DRUG CONTAINER HARNESS TO PERMIT AMBULATORY INFUSION AND FACILITATE CONSTANT DRUG DELIVERY RATE

Abstract: A harness (10) of preferred construction for wear by a human being provides a structure for minimizing the temperature rang of an ambulatory liquid drug supply in a container (56). The harness includes fastening structures which retain the container (56) of the drug supply which is to be infused into the venous system, in a manner which allows the patient to be ambulatory. The harness is particularly designed for those infusion devices in which the liquid drug viscosity has a measurable effect on drug delivery rate, such as those employing a pressurized bladder (58). The harness keeps the drug supply in close proximity to the skin of the person to enable heat transfer from the person to the drug supply to a degree which limits the effects of atmospheric temperature change on the drug supply temperature. The condition of limited temperature change stabilizes drug viscosity and therefore facilitates constant drug delivery flow rate into the person. The harness may be worn without altering normal wearing apparel and may be worn virtually inconspicuously.

Description: Description Drug Container Harness To Permit Ambulatory Infusion And Facilitate Constant Drug Delivery Rate Technical Field The present invention relates to the medical field of ambulatory drug infusion and, more particularly, to drug delivery systems where fluid delivery rate is dependent to some degree on drug viscosity. Background Art Developing research indicates that one of the most significant factors in drug performance with human beings is the rate of . delivery of the drug to the patient. It has been suggested that delivering a given dosage of drug to the patient gradually over a relatively long time period may significantly increase the beneficial effects of the drug and/or significantly reduce any adverse side effects caused by administering the dose all at once or over a short period of time, such as with a syringe injection or oral administration, including tablets. In addition to lengthening the time period of drug administration, another factor which has great effect is constant delivery rate over the delivery time period. To this end various pumps and gravity feed controllers have been made. For example, frequently a drug in liquid form is injected into a parenteral solution container of, for example, dextrose solution. The dextrose solution with the added medicament is delivered by way of administration tubing to the venous system of a patient. Pumps have been developed to more accurately deliver the solution through the administration tubing. One such pump is a peristaltic- type pump sold by Travenol Laboratories, Inc. of Deerfield, Illinois, Product Code No. 2M8015. Certain elements of that pump are disclosed in U S. Patent No. 4,155,362. Pumps such as these make possible the delivery of paren- teral solution at highly constant flow rates. Recently, research has been performed to develop a pump which would both deliver a liquid drug at a highly constant delivery rate over a period of time as long as twenty-four hours and allow the patient to be ambulatory during the period of drug infusion into the venous system. Such a device would be useful to administer drugs such as heparin, insulin or chemotherapy drugs. One such pump or infusion device employs a bladder of unique construction to hold the liquid drug to be infused. The bladder, in combination with a metering system, delivers an extremely small volume of solution into, a patient's bloodstream over a period as long as twenty-four hours, such delivery being at a highly con¬ stant fluid flow rate. Such a bladder is disclosed in U.S. Patent No. 4,201,207. The bladder eliminates the need for a motor or external power source such as a battery because the bladder is pressurized by the liquid drug- to be infused. By eliminating the need for a motor and power supply, the infusion device meets the desirable parameter of constant flow rate over relatively lengthy- time periods and forms a system of simple construction which is both small and light weight, making it excellent as an ambulatory drug supply. It has been found, however, that although the solu- tion delivery rate of such an infusion device may be made substantially constant under laboratory conditions, when the device is placed in a substantially uncontrolled environment the fluid flow rate is not nearly as constant over time. - i- We have discovered that in slow delivery-rate pres¬ surized infusion devices such as above-described, in¬ fusion rate can be abnormally affected by the viscosity of the solution to be infused, in comparison with, for example, a solution container used in combination with a motorized pump wherein solution viscosity has a minimal effect on flow rate. For most solutions administered in such a fashion, solution viscosity simply does not have more than a negligible effect on flow rate. With the above-described ambulatory infusion device even a small change in viscosity may significantly affect flow rate, particularly where the volume to be infused is small, perhaps less than 25 ml, and the infusion time period is high, typically as high as twenty-four hours. It is known that liquid discharge from a pipe is