Syringe for infusion pump

Abstract

Embodiments of syringes and components described herein prevent flexing or deformation providing not only a reduced compliance syringe barrel but also a reduced compliance syringe plunger rod and plunger seal. Embodiments of the syringes and components thereof described herein also provide improved sealing between the barrel and the syringe plunger rod and improved pressure resistance. Implementations of syringes and components described herein are advantageously suited for use with infusion pumps that may subject syringes to multiple start / stop operations sometimes at very low flow rates over a period of hours.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Provisional Application No. 63 / 407,512, filed on September 16, 2022, the disclosure of which is hereby incorporated by reference. Technical Field

[0003] The present disclosure relates generally to syringes. More particularly, the present disclosure relates to syringes for use with infusion pumps. Background Art

[0004] Infusion pumps are extremely useful medical devices for providing patients with prescribed fluids, medicaments and other treatments (collectively referred to as "infusions") in controlled amounts. For example, medicines such as antibiotics, chemotherapy agents, vasoactive drugs, insulin, blood products and analgesics are usually delivered to patients via infusion pumps, as are nutrients and other supplements. Infusion pumps have been used in hospitals, nursing homes, and other short-term and long-term medical institutions and home care. Infusion pumps may be particularly useful for the delivery of medical treatments that require a long period of time to be administered to them. There are many types of infusion pumps, including large-volume pumps, patient-controlled analgesia (PCA) pumps, elastic pumps, syringe pumps (syringe drivers), enteral pumps and insulin pumps. Infusion pumps are typically used for various drug delivery routes, including intravenous delivery, intraarterial delivery, subcutaneous delivery, intraperitoneal delivery, intraosseous delivery, intraportal delivery, adjacent to nerve delivery, and delivered to the intraoperative site, epidural space or subarachnoid space.

[0005] Syringe pumps have many desirable features and are generally considered to be the most precise and accurate acute care infusion pumps available. Syringe pumps can support lower flow rates than large-volume or ambulatory pumps, sometimes as low as 0.01 ml / hour (using a small syringe of appropriate size). Unlike large-volume and ambulatory pumps, which utilize proprietary or dedicated consumables, syringe pumps typically accommodate a wide range of commonly used or "off-the-shelf" brands and sizes of syringes, which are typically coupled with a non-proprietary extension kit for delivering the infusion to the patient.

[0006] However, traditional ready-made syringes are not specially designed to be used in syringe pumps, because very small percentage of syringes in the whole world are used with pumps. Usually, ready-made syringes are designed to be used for hand-operated use, manual use. But when used with syringe pumps, pumps must identify or otherwise be constructed with the relevant characteristics of ready-made syringes for the correct operation of pumps. The problem of syringe pump systems may come from both pumps and syringes. Some syringe pumps may be subject to performance limitations, particularly at low flow rates (<5 milliliters per hour and particularly below 0.1 mL / hr), subject to performance limitations, including but not limited to the long start-up time to reach the target flow rate, inconsistent flow distribution during the infusion delivery, long warning obstruction and inadvertently delivering large doses or allowing the risk of retrograde flow. In addition, due to syringe compliance (e.g., deformation under pressure), some ready-made syringes may also cause inaccuracy, which increases the time for syringe pumps to reach the target flow rate of planning, the time for syringe pumps to identify obstruction, and causes undesirable large dose volume flow or no flow period and other challenges caused by the height variation of the syringe pumps running. As multiple pumps are added to the same infusion line, variations in back pressure may introduce further inaccuracies.

[0007] Off-the-shelf syringes may change in characteristics over time, intentionally or unintentionally, thereby affecting the performance of the pump. In addition, off-the-shelf syringes may cause flow inconsistencies and short-term inaccuracies, particularly in the case of "stick-slip" behavior, in which flow delivery is discretized in delivery after an inadvertent period of no flow (or reduced flow). Some off-the-shelf syringes exhibit high friction, which, combined with the mechanical compliance of the pump, may be the cause of the stick-slip behavior and delayed onset of flow. In an experiment conducted in connection with the present disclosure, a commercial fifty milliliter syringe was operated in a syringe pump at a flow rate of 0.5 milliliters per hour for eighty-four hours. As depicted in Figure 1, after nearly thirty hours of nominal flow, spontaneous onset of stick-slip flow began to occur, resulting in inconsistent fluid delivery from the syringe.

