CONTINUOUS DRUG SOLUTION INJECTOR EQUIPPED WITH BALLOON

Abstract: This invention relates to a continuous drug solution injector equipped with a balloon and used for injecting a drug solution filled in a balloon made of an elastic material into the human body within a predetermined period of time by utilizing the shrinking force of the balloon. A bottomed cylinder (3) is fitted slidably with its bottom facing outward into a tubular body (1) which is formed by connectong a drug solution charge portion (5) having a valve member and a drug solution discharge portion (6) having a drug solution discharge control portion through a flow path change-over valve (4) disposed at an intermediate portion. A plurality of holes (12 or 31) are bored in the tubular body or the cylinder. The peripheral edges of the balloon (2) are fixed air-tight to both the tubular body and the cylinder in such a manner as to encompass the junction between the tubular body and the cylinder as well as the holes. Thus the cylinder can slide relative to the tubular body with the aid of the elasticity of the balloon and the inner pressure of the drug solution when the balloon undergoes expansion and shrinkage, and the balloon can undergo expansion and shrinkage in substantially the same quantity in the direction of the center axis in a longitudinal direction and an axial direction vertical to the former, whereby the drug solution can be injected uniformly without intermission.

Description: TECHNICAL FIELD The present invention relates to an infuser with a balloon for continuously infusing a solution of medicine which is intended to be used in infusing into the human body a predetermined volume of the solution of medicine that has already been infused into the balloon within a predetermined period of time. BACKGROUND ART There are two conventional method of infusing a solution of medicine into the human body over a relatively long period of time: in one method, the solution of medicine injected from an injecting needle or catheter which is attached to a syringe containing the solution of medicine by operating the syringe manually, electrically or by utilizing the action of a spring; and in the other method, an instillation bottle containing the solution of medicine is used, and the solution is caused to drop therefrom under gravity or in an electrical manner. In a case where the solution of medicine is infused into the human body over from a few minutes to a few hours, an injecting needle of a catheter must be kept attached to a syringe or instillation bottle serving as a medicine supplier, and this causes great inconvenience to the operator as well as to the patient. For instance, in a case where an infusion is continuously carried out in a manual fashion, the movement of both the patient and the operator is restricted for a certain period of time, and this given them great pains mentally and physically. It is generally believed that people can take the same posture only for 1 or 2 minutes under such a condition. In contrast, in a case where the infusion of the solution of medicine is carried out electrically or by utilizing the action of a spring, a power source must be secured near the infusion site, and a syringe must properly be placed. This also restricts the action of the patient. In addition, when the solution of medicine is continuously infused into the human body by utilizing the instillation method, a comparatively large amount of a supplemental liquid relative to the medicine needs to be used together, and even if the patient does not require such a supplemental liquid, he/she must be subject to the infusion of the same. Moreover, an instillation bottle or container must be placed at a position higher than where the patient is lying, and a complicated and long conduit is required to connect the injecting needle or catheter to the instillation bottle. This also restricts the movement of the patient, and the operator is required to confirm whether or not the instillation of the solution of medicine is being carried out properly. Japanese Patent Publication No. 45799/1980 discloses a flow control device for use in infusing a solution of medicine into the human body. In this device, a core having a spiral groove formed therein is inserted in a sleeve, and this sleeve is clamped by means of a ring so as to control the flow of the solution. However, with this flow control device, it is not possible to continuously infuse the solution of medicine over a long period of time. U.S. Patent No. 4,318,400 discloses an infuser for continuously infusing a solution of medicine. In this infuser, a balloon containing therein the solution of medicine is inserted in a cylinder, and the balloon contracts in the axial direction with the solution of medicine contained therein being injected therefrom by virtue of the contracting action of the balloon. However, this infuser is