will likely not be able to compensate for loss of flow(rate) in the case of partial or total occlusion, the controller 144 operating according to such a compensation method may have an increased occlusion detection speed (or a decreased occlusion detection time). In addition, the above infusion system 100 may better address variations in pressure (and flow)occurring during vertical displacement of the infusion device 102 relative to the aforementioned container or patient.

[0029] Having discussed the system 100 in general terms, further details are now discussed relative to Figs. 1-3.

[0030] Referring first to Fig. 2, the pump 102 includes a housing 150 having a front face 152 and a display device 154 disposed thereon. The display device 154 may be a touch-sensitive display, allowing a user to enter commands for operation of the pump 102 and displaying operational information regarding the process of an actual infusion operation. The pump 102 may also include a plurality of input devices 156, for example buttons, configured to allow a user to enter commands.

[0031] The pump 102 also includes a receptacle 158 in which the syringe 110 is disposed. The pump 102 may also include a holding or fixation device 160, which may include a releasable clamp element, to secure the syringe 110 in position in the receptacle 158. The clamp 160 may also provide a mechanical connection between the pump 102, and in particular the housing 150, and the syringe 110.

[0032] As mentioned above, the pump 102 also includes the pusher device 124 that is engaged with the syringe 110, and in particular the plunger 116. The pusher device 124 has a face 162 that is in engagement with the first end 118 (or plunger head). The plunger head 118 may be fixed to the pusher device 124 with a holding or fixation device 164, which also may include a releasable clamp. Asillustrated, the clamp 164 may be disposed around or about the head 118, such that the head 118 is held in tight abutment with the pusher device 124.

[0033] During operation of the pump 102, the pusher device 124 may be electromotively driven in an actuation direction A such that the second end 120 (or piston 122) is advanced along the barrel 112 (see Fig. 1 ), and a fluid (such as a medical fluid) contained in the barrel 112 is delivered via the infusion line 130 towards the container or patient. An electromotive drive (e.g., one or more gears connected to an electric motor) may be disposed within the housing 150 and connected to the pusher device 124 by a drive shaft 166 (which may be the part of the pusher device 124 that deforms during operation). Like the sensor system 106, the electromotive drive also may be coupled to the controller 144, and the controller 144 may be configured (e.g., programmed) to operate the electromotive drive to cause the pusher device 124 to move, e.g., in the actuation direction A, in an opposite direction to the actuation direction A, or to pause (i. e. , to move neither in the actuation direction A or in the opposite direction). According to an embodiment, the electromotive drive is configured as described in US Pat. No. 11364338, which is incorporated by reference herein in its entirety.

[0034] As mentioned above, the sensor 140 is disposed between the pusher device 124 and the head 118, and may be configured to measure the force exerted by the head 118. Specifically, the sensor 140 may be capable of measuring a force when the pusher device 124 is actuated to push the piston 122 in the actuation direction A into the barrel 112 to deliver a fluid from the barrel 112 in a downstream direction towards the container or patient. Because of the tightabutment between the head 118 and the pusher device 124 (as a consequence of the fixation device 164), the force sensor 140 also may be capable of measuring the force between the pusher device 124 and the head 118 when the pusher device 124 is actuated in a direction opposite to the actuation direction A such that the piston 122 is pulled out of the barrel 112 and a fluid is drawn in an upstream direction through the infusion line 130. According to an embodiment, the force sensor 140 is configured as described in US Pat. No. 9731068, which is incorporated by reference herein in its entirety.

[0035] A system 100 such as illustrated in Fig. 1 and / or Fig. 2 may operate according to the method described generally above, an embodiment of which is illustrated in Fig. 3 and designated as method 200. The controller 144 may be configured to carry out this method 200 to operate the system 100, and in particular the infusion pump 102.

[0036] The method 200 may begin at a block 202. At the block 202, the pusher device 124 is displaced a distance according to a desired flow from the syringe 110. In a general sense, this may be described as actuating the driver according to a desired flow. The flow may be of an amount (or volume) to be delivered, or of a rate to be delivered (amount per unit time).

