WO2025189077A1 - Syringes for infusion pumps - Google Patents

Abstract

Embodiments of syringes may comprise a barrel including a body, a distal end extending to a tip, and a proximal end open to a cavity defined within the barrel. The cavity may have an inner wall coated with a lubricous material. A plunger rod including a shaft, a thumb press at a first end of the shaft, and a sealing area at a second end of the shaft may be included, the sealing area having a first ring, a flange, and a second ring between the first ring and the flange. The syringe may further comprise a sealing element having an inner seal structure, an outer seal structure, and a nose extending from a surface of the inner seal structure distal from the plunger rod. The outer seal structure may have a cantilevered outer edge.

Description

SYRINGES FOR INFUSION PUMPS

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application No. 63/563,259, filed March 8, 2024, the disclosure of which is hereby incorporated by reference.

FIELD

The present disclosure generally pertains to syringes. More particularly, the present disclosure pertains to syringes for use with infusion pumps.

BACKGROUND

Infusion pumps are extremely useful medical devices for providing prescribed fluids, drugs, and other therapies (collectively, “infusates”) to patients in controlled amounts. For example, medications such as antibiotics, chemotherapy drugs, vasoactives, insulin, blood products, and pain relievers are commonly delivered to patients via an infusion pump, as are nutrients and other supplements. Infusion pumps have been used in hospitals, nursing homes, and in other short-term and long-term medical facilities, as well as for in-home care. Infusion pumps can be particularly useful for the delivery of medical therapies requiring an extended period of time for their administration. There are many types of infusion pumps, including large volume, patient-controlled analgesia (PCA), elastomeric, syringe (syringe driver), enteral, and insulin pumps. Infusion pumps are typically useful in various routes of medication delivery, including intravenously, intra-arterially, subcutaneously, intraperitoneally, intraosseous, intraportal, in close proximity to nerves, and into an intraoperative site, epidural space or subarachnoid space.

Syringe pumps have a number of desirable characteristics, and are generally perceived as the most precise and accurate acute care infusion pumps available. Syringe pumps may support lower flow rates than large volume pumps or ambulatory pumps, sometimes as low as 0.01 milliliters/hour (with appropriately sized small syringes). Unlike large volume and ambulatory pumps that utilize proprietary or dedicated consumables, syringe pumps typically accommodate wide ranges of commonly used or ‘'off-the-shelf’ syringe brands and sizes that are typically coupled with non-proprietary extension sets for delivering infusates to patients.

However, traditional off-the-shelf syringes are not specifically designed for use in syringe pumps, as a very small percentage of worldwide syringes are used with pumps. Typically, off- the-shelf syringes are designed for manual, hand use. But when used with a syringe pump, the pump must identify or otherwise be configured with relevant characteristics of an off-the-shelf syringe for proper operation of the pump. Problems with syringe pump systems can arise from both the pump and the syringe. Some syringe pumps can suffer from performance limitations, particularly at low flow rates (< 5 milliliters per hour and particularly below 0.1 mL/hr), including but not limited to long start-up times to reach target flow rates, inconsistent flow profiles during infusate delivery, long times to alarm an occlusion, and risk of inadvertently delivering a bolus or allowing retrograde flow.

Further, some off-the-shelf syringes can also contribute to inaccuracies due to syringe compliance (e.g., deformation under pressure), which increases the time for a syringe pump to reach a programmed target flow rate, the time for a syringe pump to recognize an occlusion, and the volume of unintended boluses or no-flow period due to height changes to a running syringe pump, among other challenges. Further inaccuracies may arise from changes in backpressure due to multiple pumps being added to the same infusion line.

