TISSUE SATURATION RESPONSIVE RAPID AUTOMATICALLY VARIABLE FLOW RATE INFUSION SYSTEM

Abstract

Infusion systems and methods for administering an infusion fluid into a patients anatomic space at a variable flow rate without flow control include an administration set having a flexible tube fluidically connected to a needle connector, the needle connector including a receiving end fluidically connected to flexible tube, and an administering end opposite the receiving end and fluidically connected with an infusion needle, and the infusion needle having an inside diameter of about 0.0104 inches to about 0.0135 inches and fluidically connected to the administering end of the flexible tubing to deliver the infusion fluid to the patients anatomic space at variable flow rates dependent upon the saturation of the infusion fluid at the patients injection site.

Claims

1. An infusion system for administering an infusion fluid into a patient's anatomic space at a variable flow rate without flow control, the system comprising: an administration set including: a flexible tube fluidically connected to a needle connector; the needle connector including a receiving end fluidically connected to flexible tube, and an administering end opposite the receiving end and fluidically connected with an infusion needle; and the infusion needle having an inside diameter of about 0.0104 inches to about 0.0135 inches and being fluidically connected to the administering end of the flexible tubing to deliver the infusion fluid to the patient's anatomic space at variable flow rates dependent upon the saturation of the infusion fluid at the patient's injection site.

2. The infusion system of claim 1, wherein the infusion fluid is at least one of the group of an immunoglobulin, a chemotherapeutic fluid, a monoclonal antibody, an antibiotic, an analgesia fluid, and a hydration fluid.

3. The infusion system of claim 1, wherein the flexible tube has an inside diameter of about 0.039 inches to about 0.045 inches.

4. The infusion system of claim 3, wherein the administration set further comprises: a flexible assembly that conforms to the patient's body to position the needle and reduce the risk of vessel damage.

5. The infusion system of claim 1, further comprising: an infusion pump configured to deliver infusion fluid at a variable flow rate and at a pressure of about 4 to about 9 psi.

6. The infusion system of claim 5, wherein the infusion pump comprises a compact micro syringe infuser; and wherein the administration set is connected directly to the compact micro syringe infuser.

7. The infusion system of claim 6, wherein the compact micro syringe infuser includes a fluid reservoir with a volume of about 5-10 ml; and wherein the administration set is pre-calibrated and includes a length of the tubing measuring about 3 inches to about 7 inches from the micro syringe infuser to the infusion needle.

8. The infusion system of claim 5, wherein the infusion pump is configured to deliver infusion fluid at a variable flow rate and at a pressure of about 4 to about 9 psi.

9. The infusion system of claim 1, wherein the needle connector transitions a size difference from the flexible tubing to the needle to continue laminar flow.

10. The infusion system of claim 1, wherein the infusion system is configured to attach to the patient via an adhesive patch.

11. The infusion system of claim 1, wherein the infusion system includes a garment configured to secure and house the infusion system and worn by the patient.

12. A method for administering an infusion fluid into a patient's anatomic space at a variable flow rate without flow control, the method comprising the steps of: receiving the infusion fluid from an infusion fluid reservoir at a low pressure into flexible tube; delivering the infusion fluid from the flexible tube to a receiving end of a needle connector, the needle connector being configured to maintain laminar flow of the infusion fluid; passing the infusion fluid from the receiving end of the needle connector to an administering end of the needle connector; delivering the infusion fluid from the administering end of the needle connector to an infusion needle; and delivering the infusion fluid to the patient's anatomic space at automatically variable flow rates dependent upon the saturation of the infusion fluid at the patient's anatomic space.

13. The infusion method of claim 12, wherein the infusion fluid is at least one of an immunoglobulin, a chemotherapeutic fluid, a monoclonal antibody, an antibiotic, an analgesia fluid, and a hydration fluid.

14. The infusion method of claim 12, further comprising: delivering the infusion fluid to a plurality of infusion needles.

15. The infusion method of claim 12, further comprising the step of using a flexible assembly that conforms to the patient's body to position the needle and reduce the risk of vessel damage.

16. The infusion method of claim 12, further comprising: receiving the infusion fluid from an infusion pump with the flexible tube, wherein the infusion pump is configured to deliver the infusion fluid at a variable flow rate and at a pressure of about 4 to about 9 psi.

