NZ755823B2 - Volume-based flow rate compensation technique for infusion therapy - Google Patents

Abstract

infusion pump is provided for pumping fluid through an administrative set at a desired flow rate over a specified duration, and includes a pumping mechanism for releasably receiving and for exerting a pulsing force on the administrative set, thus pressurizing a portion of the set for creating a flow of fluid from a set outlet. A controller is connected to and is configured for operating the pumping mechanism, the controller determines a pulse frequency based on a volume of fluid infused over a portion of the specified duration and the desired flow rate, outputs a control signal to the pumping mechanism for operating the pumping mechanism based on the determined pulse frequency, determines a first pulse frequency based on the desired flow rate; and adjusts the first pulse frequency based on the volume of fluid infused to provide a second pulse frequency being different from the first pulse frequency, whereby said second pulse frequency compensates for the degradation of the material of the tubular administrative set based on a comparison of historical data of administrative set flow rate accuracy. low of fluid from a set outlet. A controller is connected to and is configured for operating the pumping mechanism, the controller determines a pulse frequency based on a volume of fluid infused over a portion of the specified duration and the desired flow rate, outputs a control signal to the pumping mechanism for operating the pumping mechanism based on the determined pulse frequency, determines a first pulse frequency based on the desired flow rate; and adjusts the first pulse frequency based on the volume of fluid infused to provide a second pulse frequency being different from the first pulse frequency, whereby said second pulse frequency compensates for the degradation of the material of the tubular administrative set based on a comparison of historical data of administrative set flow rate accuracy.

Description

(12) Granted patent specificaon (19) NZ (11) 755823 (13) B2 (47) aon date: 2021.12.24 (54) VOLUME-BASED FLOW RATE COMPENSATION TECHNIQUE FOR INFUSION Y (51) Internaonal Patent Classificaon(s): A61M 5/168 A61M 5/172 A61M 5/142 (22) Filing date: (73) Owner(s): 2018.02.08 BAXTER INTERNATIONAL INC.

BAXTER HEALTHCARE SA (23) Complete specificaon filing date: 2018.02.08 (74) Contact: AJ PARK (30) Internaonal Priority Data: US 62/457,648 2017.02.10 (72) or(s): HOPKINS, Patrick Michael (86) aonal Applicaon No.: WEBER, Harry John SUN, Haonan (87) Internaonal Publicaon number: WO/2018/148427 (57) Abstract: An infusion pump is provided for g fluid through an administrave set at a desired flow rate over a specified duraon, and includes a pumping mechanism for releasably receiving and for exerng a pulsing force on the administrave set, thus pressurizing a poron of the set for creang a flow of fluid from a set . A controller is connected to and is configured for operang the pumping mechanism, the controller determines a pulse frequency based on a volume of fluid infused over a poron of the ed duraon and the desired flow rate, outputs a control signal to the pumping mechanism for operang the pumping mechanism based on the determined pulse frequency, determines a first pulse frequency based on the desired flow rate; and s the first pulse ncy based on the volume of fluid infused to provide a second pulse frequency being different from the first pulse frequency, whereby said second pulse frequency compensates for the degradaon of the material of the tubular administrave set based on a comparison of historical data of administrave set flow rate accuracy.

NZ 755823 B2 VOLUME-BASED FLOW RATE COMPENSATION TECHNIQUE FOR ON THERAPY BACKGROUND The present invention relates to systems used for medication delivery, and more particularly to a system designed for more accurately delivering medication through infusion therapy over a long duration. s medications may be provided to a patient via infusion therapy, which is conventionally practiced with an infusion pump such as a peristaltic pump. Peristaltic pumps typically e by directly manipulating an administration set through which the tion is red. As is well known in the art, a main component of an infusion set is a length of plastic , with fittings for connection to supplies of medication, saline solution or the like. The fittings are configured for receiving medication through y flow, or by injection, such as using a syringe. Over time, manipulation of the tubing causes a physical degradation of the administration set in the area manipulated by the infusion pump. That is, prolonged physical manipulation of the administration set by the peristaltic pump causes a reduction in springback or lity of the administration set tube, thereby reducing the fluid volume in each pumping cycle. onally, guidelines issued by the Centers for Disease Control suggest that an infusion pump should use the same administration set for no more than one week. Accordingly, infusion pump manufacturers provide pumps capable of accurately delivering the infusion fluid over a long duration (for example 72-96 hours). However, as discussed above, fatigue of the stration set results in significant error over time, since less fluid is actually pumped than would be predicted given the pump performance characteristics and the use of fresh tubing.