disadvantageous in that the solution contained in the balloon cannot completely be discharged therefrom. In view of the above drawbacks, the applicant of the present invention previously disclosed "An Infuser with a Balloon for Continuously Infusing a Solution of Medicine" (Japanese Patent No. 1384289) with a view to providing an infuser for continuously infusing the solution of medicine that is intended to be used for continuously infusing the solution of medicine into the human body over a comparatively long period of time and which is simple in construction, easy to handle and reliable in safety. This patented infuser comprises a tubular main body having a flow path for a solution of medicine that is formed along the longitudinal axis of the tubular main body, a portion with a check valve provided at one end of the tubular main body to allow the solution of medicine to be infused therefrom into the tubular main body, a portion provided at the other end of the tubular main body to allow a solution of medicine to be injected therefrom, a member provided at an intermediate position along the length of the tubular main body to shut off the flow path, an inlet hole and an outlet hole or outlet hole with a fine porous membrane provided in the neighborhood of the shut off member on the medicine infused portion side and medicine injecting portion side, respectively, in such a manner as to extend through the wall of the tubular main body, and a balloon made from an elastic material and surrounding the inlet and outlet holes, the balloon being air-tightly secured to the outer periphery of the tubular main body at the perimeter thereof. In addition, the applicant of the present invention also previously disclosed "An Infuser with a Balloon for Continuously Infusing a Solution of Medicine into a Blood Vessel" (the Official Gazette of Japanese Patent Public Disclosure No. 11465/1987) which comprises the above patented infuser and an intravascular retainer connected to the medicine injecting portion of the same infuser. Moreover, the applicant of the present invention also previously disclosed "An Infusing Catheter for Continuously Infusing a Solution of Medicine into a Urinary Bladder" (the Official Gazette of Japanese Patent Public Disclosure No. 11464/1987) that is intended to be used when continuously infusing the solution of medicine into the human body over a comparatively long period of time and which is simple in construction, easy to handle and reliable in safety. In this catheter, a conventional common catheter for a urinary bladder is employed, and a recess is formed in a part of the outer periphery of the catheter at the proximate end thereof. A balloon made from an elastic material is provided on the catheter so as to surround the recess, and the balloon is air-tightly secured to the outer periphery of the catheter at the perimeter thereof. A capillary tube is provided on the wall of the catheter along the longitudinal axis thereof. This capillary tube is made open at the proximate end thereof so as to form an outlet port for a solution of medicine and is caused to communicate with the recess at the proximate end. A portion allowing the solution of medicine to be infused therefrom into the balloon is air-tightly secured to the balloon at the central portion thereof, and a central passageway is provided at the center of the portion allowing the medicine to be infused. A valve is provided on the central passageway at the inlet end thereof, and the passageway is caused to communicate with the recess at the outlet end thereof. The above-described infuser or catheter is provided with a capillary hole or capillary tube for controlling the time during which the solution of medicine is allowed to flow out. It is, however, difficult to actually form such a capillary hole or capillary tube, and even if this is possible, they are easy to be clogged with foreign matters. In view of the above drawbacks, the applicant of the present invention succeeded in contriving a method of forming a capillary tube for controlling the time during which the solution of medicine is allowed to flow out with ease and previously disclosed "An Infuser with a Balloon for Continuously Infusing a Solution of Medicine" having a structure in which the clogging of a capillary tube is prevented (PCT-JP-88-01055). This infuser comprises a tubular main body having a flow path for a solution of medicine that is formed along the longitudinal axis of the tubular main body. This tubular main body is provided with at one end thereof a portion with a check valve allowing the solution of medicine to be infused therefrom into the tubular main body and a portion allowing the solution of medicine to be injected therefrom at the other end thereof. A predetermined volume of a normal temperature or thermosetting pourable resin that exhibits no adhesiveness relative to a specific material is