17. The infusion method of claim 16, wherein the infusion pump comprises a compact micro syringe infuser configured to deliver the infusion fluid at a pressure of about 4 to about 9 psi; and wherein the flexible tube is connected directly to the compact micro syringe infuser.

18. The infusion method of claim 17, wherein the compact micro syringe infuser includes a fluid reservoir with a volume of about 5-10 ml; and wherein the combination of the flexible tubing and the infusion needle is pre-calibrated and includes a length of the tubing measuring about 3 inches to about 7 inches from the micro syringe infuser to the infusion needle.

19. The infusion method of claim 12, wherein the flexible tube has an inside diameter of about 0.039 inches to about 0.045 inches and the infusion needle has an inside diameter of about 0.0104 inches to about 0.0135 inches.

20. The infusion method of claim 12, wherein the infusion system is configured to attach to the patient via an adhesive patch.

21. The infusion method of claim 12, wherein the infusion system includes a garment configured to secure and house the infusion system and worn by the patient.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the inventive concepts.

[0052] FIG. 1 illustrates an exemplary embodiment of a variable flow rate infusion system having a three-legged needle set constructed according to the principles of the invention for delivering an infusion fluid to patients as part of their infusion therapy.

[0053] FIG. 2 illustrates another exemplary embodiment of a variable flow rate infusion system having a one-legged needle set constructed according to the principles of the invention for delivering an infusion fluid to patients as part of their infusion therapy.

[0054] FIGS. 3A-3D illustrate an exemplary embodiment of a needle connector constructed according to the principles of the invention for delivering an infusion fluid to patients as part of their infusion therapy.

[0055] FIG. 4 illustrates an exemplary embodiment of an infusion pump used in a variable flow rate infusion system constructed according to the principles of the invention, where the infusion pump is a micro syringe infuser.

[0056] FIG. 5 illustrates an exemplary embodiment of an infusion pump used in a variable flow rate infusion system constructed according to the principles of the invention, where the infusion pump is worn on a garment.

[0057] FIG. 6 illustrates an exemplary embodiment of an infusion pump used in a variable flow rate infusion system constructed according to the principles of the invention, where the infusion pump is attached to the patient with an adhesive patch.

DETAILED DESCRIPTION

[0058] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments or implementations of the invention. As used herein “embodiments” and “implementations” are interchangeable words that are non-limiting examples of devices or methods employing one or more of the inventive concepts disclosed herein. It is apparent, however, that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various exemplary embodiments. Further, various exemplary embodiments may be different, but do not have to be exclusive. For example, specific shapes, configurations, and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment without departing from the inventive concepts.

[0059] Unless otherwise specified, the illustrated exemplary embodiments are to be understood as providing exemplary features of varying detail of some ways in which the inventive concepts may be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, and/or aspects, etc. (hereinafter individually or collectively referred to as “elements”), of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts.

[0060] The use of cross-hatching and/or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities between illustrated elements, and/or any other characteristic, attribute, property, etc., of the elements, unless specified. Further, in the accompanying drawings, the size and relative sizes of elements may be exaggerated for clarity and/or descriptive purposes. When an exemplary embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. Also, like reference numerals denote like elements.

[0061] When an element, such as a layer, is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. To this end, the term “connected” may refer to physical, electrical, and/or fluid connection, with or without intervening elements. Further, the D1-axis, the D2-axis, and the D3-axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z—axes, and may be interpreted in a broader sense. For example, the D1-axis, the D2-axis, and the D3-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0062] Although the terms “first,” “second,” etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure.

[0063] Spatially relative terms, such as “beneath,” “below,” “under,” “lower,” “above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), and the like, may be used herein for descriptive purposes, and, thereby, to describe one elements relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly.

[0064] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms “substantially,” “about,” and other similar terms, are used as terms of approximation and not as terms of degree, and, as such, are utilized to account for inherent deviations in measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art.

[0065] Various exemplary embodiments are described herein with reference to sectional and/or exploded illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments disclosed herein should not necessarily be construed as limited to the particular illustrated shapes of regions but are to include deviations in shapes that result from, for instance, manufacturing. In this manner, regions illustrated in the drawings may be schematic in nature and the shapes of these regions may not reflect actual shapes of regions of a device and, as such, are not necessarily intended to be limiting.