[0037] At a block 204, a signal is received from the sensor 140. This signal may be received at roughly the same time as the displacement of the pusher device 124. Alternatively, the signal may be received shortly after the pusher device 124 is displaced the distance. Consequently, the position of the block 204as separate from and downstream of the block 202 is not intended to require a temporal separation and sequencing of the events.

[0038] The method 200 continues to blocks 206, 208. At the block 206, a deformation (of the pusher device 124) is determined based on the signal, and at the block 208 a volume change of the syringe 110 (and potentially line 130) is determined based on the signal. Again, the separation of the actions of blocks 206, 208 is not intended to suggest a temporal separation or sequencing of the events. Indeed, the actions at blocks 206, 208 may occur at the same or nearly the same time, or the actions of one block may precede the action of the other block (e.g., the actions of block 206 may precede the actions of the block 208). It is also possible for the method to include only the block 206 and only optionally include the block 208.

[0039] According to some embodiments, the actions of blocks 206 and 208 may be dependent on each other. For example, the actions required to determine the deformation of the pusher device may require determination of a force from the signal received. The force determined may then be utilized in the determination of a pressure used to determine (in combination with compliance data) a volume change of the syringe (and / or infusion line / set).

[0040] The method 200 continues at block 210 with the determination of a distance correction for the distance based on the deformation of the pusher device and optionally the volume change of the syringe 110. The determination of the distance correction may be carried out using a PID (Proportional - Integral - Derivative) controller, as PID control is a well-established way of driving a systemtowards a target control parameter. Indeed, use of a PID controller is presently believed to be particularly advantageous in the context of the method 200.

[0041] While the actions of block 210 are represented as a single block in the method 200 of Fig. 3, several actions may be required to determine the distance correction. As illustrated in Fig. 4 according to one exemplary variant, a distance correction may be determined for the deformation of the pusher device and a distance correction may be determined for the volume change of syringe, and these distance corrections may be combined (e.g., added) to determine the distance correction based on the deformation of the pusher device 124 and the volume change of the syringe 110 in those embodiments where the volume change of the syringe 110 is optionally included in the determination of the distance correction. Further, the distance correction determined for the volume change may require a calculation to be performed to determine the distance correction based on the volume change, while the distance correction determined for the pusher device deformation may be taken directly from a value of the deflection of the pusher device 124. Where a PID controller is included as part of the method 200, the PID control may be split into two different processes, likely with two different sets of parameters for the PID control, a first process dedicated to pusher device deformation compensation and a second process dedicated to compliance compensation.

[0042] As represented in Fig. 3, the method 200 then passes to a block 212 where the distance correction is applied to the distance. That is, the pusher device 202 is adjusted so that the distance moved by the pusher device is thecombination of the original distance and the distance correction. For example, the application of the distance correction may involve operating the drive associated with the pusher device 124 to move the pusher device a distance equal to the sum of the original distance and the distance correction. This may be referred to as a corrected distance. As one alternative, where the pusher device 124 has already moved the distance, the pusher device 124 may be moved an additional distance according to the distance correction.

[0043] The method 200 may continue with one or more cycles of the actions of blocks 202-212 (with the actions of block 208 optionally included). Indeed, a likely implementation of the method 200 would have a cycle of the actions blocks 202- 212 repeated every second, for example. Consequently, the method 200 has been illustrated with the method passing from block 212 to block 202.

[0044] As has already been noted, there are many additional actions that may occur at each of the blocks 202-212. Indeed, it is also envisioned that additional actions may precede and follow blocks 202-212. For example, the steps of blocks 202-212 may not proceed until a flow command (e.g., a desired flow rate) has been received via the touch-sensitive display 154 or the input devices / buttons 156. See block 214 in Figs. 3 and 4. Further, this flow command may need to be converted into a displacement before the pusher device is displaced at block 202.Likewise, a decision block may be interposed between the block 212 and block 202 on the return loop, the decision being whether the flow command is complete (e.g., the desired amount of fluid has been delivered, potentially as a desired flowrate). Once the flow command has been completed, the method 200 may be completed.

[0045] In addition to the above actions occurring before or after the actions of blocks 202-212, the following may occur as part of the method 200. In the following, the controller 144 of the system 100 may configured to carry out these actions.