One solution to this decreased accuracy is to change administration sets more frequently. These frequent stration set changes, however, increase hospital costs by both increasing both physical resources consumed (i.e., more administration sets are used for each patient) and time required for t care (i.e., a ver is required to spend more time with each patient due to more frequent administration set changes).

In the on therapy market, it is preferred to use administration sets made of hydrocarbon-based plastics, like PVC. One advantage is cost. PVC sets are simple and cheap to cture as they are generally extruded as a continuous piece of tubing. The continuous nature of the PVC set has the added benefit of providing a continuous sterile barrier throughout the set. An additional advantage of PVC sets is that they can be used interchangeably in pump-based therapies and in manual/gravity applications.

An alternative to PVC sets is sets made of polymer-based materials, such as silicone. These sets use a dedicated silicone pumping segment which is connected to non-pumping segments via joints. The silicone t provides relatively consistent and accurate mance over the course of an infusion, compared to PVC tubing. However, the silicone segment and the connecting joints require more parts and assembly time, thereby increasing the cost of the set. Additionally, the extra joints increase the risk of fluid leaks and pose sterility concerns, compared to PVC-based sets.

The silicone based sets are more difficult and expensive to use for a manual/gravity therapy.

Large Volume eral (LVP) infusion pumps using sets made of materials like PVC display favorable accuracy for short term infusions.

However, as described above, over long-duration infusions, the tubing loses resiliency, g to under-infusion and flow rate accuracy drift. In each pumping cycle, there are two primary phases: the delivery phase and the fill phase. In the ry phase, an active force is applied to the tubing by the pump ism to compress the tubing and move fluid downstream. During the fill phase, the pumping mechanism releases the tubing, allowing it to fill again. However, this s passively depends on the resiliency of the tubing to spring back to its full inner diameter and re-fill for the next cycle.

After repeated pumping cycles, the tubing undergoes permanent material property changes, which decrease its resiliency and in effect, the fill volume of each cycle. With the tubing unable to fill to its full volume, the maximum amount the pump can deliver each cycle is correspondingly limited, leading to under infusion and accuracy drift. This behavior is a function of the amount of pump cycles applied to the set.

The above performance degradation causes clinicians to either shift the location of the tube set in the pump channel to a “fresh section” during a therapy, potentially g to an interruption in therapy; or to change sets more frequently, ially causing interruption in therapy and/or increased risk of infection. The practice of moving the set after a short amount of time is currently recommended in pump operator manuals.

Although the problem of tubing degradation over time is well known in the industry, there have been a variety of ches to find a medically effective and cost-efficient solution. Some infusion pump manufacturers have opted to improve accuracy by developing administration sets with a dedicated silicone pump segment. Silicone retains its resiliency and ore maintains fill volume over many pump cycles. But while silicone tubing has improved accuracy over long durations, this strategy presents several significant drawbacks.

Sets with ted g and non-pumping segments have multiple ons to join the segments together, thereby increasing manufacturing costs due to the added parts and assembly time/labor. While PVC sets are traditionally composed of a single, continuous piece of , providing a sterile r through the length of the set, this option of using connecting joints in sets with dedicated pump segments ses the risk of fluid leaks and pose sterility concerns. Another drawback of silicone tubing sets is that in the manufacturing operation, potentially harmful curing agents are often used which could potentially leach into the fluid path of the tubing.

Further, silicone is porous and can permit air ingress, posing a sterility concern.

Manufacturers have also addressed the problem of administration set tubing fatigue by ing the pumping mechanism to actively move the tubing back into the filling position. One manufacturer has employed a shuttle mechanism which actively moves the tubing back into the g position instead of passively relying on tubing resiliency. r, this modification added design and manufacturing complexity, cost, and weight to the pump.

The added motion also requires more energy from the pump, which in turn diminishes the battery life of the device.

Still r approach to the tubing degradation problem involves software compensation, where a flow rate compensation algorithm was developed which accounted for ature, Back Pressure, and Flow Rate, as seen in the equation below.