filled in the other end of the tubular main body, and a linear, spiral or winding capillary wire made from a specific material and having a predetermined diameter is embedded in the pourable resin. This capillary wire is caused to extend into the tubular main body at one end thereof, and at the other end thereof it is guided so as to extend through the medicine injecting portion to the outside of the tubular main body. Holes are formed in the tubular main body in such a manner as to extend through the wall thereof, and a balloon made from an elastic material is provided so as to surround the holes with the perimeter thereof being air-tightly fixed to the outer periphery of the tubular main body. The capillary wire is drawn to the outside of the tubular main body so as to form a capillary hole through the pourable resin portion, and a retainer adapted to indwell the human body can be fitted to the medicine injecting portion. This medicine infuser, however, has a drawback that minute burrs are caused on the inner surface of the capillary hole after the capillary wire has been drawn out. Thus, it is difficult to form a hole steadily functioning. Then, the present applicant has disclosed "An Infuser with a Balloon for Continuously Infusing a Solution of Medicine" in which the time during which the solution of medicine is allowed to flow out is able to be variously changed and which has a steady capillary hole through which the solution of medicine is allowed to flow out (PCT-JP-89-00515, EP-A-0 427 852). This infuser comprises a tubular main body having a flow path for a solution of medicine that is formed along the longitudinal axis of the tubular main body. This tubular main body is provided with at one end thereof a portion with a check valve or one-way cock allowing the solution of medicine to be infused therefrom into the tubular main body and a portion allowing the solution of medicine to be injected therefrom at the other end thereof. A control portion for controlling the outflow of the solution of medicine is also provided adjacent to the medicine infused portion at the other end of the tubular main body. A plurality of holes are formed in the tubular main body in such a manner as to extend through the wall thereof, and a balloon made from an elastic material is provided so as to surround the holes with the perimeter thereof being air-tightly fixed to the outer periphery of the tubular main body. In the infuser with a balloon for continuously infusing a solution of medicine developed by the present applicant, however, a rate of expansion and contraction of a balloon is different between a center portion and both end portions thereof, since the perimeters of the balloon are secured to the tubular main body. Consequently, the solution of medicine attains a high pressure and flow rate at the beginning of ejection while the solution attains a low pressure and flow rate at the ending of ejection. We are aware of EP-A-0 295 504 which discloses an infuser in accordance with the pre-characterising portion of claim 1. According to our invention, in an infuser in accordance with the pre-characterising portion of claim 1, the slidable member is a cylinder with a bottom, the bottom of the cylinder being directed outwardly, the cylinder or the other end of the body being provided with a plurality of holes, and the outlet portion is separate from the tubular body. By making the outlet portion separate it can be replaced by similar outlet portions provided with control portions having different discharge times. Thus the discharge time of a given drug solution can be selected to suit any particular application. Preferably, scale marks are formed longitudinally on the outer periphery of the body which carries the cylinder. BRIEF DESCRIPTION OF DRAWINGS : Fig. 1 is a longitudinal cross-sectional view of an infuser for continuously infusing a solution of medicine according to the present invention. Fig. 2 is a transverse cross-sectional view taken along the line II-II of Fig. 1. Fig. 3 is a transverse cross-sectional view taken along the line III-III of Fig. 1. Fig. 4 is an explanatory view of operation of the infuser according to the present invention. Fig. 5 is a longitudinal cross-sectional views of an alternation of the infuser according to the present invention. Fig. 6 shows side views of retainers adapted to indwell the human body and designed to be connected to the infuser for continuously infusing the solution of medicine according to the present invention. Fig. 7 shows longitudinal cross-sectional views, partially enlarged, of various modifications that can be made to the control portion of the infuser for continuously infusing the solution of medicine according to the present invention that is adapted to control outflow of the solution of medicine. Fig. 8 is an explanatory view of effect of the infuser according to the present invention. Fig. 