[0046] As relates to block 206, a force may be determined based on the signal received at block 204. Based on this force, the deformation of the pusher device is determined. The deformation may be determined according to a lookup table or database, or alternatively the deformation (deflection) may be calculated. For example, the deformation may be determined according to the following equation:Deformation = Force / StiffnessDeformation may be in millimeters, Force may be in Newtons, and Stiffness may be in millimeters / Newton, for example. The value for Stiffness may be programmed into the controller 144, for instance, or may be accessed from a lookup table or database.

[0047] Based on this deformation, a deformation correction may be determined. For example, the deformation correction may be a value that may be added to the displacement distance to correct the displacement distance for the distance lost to the deformation or deflection of the pusher device 124. This deformation correction may then be included in the distance correction, for example by combining it with the volume change correction, as illustrated in Fig.4. Where the volume change correction also is in the form of a value to be addedto the displacement distance, the deformation correction may be added to the volume change correction so as to be included in the distance correction.

[0048] As relates to block 208, a pressure may be determined based on the signal received. Based on this pressure, the volume change of the syringe 110, and potentially the infusion line / set 104, may be determined by combining the pressure data with compliance data regarding the syringe 110 and optionally the infusion line / set 104. As noted above, this compliance data may be obtained from a list or database accessed by the controller 114. The compliance data in the list or database may be organized according to syringe brand and model, for example, and the compliance data may be selected (by the controller 144) based on the brand and model of syringe 110 included in the infusion pump 102.

[0049] A volume change correction based on the volume change may then be determined. For example, the volume change calculated may be in direct proportion to the amount of correction required. According to one embodiment, the volume change will be converted into a value corresponding to a correction to the displacement distance. For example, once the volume is known, assuming a cylindrical barrel 112 of known cross-section, the distance which the plunger 116 must move to deliver, for example, a comparable volume can be calculated. Alternatively, a lookup table or database may be provided. Where the volume change correction is in the form of a value to be added to the displacement distance, the volume change correction may be added to the deformation correction so as to be included in the distance correction.

[0050] As regards those embodiments wherein the actions of blocks 202-212 may be repeated, the subsequent cycles of the actions of blocks 202 also may be described in the following fashion. According to this expression of the second and subsequent cycles of the method 200, the second cycle and subsequent cycles may include receiving another signal from the sensor. The cycle may then include determining another deformation of the pusher device based on the signal, optionally determining another volume change of the syringe based on the signal, and determining another distance correction for the distance based on the another deformation of the pusher device and the another volume change of the syringe, if included. Further, the cycle may include applying the another distance correction to the distance to generate a further corrected distance. The cycle may then return to receipt of another signal from the sensor.

[0051] In this expression of the second and subsequent cycles of the method 200, the other variants to the first cycle described above would apply with equal force to the second and subsequent cycles. Moreover, the controller 144 may be configured to perform these second and subsequent cycles in the fashion the controller 144 may be configured to perform the first cycle.

[0052] While the above method 200 is particularly suited for the infusion pump 102 illustrated in Figs. 1 and 2 (i.e. , a syringe pump), the infusion pump of the disclosed system is not limited to only syringe pumps. For example, the infusion system may include an infusion pump in the form of a volumetric pump instead. As such, an embodiment of an infusion system including an infusion pump in the form of a volumetric pump is illustrated in Fig. 5. Similar structures between theembodiment of Fig. 5 and the embodiment of Figs. 1 and 2 are numbered similarly, with a prime for those structures appearing in the embodiment of Fig. 5.

[0053] Referring now to Fig. 5, the system 100’ includes an infusion pump 102’, an infusion set 104’ and a sensor assembly 106’. Moreover, the infusion set 104’ may include an infusion line with a first end and a second end. Moreover, the sensor assembly 106’ includes a sensor 220 that is disposed along the infusion line of the infusion set 104’, and that is used to determine the fluid pressure in the infusion line of the infusion set 104’.