[0008] While valuable improvements have been and continue to be made to the construction, configuration, and operation of syringe pumps, there remains a need for improvements to the syringes themselves for use with syringe pumps. The present disclosure addresses these issues. Summary of the invention

[0009]

[0013] Embodiments described herein or otherwise contemplated generally provide advantages of improved ease of use, handling, accuracy, and patient safety in the delivery of infusates, among other advantages.

[0010] Among features and advantages of embodiments, a syringe pump operated on a syringe according to embodiments described herein is characterized by reduced pump startup time and reduced syringe replacement time. Among features and advantages of embodiments, the time to detect a syringe pump occlusion is reduced. Among features and advantages of embodiments, the integrity of the delivered infusate dose is increased.

[0011] Among the features and advantages of embodiments, flow consistency of a medicament delivered from a syringe is improved, and delivery anomalies, such as stick-slip, are reduced. Embodiments of the syringe described herein improve short-term and long-term pump accuracy over the entire range of pump operation, reducing the dependence of performance on environmental conditions, such as back pressure, temperature, or fluid changes.

[0012] Among features and advantages of embodiments, undesired large dose volume flows and no-flow periods (eg, due to height variations of an operating syringe pump) are reduced.

[0013] Embodiments of the syringes and components thereof described herein prevent flexing or deformation and provide not only a syringe barrel with reduced compliance but also a syringe plunger rod and plunger seal with reduced compliance. Embodiments of the syringes and components thereof described herein also provide an improved seal between the barrel and the syringe plunger rod and improved compression resistance. Embodiments of the syringes and components thereof described herein are advantageously suitable for use with an infusion pump that can subject the syringe to multiple start / stop operations over a period of hours, sometimes at very low flow rates.

[0014] The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter of the present disclosure.The following figures and detailed description more particularly exemplify various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The subject matter of the present disclosure may be more fully understood by considering the following detailed description of various embodiments in conjunction with the accompanying drawings, in which:

[0016] FIG. 1 is a graph of flow rate versus time for a prior art syringe depicting inconsistent fluid delivery from the syringe.

[0017] Figure 2 is a perspective view of an exemplary syringe pump for use with embodiments of the present disclosure.

[0018] Figure 3 is an exploded perspective view of a syringe according to an embodiment of the present disclosure.

[0019] Figure 4 is a perspective view of a plunger rod according to an embodiment of the present disclosure.

[0020] Figure 5 is a perspective view of a plunger rod sealing element according to an embodiment of the present disclosure.

[0021] Figure 6 is a perspective view of a plunger rod having a sealing element coupled thereto according to an embodiment of the present disclosure.

[0022] Figure 7 is a cross-sectional view of the distal end of a syringe according to an embodiment of the present disclosure.

[0023] Figure 8 is another perspective view of a plunger rod with a sealing element coupled thereto.

[0024] Fig. 9 is a perspective view of a distal end of a syringe according to an embodiment of the present disclosure.

[0025] Fig.10 is a graph depicting the compliance of a prior art syringe compared to a syringe according to an embodiment of the present disclosure.

[0026] Fig.11 is a graph depicting test results of force versus distance for a prior art syringe compared to a syringe according to an embodiment of the present disclosure.

[0027] Fig.12 is a graph depicting test results of flow rate versus time for a prior art syringe operated in a syringe pump compared to a syringe according to an embodiment of the present disclosure for a first set of test conditions.

[0028] Fig.13 is a graph depicting test results of flow rate versus time for a prior art syringe operated in a syringe pump compared to a syringe according to an embodiment of the present disclosure for a second set of test conditions.

[0029] Fig.14 is a graph depicting test results of flow rate versus time for a prior art syringe compared to a syringe according to an embodiment of the present disclosure for a third set of test conditions.