dependent upon the diameter of the pipe, the length of the pipe, the pressure drop along the length of the pipe and the viscosity of the liquid. With a given pressurized in¬ fusion device the only one of these factors which is not known is liquid viscosity. Liquid viscosity is a func¬ tion of temperature, so therefore temperature control is important for the control of the discharge, i.e., the fluid delivery rate. We have found that because of the extreme sensitivity of the flow rate of such an ambulatory infusion device to solution viscosity, a temperature change of as little as one degree centigrade in the drug supply solution has an effect on solution viscosity significant enough to cause measurable change in drug delivery rate, particularly where the total volume to be infused is small. Depending on the drug solution to be infused, this difference can be critical to the degree of benefit afforded by the drug to the patient. _£_i--2— -^ Summary of the Invention We have developed an apparatus and method for mini¬ mizing the temperature range of an ambulatory drug supply, thereby stabilizing both drug supply viscosity and drug delivery rate into the patient. The apparatus includes body attachment means permitting the person to be ambula¬ tory and fastening means secured to and extending from a portion of the body attachment means to secure the drug supply container, retaining the liquid drug supply in a position in close proximity to the skin, thereby utilizing the body heat generated by the person so as to minimize temperature change to the drug supply. More particularly, in accordance with the invention a harness designed to be worn by a human being is disclosed, the harness retaining a liquid drug supply container while permitting the person to be ambulatory during drug in¬ fusion, wherein the harness includes a horizontal strap extending around the back and frontside of a person's tor¬ so, support straps attached to and extending between the back and frontsides of the horizontal strap to secure the harness over a person's shoulders, and fastening means secured to the frontside of the horizontal strap for re¬ taining the drug supply container in a predetermined posi¬ tion. The fastening means may include two closed loops of elastic material in which the drug supply container can be retained. The harness is designed to keep the drug supply container in close proximity to the skin, thereby permitting heat transfer from the person to the drug sup¬ ply. By allowing relatively constant body heat to trans- fer to the drug supply, drug delivery rate for certain infusion devices will be less susceptible to temperature change due to changes in atmospheric temperature. In a preferred embodiment the two support straps converge at and are fastened to a point substantially in the middle of the frontside of the horizontal strap and the support straps are adjustable. The fastening strips or loops extending from the frontside can be designed to retain the container on top of the horizontal strap or below it. Such a harness enables a patient to be ambulatory during drug infusion and.enables a pressurized infusion device to perform more accurately. The harness is designed to be worn under standard clothing otherwise worn about the torso such as a shirt. It does not inter¬ fere with undergarments, such as a bra. Brief Description of the Drawings Figure 1 is a perspective view of the harness of the invention as worn over a bra and retaining a drug supply container connected by administration tubing to an injection site. Figure 2 is a perspective view of the harness with a drug supply container therein, as worn underneath standard unmodified apparel. Figure 3 is a fragmentary, front elevational view of a modified harness. Figure 4 is a perspective view of the harness. Description of Specific Embodiment Referring to the drawings, Figure 4 shows a harness 10 in accordance with the present invention, able to serve as means for minimizing the temperature range of a liquid drug supply carried by the harness 10. The harness 10 includes a horizontal strap 12, including a frontside 14 and backside 16. The horizontal strap 12 is preferably flexible and elastic. Latch 18 and hook 20 of known construction are disposed in the middle of the backside 16 at first and second ends 22, 24, respectively, of the horizontal strap 12. Two flexible support straps 26, 28 are fastened at their first ends 30, 32 by known means such as stitching 34 to the backside 16 of the horizontal strap 12. First ends 30, 32 are spaced apart along the backside 16. The support straps 26, 28 extend upwardly from first ends 30, 32 and converge at their second ends 36, 38. Second ends 36, 38 are fastened substantially at the mid¬ point 40 of the frontside 14, again by known means such as stitching 34. Length adjusting means are disposed along the support straps 26, 28 near the second ends 36, 38 thereof. The length adjusting means may include buckles 42 through which the support straps may be threaded. Fastening means for the infusion device or other drug container are provided by unitary, elastic, fasten¬ ing strips 44, 46 a portion of which is fastened to said frontside 14 by means such as stitching. The fastening strips 44, 46 form closed loops which may be disposed substantially