[0054] As noted above, the infusion pump 102’ is configured as a volumetric infusion pump. According to the illustrated embodiment, the pump 102’ has a housing 222 and a front face 224 comprising a channel, recess, or receptacle 226 in which a pump module 228 of the infusion set 104’ can be received. The pump module 226 may be configured to cooperate with a driver in the form of a wobble device that applies a wobbling action on the pump module 228 (and in particular on a membrane of the pump module) to peristaltically pump a medical fluid through the infusion set 104’ towards a container or a patient. A comparable driver in the system 100 may include the pusher device 124. A housing element 230 (also referred to as a door) is pivotable about a pivoting axis relative to the remainder of the housing 222, and can be moved towards the front face 224 such that in a closed state the infusion set 104’ is held to the infusion pump 102’.

[0055] Tubing extends in both directions from the pump module 228. An upstream tube section connects the pump module 228 to a container (not shown) containing a medical fluid, whereas a downstream pump section connects thepump module 228 to a container or a patient (also not shown) for delivering the medical fluid to the patient or the container. The downstream section includes the section to the left of the pump module 228 in embodiment illustrated in Fig. 5. Thus, the sensor 220 can be used to sense the pressure in a region downstream of the module 228.

[0056] As to such an embodiment of a system 100’ illustrated in Fig. 5, the controller associated with the system 100’ may perform a method 240 as illustrated in Fig. 6. The method 200 may begin at a block 242 with receipt of a flow command (e.g., a desired amount (or volume) or a desired flow rate), which might be received via a touch-sensitive display or other input devices / buttons. At the block 244, a driver (e.g., the wobble device) of the infusion pump 102’ is actuated according to the desired flow, which may be an amount (or volume) to be delivered or a rate to be delivered (amount per unit time).

[0057] At a block 246, a signal is received from the sensor 140. This signal may be received at roughly the same time as the actuation of the driver. Alternatively, the signal may be received shortly after the driver has been actuated. Consequently, the position of the block 246 as separate from and downstream of the block 244 is not intended to require a temporal separation and sequencing of the events.

[0058] The method 240 continues to block 248. At the block 248, a volume change of the line of the set 104’ is determined based on the signal. The method 240 continues at block 250 with the determination of a correction for the actuation of the driver based on the volume change of the line of the set 104’, a volumecompensation or correction. The determination may be carried out using a PID (Proportional - Integral - Derivative) controller, as PID control is a well- established way of driving a system towards a target control parameter. Indeed, use of a PID controller is presently believed to be particularly advantageous in the context of the method 240. As illustrated in Fig. 6, the method 242 then passes to a block 252 where the correction is applied to the driver.

[0059] The method 240 may continue with one or more cycles of the actions of blocks 244-252. Indeed, a likely implementation of the method 200 would have a cycle of the actions blocks 244-252 repeated every second, for example.Consequently, the method 240 has been illustrated with the method passing from block 252 to block 244.

[0060] The pump volumetric with pump module and wobble device is only one possible embodiment of volumetric pump that may be used in an alternate embodiment of the system. It will be recognized that other volumetric infusion pump / infusion set pairs may omit the pump module. For example, the line may instead be disposed in a channel, and a rotor or a plurality of pump fingers may act on the line to force fluid in a specified direction. Otherwise, the use of a downstream sensor to determine a pressure change may be used with such alternative embodiments.

[0061] As stated above, the controller controlling the operation of the infusion device according to such a compensation method may provide one or more benefits. These benefits may be related to direct control of the operation of the pusher device (and associated drive) or other drivers to vary operation inaccordance with detected conditions. This is in contrast with existing solutions that rely on brute force or overengineering the infusion device to overcome the same challenges.

[0062] For example, the conventional solution to overcome initial “sticking” of the syringe in a syringe pump is to administer a bolus (sized according to syringe characteristics). This is an example of a brute force solution, one which includes risks associated with bolus administration. Moreover, it is known to attempt to improve occlusion detection by making the infusion device as stiff as possible to limit the time required to reach the time to detection, which typically involves reaching a pressure threshold. Still, even with a perfect pump (with infinite stiffness), the time to reach a pressure threshold can be inconveniently long, especially when the pressure threshold is high (e.g., an hour to reach 1 bar with 1 ml / hour flowrate using a 50cc syringe). Pump stiffness is also a common solution to minimize the consequences of vertical displacement on flowrate, albeit an incomplete solution because in reality stiffness can only be maximized, not completely achieved.