9 is an explanatory view showing various applications of the infuser for continuously infusing the solution of medicine according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION : Referring to Figs. 1 to 5, a basic structure of the infuser for continuously infusing a solution of medicine according to the present invention will now be described. The medicine infuser according to the present invention comprises a tubular main body 1, a balloon 2, a cylinder 3, a change-over valve 4 for a flow path, an inlet portion 5 for the solution of medicine, and an outlet portion 6 for the solution of medicine. In this tubular main body 1, a flow path 11 for a solution of medicine is formed in such a manner as to extend in the longitudinal direction of the tubular main body. The inlet portion 5 allowing the solution of medicine to be infused therefrom into the tubular main body is provided at one end (at the right-hand end as viewed in Fig. 1) of the tubular main body 1, the change-over valve 4 for the flow path 11 is provided at an intermediate portion of the body 1, and the cylinder 3 with a bottom directed outwardly is connected slidably to the other end (at the left-hand end as viewed in Fig. 1). The change-over valve 4 is provided with the outlet portion 6 for the solution of medicine. The inlet portion 5, the change-over valve 4, the outlet portion 6 and the tubular main body 1, are made of separate parts as shown in the drawings for the convenience of manufacturing and handling. The inlet portion 5 is provided with a conventional check valve, injection port, or one-way cock 51. The check valve, injection port, or one-way cock 51 serves to allow the solution of medicine to flow to a direction indicated by an arrow 511 and not to allow the solution to flow to the opposite direction, or serves to open or close the flow path for the solution of medicine. The change-over valve 4 for the flow path 11 serves to make a communication between the inlet portion 5 and the cylinder 3, between the cylinder 3 and the outlet portion 6, between the inlet portion 5 and the outlet portion 6, or among all of them. For example, it may be a conventional three-way cock. The cylinder 3 may be slidably mounted on the interior or the exterior of the tubular main body 1 as shown in Fig. 1 or 5. When the cylinder 3 is mounted on the interior, the cylinder is provided with a plurality of holes 31. When the cylinder is mounted on the exterior, the tubular main body is provided with a plurality of holes 12 (Fig. 5). These holes 31 or 12 communicate with the flow path 11 of the main body 1. Scale marks 13 are formed longitudinally on the outer periphery of the main body 1. The scale marks 13 indicate an amount of movement of the cylinder 3, and thus a user can know an amount of inflow or outflow of the solution of medicine. The balloon 2 is attached to the tubular main body 1 and the cylinder 3 so that the balloon 2 can surrounds the connected portions of them. As shown in Fig. 1 or 5, one perimeter 21 of the balloon 2 is air-tightly secured to the outer periphery of the body 1 at a given position and the other perimeter 22 of the balloon 2 is air-tightly secured to the outer periphery of the cylinder 3 at a given position, so that the balloon 2 can cover with the open end of the tubular main body 1 or the open end of the cylinder 3 and the holes 31 or 12. By the construction described above, the solution of medicine which leaks from the connected portions between the tubular main body 1 and the cylinder 3 or the holes is closed in the balloon 2 and can not flow out of the infuser. It is desirable that this balloon 2 is made from a material having good contraction and expansion properties, as well as good resistance to wear and toughness so that it is not easily damaged when a force is applied thereto from the outside. In particular, such a material is desirably transparent or translucent. Retailed silicon rubber, latex rubber and so forth can be used as an optimal material for such use. As shown in Fig. 1, the balloon 2 is tightly in contact with the tubular main body 1 and the cylinder 3 over the whole portion thereof in a normal state in which the infusion of the solution of medicine has not yet been started, while, as shown in Fig. 4, when it is put into operation with the solution of medicine being started to be infused into the tubular main body 1 and the cylinder 3, the balloon starts to separate from the outer periphery of the tubular main body 1 and the cylinder 3 and expands with the perimeters 21 and 22 thereof being left secured to the tubular main body 1 and the cylinder 3. The control portion 7 for controlling the outflow of the solution of medicine is provided in the outlet portion 6 so that the control portion 7 communicates with the flow path 11. The control portion 7 controls an outflow time for which the solution of medicine infused in the balloon 