PE = 569P2 — 4630P — 129PT + 2.3PF + 15T3 — 1283T2 + 37510T + lTF — 33F - 363912 0 Where: I PE = Predictive Error; I P = Back Pressure; I T: Temperature; and I F = Flow Rate While the exact value of the coefficients and power of the exponents in the above thm are unique to a particular infusion pump, only three factors were deemed to have icant impact on flow rate accuracy to warrant compensation: Temperature, Back Pressure, and Flow Rate. As evidenced by the magnitude of the coefficients and power of the exponents, the above thm deemed Temperature as having the most impact on flow rate accuracy, followed by Back Pressure and to an even lesser degree, Flow Rate having less impact on the accuracy. No other factors were compensated for.

Accordingly, there is a need for a simpler, more universal approach to the problem of infusion administrative tubing set degradation that is applicable to a wider range of infusion pumps.

SUMMARY The listed need is met or exceeded by the present volume- based flow rate compensation for infusion therapy. The present invention is provided in the form of an improved infusion pump featuring a controller that is provided with improved operational re designed to adjust the infusion pump pulse frequency based on the volume infused through the administrative set. It has been found that by monitoring the volume of fluid infused, applying a Tubing Degradation Function that correlates historical tubing performance with volume infused, and adjusting the pulse frequency accordingly, the percent error of actual volume infused compared to pump target volume is relatively low compared to the conventional infusion pump systems described above. The technique applied by the present infusion pump is contrasted with tional systems, where pulse ncy is adjusted based on correlating percent error as a function of time or flow rate.

An important feature of the present infusion pump and the benefit of the present volurne—based flow rate accuracy compensation technique is that there is no cost once the software is developed and implemented. The cost of the pump will not increase since there are no parts added, re d, or changes to manufacturing or service ses. Once the software is ped and ented, there is no additional cost or ment required. There is also potential to apply this technique to a wide variety of infusion pumps.

The present infusion pump enables clinicians to use administration sets with materials like PVC for longer periods of time, thereby offering a huge cost and sales advantage over itors with more expensive sets. Coupled with this is that there is no increase in the cost of the pump.

Clinicians will no longer have to move the set after a short amount of time, reducing physical time and operational cost for the hospital or clinic. Also, adjusting flow rate as a function of volume provides a simple, generalized means of improving flow rate accuracy that is applicable irrespective of the programmed flow rate. Further, infusion pumps y have the capability of tracking volume infused, enabling simple implementation of the proposed technique.

More specifically, an infusion pump is ed that is configured for pumping fluid through a tubular administrative set at a desired flow rate over a specified duration, and includes a pumping mechanism constructed and arranged for ably receiving the tubular strative set and for exerting a pulsing force on the tubular administrative set, thus pressurizing a portion of the tubular administrative set for creating a flow of fluid from an outlet of the tubular administrative set. A controller is connected to the pumping mechanism and is configured for operating the pumping ism, the controller is configured to determine a pulse frequency based on a volume of fluid infused over a portion of the specified duration and the desired flow rate, output a control signal to the g mechanism for operating the pumping mechanism based on the determined pulse frequency, determining a first pulse frequency based on the desired flow rate; and adjusting the first pulse ncy based on the volume of fluid infused to provide a second pulse ncy, the second pulse frequency being different from the first pulse frequency.

In another embodiment, a method is provided for controlling a g mechanism of an infusion pump ing a tubular administrative set and a pumping mechanism, the pumping mechanism being constructed and arranged for releasably receiving the tubular administrative set and for exerting a pulsing force on the r administrative set for creating a flow of fluid from an outlet of the tubular administrative set, the method controlling the pumping mechanism to pump fluid through the r administrative set at a desired flow rate over a ied duration. The method includes determining a pulse frequency based on a volume of fluid infused over a portion of the specified duration and the desired flow rate, outputting a control signal to the pumping mechanism for operating the pumping mechanism based on the determined pulse frequency, determining a first pulse frequency based on the desired flow rate, and adjusting the first pulse frequency based on the volume of fluid infused to provide a second pulse frequency, the second pulse frequency being different from the first pulse ncy.

