Improved air-in-line detection for infusion pumps

Abstract

A control module of an infusion pump is structured to receive an administration set along a mating side of the control module. The control module includes on a mating side an expulsor, an upstream valve, a downstream valve, and an air-in-line detector downstream of the downstream valve. The administration set includes a pressure plate having a high-volume peristaltic tube, a first major surface, and a longitudinal axis. The pressure plate further has attachment features structured to mate with corresponding attachment features of the control module to align the high-volume peristaltic tube with the longitudinal axis. When the pressure plate and control module are mated, the expulsor engages a first portion of the peristaltic tube and the air-in-line detector engages a second portion of the peristaltic tube. A raised feature in the pressure plate acts to optimally position the high-volume peristaltic tube within a detection zone of the air-in-line detector.

Description

[0001] Attorney Docket No. 571120-44

[0002] IMPROVED AIR-IN-LINE DETECTION FOR INFUSION PUMPS

[0003] CROSS REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of Provisional Application No. 63 / 713,411, filed October 29, 2024, the disclosure of which is hereby incorporated by reference.

[0005] TECHNICAL FIELD

[0006] This disclosure relates to infusion pumps, and more particularly, to systems and methods for improved air-in-line detection for infusion pumps.

[0007] BACKGROUND

[0008] In view of the importance of avoiding introduction of gas (air or other) into the vasculature of patients, infusion pumps typically incorporate an air-in-line detector (AILD) to sense the presence of gas bubbles in lines or tubes that deliver medicaments and other infusates to patients. Many AILDs utilize ultrasonic devices or systems to sense differing acoustic properties (e.g., transmission and reflection) of portions of a line filled with liquid, gas, or a mixture of the two. In some cases, an infusion pump can annunciate an air detection alarm when predetermined conditions are met in regard to AILD sensing, alerting a user of the pump to a possibility of an air-in-line condition that may require remediation.

[0009] Implementing a useful AILD system can require, or benefit from, careful arrangement and adjustment of hardware, and judicious choice of the predetermined conditions or parameters that define when an alarm is to be sounded or displayed. A system that is less than optimally Attorney Docket No. 571120-44 implemented may fail to alarm when an air-in-line condition exists, or may provide excessive false alarms. The latter case can contribute to the annoyance of caregivers and even more problematic “alarm fatigue” (desensitization to alarms). In some cases, a poorly implemented AILD system may be deactivated, eliminating any possible benefit. It would therefore be desirable to provide improved air-in-line detection for infusion pumps.

[0010] SUMMARY

[0011] This disclosure relates to infusion pumps, and more particularly, to systems and methods for improved air-in-line detection for infusion pumps.

[0012] In an illustrative but non-limiting example, the disclosure provides a remote reservoir adapter configured to couple to a control module of a peristaltic infusion pump. The control module can be structured to receive the remote reservoir adapter along a mating side of the control module. On the mating side, the control module can include an expulsor, an upstream valve (relative to the expulsor), a downstream valve, and an air-in-line detector downstream of the downstream valve. The remote reservoir adapter can include a pressure plate and a peristaltic tube. The pressure plate can include a first major surface and a longitudinal axis. The pressure plate further can have attachment features structured to mate with corresponding attachment features of the control module such that the pressure plate is maintained in a fixed position relative to the control module. The peristaltic tube can be located along the pressure plate corresponding to the first major surface of the pressure plate, substantially aligned with the longitudinal axis, and positioned such that when the attachment features of the pressure plate and control module are mated, the expulsor engages the first portion of the peristaltic tube and the Attorney Docket No. 571120-44 air-in-line detector engages the second portion of the peristaltic tube. The pressure plate includes a raised feature, that provides improved placement and positioning of the tube adjacent to the airin-line detector to thereby improve operation of the air-in-line detector.

[0013] The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Subject matter hereof may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying figures, in which:

[0016] Figure 1 is a schematic perspective view of an example of an infusion pump system that includes a control module and a remote reservoir adapter;

[0017] Figure 2 is a schematic partial perspective view of the infusion pump system of Figure 1 with the remote reservoir adapter separated from the control module;

[0018] Figure 2A is a schematic perspective view of a portion of the remote reservoir adapter of Figure 2, depicted without a peristaltic tube to provide visibility to a raised feature thereof;

[0019] Figure 2B is a magnified perspective view of the raised feature depicted in Figure 2A; and

[0020] Figure 2C is a magnified cross-sectional view of the raised feature depicted in Figures 2A-B, in use with an infusion pump system as depicted in Figure 1. Attorney Docket No. 571120-44

[0021] While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims.