2 flows out of the outlet portion 6. It is desirable that the control portion 7 is selected from one of those disclosed in PCT-JP-89-00515 of the present applicant. Various modifications of this control portion 7 are shown in Fig. 7. Figs. 7(A) to (E) show modification examples of the control portion 7 wherein a capillary tube 71 having a capillary hole and made from resin, metal, ceramic or the like is embedded in a synthetic resin 72. The tube 71 may be embedded in the synthetic resin 72 in a linear (A), winding (B) or spiral (C) fashion. A hole may be formed through the synthetic resin 72 portion by means of laser or the like in order to replace the linear capillary tube 71. Fig. 7(D) shows an example wherein a capillary wire 74 is inserted into the capillary tube 71 in such a manner as to be allowed to freely to in and out thereof, and Fig. 7(E) shows an example wherein a tube 75 having a diameter smaller than that of the tube 71 is inserted into the latter. Fig. 7(F) shows an example wherein a porous material 73 is filled in the control portion 7. Active carbon, pumice stone, resin particles, silicone gel, urethane gel and so forth may be used as a porous or permeable and diffusible material. The length of the capillary hole of the tube 71 or porosity of the porous or permeable and diffusible material 73 can be one of the important factors to decide on the time during which the solution of medicine is allowed to flow out. Referring to Figs. 1 and 4, a functional example of the infuser for continuously infusing the solution of medicine according to the present invention will now be described. First, the inlet portion 5 is caused to be in communication with the cylinder 3 and to be shut off the outlet 6 by operating the change-over valve 4 (Fig. 1). A predetermined volume of a solution of medicine is infused into the infuser from the inlet portion 5 of the infuser. The solution of medicine is caused to flow into the balloon 2 via the flow path 11 and holes 31 both formed in the tubular main body 1, thereby causing the balloon 2 to expand. The medicine continues to be infused until the balloon becomes full thereof. The medicine so infused into the balloon 2 is prevented from flowing in the reverse direction by means of the check valve, injection port or one-way cock 51. In a case where the ingress of air into the balloon 2 or the flow path 11 for the solution of medicine needs to be prevented, the solution of medicine of the same type or isotonic sodium chloride solution may be infused into the flow path 11 in advance. Alternatively, the infuser should be erected in such a manner that the inlet portion 5 becomes the top thereof. This allows air in the balloon 2 to enter the flow path 11 via the holes 31, and air in the flow path 11 eventually gathers in the vicinity of the inlet portion 5. Air so gathering in the neighborhood of the inlet portion 5 can be easily discharged by means of an air bleeding capillary tube (not shown). After a predetermined volume of the medicine has been infused into the balloon 2, a cap (not shown) attached to the distal end of the outlet portion 6 is then taken off, and a separately prepared necessary retainer 8 adapted to indwell the human body, such as an injecting needle, is fitted to the outlet portion 6 instead (Fig. 6). Next, the cylinder 3 is caused to be in communication with the outlet portion 6 by operating the change-over valve 4 for the flow path (Fig. 5(B)). Then, the inlet portion 5 may either communicate with the outlet portion 6 or shut off the outlet portion 6. Even if the inlet portion 5 communicates with the outlet portion 6, the one-way cock 51 prevents the solution of medicine from flowing out of the inlet portion 5. The medicine filling the balloon 2 is caused to flow into the injecting needle or the like via the holes 31, the flow path 11, the capillary tube 71 having a capillary hole, and the outlet portion 6 is virtue of the contracting action of the balloon 2. Finally, a normal air bleeding operation is carried out. In order to confirm whether or not air is completely bleeded, the respective constituent elements should desirably be transparent or translucent. The injecting time of the solution of medicine depends on the volume of the medicine infused in the balloon 2 and the viscosity of the medicine, the contraction properties of the balloon 2, the transverse cross-sectional area and length of the capillary hole, the internal pressure of a part of the human body where the medicine is infused, and so forth. The actual injecting time of the infuser may be measured by employing a standard solution of medicine, and this may be carried out on each infuser. When the balloon expands and contracts, the cylinder 3 moves relative to the tubular main body by the elasticity of the balloon 2 and the pressure of the solution of medicine in the balloon 2. This movement of the cylinder 3 makes