In still r embodiment, an apparatus is provided, including computer-executable instructions stored on a non-transitory medium, wherein the instructions, when executed by a processor, cause the processor to: determine a volume of fluid infused from an outlet of a tubular administrative set of an infusion pump over a period of time, determine a pulse frequency based on the determined volume of fluid infused over the period of time and a desired flow rate of fluid infused from the outlet of the tubular administrative set; and outputting a control signal to a pumping mechanism for operating the pumping mechanism based on the determined pulse frequency, wherein the pumping mechanism is constructed and arranged for releasably receiving the tubular administrative set and for exerting a pulsing force on the tubular administrative set for creating a flow of fluid from the outlet of the tubular administrative set.

BRIEF DESCRIPTION OF THE DRAWINGS is a front ion of the t infusion pump connected to an administrative tubing set; is a tic m of the present infusion pump; is a graph of mance Accuracy t Error vs.

Infusion Time; is a graph of Performance Accuracy Percent Error vs.

Infusion Volume; is a graph of the data-generated curve used for providing an initial n of the Tubing ation Function; and is a graph of the basic curve of which has been adjusted using empirical data and provides a more accurate format for conversion into the desired function for conversion into an algorithm suitable for use in the controller.

DETAILED DESCRIPTION Referring now to FIGS. 1 and 2, an on pump fluid transfer system is generally ated 10. The infusion system 10 is designed for use in dispensing medication, stored in a medication container 12, lly a bag, bottle, syringe, or other standard container used to contain liquid medications.

There is no particular restriction regarding what containers 12 may be used. As is known in the art, the medication container 12 is connected to an administration set or tubing set 14, including a length of flexible plastic tubing 16 and at least one al luer fitting 18 through which a medical practitioner inserts supplemental fluids, such as complementary medications and the like prior to administration to the patient. As is known in the art, the administration set 14 is optionally provided with other fittings and connections, including but not limited to line clamps 19.

An infusion pump 20 has a chamber 22 for receiving a n of the tubing 16 and exposing the portion to a periodic pulsing or pressing force designed to force a discrete volume of the liquid h the tubing.

Ultimately the tubing 16 is connected to an administration set outlet, also referred to as a catheter 24 for tion to a patient. The catheter 24 is contemplated as being any standard equipment for use with a t. For example, catheters 24 include a temporary catheter inserted into a peripheral vein, a peripherally ed l catheter, a central venous catheter, or other catheter known to those in the art.

As shown in the infusion pump 20 is any known pump used to administer fluid intravenously. The pump 20 is used to help te fluid flow through the system 10, and may be used to vary an infusion rate based on, for example time and/or patient demand. The pump 20 may include one or more “channels,” with each channel used to regulate fluid flow from a distinct medication container through a distinct tubing set.

WO 48427 Refening now to the infusion pump 20, such as a linear peristaltic infusion pump or the like well-known in the art, is shown tically. The infusion pump 20 includes at least a g mechanism 26 configured for generating periodic pulses which compress the portion of tubing 16 d in the chamber 22. Signals for controlling the pumping mechanism 26 are generated by a controller 28, such as a computerized device having at least a memory 30, a processor 32, one or more sensors 34, an input device 36, a display 38, and preferably a network or other communication interface 40. A power source 42 is preferably also incorporated into the infusion pump 20.

The pumping mechanism 26 may be any pump ism useful to facilitate fluid flow in a large-volume infusion pump. As a non-limiting example, a linear peristaltic pump is considered suitable. Other non-limiting examples include multi—finger peristaltic pumping mechanisms; single finger peristaltic pumping mechanisms and rotary pumps that act along a tube length to propel fluid through a tube. The controller 28 is preferably incorporated into the infusion pump 20, and is used to control the pumping mechanism 26.

More specifically, the controller 28 is ted to the pumping mechanism 26 and is configured for determining a pulse frequency exerted on the tubing set 14.

It is preferable that the memory 30 is a non-transitory computer- readable recording medium, such as a read only memory (ROM), random access memory (RAM), hard disk, non-volatile flash memory or other electronically erasable programmable read-only memories (EEPROMs), or optical or magneto-optical memory storage media. ably, the memory 30 stores at least instructions which, when executed, tate l of the pumping mechanism 26. The processor 32 is ably a microprocessor or other central processing unit capable of executing the instructions stored in the memory 30.