Off-the-shelf syringes can characteristically change over time, knowingly or unknowingly, thereby impacting pump performance. Further, off-the-shelf syringes can contribute to flow inconsistency and short-term inaccuracy, particularly with “stick slip” behavior, where flow delivery is discretized in delivery following periods of inadvertent no (or reduced) flow. Some off-the-shelf syringes exhibit high friction forces which, in combination with mechanical compliances of a pump, can be a source of stick-slip behavior and delayed start- of-flow. In one experiment that was conducted, pertaining to the present disclosure, a commercially available fifty milliliter syringe was operated in a syringe pump at a flow rate of 0.5 milliliters per hour, for a duration of eighty-four hours. After nearly thirty hours of nominal flow, a spontaneous onset of stick-slip flow episodes began, resulting in inconsistent fluid delivery from the syringe.

While valuable improvements to syringe pump construction, configurations, and operations have been and continue to be made, there remains a need for improvements to syringes themselves for their uses with syringe pumps. The present disclosure addresses these concerns.

SUMMARY Embodiments described or otherwise contemplated herein substantially provide the advantages of improving ease of use, operation, accuracy, and patient safety in the delivery of infusates, among other advantages.

In a feature and advantages of embodiments, completeness of delivery of an infusate dose to a patient is increased because of a seal created between components of the syringe that eliminates or at least reduces infusate leakage out of the syringe compared to a typical off the shelf syringe. Specifically, embodiments of syringes and components thereof described herein provide reduced compliance from flexing or deformation, of not only the syringe barrel but also of the syringe plunger rod and plunger sealing area. Embodiments of syringes and components thereof described herein also provide improved sealing between the barrel and the syringe plunger rod, and improved resistance to pressure anomalies. Embodiments of syringes and components thereof described herein are advantageously suited for use with an infusion pump which may subject syringes to many start and stop operations over a period of hours, sometimes at very low flow rates. Testing has shown that reducing compliance of the syringe has direct, measurable impact on improving start-up delay, occlusion detection, post-occlusion bolus, and boluses due to dynamic pump height change. Embodiments of the present disclosure reduce compliance and provide such measurable improvements.

In an embodiment, a syringe of the present disclosure may comprise a barrel including a body, a distal end extending to a tip, and a proximal end open to a cavity defined within the barrel. The cavity may have an inner wall coated with a lubricous material. The syringe may further comprise a plunger rod including a shaft, a thumb press at a first end of the shaft, and a sealing area at a second end of the shaft, the sealing area having a first ring, a flange, and a second ring between the first ring and the flange. The syringe may further comprise a sealing element having an inner seal structure, an outer seal structure, and a nose extending from a surface of the inner seal structure distal from the plunger rod. The outer seal structure may have a cantilevered outer edge. The sealing element may be configured to be operably coupled with the sealing area of the plunger rod such that the first and second rings are arranged within the sealing area and the flange abuts a surface of the sealing area proximate the plunger rod.

The plunger rod can be configured to be operably coupled within the cavity of the barrel, and translatable along a length of the barrel so as to selectively expel fluid from the cavity out of the tip of the barrel. The nose of the sealing element can be configured to extend into the tip of the barrel when the plunger rod is fully depressed with respect to the ban-el, so as to expel any liquid remaining in the tip. The cantilevered outer edge can be configured to flex inward toward the inner seal structure when the cantilevered outer sealing edge is inserted into the barrel, thereby creating a seal between the cavity and the external environment to avoid fluid leakage and to enable more consistent motion of the plunger within the barrel under varied conditions.

In a feature and advantages of embodiments, syringes according to the present disclosure provide improved, consistent sealing with only a single monolithic seal - as opposed to other arrangements utilizing double or triple sealing elements. A single sealing element advantageously reduces friction during operation, and according to embodiments of the disclosure, maintain prevention of siphoning of the syringe during operation .

The above summary is not intended to describe each illustrated embodiment or every implementation of the inventive subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG. 1 is a perspective view of an example syringe pump for use with embodiments of the disclosure.

FIG. 2 is a perspective exploded view of a syringe, according to an embodiment of the disclosure.

FIG. 3 is a perspective detail view of a plunger rod sealing element, according to an embodiment of the disclosure.