[0066] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

[0067] Variable flow rate infusion systems and methods constructed according to the principles and exemplary embodiments of the invention accurately and reproducibly deliver an infusion fluid to a patient at a desired anatomical location by allowing for direct control of the infusion system pressure by the infusion driver (pump). The system pressure is created by the driver alone, and the flow rate of the delivered infusion fluid is determined by the difference in the infusion driver pressure and the site pressure, as detailed further below. In some situations, the pressure, and therefore the infusion system flow, rate may be determined by the patient, who can accept a delivered volume of an infusion liquid at a pressure/speed that does not cause discomfort. For example, a patient can receive the infusion fluid at a flow rate to arrive at a total infusion time while keeping the fluid pressure within a comfortable limit. If the rate is not tolerable, the patient could halt the infusion totally with a slide clamp, wait some time, and restart. This will allow the perfusion to take place without more drug being delivered to the site. Pressures will reduce and it will take longer to infuse the drug, however. Faster flow rates translate to shorter infusion times at higher pressures, while slower flow rates create lower infusion fluid pressures but longer treatment times. With variable flow rate infusion systems and methods according to exemplary embodiments of the invention, a patient or clinician selects this infusion system to minimize the amount of pain or discomfort caused by resistance of fluid-filled tissue space and associated pressures while also increasing the fluid flow rate.

[0068] Similarly, a patient or clinician can use needle sets with multiple needles (e.g., from 2-8 needles) in parallel so as to infuse the patient at multiple sites to decrease the overall infusion time. In exemplary embodiments of the invention, no change in flow rate per needle and no change in pressure need to occur.

[0069] The maximum pressure of the (pump) driver will always be (equal to or) higher than any other pressure in the system. For example, when an occlusion occurs, the site pressure builds up. When the site pressure equals the driver pressure, the pressure differential is zero, and all (fluid) flow stops. At site pressures lower than pump pressure, some flow will occur.

[0070] According to the principles and some exemplary embodiments of the invention, a predetermined maximum pump (driver) pressure may be used to automatically prevent continuous drug (fluid) flow into surrounding tissues if the site system pressure exceeds the maximum or a range of pressures. That is, if the infusion site pressure builds to the predetermined maximum pump pressure, the pump can be shut down or the infusion fluid flow can be manually clamped off at the administration set using side clamps as noted above to stop fluid flow and to resume fluid flow (when the infusion site pressure dissipates) during an infusion. The pressure limits and ranges limit the delivery of an infusion fluid into unintended tissues by eliminating the need for a continuous flow of fluid during the placement of a needle and allow the identification of a fluid-filled space once the resumption of fluid-flow occurs within patient tissues.

Example System Components

[0071] According to one exemplary embodiment of the invention, the variable flow rate infusion system includes an administration needle set that includes inlet tubing, a tubing-to-needle connector, and a needle itself. In one example embodiment, the inlet tubing has a diameter of about 0.040 inches (compared to 0.033 diameter of known systems). The connector smoothly transitions the size difference from the tubing to the needle ensuring laminar flow is maintained. Previous systems included abrupt transitions from tubing to needle and did not maintain laminar flow. Further, the needle in exemplary embodiments of the invention is larger at about 0.0114 inches compared to 0.0098 in one known previous systems (Comparative Embodiment). These increases in inside diameters results in significant increases in flow rates as shown in detail below.

The Design Principle

[0072] Exemplary embodiments of the invention perform their intended function using the Hagen-Poiseuille equation (HPE) to determine the flow rate of a fluid, with some viscosity, given the length and radius of fluid-pathed components (i.e., the needle tubing) within the administration set, and the differential pressure between the pressure source (i.e., the infusion driver) and the patient's infusion anatomic site. To use the HPE, the following assumptions are met: the fluid is incompressible, Newtonian, is not accelerating within the administration set, is in laminar flow through the fluid-pathed components of the administration set that maintain a constant circular cross-sectional area, and has a length that is substantially larger than its diameter.