[0063] By providing the above system 100, 100’ operating according to the method disclosed (and its variants), solutions can be provided to one or more of the problems in a way that emphasizes direct, active control. This is contrasted with indirect, often passive, methods that do not control for variations in operation, but attempt to override the variations or reduce / eliminate the variations and their effects. It is believed by providing the system 100, 100’ and its method ofoperations, these problems can be resolved without creating the potential for additional issues in operation or design of an infusion system.

[0064] Thus, an improved infusion system and method has been described. The description provided above is intended for illustrative purposes, and is not intended to limit the scope of the disclosure to any particular method, system, apparatus, or device described herein. For example, further embodiments may include pneumatically-driven volumetric pumps as part of the infusion system and method.Aspects

[0065] Aspect 1 . An infusion system comprising: an infusion device comprising a driver and an infusion set coupled to the driver; a sensor assembly comprising a sensor coupled to the infusion device; and a controller coupled to the driver and the sensor assembly, the controller being configured to: actuate the driver according to a desired flow, receive a signal from the sensor, determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.

[0066] Aspect 2. The infusion system according to Aspect 1 , the infusion set having a downstream tube section, and the sensor is coupled to the downstream tube section.

[0067] Aspect 3. The infusion system according to Aspect 1 or 2, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine the volume change correction based on the volume change of the infusion set.

[0068] Aspect 4. The infusion system according to Aspect 3, wherein the volume change is based on the pressure and a compliance for the infusion set.

[0069] Aspect 5. The infusion system according to Aspect 4, wherein the controller is configured to select the compliance according to an infusion set brand and model.

[0070] Aspect 6. The infusion system according to Aspect 1 , wherein: the infusion set comprises a syringe including a barrel and a plunger, and the driver comprises a pusher device in engagement with the plunger; the sensor is disposed between the plunger and the pusher device; and the controller is coupled to the pusher device and the sensor assembly, the controller being configured to: displace the pusher device a distance according to the desired flow, receive the signal from the sensor, determine a deformation of the pusher device based on the signal, determine a volume change of the syringe based on the signal,determine a distance correction for the distance based on the deformation of the pusher device and the volume change of the syringe, and apply the distance correction to the distance.

[0071] Aspect 7. The infusion system according to Aspect 6, wherein the controller is configured to determine a force based on the signal received, to determine the deformation of the pusher device based on the force, determine a deformation correction based on the deformation, and include in the deformation correction in the distance correction.

[0072] Aspect 8. The infusion system according to Aspect 6 or 7, wherein the controller is configured to determine the deformation of the pusher device according to:Deformation = Force / Stiffness.

[0073] Aspect 9. The infusion system according to Aspect 7, wherein the deformation correction is a value added to the distance.

[0074] Aspect 10. The infusion system according to any one of Aspects 6 to 9, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine a volume change correction based on the volume change, and include the volume change correction in the distance correction.

[0075] Aspect 11 . The infusion system according to Aspect 10, wherein the volume change is based on the pressure and a compliance for the syringe.

[0076] Aspect 12. The infusion system according to Aspect 11 , wherein the controller is configured to select the compliance according to a syringe brand and model.

[0077] Aspect 13. The infusion system according to any one of Aspects 10 to12, wherein the volume change correction is a value added to the distance.

[0078] Aspect 14. The infusion system according to any one of Aspects 6 to13, wherein the controller is configured to apply the distance correction to the distance by adding the distance correction to the distance to generate a corrected distance, and displace the pusher device the corrected distance.

[0079] Aspect 15. The infusion system according to Aspect 6 to 14, wherein the controller is configured to: receive another signal from the sensor, determine another deformation of the pusher device based on the signal, determine another volume change of the syringe based on the signal, determine another distance correction for the distance based on the another deformation of the pusher device and the another volume change of the syringe, and apply the another distance correction to the distance to generate a further corrected distance.

[0080] Aspect 16. An infusion system comprising: an infusion device comprising a syringe including a barrel and a plunger, and a pusher device in engagement with the plunger;a sensor assembly comprising a sensor disposed between the plunger and the pusher device; and a controller coupled to the pusher device and the sensor assembly, the controller being configured to: displace the pusher device a distance according to a desired flow, receive a signal from the sensor, determine a deformation of the pusher device based on the signal, determine a distance correction for the distance based on the deformation of the pusher device, and apply the distance correction to the distance.