[0030] Although each embodiment can be modified into various modifications and alternative forms, the details of each embodiment have been shown by way of example in the drawings and will be described in detail. However, it should be understood that it is not intended to limit the subject matter of the present disclosure to the specific embodiments described. On the contrary, it is intended to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the subject matter of the present disclosure according to the attached claims. DETAILED DESCRIPTION

[0031] Now refer to Figure 2, depicts an example of a syringe pump 100 for use with embodiments of the present disclosure. The syringe pump 100 may include a housing 102, a user interface 104, a syringe drive assembly 106, and a syringe receiver 108.

[0032] The syringe drive assembly 106 can be used to control the injection of an infusion from a syringe already installed in the pump 100 by mechanically advancing a plunger into the syringe to deliver an infusate at a controlled rate through an infusion line fluidly connected to the syringe. Figure 2 The pump 100 is used to deliver a prescribed amount or dose of infusate to a patient (not shown). In the example, a motor within the pump 100 rotates a lead screw, which in turn moves a plunger driver head assembly of a syringe drive assembly 106 in a direction toward a syringe receiver 108. This motion then pushes the plunger into the barrel of a syringe located within the receiver 108, where the barrel remains substantially in place. Moving the syringe plunger forward is used to displace a volume of infusate in the syringe outward from the syringe into an infusion line and ultimately to the patient.

[0033] exist Figure 2 In the exemplary pump 100 of , the syringe receiver 108 provides a cavity extending across the front of the syringe pump 100 so that a syringe installed in the syringe receiver 108 is easily and continuously visible. The syringe receiver 108 is shaped and sized to accept syringes of various sizes and brands installed therein for delivery of infusates.

[0034] Now the overall reference Figures 3 to 9 , depicts an example of a syringe 200 according to an embodiment of the present disclosure, the syringe 200 includes a barrel 210, a plunger rod 240, and a sealing element 270. The sealing element 270 is coupled to a Figure 6In the case of the plunger rod 240 in the barrel 210, the plunger rod 240 can be operated to translate along the longitudinal axis of the barrel 210 to discharge the infusate in the barrel 210. The barrel 210 generally includes a tip 212 at the distal end, a neck 216, a body 218 and a flange 220 at the proximal end. The tip 212 includes a hole therein, and can be configured to be connected to various types of extension kits as desired, and the extension kits include Luer locks, enteral catheters (including ENFit) and epidural catheters (including NRFit) tips, and other types of extension kits including extension kits that meet current ISO standards. As depicted in the figure, the neck 216 can be tapered, but other variations can also be envisioned. The body 218 of the barrel 210 can be sized and shaped to be used for various common syringe capacities, such as from 1 ml to 100 ml. The flange 220 can be configured to interact with the corresponding retention features of the syringe pump, such as being configured to help fix the syringe 200 in the pump during operation. There is a hole at the proximal end of the barrel 210, which leads to a cavity 224 and an inner wall 226 defined in the barrel 210. The cavity 224 is configured to hold the infusate therein. In an embodiment, a coating 228 (not labeled in the figure) can be applied to the inner wall 226. In an embodiment, the coating 228 can include silicone oil, non-silicone oil substitutes, or other coatings for lubrication. In an embodiment, the coating 228 can include a tribofilm.

[0035] Also refer to Figure 4 , the plunger rod 240 includes a substantially rigid nose 242 at the distal end, a plunger face (or stop) 244, a pressing portion 246 at the proximal end, and a shaft 247. As generally depicted in the figure, the shaft 247 includes a plurality of ribs 248 arranged in a "+" configuration. Other configurations of the ribs 248 are also conceivable. In an embodiment, the nose 242 is configured to extend into the tip portion 212 of the barrel 210 when the syringe is fully depressed, so as to advantageously discharge any infusion in the tip 212 without causing deflection of the plunger face 244. In addition, the profile of the plunger face 244 can be configured to match the profile of the neck 216 of the barrel 210. In an embodiment, the plunger face 244 may include a dent located thereon to prevent or reduce accidental coupling between the plunger face 244 and the interior of the neck 216 (e.g., in the manner of a suction cup). In embodiments, the rigidity of plunger face 244 greatly reduces compliance compared to some prior art approaches that may feature elastic materials that tend to compress or expand during use, for example.