[0073] Given the above, the HPE can be written as:

[00001]$Q=\frac{\Delta p\pi R^4}{8L\mu }$

where:

[0074] Q is the volumetric flow rate of the infusion fluid

[0075] Δp is the differential pressure between the pressure source and the patient's infusion anatomic site

[0076] R is the radius of the fluid-pathed component

[0077] L is the length of the fluid-pathed component

[0078] μ is the dynamic viscosity of the infusion fluid.

[0079] An administration set constructed according to some exemplary embodiments of the invention can achieve a low-restriction flow rate through the needle set. Following the HPE, the fluid-pathed components (i.e., the needle tubing) impact the flow rate through their radius (R) and length (L). For simplicity, the flow rate (Q) is proportional to the radius (R) and inversely proportional to the length (L) of the fluid-pathed components. Given the derivation of the HPE (not shown), the radius (R) is to the fourth power (R.sup.4) demonstrating that the radius (R) substantially affects the flow rate (Q) in comparison to the length (L) of fluid pathed components.

[0080] The administration set constructed according to some exemplary embodiments of the invention achieves a low-restriction flow rate through the needle sets, which are comprised of the fluid-pathed components: the needle and the needle tubing, in which both are joined via a needle connector. To achieve a low-restriction flow rate, the needle may have an inside diameter of about 0.0104 inches to about 0.0135 inches and does not exceed a length of about 1.054 inches and the needle tubing has an inside diameter of about 0.039 inches to about 0.045 inches with lengths that may be about 3 inches to about 7 inches and about 18 inches to about 26 inches.

[0081] The differential pressure (Δp) of the system is the pressure drop of the system along the fluid-pathed components of the administration set between pressure source (i.e., the infusion driver) and the patient's infusion anatomic site. For simplicity, the flow rate (Q) is proportional to the differential pressure (Δp).

[0082] In one simplified example, a patient prepares for an infusion for the subcutaneous delivery of an infusion fluid using a constant pressure source, 5 psi for example, to deliver the infusion fluid. Assuming very low or no pressure, 0 psi for example, at the patient's infusion anatomic site at the beginning of the infusion the flow rate is as fast as possible, following the principles of the HPE. The differential pressure (Δp) is:

(Δp)=Pressure.sub.Pressure Source−Pressure.sub.Anatomic Site

such that in this example Δp=5 psi−0 psi=5 psi.

[0083] At a point later in the infusion, the patient's infusion anatomic site will begin to fill with the infusion fluid. This is called site saturation. As the anatomic site saturates, the pressure at the anatomic site increases—a natural biological function. As the rate of infusion may exceed the rate of infusion fluid perfusion into nearby spaces (i.e., extracellular matrix) at the anatomic site, the pressure will increase. At this point later in the infusion, the pressure at the anatomic site will now be higher than previous, 1 psi for example. Now, the differential pressure (Δp) is Δp=5 psi−1 psi=4 psi.

[0084] The initial differential pressure (Δp) was 5 psi at the start of the infusion and 4 psi at some point later on during the infusion. Given, all other HPE values remain constant, only the flow rate (Q) can change in response to the differential pressure (Δp). For simplicity, the differential pressure (Δp) is proportional to the flow rate (Q), and the pressure at the anatomic site is proportional to site saturation. As such, as the pressure at the anatomic site increases, the differential pressure (Δp) decreases and the flow rate (Q) decreases. As the infusion progresses, the patient's infusion anatomic site is increasingly filled and as such, flow rate (Q) decreases. As a result, the flow rate (Q) changes throughout the infusion.

[0085] Intrinsically, the specifications of fluid-pathed components (i.e., the needle and needle tubing) do not constitute “low-restriction flow rate administration sets” on their own. The flow rates (Q) of each fluid-pathed component must be combined to determine the total flow rate of the administration set. This may be done using the following total flow equation (TFE) (derivation not shown):

[00002]$Q_{T\mathrm{otal}\mathrm{Flow}\mathrm{Rate}}=\frac{\left(Q_{\mathrm{Needle}}\right)\left(Q_{\mathrm{Needle}\mathrm{Tubing}}\right)}{\left(Q_{\mathrm{Needle}}+Q_{\mathrm{Needle}\mathrm{Tubing}}\right)}$

where:

[0086] Q.sub.Total Flow Rate is the total flow rate of the administration set

[0087] Q.sub.Needle is the flow rate of the needle

[0088] Q.sub.Needle Tubing is the flow rate of the needle tubing.