FIG. 4A is a side view of a syringe, according to an embodiment of the disclosure.

FIG. 4B is a cross-sectional view of the syringe of FIG. 4A taken along line A, according to an embodiment of the disclosure.

FIG. 4C is a detail view of a portion B of the syringe of FIG. 4B, according to an embodiment of the disclosure.

FIG. 5A is a side view of a plunger rod sealing element attached to a plunger rod, before insertion into a syringe barrel, accordin g to an embodiment of the disclosure.

FIG. 5B is a side view of a plunger rod sealing element attached to a plunger rod, during insertion into a syringe barrel, according to an embodiment of the disclosure.

FIG. 5C is a side view of a plunger rod sealing element attached to a plunger rod, after insertion into a syringe barrel , according to an embodiment of the disclosure. 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 inventive subject matter 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 die claims.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figure 1, an example of a syringe pump 100 is depicted for use with embodiments of the present disclosure. Syringe pump 100 can include a housing 102, user interface 104, a syringe drive assembly 106, and a syringe receptacle 108.

The syringe drive assembly 106 can be employed for controlling delivery of a prescribed amount or dose of an infusate from a syringe (not illustrated in Figure 1), that has been installed in the pump 100, to a patient by mechanically advancing a plunger in the syringe to deliver the infusate at a controlled rate through an infusion line fluidly connected to the syringe. In an example, a motor within pump 100 rotates a lead screw which, in turn, causes a plunger driver head assembly of the syringe drive assembly 106 to move in a direction toward the syringe receptacle 108. This movement then pushes the plunger within a barrel of the syringe located within the receptacle 108, where the barrel is held substantially in place with negligible or no movement of the syringe barrel relative to the housing 102 . Moving the syringe plunger forward therefore acts to displace a volume of infusate in the syringe outwardly from the syringe, into the infusion line, and ultimately to the patient. In the example syringe pump 100 of Figure I, the syringe receptacle 108 provides a cavity extending across the front of the syringe pump 100 such that a syringe installed therein is readily and sustainably visible. The syringe receptacle 108 is shaped and sized to accommodate installation of syringes of various sizes and brands therein for delivery of infusates.

Referring now generally to Figures 2-5C, an example of a syringe 200, according to an embodiment of die disclosure, is depicted including a barrel 210, a plunger rod 240, and a sealing element 270. With sealing element 270 coupled to plunger rod 240 as shown, for example, in Figure 4B, plunger rod 240 is operable to translate along a longitudinal axis of barrel 210 to expel infusate within barrel 210. Barrel 210 generally includes a tip 212 at a distal end, a neck 216, a body 218, and a flange 220 at a proximal end. Neck 216 may include an aperture therethrough and extending through tip 212, that can be configured as desired for coupling to a variety of types of extension sets, including Luer lock, enteral (including ENFit) and epidural catheter (including NRFit) tip, and other types of extension sets including those in compliance with current ISO standards. Tip 212 and neck 216 may be integrally coupled together or otherwise formed as a monolithic piece, or they may be removably coupled together such that tip 212 can be removed from neck 216. In embodiments, one or more of barrel 210 and plunger rod 240 may be constructed of polycarbonate.

Neck 216 may be substantially linear or cylindrical as depicted in the figures, although other variations such as a tapered or conical profile are contemplated by this disclosure. Body 218 of barrel 210 can be sized and shaped for a variety of common syringe capacities, for example from 1 milliliter to 100 milliliters. Flange 220 can be configured to interact with a corresponding retention feature of a syringe pump, for example to assist in securing syringe 200 in the pump during operation. At the proximal end of barrel 210 is an aperture, leading into a cavity 224 defined within barrel 210, and an inner wall 226 as shown particularly in Figure 4B. Cavity 224 can be configured to dispensingly retain infusate therein. In embodiments, a coating (not illustrated) may be applied to inner wall 226. In embodiments, the coating may comprise a silicone oil, a non-silicone oil alternative, or another coating for lubricity. In an embodiment, the coating may comprise a tribofilni material.