[0022] DETAILED DESCRIPTION OF THE DRAWINGS

[0023] The following description should be read with reference to the drawings, in which like elements in different drawings may be numbered in like fashion. The drawings, which are not necessarily to scale, depict selected examples and are not intended to limit the scope of the disclosure. Although examples of construction, dimensions, and materials may be illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.

[0024] Figure 1 is a schematic perspective view of an example embodiment of an infusion pump system 100 that includes a control module 102 and an optional remote reservoir adapter (“RRA”) 104. Infusion pump system 100 can be a CADD® (Computerized Ambulatory Drug Delivery) infusion pump system from ICU Medical, Inc., although the teachings of the present disclosure are not limited to CADD® infusion pumps and may be practiced with any suitable infusion pump system.

[0025] Control module 102 of infusion pump system 100 can include a user interface having a display screen 105 and a control pad 106 (push buttons, etc., of the control pad are not Attorney Docket No. 571120-44 illustrated). Control module 102 can also include a battery door 108, including a knob 109 for locking and unlocking the door 108, which can cover a battery compartment in which batteries for powering the pump system 100 can be housed. In some examples, a combination battery and wireless communication module can be present approximately where battery door 108 is illustrated. Control module 102 can also include any or all of a power switch 112, and, visible in Figure 2: an input / output port 114 such as a USB port or other appropriate interface for connecting pump system 100 to a computer having software designed to interface with pump system 100, a power jack 116 for connecting a power cord for powering pump 100, and a remote dose cord jack 118 for connecting a remote dose cord that provides a way to activate patient- controlled administration (or “PCA”) of doses from pump system 100.

[0026] Example infusion pump system 100 can include a replaceable RRA 104 connected to control module 102. In an embodiment, RRA 104 can be fluidically coupled to a remote reservoir or IV bag that contains a prescribed infusate (not shown) to be delivered to a patient as will be further described. Tubing 119 can extend from RRA 104 and fluidly communicates with an infusion set or catheter (not shown) to deliver the infusate to the patient. The control module 102 can be used to control the flow of infusate from RRA 104. One example of such an RRA is included in CADD™ Administration Sets from ICU Medical, Inc., though other hardware configurations can be used in other examples.

[0027] Figure 2 is a schematic partial perspective view of the example of infusion pump system 100 with RRA 104 separated from control module 102, and rotated to provide views of their mating structures. Control module 102 and RRA 104 can be configured to be connected at a mating side 120 of control module 102 and pressure plate 122 of RRA 104, respectively. Attorney Docket No. 571120-44

[0028] In this example embodiment, mating side 120 of control module 102 can include hinge pins 124 and 126 located proximally to a first end of mating side 120, although in other examples a single hinge pin or more than two hinge pins can be employed. Hinge pins 124 and 126 are further located in hinge wells 125 and 127, respectively.

[0029] Mating side 120 of control module 102 can include a latch receptacle 130 that is located proximally to a second end of mating side 120 opposite the first end thereof. Control module 102 can include a latch mechanism 132 associated with latch receptacle 130, and a latch lever 133 (see also Figure 1) to allow a user to manipulate the latch mechanism.

[0030] Pressure plate 122 of RRA 104 can include a body 123 having first 110 and second (not visible) major surfaces (top and bottom, respectively, relative to Figure 2), a longitudinal axis and a transverse axis, first and second longitudinal sides, and first 134 and second 136 transverse ends. Pressure plate 122 can include first and second securing hooks 138, 140 extending away from first major surface 110 of body 123 proximal first transverse end 134. First and second securing hooks 138, 140 each can be structured to reversibly and hingedly couple to a corresponding one of hinge pins 124, 126 of mating side 120 of control module 102. Irrespective of this example embodiment, in the present disclosure, any suitable arrangements of securing hook(s) and hinge pin(s) are contemplated.

[0031] Pressure plate 122 also can include an arch 142 extending away from first major surface 110 of body 123 proximally to second transverse end 136. Arch 142 and latch receptacle 130 of mating side 120 of control module 102 can be structured such that arch 142 is received by latch receptacle 130 as pressure plate 122 is pivoted about pins 124, 126 toward control module 102. Arch 142 can be structured to be captured by latch mechanism 132 of control module 102 and Attorney Docket No. 571120-44 drawn toward mating side 120 of module 102 by latch mechanism 132. When arch 142 is captured by latch mechanism 132 and hooks 138, 140 are coupled to pins 124, 126, pressure plate 122 is secured thereby to control module 102.