[0089] Here, Q.sub.Needle and Q.sub.Needle Tubing can be calculated using the HPE as mentioned earlier. In the case of administration sets with multiple legs of needle and needle tubing, the total flow rate of administration set can be calculated by:

Q.sub.Total Flow Rate Multiple Legs=(n)(Q.sub.Total Flow Rate)

where: [0090] Q.sub.Total Flow Rate Multiple Legs is the total flow of the administration set containing more than one needle and needle tubing, collectively called a “needle leg” [0091] N is the number of needle legs in the administration set [0092] Q.sub.Total Flow Rate is the total flow rate of the administration set.

[0093] Administration sets constructed according to some exemplary embodiments of the invention may be compared to previous systems also claiming a low-restriction flow rate administration sets, such as those presented in US Patent Publication Number 2019/0201620 and/or known systems discussed above.

[0094] The following example compares an administration set constructed according to an exemplary embodiment of the invention of the invention (“IHS Set”) to the administration set of the Comparative Embodiment, with regard to flow rate performance. In the example, the same infusion fluid, with a dynamic viscosity (μ) of 13.7 cP (the viscosity of Hizentra®) is delivered through each administration set, an experimental differential pressure (Δp) of 13.5 psi is used, and all other infusion parameters are the same for both administration sets. As such, the flow performance (Q) is determined by the radius (R) and length (L) of the fluid-pathed components—the needle and needle tubing. As the radius (R) is raised to the fourth power (R.sup.4) it substantially affects the flow rate (Q) more than length (L) for both the needle and the needle tubing and as such, the length (L) is negligible in this simplified example, and is an experimental length value of 1 inch for the needle and 24 inches for the needle tubing for both IHS Set and Comparative Embodiment administration sets. The true diameters for the needle and needle tubing of both administration sets is used. In some exemplary embodiments of the invention, the IHS Set has a needle diameter of 0.0110 inches and a needle tubing diameter of 0.040 inches. The Comparative Embodiment has a needle diameter of 0.0098 inches and a needle tubing diameter of 0.033 inches. Now, using the HPE to determine flow rates (Q):

IHS Set

[0095] [00003]$Q_{\mathrm{IHS}\mathrm{Set}\mathrm{Needle}}=\frac{\left(13.5\mathrm{PSI}\right)\pi {\left(\frac{{0.011}^{″}}{2}\right)}^4}{8\left(1^{″}\right)\left(13.7\mathrm{cP}\right)}=\sim 145\mathrm{ml}/\mathrm{hr}$$Q_{\mathrm{IHS}\mathrm{Set}\mathrm{Needle}\mathrm{Tubing}}=\frac{\left(13.5\mathrm{PSI}\right)\pi {\left(\frac{{0.04}^{″}}{2}\right)}^4}{8\left({24}^{″}\right)\left(13.7\mathrm{cP}\right)}=\sim 1050\mathrm{ml}/\mathrm{hr}$

Comparative Embodiment

[0096] [00004]$Q_{\mathrm{Super}26\mathrm{Needle}}=\frac{\left(13.5\mathrm{PSI}\right)\pi {\left(\frac{0{\text{.0098}}^{″}}{2}\right)}^4}{8\left(1^{″}\right)\left(13.7\mathrm{cP}\right)}=\sim 90\mathrm{ml}/\mathrm{hr}$$Q_{\mathrm{Super}26\mathrm{Needle}\mathrm{Tubing}}=\frac{\left(13.5\mathrm{PSI}\right)\pi {\left(\frac{{0.033}^{″}}{2}\right)}^4}{8\left({24}^{″}\right)\left(13.7\mathrm{cP}\right)}=\sim 490\mathrm{ml}/\mathrm{hr}$

[0097] The flow rates (Q) of each individual fluid-pathed component are calculated for each set using the HPE, shown above. Now, the total flow rate of each administration set is calculated (both sets are assumed to only have one needle and needle tubing each in this example). Now, using the TFE determine total flow rate (Q.sub.Total Flow Rate):