the expansion and contraction of the balloon 2 uniform, since the balloon 2 is expanded or contracted by the same value in the longitudinal axial direction and in the axial direction perpendicular to the longitudinal axial direction. Consequently, as shown in Fig. 8, outflow characteristics B of the infuser according to the present invention is always uniform in comparison with outflow characteristics A of the infuser according to the prior art (PCT-JP-89-00515). Fig. 6 shows main examples of retainers 8 adapted to indwell the human body that may be connected to the outlet portion 6 of the infuser of the present invention. Fig. 6(A) shows a normal injecting needle, Fig. 6(B) an injecting needle having a flexible conduit, and Fig. 6(C) a normal catheter. Basically, a spherical balloon 2 is employed in the present invention, but the balloon 2 used may be formed in any shapes depending on the infusing site of the human body. For instance, a flat elliptical balloon may be utilized. A transparent cover 81 [Fig. 9(A) or (B)] covering the exterior of the balloon 2 may be detachably mounted on the tubular main body 1 for fear that the balloon is ruptured when it is brought into contact with an article having a sharp point, edge or the like. In this case, a belt 811 or a strap 821 is preferably provided so as to facilitate the securing of the infuser 100 to the human body. Fig. 9(C) shows an example wherein the infuser 100 for continuously infusing a solution of medicine according to the present invention is connected to the inlet portion 911 of a catheter 91 for the urinary or digestive organs. Fig. 9(D) shows an example wherein the infuser 100 for continuously infusing a solution of medicine according to the present invention is connected to the inlet portion 921 of a catheter 92 for veins. Fig. 9(E) shows an example wherein the infuser 100 for continuously infusing a solution of medicine according to the present invention is connected to the inlet portion 931 of a catheter 93 for use in the field of obstetrics and gynecology. Fig. 9(F) shows an example wherein the infuser 100 for continuously infusing a solution of medicine according to the present invention is connected to the inlet portion 941 of a catheter 94 for use in the field of encephalon surgery. Since the infuser for continuously infusing a solution of medicine in accordance with the present invention is adapted to function not only as a container for a medicine but also as a drug infuser, it is simple in construction and easy to handle. Due to this the infuser of the present invention does not restrict the action and movement of the patient, and in addition it reduces the labour and actual working hours of the operator. Moreover, once air is bleeded, the ingress of air is not allowed until the balloon is completely contracted. Furthermore, since the infuser in accordance with the present invention has an uniform outflow characteristics for the solution of medicine, the remedy effect is improved and stabilized. INDUSTRIAL APPLICABILITY : The infuser for continuously infusing a solution of medicine in accordance with the present invention is able to be widely used as a medical appliance for human or animal.

Claims: An infuser with a balloon for continuously infusing a solution of medicine, comprising: a tubular main body (1) having a flow path (11) for the solution of medicine which is formed along the longitudinal axis of said body (1); an inlet portion (5) for the solution of medicine having a check valve, an injection port, or a one-way cock (51) and connected to one end of said body (1); a slidable member connected to the other end of said body (1); a change-over valve (4) provided in said flow path (11) at an intermediate portion of said body; an outlet portion (6) for the solution of medicine connected to said change-over valve (4); a control portion (7) for controlling outflow of the solution of medicine provided in said outlet portion (6); and a balloon (2) made from an elastic material for surrounding said holes, one perimeter (21) of said balloon being air-tightly secured to the outer periphery of said body at a given position and the other perimeter (22) of said balloon is air-tightly secured to the outer periphery of said cylinder at a given position, characterised in that the slidable member is a cylinder with a bottom, the bottom of the cylinder being directed outwardly, the cylinder (3) or the other end of the body being provided with a plurality of holes (31 or 12), and the outlet portion (6) is separate from the tubular body (1). An infuser as set forth in claim 1, wherein scale marks (13) are formed longitudinally on the outer periphery of said body which carries the cylinder.

Inventors: TSUKADA OSAMU, TSUKADA, OSAMU
Applicants: TSUKADA MEDICAL RESEARCH CO LT, TSUKADA MEDICAL RESEARCH CO., LTD.
Application year: 1990
Main classification: A61M5
IPC codes: A61M5