Referring specifically to Figure 2, plunger rod 240 may include a thumb press 246 at a proximal end, a shaft 247, and a sealing area 250 at a distal end opposite the thumb press 246. Shaft 247 generally extends from the thumb press 246 to the sealing area 250 along a length of plunger rod 240. As generally depicted in the Figures, shaft 247 may include a plurality of ribs 248 arranged in a ‘+’ configuration. The “+” configuration refers to shaft 247 having four equally spaced-apart ribs 248 arranged along a 360-degree axis of rotation. Other configurations of ribs 248 are also contemplated by this disclosure, including configurations with more than or less than four ribs 248.

A portion of sealing area 250 can be configured for receipt of sealing element 270 thereupon. Sealing area 250 generally includes a lower (or first) ring 252, an upper (or second) ring 254, and a lower (or first) flange 256. With specific reference to Figures 4B and 4C, sealing element 270 is couplable to sealing area 250 such that lower and upper rings 252, 254 can be received within sealing element 270, and lower flange 256 can abut a top portion of sealing element 270. Plunger 240 further includes a reinforcing ring (or upper/second flange) 258, adjacent sealing area 250. Reinforcing ring 258 may have a diameter similar to the diameter of lower flange 256. Reinforcing ring 258 can be configured to limit side-to-side deflection of plunger rod 240 with respect to barrel 210, thereby reducing syringe leakage due to normal forces acting on the syringe while installed in or external to the syringe pump, while also reducing the force required to actuate the syringe plunger.

Suitable materials for plunger rod 240 include medical grade plastics that are rigid and easy to process, such as via injection molding. One such well-known material is polycarbonate. Other medical grade materials known to one of ordinary skill in the art are also contemplated by this disclosure.

Referring specifically to Figures 3 and 4C-5C, sealing element 270 can include a nose 272 couplable to an inner seal structure 274, and an outer seal structure 280 connected to and surrounding inner seal structure 274. Nose 272 may extend from a surface of inner seal structure 274 proximate barrel 210 and distal from plunger rod 240. In embodiments, sealing element 270 may include a gap 276 between an unconnected portion of inner and outer seal structures 274, 280, as shown particularly in Figure 4C (276 being designated as a rotated symbol in Figure 4C). As depicted generally in the Figures, outer seal structure 280 may include a cantilevered outer edge 282 and an indented edge portion 286 arranged around an outer diameter of outer seal structure 280. Cantilevered outer edge 282 and indented edge portion 286 may comprise smooth surfaces, as depicted, or in other embodiments may include texturing or raised or lowered dimpling to tailor the friction characteristics of outer seal structure 280 as desired. Similarly, while cantilevered outer edge 282 and indented edge portion 286 are depicted as being generally asymmetric, it will be understood that symmetric configurations are also contemplated as may be necessary or desirable. Components of sealing element 270 are generally manufactured integrally together to form a monolithic piece, though other suitable configurations such as an assembly of elements are contemplated by this disclosure. Suitable materials for sealing element 270 can include isoprene, isobutylene isoprene rubber, or other materials known to one of ordinary skill in the art.

In an embodiment, nose 272 can be configured to extend into tip 212 of barrel 210 when the syringe is fully depressed, so as to advantageously expel any infusate in tip 212 without causing flexion of inner seal structure 274. In an embodiment, nose 272 is configured in a shortened configuration to eliminate interference with micro needless valves. Additionally, the profile of inner seal structure 274 can be designed to match the profile of neck 216 of barrel 210. In an embodiment, inner seal structure 274 may include dimpling thereon, so as to prevent or reduce inadvertent coupling between inner seal structure 274 and the inside of neck 216 (e.g., in the manner of a suction cup). In embodiments, the rigidity of inner seal structure 274 greatly reduces compliance compared to some prior syringes which may have, for example, featured less supported elastomeric material prone to compression or expansion during use.