coaxially, the axis extending parallel to the length of the frontside 14. Turning now to Figure 2, there is shown the above- described harness 10 as worn about a male torso 48. Support straps 26, 28 are spaced at their first ends 30, 32 along the backside 16, permitting support straps 26, 28 to be worn about the shoulders 52, 54. An infusion device or other liquid supply container 56 is inserted through the fastening strips 44, 46. As shown, liquid supply container 56 is an infusion device having a pressurized bladder 58 with the liquid drug supply therein. It should be understood, however, that other liquid supply containers which operate under differ¬ ent principles may be retained by the harness 10. Administration tubing 60 or other conduit extends from an outlet port 62 in the liquid supply container 56 to an injection site 64 shown here in the arm 66 of the patient. Usually, a catheter 68 communicates between the administration tubing 60 and the venous system of the patient at the injection site 64. Administration tubing 60 is retained in place and close to the body by means of a band 70 and/or tape 72. The tubing 60 may extend up¬ wardly from the outlet 62 and may be wrapped around one of the shoulder straps 26, 28 to position the tubing for extending down the arm 66 of the patient. The harness 10 maintains the supply container 56 adjacent to the horizontal strap 12 in a position on the torso so as not to inhibit patient movement and at the same time to be in a position in close proximity to the skin to permit heat transfer, thereby limiting the temperature range of the drug supply which would other¬ wise be totally subject to atmospheric temperature changes. Thus, the patient can be ambulatory and per¬ form most activities while permitting an extremely low volume of liquid drug to be infused over a fairly lengthy period of time, such as a twenty-four hour period, thereby reducing harmful side effects and increasing the beneficial value of the infused drug which may commonly be, for example, heparin in dextrose solution, insulin, or chemotherapy drugs. In addition, with an infusion device employing a pressurized system where liquid viscosity measurably affects fluid flow rate, the harness of the present invention stabilizes the liquid drug temperature and thus the drug viscosity in the supply container 56. The administration tubing 60 preferably has a small lu¬ men so that the volume of liquid in the tubing and the time period over which a particular volume of liquid remains therein is small. In addition the harness facilitates wearing the tubing 60 adjacent the skin. A shirt 74, shown in phantom in Figure 2, or other normal, unaltered wearing apparel may be worn over the harness with the supply container therein. Preferably, the support straps 26, 28 converge at a point above the supply container 56 so as to prevent sagging of the frontside 14 with the infusion device thereon. The buckles 42 or other length adjusting means are placed near the second ends 36, 38 to facilitate easy adjustment by the wearer. The second ends 36, 38 of the support straps 26, 28 may of course be spaced apart on frontside 14 while still supporting the in¬ fusion device; however, as seen in Figure 1, the con¬ verging support straps 26, 28 facilitate wear about the torso 76 of a female. As seen in Figure 1, support straps 26, 28 extend between cups 80, 82 of bra 84. Such a harness construc¬ tion enables wear in conjunction with undergarments in an inconspicuous manner. Figure 3 shows a modified embodiment of the inven- tion wherein fastening strips 44', 46' are fastened to the frontside 14 of the horizontal strap 12 in a manner such that the liquid supply container 56 is retained about a torso 48, 76 below the horizontal strap 12, which may further facilitate heat transfer from the body, although such a construction may allow for some unwanted move¬ ment of the container 56. Another embodiment of the in¬ vention includes placement of the fastening means on the body attachment means at a location other than the front- side 14 of the horizontal strap 12, such as at, but not limited to, the backside 16 near the frontside 14 (not shown) . Further embodiments include substitution of multiple piece fastening strips which can close to an adjustable circumference by conventional means such as a buckle to become a formed closed loop. Alternatively, a flexible perimeter-adjustable sleeve (not shown) may be secured substantially parallel with the frontside 14 in substitu¬ tion for the fastening strips 44, 46. Harness means in accordance with the present inven¬ tion could be made by attaching fastening means to a bra 84 but this involves alteration of otherwise normal wearing apparel. The preferred embodiment discloses a harness which may be used by either sex under normal clothing to enable inconspicuous wearing of an infusion device. Most importantly, the harness limits the effect of atmospheric temperature changes on fluid viscosity by effectively keeping the drug supply close to the skin and thus in a more temperature-constant environment. While the above description is meant to provide an enabling construction for the preferred embodiments of the invention, it is not intended to limit the scope of the invention, which is claimed as follows.