The controller 28 also includes the one or more sensors 34 used to r at least one characteristic value relating to a status of the infusion pump 20. Non-limiting examples of this characteristic value include an amount of time that has elapsed during the infusion process, and the intended volume of liquid dispensed through the administration set 14 loaded in the infusion pump 20. Those of skill in the art will ize that other characteristic values may be monitored t departing from the scope of this invention.

Because each of the s 34 monitors a characteristic value related to the pumping process of the on pump, the sensors are operably connected to the g mechanism 26.

A keypad or similar device that accepts data input by a user serves as the input device 36. The display 38 is preferably a liquid crystal display, cathode ray tube, plasma display, or other device capable of outputting data from the memory and processor in a way that is easily discernible by a user. Alternatively, the input device 36 and the display 38 may be incorporated into a single input/output device such as a touch screen display. The input device 36 and/or the display 38 are ally integral with the infusion pump , or may be separate from, but connected to the infusion pump, ed that the input device and/or the display are configured for bi-directional communication with the infusion pump.

The network communication interface 40 allows the infusion pump 20 to connect to a local area network (LAN), wide area network (WAN), and/or the Internet. The network tion may be a wired connection using, for example, the IEEE 802.3 standard, or a wireless connection using standards such as IEEE 802.11 a/b/g/n/ac, or any newly developed standards that supersede these. Additionally, the network connection 40 may connect to a ar/mobile data network using a protocol such as LTE, WiMAX, UMTS, CDMA, HSPA, HSPA+, GPRS, and the like.

The power source 42 is any known power source sufficient to provide power to both the pumping mechanism 26 and the controller 28. As non-limiting examples, the power source 42 may include one or more of a battery, a fuel cell, and a connection to a power line.

In operation, the pump 20 is used to convey fluid from the upstream source container 12, through the tubing 16 of the administration set 14 in a downstream direction towards and into a t through the catheter or access site 24. Conventional peristaltic pumps rely on one or more fingers or occluders tially compressing a pumping portion of the flexible tube 16.

With a primed tube (one already filled with fluid) the upstream er sses the tube 16, followed in sequence by the next downstream occluder, until each of the occluders present has compressed the tube. As the occluders apply pressure to the tube 16, the portion of tube under compression is d closed (occluded), thus forcing the fluid to move downstream through the tube. When compression by all of the occluders is te or nearly complete, the upstream occluder begins to re-open, 0r ress, the tube 16. The opening of the occluders also occurs sequentially from the upstream direction towards the downstream direction. As the tube 16 decompresses or re-opens to its natural state after release of the occluder, fluid flows into the pumping section of the tube from the source container 12 under the force of gravity and ambient pressure. The extent to which the pumping section of the tube 16 re-opens depends upon the t elasticity of the pumping section of the tube. Therefore, the amount of fluid that flows into the pumping section as or after the occluders have opened is also dependent upon the elasticity of the pumping section of the tube 16.

However, over time, the mechanical manipulation of the flexible tube 16 by the occluders leads to a physical breakdown of the tube, whereby the flexible tube no longer fully re-opens to its original shape. The pump ller 28 is programmed to monitor the intended volume of liquid dispensed as a function of the tube diameter and the number of pulses or occlusions, also referred to as pulse frequency, in view of the mance of a new, fresh tube 16. Accordingly, as the tube 16 degrades through continued , over time, the fluid volume moved through each cycle of the pump 20 is reduced, leading to an overall ion in the infusion fluid provided to a patient. Moreover, traditional infusion pumps rely on an open-loop control to maintain a flow rate by maintaining pulse rate, and do not take this reduction in provided volume into account. ingly, pump accuracy degrades over time. It should be noted that in the above bed sequence of compression by the occluders, at all times, at least one er remains compressed at any given time to prevent a free-flow ion as is known in the art. Also, the pumping may be accomplished with a single occluding member. This case would include that addition of an upstream valve located am of the occluding member and a downstream valve located downstream of the occluding member. Compression and release of the upstream valve, occluding member and downstream valve are ced as is known in the art to achieve the desired fluid movement.

After the administration set 14 is properly loaded into the infusion pump 20, the material used to form the administration set is specified.