[0081] Aspect 17. The infusion system according to Aspect 16, wherein the controller is configured to determine a force based on the signal received, to determine the deformation of the pusher device based on the force, determine a deformation correction based on the deformation, and include in the deformation correction in the distance correction.

[0082] Aspect 18. The infusion system according to Aspect 16 or 17, wherein the controller is configured to determine the deformation of the pusher device according to:Deformation = Force / Stiffness.

[0083] Aspect 19. The infusion system according to Aspect 17, wherein the deformation correction is a value added to the distance.

[0084] Aspect 20. The infusion system according to any one of claims 16 to 19, wherein the controller being configured to:determine a volume change of the syringe based on the signal, determine a distance correction for the distance based on the deformation of the pusher device and the volume change of the syringe, and apply the distance correction to the distance.

[0085] Aspect 21 . The infusion system according to Aspects 20, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine a volume change correction based on the volume change, and include the volume change correction in the distance correction.

[0086] Aspect 22. The infusion system according to Aspect 21 , wherein the volume change is based on the pressure and a compliance for the syringe.

[0087] Aspect 23. The infusion system according to Aspect 22, wherein the controller is configured to select the compliance according to a syringe brand and model.

[0088] Aspect 24. The infusion system according to any one of Aspects 21 to23, wherein the volume change correction is a value added to the distance.

[0089] Aspect 25. The infusion system according to any one of Aspects 16 to24, wherein the controller is configured to apply the distance correction to the distance by adding the distance correction to the distance to generate a corrected distance, and displace the pusher device the corrected distance.

[0090] Aspect 26. The infusion system according to any one of Aspect 16 to25, wherein the controller is configured to: receive another signal from the sensor,determine another deformation of the pusher device based on the signal, determine another distance correction for the distance based on the another deformation of the pusher device, and apply the another distance correction to the distance to generate a further corrected distance.

[0091] Aspect 27. An infusion system comprising: an infusion device comprising a driver and an infusion set coupled to the driver, the infusion set having a downstream tube section; a sensor assembly comprising a sensor coupled to the downstream tube section; and a controller coupled to the driver and the sensor assembly, the controller being configured to: actuate the driver according to a desired flow, receive a signal from the sensor, determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.

[0092] Aspect 28. The infusion system according to Aspect 27, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine the volume change correction based on the volume change of the infusion set.

[0093] Aspect 29. The infusion system according to Aspect 28, wherein the volume change is based on the pressure and a compliance for the infusion set.

[0094] Aspect 30. The infusion system according to Aspect 29, wherein the controller is configured to select the compliance according to an infusion set brand and model.

Claims

FLU23-02 PRO (9600-0005)CLAIMS:

1. An infusion system comprising: an infusion device comprising a driver and an infusion set coupled to the driver; a sensor assembly comprising a sensor coupled to the infusion device; and a controller coupled to the driver and the sensor assembly, the controller being configured to: actuate the driver according to a desired flow, receive a signal from the sensor, determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.

2. The infusion system according to claim 1 , the infusion set having a downstream tube section, and the sensor is coupled to the downstream tube section.

3. The infusion system according to claim 1 or 2, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine the volume change correction based on the volume change of the infusion set.

4. The infusion system according to claim 3, wherein the volume change is based on the pressure and a compliance for the infusion set.

5. The infusion system according to claim 4, wherein the controller is configured to select the compliance according to an infusion set brand and model.

6. The infusion system according to claim 1 , wherein: the infusion set comprises a syringe including a barrel and a plunger, and the driver comprises a pusher device in engagement with the plunger; the sensor is disposed between the plunger and the pusher device; and the controller is coupled to the pusher device and the sensor assembly, the controller being configured to: displace the pusher device a distance according to the desired flow, receive the signal from the sensor, determine a deformation of the pusher device based on the signal, determine a volume change of the syringe based on the signal, determine a distance correction for the distance based on the deformation of the pusher device and the volume change of the syringe, and apply the distance correction to the distance.

7. The infusion system according to claim 6, wherein the controller is configured to determine a force based on the signal received, to determine the deformation of the pusher device based on the force, determine a deformationcorrection based on the deformation, and include in the deformation correction in the distance correction.