[0032] Pressure plate 122 can be formed from any suitable material. In an embodiment, pressure plate 122 is formed from polycarbonate material, though other materials may be used. Pressure plate 122 may be joined, for example via bonding or ultrasonic welding, with a casing 144 (which may also be formed primarily of polycarbonate material) to together provide a housing of RRA 104. RRA 104 can be fluidically coupled to a remote reservoir or IV bag as aforementioned. A peristaltic tube 148 coupled to pressure plate 122 of RRA 104 provides a fluid path from the remote reservoir to a patient, via, for example, downstream tubing 119 fluidically connected to peristaltic tube 148. In this example embodiment, peristaltic tube 148 can be substantially longitudinally located along first major surface 110 of body 123 of pressure plate 122, and can provide a fluid path that is substantially parallel to first major surface 110. In this example embodiment, the fluid path provided by peristaltic tube 148 can extend substantially to first transverse end 134 of body 123.

[0033] In this example embodiment, mating side 120 of control module 102 can include an airin-line detector (AILD) 158 that partially surrounds peristaltic tube 148 when RRA 104 is secured to control module 102. AILD 158 can include a channel or groove into which a segment of peristaltic tube 148 resides when RRA 104 is secured to module 102. In an embodiment, AILD 158 can include at least one ultrasonic transducer located immediately adjacent to or in the groove in mating side 120 of module 102.

[0034] When RRA 104 is secured to control module 102, as illustrated in Figure 1, module 102 Attorney Docket No. 571120-44 can pump an infusate through peristaltic tube 148 by way of a peristaltic-type pump mechanism. Tube engaging members visible in the example embodiment of Figure 2 include downstream valve 152, upstream valve 154, and expulsor 156, which may engage and squeeze (or compress) peristaltic tube 148 against pressure plate 122 in a coordinated manner to effect a peristaltic-type pumping action, as described for example in U.S. Patent No. 4,559,038. In a simplified brief summary, a repeatable peristaltic-type pumping cycle can include:

[0035] (I) an expulsion phase, during which upstream valve 154 is closed e.g., valve 154 compresses peristaltic tube 148 against first major surface 110 of pressure plate 122 such that an inner lumen of tube 148 is occluded), preventing backflow toward the remote reservoir; downstream valve 152 is open (e.g., valve 152 is withdrawn away from pressure plate 122), permitting flow through a resulting open lumen of tube 148; and expulsor 156 progresses from an initial position away from pressure plate 122 to a position that squeezes peristaltic tube 148 against pressure plate 122, such that infusate in a portion of tube 148 engaged by expulsor 156 is substantially urged or pushed downstream for delivery to the patient; and

[0036] (II) a fill phase, during which downstream valve 152 is closed, preventing backflow of infusate from a patient-side of tube downstream tubing 119 toward RRA 104; upstream valve 154 is open, permitting flow from the reservoir into tube 148; and expulsor 156 progresses from a position squeezing tube 148 against pressure plate 122 to a position away from plate 122, such that as tube 148 resiliently returns from a squeezed or compressed state to an open state, fluid is drawn into tube 148 in a vicinity of expulsor 156 from the reservoir upstream of RRA 104. Attorney Docket No. 571120-44

[0037] Phases (I) and (II) can be repeated as needed to deliver infusate from a reservoir to a patient. Averaged over multiple cycles, increasing a rate of delivery of the infusate can be effected primarily in several ways. One way is to increase the rate of repetition of phases (I) and (II), thereby increasing the number of expulsions per time. Another way is to increase the outer diameter of the peristaltic tube, which increases the volume of fluid moved during each expulsion. A peristaltic tube having an outer diameter that is relatively larger than other tubing is often referred to as “high volume” or “high flow” tubing. In these examples, a high-volume peristaltic tube such as tube 148 can have an inner diameter of about 4.06 ± 0.05 mm (160 ± 2 mils) with a wall thickness of about 0.863 mm (about 34 mils), for a total outer diameter of about 5.79 ± 0.05 mm (about 228 ± 2 mils). A single pumping cycle on high-volume peristaltic tube such as tube 148 can result in delivery of about 100 microliters of infusate.

[0038] In another example embodiment, an infusion pump can deliver fluid from a cassette (not illustrated) housing an internal reservoir that is coupled to a pressure plate having a construction and configuration similar in several respects to pressure plate 122. Such a cassette can be employed, for example, when a therapy requires a volume or flow of infusate that is lower than that of a remote reservoir or IV bag using an RRA. Examples of such cassettes include CADD™ Medication Cassette Reservoirs (not illustrated) that are commercially available from ICU Medical, Inc., typically in 50 ml, 100 ml, and 250 ml volume capacities. While other capacity cassettes are possible, remote reservoirs and IV bags have an ability to provide, as compared to cassette reservoirs, very large volumes such as 500 ml, 1000 ml, 2000 ml, and greater.