This may require a manual specification by the user, such as through an entry of the specific material (e.g., PVC plasticized with either DEHP or non-DEHP plasticizers, polyethylene, silicone etc.) and/or a model number corresponding to the loaded set using the input device. Alternatively, some embodiments may include, as in input device, a reader capable of reading a barcode, QR code, or other similar machine-readable code to input the model of the administration set. Still other embodiments of the infusion pump are suitable for use with only administration sets formed from a particular material, or with only a particular model of stration set. In this case, the material is ed automatically, or presumed, without requiring user interaction.

A main feature of the present infusion pump 20 is that the pump controller 28, not only determines the pulse frequency exerted on the tubing set 16 for obtaining a desired or target volume of sed liquid, but is also provided with an algorithm or mathematical function, referred to as a Tubing Degradation Function, and is constructed and arranged to adjust the pulse frequency ing to the Tubing Degradation Function for obtaining a target fluid volume dispensed by the administrative set.

WO 48427 In operation, over the course of the on, the pump speed or pulse frequency is adjusted (i.e faster or slower) by a predetermined amount to compensate for diminished performance, degradation and material property change in the administration set. The predetermined amount is calculated based on historical data that correlates flow rate accuracy (% Error) with volume infused, as opposed to correlating % Error as a function of time or flow rate, as has previously been done in other applications.

Data and Tests Conducted Referring now to FIGS. 3 and 4, three different flow rates (25, 125, and 400 mL/hr) were tested using the same conditions (fluid infused, t code), cturing lot, environmental conditions, head height).

Infusion duration ed for each test in order to test to the clinically appropriate limits of 72 hours or 12L, whichever comes first. Flow rate data was ed and flow rate accuracy was assessed using a 1 hour moving average at each time-point in order to capture the accuracy of each hour of infusion.

Data Analysis As seen in plotting flow rate accuracy (% Error) of the selected flow rates as a function of time yields a wide spread of the data and no reliable trend that could be used to adjust for changes in performance. At any given time point, the cy between flow rates could vary as much as 10%, rendering a time-based adjustment ineffective.

Referring now to the t pump controller 28 is configured for compensating for administrative set tubing degradation by adjusting pulse frequency based on volume infused, as opposed to time-based adjustment. In plots are depicted of the same accuracy data as but d of time as the X-axis, the data was plotted against volume infused.

The results show highly consistent behavior correlating % Error to volume infused, irrespective of programmed flow rate. At any given volume point, the difference in accuracy n flow rates is at a maximum of around 3.5% (roughly 3 times more consistent than the time-based approach), allowing this technique to be applied generally across the anticipated on rates of the pump.

Using the trend ed in an algorithm can be ped to adjust the pump speed over the course of the on based on volume infused. The technique can be applied generally for a wide range of flow rates, as is evidenced by the consistency in the data which spans from 25 — 400 mL/hr. Additionally, the predominant input to the compensation algorithm is “volume infused”, which infusion pumps currently track, enabling simple implementation.

It will be appreciated that the present system contemplates that there will be performance ions from tube-to-tube, so that no two samples of the same type of tubing set will perform identically. Similarly, individual infusion pumps of a particular manufacturer’s model number will experience slight mance differences. Despite these differences, the present pump ing a volume-based control regimen has been found to achieve relatively consistent performance across a variety of flow rates, as opposed to a time-based control regimen. As seen in there is a 3.5% span of accuracy at a particular preset volume, ed to the 10% span at a given time shown in As far as generating the Tubing Degradation Function, using empirical data, a correlation between flow rate accuracy and infused volume can be established. Then, a lookup table can be ted to store infusion volume (V1, V2, Vn), the error value at that infusion volume, (E1, E2, En) and the corresponding adjustment value for the predicted error (A1, A2, An). Once the pump has infused a volume, Vn which corresponds to a known undesirable accuracy, En, the pump will then adjust the flow rate by the adjustment value, An, in order to maintain the flow rate accuracy within a desired range (Table 1). Accordingly, the adjustment value takes the form of the Tubing ation Function, which causes the pump to operate at an adjusted pulse frequency, distinct from the original frequency programmed into the pump. It will be appreciated that the adjusted pulse frequency is ally periodically updated as the target volume is dispensed.