[0036] Continue to refer to Figure 4, the plunger rod 240 also includes a sealing area 250, which in the depicted embodiment is adjacent to the plunger face 244. The sealing area 250 is configured to receive a sealing element 270 thereon and generally includes an inner ring 252, a lower (or first) flange 254, and an upper (or second) flange 256. Figure 7 , the sealing element 270 can be coupled to the sealing area 250 such that the sealing element 270 is bounded by the lower flange 254 and the upper flange 256. The inner ring 252 provides support for the sealing element 250 between the flange 254 and the flange 256. The plunger 240 also includes a reinforcement ring 258 adjacent to the sealing area 250. The reinforcement ring 258 can have a diameter similar to the diameter of the lower flange 254 and the upper flange 256. The reinforcement ring 258 is configured to limit lateral deflection of the plunger rod 240 relative to the barrel 210, thereby reducing syringe leakage caused by normal forces acting on the syringe when installed in the pump or located outside the pump, and also reducing the force required to actuate the syringe plunger.

[0037] Suitable materials for the plunger rod 240 include medical grade plastics that are rigid and easily processed, such as via injection molding. One such well-known material is polycarbonate.

[0038] Now refer to Figures 5 to 7 , the sealing element 270 includes a body 272, an inner diameter 274, and an outer diameter 278. In an embodiment, the inner diameter 274 may include a circumferential channel 276 configured to cooperate with the inner ring 252 of the plunger rod 240. The outer diameter 278 includes one or more seals. As generally depicted in the figure, the sealing element 270 includes a first seal 280 and a second seal 282 arranged on the outer diameter 278. The seals 280 and 282 may include a smooth surface as depicted, or in other embodiments may include textured or raised or lowered indentations to customize the friction characteristics of the sealing element 270 as desired. Similarly, although the seals 280 and 282 are depicted as being generally symmetrical, it will be understood that asymmetrical configurations may also be envisioned as desired. In addition, the sealing element 270 includes a flange 284 configured to help retain the sealing element 270 in the sealing area 250 of the plunger rod 240 by providing a solid surface to abut the upper flange 256 of the plunger rod 240. The flange 284 also supports the die cutting process to separate the compression molded sheet of multiple sealing elements from the elements that are manufactured integrally together. Suitable materials for the sealing element 270 can include isoprene or isobutylene isoprene rubber.

[0039] Figure 8 Another perspective view of a plunger rod is depicted having a sealing element coupled thereto. Fig. 9is a perspective view of a distal end of a syringe according to an embodiment of the present disclosure.

[0040] Several prototype syringes were prepared and tested according to embodiments of the present disclosure. Fig.10 A volume displacement test was performed on a 60 mL prior art syringe and a 60 mL improved syringe constructed according to an embodiment of the present disclosure. The volume displacement test was performed using a liquid filled syringe by first fixing the syringe plunger in a specific test position. A rigid liquid filled tube was attached to the syringe, wherein an air pressure source was connected to the end of the tube. The air pressure was increased, causing the water-air boundary to shift toward the syringe. The displacement was measured and converted into a "displaced volume", and the displacement was calculated as Fig.10 A person of ordinary skill in the art will understand that Fig.10 In the context of , the "compliance" of a syringe is the parameter that relates the displaced volume to the pressure applied at a selected pressure.

[0041] Reference Fig.10 , line 302 depicts the volume displacement of a prior art syringe on (y-axis) as a function of applied pressure (x-axis) with the plunger / stopper of the syringe at the outlet (empty, e.g., all fluid discharged). Thus, line 302 represents only the volume displacement of the plunger component. Line 304 depicts the volume displacement with the stopper / plunger in the capacity (fully extended) position, so the difference between line 304 and line 302 represents only the volume displacement of the barrel component of the prior art syringe.