[0039] The modular nature of infusion pump system 100 allows the same control module 102 to be paired with different RRAs, cassettes, and administration sets to better accommodate specific Attorney Docket No. 571120-44 patient therapies. For example, different reservoir volumes and different delivery rates (e.g., with different peristaltic tubes) can be selected with appropriate choices of RRAs, cassettes, and administration sets. Some challenges can arise for making the same control module 102 function well with such diversity of attachable hardware. The present disclosure is directed in some aspects toward improving the function of air-in-line detection in infusion pump system 100 when operated at relatively higher delivery rates as well as relatively lower delivery rates.

[0040] Referring again to Figures 1 and 2, AILD 158 of control module 102 can be an ultrasonic detector with an acoustic transmitter positioned on one side of the aforementioned groove that accommodates tube 148, and an acoustic receiver positioned on the other side of the groove. The presence of air in tube 148 residing in the groove can be inferred from the transmission of sound waves through the tube. The acoustic impedance of the portion of tube 148 located proximal to AILD 158 can vary depending on whether the tube contains liquid, gas, or a mixture of the two. Generally, a liquid-filled tube can transmit acoustic waves more efficiently than a tube containing gas (which can be regarded, relatively, as an acoustic open circuit). In practice, AILD 158 can be effectively “tuned” or calibrated e.g., by adjusting threshold values used to evaluate measured quantities related to detected acoustic properties) such that gas bubbles larger than a specified threshold volume can be detected, and smaller than the threshold ignored.

[0041] Small bubbles can be ignored in some circumstances as they may present negligible risk of harm to a patient. If not ignored, their detection can result in relatively frequent annunciation of air-in-line alarms that a caregiver may, over time, become motivated to disregard (the so- called effect of “alarm fatigue”), potentially leading to the hazard of the caregiver disregarding a more serious alarm. Attorney Docket No. 571120-44

[0042] Peristaltic tubes of the present disclosure can have substantially circular cross-sections when not compressed in a coupling of RRA 104 with control module 102, or otherwise influenced by external forces. Thus, in particular, any or all portions of standard and high- volume peristaltic tube can have substantially circular cross-sections when not compressed.

[0043] It has been observed empirically that some air detection problems can arise more frequently when used with a high-volume peristaltic tube such as tube 148 as aforementioned than when used with a smaller, standard peristaltic tube. With relatively larger diameter high- volume peristaltic tube 148, portions of tube 148 might not reside adequately or optimally in a detection zone of AILD 158 due to the aforementioned groove of AILD 158 being, for example, a size that might be smaller than would adequately or optimally accommodate a relatively high- volume tube 148 therewithin. This can occur because the groove of AILD 158 may be designed primarily for use with standard, smaller sized peristaltic tubes.

[0044] An advantage of the aforementioned raised feature will now be described, with regard to tube 148 and the groove of AILD 158.

[0045] Figure 2A is a schematic perspective view of a portion of pressure plate 122 of Figure 2, depicted without tubes 148 and 119 for clarity of the following description. In Figure 2, and more visibly in Figure 2 A and Figure 2B, a raised feature or “rib” 290 is secured to or formed in pressure plate 122. It is to be appreciated and understood that raised feature 290 functions to improve AILD sensor performance as will be further described.

[0046] An example of feature 290, as shown in Figures 2 A and 2B, may be generally characterized as substantially similar to a solid trapezoidal prism with sloped or curved opposite sides 291 and 292 (as particularly visible in Figure 2B). In use of pump 100, when pressure plate Attorney Docket No. 571120-44 122 of RRA 104 is coupled to control module 102, feature 290 acts to position tube 148 more completely within the channel or groove of AILD 158, with the sloped or curved sides 291 and 292 of feature 290 acting to fold portions of tube 148 into substantially closed portions (as more clearly depicted in Figure 2C) without excessively pinching or adversely affecting those portions of tube 148. It is to be appreciated and understood that, specifically, an improvement in interfacing high-volume tube 148 with AILD 158 is achieved by feature 290 that effectively folds portions of tube 148 adjacent to channel or groove of AILD 158 so that an inner diameter of tube 148 resides more fully within a sensing zone of AILD 158 than would otherwise occur. Accordingly, a bubble in high- volume tube 148 will have a greater potential of being correctly sensed by AILD 158 with such effect of feature 290 on tube 148.