Volume d Error Value Adjustment Value Refening now to FIGS. 5 and 6, as an alternative technique, using empirical data, a correlation between flow rate accuracy and infused volume can be ished, as shown at Then, at predetermined volume points over the course of the infusion, the pump rate will be adjusted by known s in order to maintain the flow rate cy within a desired range. As seen in the data of is subjected to fine adjustment by using cal data, a correlation between flow rate accuracy and infused volume can be established, generating a compensation equation which becomes the Tubing Degradation Function. The pump, which already tracks infusion volume, will adjust the infusion rate in the form of changing the pulse frequency based on the Tubing Degradation Function at a pre-determined interval, providing continuous adjustment to compensate for flow rate error.

Thus, the adjusted pulse frequency is contemplated as changing over the course of the infusion.

While a ular embodiment of the volume-based flow rate compensation for infusion therapy has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be WO 48427 made thereto without departing from the invention in its broader aspects and as set forth in the following claims.

Claims (6)

CLAIMS :

1. An infusion pump configured for pumping fluid through a tubular strative set at a desired flow rate over a specified duration, comprising: a pumping mechanism constructed and arranged for releasably receiving the tubular administrative set and for exerting a pulsing force on the tubular administrative set, thus pressurizing a portion of the tubular strative set for creating a flow of fluid from an outlet of the tubular administrative set; and a controller connected to said pumping mechanism, said controller being configured to: operate said pumping mechanism; determine a first pulse frequency based on a volume of fluid infused over a portion of the specified duration and the d flow rate; and output a control signal to said pumping mechanism for operating said pumping mechanism based on the determined first pulse ncy; terized in that said controller is further configured to: receive an input as to the type of material used to form the tubular administrative set; adjust the first pulse frequency based on the volume of fluid infused to provide a second pulse frequency, wherein said second pulse frequency is different from said first pulse frequency, and wherein said adjustment includes processing the first pulse frequency using a Tubing Degradation Function that compensates for the degradation of the tubing and is compiled based on a comparison of historical data of administrative set flow rate accuracy in terms of % error with volume of fluid infused compared with target pump volume, such that said second pulse frequency maintains the target pump volume by sating for the degradation of the al of the tubular administrative set.

2. The infusion pump of claim 1, wherein said adjusting said first pulse ncy includes at least one of increasing and decreasing said first pulse ncy.

3. The infusion pump of claim 1, wherein said controller is further configured to: receive an input from a sensor representing a volume of fluid d from the tubular administrative set; and determine the volume of fluid infused over the portion of the specified duration based on the received input.

4. The infusion pump of claim 3, further sing: a sensor connected to said r administrative set for sensing the volume of fluid infused from the tubular strative set.

5. The infusion pump of claim 1, wherein said controller comprises: a processor; a memory connected to said processor; and non-transitory instructions stored in said memory and executable by said processor for causing said processor to: determine the first pulse frequency based on the volume of fluid infused over the n of the specified duration and the desired flow rate; and output the control signal to said pumping mechanism for operating said pumping mechanism based on the determined first pulse frequency.

6. An apparatus comprising: computer-executable instructions stored on a non-transitory medium, wherein the instructions, when executed by a processor, cause the processor to: determine a volume of fluid infused from an outlet of a tubular administrative set of an infusion pump over a period of time; determine a pulse frequency based on the determined volume of fluid infused over the period of time and a desired flow rate of fluid infused from the outlet of the tubular administrative set; and outputting a control signal to a pumping ism for operating the pumping mechanism based on the determined pulse frequency, wherein the pumping mechanism is constructed and arranged for releasably receiving the tubular administrative set and for exerting a pulsing force on the tubular administrative set for creating a flow of fluid from the outlet of the tubular administrative set; wherein said determining the pulse frequency comprises: ining a first pulse frequency based on the desired flow rate; receiving an input as to the type of material used to form the tubular strative set; and adjusting the first pulse ncy based on the determined volume of fluid infused to provide a second pulse frequency, said second pulse frequency being ent from said first pulse frequency, wherein said adjusting the first pulse ncy comprises processing the first pulse frequency using a Tubing Degradation Function, said Tubing Degradation Function compensating for the degradation of the tubing and being compiled based on a comparison of ical data of administrative set flow rate accuracy in terms of % error with volume of fluid infused compared with target pump volume, such that said second frequency maintains the target pump volume by sating for the degradation of the material of the tubular administrative set.