[0042] Then, as described in the examples herein and as previously described Figures 3 to 9 The illustrated improved syringe is tested. Line 306 depicts the volume displacement when the plunger / stop is located at the outlet (emptying). Therefore, line 306 only represents the volume displacement of the plunger component. Line 308 depicts the volume displacement when the plunger is fully extended from the barrel, so the difference between line 308 and line 306 only represents the volume displacement of the barrel component. Therefore, compared with the syringe of the prior art, the improved syringe in the full position shows a reduction of about eighty percent in volume displacement. Volume displacement represents the ability of the syringe to expand under pressure to accommodate the incremental fluid volume. In the operation using a syringe pump, the syringe pump applies pressure to the syringe plunger to displace the fluid toward the patient in a controlled manner, and the reduction in volume displacement means that the start-up time is reduced, because less plunger mechanical displacement is required before steady-state delivery to pressurize the system and reach mechanical balance. The reduction in volume displacement similarly reduces the time of the occlusion alarm, because the ability of the syringe to absorb incremental fluid under pressure is reduced, and therefore the threshold pressure is reached faster than the syringe with a higher volume displacement.

[0043] Now refer to Fig.11 , tests were also conducted to determine the stick-slip behavior of prior art syringes and syringes constructed according to embodiments of the present disclosure. The force initially applied to the plunger rod must overcome any static friction between the plunger seal and the interior of the barrel. The force required to overcome the static friction and allow the plunger to begin moving is denoted as Fs, the starting force. After Fs, the required force is increased by dropping and then rising to Fs. 最大 For short oscillations, the maximum force is observed when the plunger moves. 最大 And calculate the mean value F 平均 , the percentage difference between the values ​​of each parameter can be determined. Relatively small differences between the values ​​of these three parameters tend to result in reduced stick-slip behavior, while larger differences between the values ​​tend to result in increased stick-slip behavior. Fig.11 , the x-axis represents distance and the y-axis represents force, while the upper line represents the improved syringe according to an embodiment of the present disclosure and the lower line represents the syringe of the prior art.

[0044] Embodiments of different syringe configurations were constructed and tested, resulting in measured percentage differences (in Fs, F 最大 With F 平均 In contrast, the prior art syringes were also tested, and the Fs, F 最大 With F 平均 The percentage difference between is thirty-six percent. Thus, the present disclosure represents a significant improvement in syringe operation.

[0045] Now refer to Figure 12 to Figure 14 , each graph depicts the test results of flow rate error of an improved syringe (left curve graph) according to an embodiment of the present disclosure compared with a syringe of the prior art (right curve graph), wherein noteworthy data are presented in the table. For example, Fig.12 The test parameters were a flow rate of 0.1 ml / hr, a temperature of 35°C, and a back pressure of 600 mmHg. As is apparent from the graph and tabular data, the improved syringe advantageously features significantly shorter start-up time, shorter time to steady state flow, and reduced steady state delivery errors.

[0046] Similarly, Fig.13 The results of tests conducted at a flow rate of 0.1 ml / hr, a temperature of 23°C, and a back pressure of 0 mmHg are depicted. As is apparent from the graph and tabular data, the improved syringe advantageously features significantly shorter start-up times, shorter times to steady-state flow, and only slightly greater steady-state delivery errors.

[0047] at last, Fig.14Results of tests conducted at a flow rate of 10 ml / hr, a temperature of 35°C, and a back pressure of 600 mmHg are depicted. As is apparent from the graph and tabular data, the improved syringe advantageously features shorter start-up time, shorter time to steady state flow, and only slightly greater steady state delivery error.

[0048] Various embodiments of systems, devices, and methods have been described herein. These embodiments are given by way of example only and are not intended to limit the scope of the subject matter claimed herein. In addition, it should be understood that the various features of the embodiments described can be combined in various ways to produce many additional embodiments. In addition, although various materials, sizes, shapes, configurations, positions, etc. for use with the disclosed embodiments have been described, other materials, sizes, shapes, configurations, positions, etc. other than those disclosed may be used without exceeding the scope of the subject matter claimed herein.