Claims: What Is Claimed Is: 1. Apparatus for minimizing the temperature range of a liquid drug supply in a container to thereby stabilize both the viscosity of the liquid drug supply and the drug flow rate from the supply into a human being, comprising: body attachment means adaptable for wear by the human being; and fastening means extending from one portion of said attachment means for securing the container both in a manner enabling the human to be ambulatory and in a position in close proximity to the skin such that suffici¬ ent body heat generated from the human being is trans¬ ferred to the container and minimizes temperature change to the drug supply caused by an atmospheric temperature change. 2. Apparatus for minimizing the temperature range of a liquid drug supply as in Claim 1, wherein said one por¬ tion of said attachment means may be worn directly ad- jacent the skin of the human being. 3. A harness to be worn by a human being to retain a liquid supply container while allowing the human to be ambulatory during infusion of the supply drug into the human, comprising: body attachment means including, a horizontal strap including a backside and a frontside for placement about the torso of the human, two support straps for said horizontal strap, a first end of each support strap secured to said horizontal strap along said backside, said first ends spaced along said backside to allow said support straps to be worn over the shoulders of the human, and a second end of each strap opposite said first ends, said straps secured to said frontside of said horizontal strap at said second ends; and fastening means extending from said body attach¬ ment means for securing the drug supply container, said fastening means retaining the drug supply container in close proximity to the person to permit heat transfer from the person to the drug supply, thereby minimizing tempera¬ ture change to the drug supply. 4. A harness to be worn by a human being to retain a liquid drug supply container while allowing the human to be ambulatory during infusion of the supply drug into the human, comprising: a horizontal strap including a backside and a frontside for placement about the torso of the human; two support straps for said horizontal strap, a first end of each support strap secured to said hori- zontal strap along said backside, said first ends spaced along said backside to allow said support straps to be worn over the shoulders of the human; a second end of each strap opposite said first ends, said straps secured to said frontside of said horizontal strap at said second ends; and fastening means extending from said horizontal strap for securing the drug supply container, said fasten¬ ing means retaining the drug supply container in close proximity to the person to permit heat transfer from the person to the drug supply, thereby minimizing temperature change to the drug supply. 5. A harness as in Claim 4, wherein said fastening means extends from said frontside. 6. A harness to be worn by a person, to carry a liquid drug supply container having administration con¬ duit which extends from the container to an injection site on the person, comprising: a flexible, elastic, horizontally disposed strap to be worn about the torso of the person, said horizontal strap including a frontside and a backside; two flexible support straps having first and second ends, said support straps fastened to said backside of said horizontal strap substantially at said first ends and extending upwardly from said backside for placement about the shoulders of the person, said support straps converging and fastened substantially at the midpoint of said frontside substantially at said second ends; and fastening means secured to said frontside for removably retaining the drug supply container in close proximity to the person, whereby the harness may be worn underneath outer garments, said harness enabling the person to be ambulatory during infusion of the supply drug, 7. A harness as in Claims 4 or 6, said fastening means further comprising at least two fastening strips, said fastening strips each manipulable into a formed closed loop such that the drug supply container may be inserted and held within said loops. 8. A harness as in Claims 4 or 6, said fastening means further comprising at least two fastening strips, wherein each of said fastening strips is unitary and elastic. 9. A harness as in Claim 7, said fastening strips being centered about the midpoint of said frontside. 10. A harness as in Claim 8, said fastening strips being centered about the midpoint of said frontside. 11. A harness as in Claims 4 or 6 wherein said sup¬ port straps further comprise length adjusting means. 12. A method for stabilizing the drug flow rate from a drug supply in a container into a human being, wherein flow rate is dependent on drug supply viscosity, comprising the steps of: adapting a harness to the human being for ambulatory wear, the harness including body attachment means and fastening means extending from one portion of the body attachment means; securing the drug supply container to the fastening means; limiting the temperature range of the drug supply by facilitating heat transfer from the human being to the drug supply; and communicating administration tubing which ex¬ tends from the drug supply container with an injection site on the human being. 13. The method as in Claim 12, wherein heat transfer is facilitated by securing the drug supply container to the fastening means in a manner such that the container is in close proximity to the skin of the human being. 14. The method as in Claims 12 or 13, including the further step of wearing unaltered apparel over the drug supply container to facilitate the heat transfer.

Inventors: BELLAMY DAVID, VYCITAL DORENE G, WINCHELL DAVID A
Applicants: BAXTER TRAVENOL LAB
Application year: 1982
Main classification: A61M5
IPC codes: A61M1, A61M3, A61M5