8. The infusion system according to claim 6 or 7, wherein the controller is configured to determine the deformation of the pusher device according to:Deformation = Force / Stiffness.

9. The infusion system according to claim 7, wherein the deformation correction is a value added to the distance.

10. The infusion system according to any one of claims 6 to 9, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine a volume change correction based on the volume change, and include the volume change correction in the distance correction.11 . The infusion system according to claim 10, wherein the volume change is based on the pressure and a compliance for the syringe.

12. The infusion system according to claim 11 , wherein the controller is configured to select the compliance according to a syringe brand and model.

13. The infusion system according to any one of claims 10 to 12, wherein the volume change correction is a value added to the distance.1 . The infusion system according to any one of claims 6 to 13, wherein the controller is configured to apply the distance correction to the distance by adding the distance correction to the distance to generate a corrected distance, and displace the pusher device the corrected distance.

15. The infusion system according to claim 6 to 14, wherein the controller is configured to: receive another signal from the sensor, determine another deformation of the pusher device based on the signal, determine another volume change of the syringe based on the signal, determine another distance correction for the distance based on the another deformation of the pusher device and the another volume change of the syringe, and apply the another distance correction to the distance to generate a further corrected distance.

16. An infusion system comprising: an infusion device comprising a syringe including a barrel and a plunger, and a pusher device in engagement with the plunger;a sensor assembly comprising a sensor disposed between the plunger and the pusher device; and a controller coupled to the pusher device and the sensor assembly, the controller being configured to: displace the pusher device a distance according to a desired flow, receive a signal from the sensor, determine a deformation of the pusher device based on the signal, determine a distance correction for the distance based on the deformation of the pusher device, and apply the distance correction to the distance.

17. The infusion system according to claim 16, wherein the controller is configured to determine a force based on the signal received, to determine the deformation of the pusher device based on the force, determine a deformation correction based on the deformation, and include in the deformation correction in the distance correction.

18. The infusion system according to claim 16 or 17, wherein the controller is configured to determine the deformation of the pusher device according to:Deformation = Force / Stiffness.

19. The infusion system according to claim 17, wherein the deformation correction is a value added to the distance.

20. The infusion system according to any one of claims 16 to 19, wherein the controller being configured to: determine a volume change of the syringe based on the signal, determine a distance correction for the distance based on the deformation of the pusher device and the volume change of the syringe, and apply the distance correction to the distance.21 . The infusion system according to claim 20, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine a volume change correction based on the volume change, and include the volume change correction in the distance correction.

22. The infusion system according to claim 21 , wherein the volume change is based on the pressure and a compliance for the syringe.

23. The infusion system according to claim 22, wherein the controller is configured to select the compliance according to a syringe brand and model.

24. The infusion system according to any one of claims 21 to 23, wherein the volume change correction is a value added to the distance.

25. The infusion system according to any one of claims 16 to 24, wherein the controller is configured to apply the distance correction to the distance by adding the distance correction to the distance to generate a corrected distance, and displace the pusher device the corrected distance.

26. The infusion system according to any one of claim 16 to 25, wherein the controller is configured to: receive another signal from the sensor, determine another deformation of the pusher device based on the signal, determine another distance correction for the distance based on the another deformation of the pusher device, and apply the another distance correction to the distance to generate a further corrected distance.

27. An infusion system comprising: an infusion device comprising a driver and an infusion set couple to the driver, the infusion set having a downstream tube section; a sensor assembly comprising a sensor coupled to the downstream tube section; and a controller coupled to the driver and the sensor assembly, the controller being configured to: actuate the driver according to a desired flow, receive a signal from the sensor,determine a volume change of the infusion set based on the signal, determine a volume change correction based on the volume change of the infusion set, and apply the volume change correction to the driver.

28. The infusion system according to claim 27, wherein the controller is configured to determine a pressure based on the signal received, to determine the volume change based on the pressure, determine the volume change correction based on the volume change of the infusion set.

29. The infusion system according to claim 28, wherein the volume change is based on the pressure and a compliance for the infusion set.

30. The infusion system according to claim 29, wherein the controller is configured to select the compliance according to an infusion set brand and model.

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