[0049] Those of ordinary skill in the relevant art will recognize that the subject matter of the present disclosure may include fewer features than those illustrated in any of the individual embodiments described above. The embodiments described herein are not meant to be an exhaustive representation of the ways in which the various features of the subject matter of the present disclosure may be combined. Therefore, the embodiments are not mutually exclusive combinations of features; on the contrary, as understood by those of ordinary skill in the art, various embodiments may include combinations of different individual features selected from different individual embodiments. In addition, unless otherwise stated, elements described with respect to one embodiment may be implemented in other embodiments, even when not described in such an embodiment.

[0050] Although a dependent claim may refer to a specific combination with one or more other claims in a claim, other embodiments may also include a combination of a dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent claims or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended.

[0051] Any incorporation by reference of the above documents is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of the above documents is further limited such that no claims included in the documents are incorporated herein by reference. Any incorporation by reference of the above documents is further limited such that any limitations provided in the documents are not incorporated herein by reference unless expressly included herein.

[0052] For purposes of claim interpretation, unless a claim recites the specific term "means for" or "step for...", it is expressly intended that the provisions of 35 USC §112(f) do not apply.

Claims

1. A syringe, comprising: a barrel including a body, a tapered distal end extending to a tip, and a proximal end opening into a cavity defined within the barrel, the cavity having an inner wall coated with a lubricating material; a plunger rod comprising a shaft, a plunger face, a distal elongated nose extending from the plunger face, a proximal pressing portion, and a sealing area having a first flange, a second flange, and an inner support disposed between the first flange and the second flange; as well as a sealing element having a first seal, a second seal and an internal passage, wherein the sealing element is configured to be operably coupled to the sealing area of ​​the plunger rod such that the internal passage of the sealing element is arranged on the inner support of the plunger rod, wherein the plunger rod is configured to be operably coupled within the cavity of the barrel and to be translatable along the length of the barrel to selectively expel fluid from the cavity out of the tip of the barrel, and Wherein, the elongated nose of the plunger rod is configured to extend into the tip of the barrel when the plunger rod is fully depressed relative to the barrel so as to expel any liquid retained in the tip without causing deformation of the plunger face.

2. A syringe comprising: a barrel including a body, a tapered distal end extending to a tip, and a proximal end opening into a cavity defined within the barrel, the cavity having an inner wall coated with a lubricating material; a plunger rod comprising a shaft, a plunger face, a distal elongated nose extending from the plunger face, a proximal pressing portion, and a sealing area; as well as a sealing element having a first sealing part and a second sealing part, wherein the sealing element is configured to be operatively coupled to the sealing area of ​​the plunger rod, wherein the plunger rod is configured to be operably coupled within the cavity of the barrel and to be translatable along the length of the barrel to selectively expel fluid from the cavity out of the tip of the barrel, and Wherein, the elongated nose of the plunger rod is configured to extend into the tip of the barrel when the plunger rod is fully depressed relative to the barrel so as to expel any liquid retained in the tip without causing deformation of the plunger face.

3. The syringe according to claim 2, wherein: The sealing area of ​​the plunger rod includes a first flange, a second flange, and an inner support disposed between the first flange and the second flange.

4. The syringe according to claim 3, wherein: The sealing element further includes an internal passage, the sealing element being configured to be operably coupled to the sealing region of the plunger rod such that the internal passage of the sealing element is disposed on the inner support of the plunger rod.

5. The syringe of claim 4, the plunger rod further comprising a reinforcement ring disposed on the shaft, the reinforcement ring configured to limit lateral deflection of the plunger rod relative to the barrel.

6. The syringe according to claim 5, wherein: The first flange is adjacent the plunger face.

7. The syringe according to claim 6, wherein: The reinforcement ring is disposed adjacent to the second flange.

8. The syringe according to claim 2, wherein: The tip of the barrel is configured to couple with an extension kit.

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