Syringe 200 can be assembled by connecting barrel 210, plunger 240, and sealing element 270 together as described herein, with cavity 224 of barrel 210 containing infusate to be delivered to a patient. Referring specifically to Figure 5A (with reference also to Figures 4B and 4C), plunger 240 and sealing element 270 are depicted as being operably coupled together with a portion of sealing area 250 received within sealing element 270, such that lower ring 252 abuts a surface of inner seal structure 274 and upper ring 254 abuts an inner surface of indented edge portion 286. The combination of plunger 240 and sealing area 250 can be positioned over barrel 210 so that nose 272 of sealing element 270 partially extends into cavity 224 along a central axis of barrel 210.

Referring now specifically to Figure 5B (with reference also to Figures 4B and 4C), the combination of plunger 240 and sealing area 250 can be partially inserted into cavity 224 such that nose 272 extends further into cavity 224 along the central axis. As sealing element 270 is inserted, cantilevered outer edge 282 is placed in contact with inner wall 226 near flange 220. Tire contact with inner wall 226 enables cantilevered outer edge 282 to flex inward toward inner seal structure 274 which reduces the size of gap 276 separating the unconnected portion of inner seal structure 274 and outer edge 282.

Referring now specifically to Figure 5C (with reference also to Figures 4B and 4C), the combination of plunger 240 and sealing area 250 can be fully inserted into barrel 210 which enables further inward flexing of cantilevered outer edge 282 to a point where gap 276 is no longer present. This creates a seal between cavity 224 and the environment outside of the syringe, which prevents or at least acts to inhibit infusate stored within barrel 210 from flowing out of the syringe 200. After full insertion, plunger 240 can be compressed inward toward barrel 210 which pushes sealing element 270 through cavity 224 thereby forcing infusate out of tip 212 and into, for example, a tubing set that is fluidly connected a patient. The seal created by the compression of cantilevered outer edge 282 against the inner barrel wall 226 prevents or at least acts to inhibit infusate from flowing in any direction except for the direction of plunger 240 when compressed inward toward barrel 210. As such, syringe 200 advantageously enables the delivery of infusate into a patient while advantageously reducing or eliminating undesirable leakage of infusate from the syringe. Various embodiments of systems, devices, and methods have been described herein. These embodiments are given by way of example and are not intended to limit the scope of the claimed inventive subject matter. 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 inventive subject matter.

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 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.

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

1. A syringe, comprising: a barrel including a body, a distal end extending to a tip, and a proximal end open to a cavity defined within the barrel, the cavity having an inner wall coated with a lubricous material; a plunger rod including a shaft, a thumb press at a first end of the shaft, and a sealing area at a second end of the shaft, the sealing area having a first ring, a flange, and a second ring between the first ring and the flange; and a sealing element having an inner seal structure, an outer seal structure, and a nose extending from a surface of the inner seal structure distal from the plunger rod, the outer seal structure having a cantilevered outer edge, wherein the sealing element is configured to be operably coupled with the sealing area of the plunger rod such that the first and second rings are arranged within the sealing area and the flange abuts a surface of the sealing area proximate the plunger rod, wherein the plunger rod is configured to be operably coupled within the cavity of the barrel, and translatable along a length of the barrel so as to selectively expel fluid from the cavity out of the tip of the barrel, wherein the nose of the sealing element is configured to extend into the tip of the barrel when the plunger rod is fully depressed with respect to the barrel, so as to expel any liquid remaining in the tip, and wherein the cantilevered outer edge is configured to flex inward toward the inner seal structure when the cantilevered outer edge is inserted into the barrel, thereby creating a seal between the cavity and the external environment to avoid fluid leakage.

2. A syringe, as shown and described herein.

3. A syringe pump system, as shown and described herein.

4. A method of operating a syringe pump system, as shown and described herein.