IHS Set

[0098] [00005]$Q_{\mathrm{Total}\mathrm{Flow}\mathrm{Rate}\mathrm{IHS}\mathrm{Set}}=\frac{\left(145\mathrm{ml}/\mathrm{hr}\right)\left(1050\mathrm{ml}/\mathrm{hr}\right)}{\left(145\mathrm{ml}/\mathrm{hr}\right)+1050\mathrm{ml}/\mathrm{hr})}=\sim 130\mathrm{ml}/\mathrm{hr}$

Comparative Embodiment

[0099] [00006]$Q_{\mathrm{Total}\mathrm{Flow}\mathrm{Rate}\mathrm{Super}26}=\frac{\left(90\mathrm{ml}/\mathrm{hr}\right)\left(490\mathrm{ml}/\mathrm{hr}\right)}{\left(90\mathrm{ml}/\mathrm{hr}\right)+490\mathrm{ml}/\mathrm{hr})}=\sim 80\mathrm{ml}/\mathrm{hr}$

[0100] The IHS Set flow rate performance is substantially faster than that of the Comparative Embodiment and as such is considered a low-restrictive flow rate tubing set that, in combination with a other infusion system components constructed according to the principles and exemplary embodiments of the invention, enables delivery of fast flow rates to the patient's anatomic site.

Additional System Components

[0101] Exemplary embodiments of the invention can also include a fluid reservoir (e.g., an infusion fluid storage device such as a syringe, a bag, or other reservoir), an infusion fluid (such as an immunoglobulin), and an infusion pump. An infusion fluid flow rate and volume per site are determined based on patient variables (e.g., diagnosis, size, weight, location of infusion, etc.) and infusion therapy variables (e.g., infusion fluid viscosity, volume of infusion fluid, needle size, tubing diameter, tubing length, infusion rates of the fluid, etc.).

[0102] According to one exemplary embodiment of the invention, the infusion pump may be a micro-pump or syringe driving device such as an infusion driver constructed according to the principles and the exemplary embodiments disclosed in the Assignee's co-pending US. Patent Application No. ______, entitled, “Systems and Methods for Precision Matched Immunoglobulin Infusion,” (Attorney docket no. 213.0001-US00) filed simultaneously herewith, the disclosure of which is incorporated by reference herein in its entirety. According to one exemplary embodiment of the invention, the infusion pump is a constant pressure/force pump to provide a constant pump pressure. In some exemplary embodiments, the infusion pump is set at a pressure of 5 psi. A target flow rate, which may be the infusion fluid flow rate, is identified and is allowed to vary during the infusion therapy treatment session as long as the fluid pressure is equal to or below the maximum infusion fluid pressure. As discussed above, the flow rate may slow (i.e., vary) as the infusion site pressure builds due to site saturation, but the infusion treatment continues, and some flow will occur, as long as the site pressure remains below the maximum pressure.

[0103] The flow rate is allowed to vary based on the pre-set maximum infusion fluid pressure during treatment. As long as the infusion fluid pressure is below the pre-set, low maximum pressure, the fluid flow rate is not as important. In some exemplary embodiments of the invention, the pre-set pump maximum pressure is a pressure between about 4 psi (200 mmHg) and about 9 psi (465 mmHg).

[0104] Variable flow rate infusion systems and methods according to the principles and exemplary embodiments of the invention provide safe and effective means for delivering a rapid infusion fluid flow rate using a fluid reservoir, an infusion fluid, an infusion pump, and a needle set to deliver the infusion fluid from the reservoir into the patient (via the needle set). According to some exemplary embodiments, the system includes a pump that delivers a infusion fluid at a fixed pressure and allows the flow rate of the infusion fluid to vary as the infusion site fills or saturates, as long as the patient's anatomic site pressure is less than the infusion pump's fixed pressure. The system generally does not require any patient or clinician interaction as the pump pressure produces a maximum pump pressure (e.g., 5 psi), and, when combined with a very low-restriction needle set, produces a maximum flow rate which is reduced by any increases in the patient's site pressure.

[0105] In one exemplary embodiment of the invention, the infusion fluid pressure (resistance measure) can be displayed visually or presented audibly, such as in a read-out or a continuous audible signal, respectively, when the pressure (resistance measure) is within or outside the pre-set range. The patient or clinician can monitor the pressure measurements to determine and/or confirm that the infusion fluid is being delivered correctly. The pump controller can record and track performance parameters for future review and correlation and adjust the pressure at the pump accordingly. In other exemplary embodiments of the invention, upon calculating the force readings, the pressure limit(s) can be pre-defined to ensure that excessive pressures are not reached.