[0047] With reference to Figures 2 and 2B, optional relief 293 in feature 290 tends to advantageously permit tube 148 to bend at an outer edge area of feature 290 when RRA 104 is coupled to control module 102. Thus, tube 148 may exit, e.g., a high volume pressure plate 122 I RRA 104 as shown in Figure 2 without being undesirably pinched or obstructed (as could otherwise occur if feature 290 had a sharper outer edge area). Optional relief 293 also allows for a smoother or more uniform transition in cross-sectional geometry of tube 148 so that a bubble therein, moving through sensing zone of AILD 158, could advantageously tend to not become stuck nor propagate backward in tube 148.

[0048] Referring again to Figures 1-2C, it is to be appreciated and understood that feature 290 of pressure plate 122 is compatible with existing control module 102 since feature 290 does not structurally interfere with AILD 158 when RRA 104 is coupled to control module 102.

[0049] Any suitable manufacturing technique(s) can be used to provide feature 290, including for Attorney Docket No. 571120-44 example plastic injection molding, plastic machining, and 3D printing.

[0050] Experimental results appear to confirm the effectiveness of prototypes of feature 290 for improving AILD sensor performance with high-volume peristaltic tubes such as tube 148. For example, in existing high-volume pressure plates without a raised feature adjacent to the AILD sensor, inconsistent bubble detection by the AILD sensor can result due to less ultrasonic beam coverage on the high volume tube. This can detrimentally occur because the AILD channel or groove is typically smaller than the tube outside diameter of, for example, 0.228 inches. In such situations, only about 40% of the tube cross section adjacent to the AILD sensor is covered by the ultrasonic beam, which leads to inconsistent bubble detection. However, with feature 290 in pressure plate 122, the performance of AILD 158 was improved due to a minimization of portions of tube 148 outside of a sensing zone of AILD 158, in substantially all spatial orientations of pump system 100. It is to be appreciated and understood that raised feature 290 advantageously urges a maximum cross-sectional portion of tube 148 to be within the sensing zone and to be more fixed and less susceptible to deleterious movement within the sensing zone (such as when, for example, RRA 104 is coupled to control module 102 and when the peristaltic- type pumping action occurs in operation of pump system 100). Additionally, problems such as AILD alarm failures and excessive false alarms were significantly diminished with feature 290 acting in cooperation with high volume tubes and AILDs.

[0051] In an embodiment, feature 290 has an overall length that is greater than a sensing zone of AILD 158, to ensure that tube 148 remains in the sensing zone even if, for example, RRA 104 moves or shifts relative to control module 102 in operation of pump system 100.

[0052] It is also to be appreciated and understood that feature 290 could also have a venturi Attorney Docket No. 571120-44 effect or cause an acceleration of infiisate through tube 148 within the sensing zone of AILD 158, that would tend to minimize deleterious occurrences of “stuck bubbles” in the sensing zone.

[0053] It is further to be appreciated and understood that although the present disclosure describes novel and inventive features of the raised feature in use with high volume or high flow tubing, embodiments of the raised feature, as described by example or otherwise contemplated herein, can also be useful for almost any peristaltic tubing whether or not characterized as high flow or high volume peristaltic tubing. In particular, the raised feature can advantageously urge such non-high flow or non-high volume tubing more optimally into a sensing zone of an AILD system. Thus, non-high flow or non-high volume tubing can also be more fixed and less susceptible to deleterious movement within the sensing zone.

[0054] Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions.

[0055] Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various Attorney Docket No. 571120-44 embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted. Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended. Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.

[0056] For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. § 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.

Claims

Attorney Docket No. 571120-44CLAIMS1. An administration set configured to couple to a control module of a peristaltic infusion pump, the control module being structured to receive the administration set along a mating side of the control module, the control module including on the mating side an expulsor, an upstream valve, a downstream valve, and an air-in-line detector downstream of the downstream valve, the administration set comprising: a pressure plate having a high- volume peristaltic tube, a first major surface, and a longitudinal axis, the pressure plate further having attachment features structured to mate with corresponding attachment features of the control module to substantially align the high- volume peristaltic tube with the longitudinal axis, such that when the attachment features of the pressure plate and control module are mated, the expulsor engages a first portion of the peristaltic tube and the air-in-line detector engages a second portion of the peristaltic tube; and a raised feature in the pressure plate that acts to optimally position the high-volume peristaltic tube within a detection zone of the air-in-line detector.

2. The administration set of claim 1, wherein the raised feature is characterized as substantially being a solid trapezoidal prism with curved sides.

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