Example Infusion System Operation

[0106] FIG. 1 illustrates a variable flow rate infusion system 10 without flow control having a needle set 100 constructed according to an exemplary embodiment of the invention. Needle set 100 includes a flexible needle positioning assembly that conforms to the patient's body to position the needle and reduce the risk of vessel damage. In some exemplary embodiments of the invention, the flexible assemblies are butterfly wing assemblies 150. Needle set 100 also includes multiple needles 140. In the exemplary embodiment of the invention shown in FIG. 1, the needles 140 are configured in a parallel configuration. In the exemplary embodiment, three needles are shown. Further, the needles 140 have a 90° needle angle to be placed subcutaneously, as deep as required specific to the patient. The needle set 100 can include a connection device 130, such as a Luer lock, for example, to connect the needle tubing 160 to the infusion pump. This exemplary embodiment contemplates that needles generally will be available with sharpened administering lengths of 6 mm, 9 mm, 12 mm and 14 mm, which depend on the thickness of the adipose tissue of the patient to ensure the fluid reaches the subcutaneous space. The needle set 100 includes needle tubing 160 that extends from the Luer lock 130 to a manifold 120 where the needle set tubing 160 divides into individual needle tubes 110. For convenience and brevity, three individual needle tubes 110 are shown in FIG. 1, but additional needle tubes 110 and needles 140 can be used. Similarly, additional butterfly 150 can also be used with each needle 140 placed on its own butterfly 150. The needle set is configured to deliver infusion fluid at a variable flow rate with low pressures.

[0107] According to exemplary embodiments of the invention, a maximum infusion fluid pressure of 5 psi is determined to be a safe and effective pressure for a patient. In other exemplary embodiments of the invention, the maximum infusion fluid pressure may be from about 4 psi to about 7 psi, as high as 9 psi. For a variable flow needle set without a series flow restriction, fluid pressures above 9 psi could be too high and dangerous to the patient. The maximum infusion fluid pressure determination is based on patient variables, patient status (e.g. naïve or experienced), the size and weight of the patient, and the location of the infusion site (e.g., subcutaneous abdominal, and other patient variables). The maximum infusion fluid pressure of 5 psi is also based on infusion therapy variables, including infusion fluid viscosity, volume of infusion fluid, needle size, needle set tubing diameters, needle set tubing lengths, infusion rates of the fluid, and other infusion therapy variables. A target flow rate is identified based on the volume of infusion fluid to be delivered and the amount of time the infusion therapy treatment will take. In some exemplary embodiments of the invention, the target flow rate is between about 5 ml/hr and 125 ml/hr. In the example of FIG. 1, the volume of infusion fluid is 60 ml, and the patient has 1 hour to complete the therapy. The target flow rate in this example is determined to be 60 ml/hr, but the actual flow rate is allowed to vary during the infusion therapy treatment session as long as the infusion fluid pressure is equal to or below the predetermined maximum infusion fluid pressure (e.g., 5 psi). An example of a very high flow rate without flow control would be an average flow rate of about 40 ml/hr for a very viscous infusion fluid, such as Hizentra®, for example.

[0108] The geometries of the needle set are selected based the maximum flow rate at the lowest pressure. Other variables may include needle material properties (e.g., thin wall stability), needle dimensions, and fluid properties (e.g., viscosity and infusion rate). For example, in one exemplary embodiment of the invention, the needles are about 1 inch long and are bent to expose about 6-14 mm. In some exemplary embodiments, the needle may have an inside diameter of about 0.0104 inches to about 0.0135 inches and does not exceed a length of about 1.054 inches, and the needle tubing has an inside diameter of about 0.039 inches to about 0.045 inches with lengths that may be about 3 inches to about 7 inches and about 18 inches to about 26 inches. In one exemplary embodiment of the invention, a needle is fluidically connected to the needle tubing via a needle connector (see FIGS. 3A-3D, for example). The outside diameter of the needle tubing (about 0.0551 inches to about 0.0787 inches) fits within one end's inside diameter (about 0.060 inches to about 0.080 inches) of the needle connector. The outside diameter of the needle (about 0.0175 inches to about 0.0228 inches) at the receiving end fits within the other end's inside diameter of the needle connector (about 0.0200 inches to about 0.0275 inches). The inside diameter of the needle connector can be sized and manufactured to house 26-24G needles with required diameters needed to fit about 0.0175 inches to about 0.0228 inches outside diameter needles. In one exemplary embodiment a needle connector is sized and manufactured for a needle with an outside diameter of 0.0181 inches and a needle tubing with outside diameter of 0.0677 inches. The inside diameters of both sides of the needle connector taper down so that glue can be filled in the gap to secure the structure and prevent the infusion fluid from leaking. Additionally, the needle seat can sit inside a butterfly assembly, such as that disclosed in the Assignee's co-pending U.S. patent application Ser. No. ______, entitled, “Systems and Methods for Precision Matched Immunoglobulin Infusion,” (Attorney docket no. 213.0001-US00) filed simultaneously herewith, the disclosure of which is incorporated by reference herein in its entirety.

[0109] FIG. 2 illustrates another variable flow rate infusion system 20 constructed according to an exemplary embodiment of the invention. Needle set 200 includes a single butterfly wing assembly 250 and a single infusion needle 210. In the exemplary embodiment of the invention shown in FIG. 2, the needle 210 is positioned on a patient's anatomical space to deliver immunoglobulin to a single site. In another exemplary embodiment (not shown separately), the needle 210 includes more additional needles configured in a parallel configuration. The needle set 200 of FIG. 2 can include a connection device 230, such as a Luer lock, for example to connect to the infusion pump. The needle set 200 includes needle set tubing 260 that extends from the Luer lock 230 to the needle 210. Depending upon the size of the needle 210, patient preference, and the anatomical sites to which the infusion fluid is to be delivered, additional butterfly wing assemblies 250 can also be used with additional needles 210. In the exemplary embodiment shown in FIG. 2, the maximum infusion fluid pressure is determined similarly to the manner of FIG. 1. Likewise, a target flow rate is identified in a similar manner, as are the needle set component geometries.

[0110] In one exemplary embodiment of the invention, the infusion pump 170 is syringe driver, such as a compact micro syringe infuser, and the needle set 200 is connected directly in a compact and low-cost disposable system worn by the patient. The volume of the micro syringe infuser is 5-10 ml, and the length of the tubing to the needle is from about 3 inches to about 7 inches. In this compact system, the micro syringe infuser is connected directly to the needle set tubing 260 at one end and directly to the needle 210 at the opposite end. As shown in an exemplary embodiment illustrated in FIG. 6, the entire micro syringe infuser (infusion pump 170) can be attached directly to the patient via an adhesive patch 191. The needle set 100 can also be attached directly to the patient via a needle set adhesive dressing 185. As shown in FIG. 5, a wearable belt 190 can house and contain a plurality of micro syringe infusers, such as four separate micro pumps in one exemplary embodiment of the invention. As shown in FIG. 4, the micro syringe infuser 170 may use helical coil springs 173, or small negator mechanisms to apply the force necessary to deliver the infusion fluid from the micro syringe infuser 170 to the needle (via administration set 100).

[0111] Variable flow rate infusion systems and methods constructed according to the principles and exemplary embodiments of the invention accurately and reproducibly deliver an infusion fluid to a patient at a desired anatomical location using an infusion pump at a substantially fixed maximum pressure to deliver an infusion fluid to a patient's anatomic site. The infusion fluid is delivered to the anatomic site as fast as permissible by the patient's anatomic site. As the pressure of the anatomic site increases, the flow rate delivered decreases. Patients and clinicians can use the invention to deliver a volume of an infusion liquid at speeds (e.g., flow rate) that do not cause discomfort. The flow rate varies automatically, in response to pressure at the patient's anatomic site, to deliver an infusion fluid at flow rates and pressures that do not cause patient harm. Faster flow rates result from low anatomic site pressures, while slower flow rates result from higher anatomic site pressures. A patient or clinician can set these variables to minimize the amount of pain or discomfort caused by resistance of fluid-filled tissue space and associated pressures during infusion therapies.

[0112] Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as would be apparent to a person of ordinary skill in the art.