Infuser with balloon for infusing medicine

An infuser for continuously infusing a solution of medicine includes a tubular main body having a flow path which extends along the longitudinal axis of the body. An inlet portion having a check valve, an injection port, or a one-way cock is connected to one end of the body. A cylinder with a closed bottom is slidably connected to the other end of the body. The bottom of the cylinder is directed outwardly. The cylinder or the other end of the body is provided with a plurality of holes. A change-over valve is provided in the flow path at an intermediate portion of the body. An outlet portion is connected to the change-over valve. A control portion for controlling the outflow of the solution of medicine is provided in the outlet portion. A balloon made from an elastic material surrounds the holes. One circumferential portion of the balloon is air-tightly secured to the outer periphery of the cylinder at a given position and another circumferential portion of the balloon is air-tightly secured to the outer periphery of the cylinder at a given position. In use, a given amount of the solution of medicine is infused into the balloon through the inlet portion. The solution of medicine in the balloon flows out continuously for a long time through the outlet control portion and an indwelling retainer attached to the outlet portion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an infuser for continuously infusing 
predetermined volume of a solution of medicine into the human body within 
a predetermined period of time. 
2. Description of the Related Art 
There are two conventional methods of infusing a solution of medicine into 
the human body over a relatively long period of time: in one method, the 
solution of medicine is 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 installation 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 gives them great pains 
mentally and physically. It is generally believed that people can remain 
in 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, 
and even if the patient does not require such a supplemental liquid, 
he/she must be subjected 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. Pat. 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 present applicant has previously 
developed "An Infuser with a Balloon for Continuously Infusing a Solution 
of Medicine" (Japanese Patent No. 1384289) for infusion into the human 
body over a comparatively long period of time and which has a simple 
structure is easy to handle and is reliably safe. 
This patented infuser comprises a tubular main body having a flow path that 
extends 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 present applicant has 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 a solution of medicine into the human body over a comparatively 
long period of time and which has a simple structure, is easy to handle 
and is safe to use. 
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 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 
communicates 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 readily clogged with foreign matters. 
In view of the above drawbacks, the present applicant 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 that is 
formed along the longitudinal axis of the tubular main body. This tubular 
main body is provided at one end thereof with a portion with a check valve 
allowing the solution of medicine to be infused therefrom into the tubular 
main body and at the other end thereof with a portion allowing the 
solution of medicine to be injected therefrom. A predetermined volume of a 
normal temperature or thermosetting pourable resin that exhibits no 
adhesiveness relative to a specific material fills the other end of the 
tubular main body, and a linear, spiral or wound capillary wire made from 
a specific material and having a predetermined diameter is embedded in the 
pourable resin. This capillary wire extends into the tubular main body at 
one end thereof, and the other end thereof 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 a circumferential 
portion 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 an 
indwelling retainer for the human body can be fitted to the medicine 
injecting portion. 
This medicine infuser, however, has a drawback in that minute burrs are 
formed on the inner surface of the capillary hole after the capillary wire 
has been drawn out. Thus, it is difficult to form a hole which will 
function steadily. 
The present applicant has also 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). 
This infuser comprises a tubular main body having a flow path that extends 
along the longitudinal axis of the tubular main body. This tubular main 
body is provided at one end thereof with 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 at the other end thereof with a portion 
allowing the solution of medicine to be injected therefrom. 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 
a circumferential portion 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 the balloon is different between a center portion and 
both end portions thereof, since the circumferential end portions of the 
balloon are secured to the tubular main body. Consequently, the solution 
of medicine flows under a high pressure and flow rate at the beginning of 
ejection while the solution flows under a low pressure and flow rate at 
the end of the ejection. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an infuser with a balloon 
for continuously infusing a solution of medicine and in which a flow rate 
of the solution can be kept constant. 
An infuser with a balloon for continuously infusing a solution of medicine 
in accordance with the present invention comprises a tubular main body 
having a flow path which is formed along the longitudinal axis of the 
body. An inlet portion having a check valve, an injection port, or a 
one-way cock is connected to one end of the body. A cylinder with a bottom 
is slidably connected to the other end of the body. The bottom of the 
cylinder is directed outwardly. The cylinder or the other end of the body 
is provided with a plurality of holes. A change-over valve is provided in 
the flow path at an intermediate portion of the body. An outlet portion 
for the solution of medicine is connected to the change-over valve. A 
control portion for controlling the outflow of the solution of medicine is 
provided in the outlet portion. A balloon made from an elastic material 
surrounds the holes. One circumferential portion of the balloon is 
air-tightly secured to the outer periphery of said body at a given 
position and another circumferential portion of the balloon is air-tightly 
secured to the outer periphery of the cylinder at a given position. 
Preferably, scale marks are formed longitudinally on the outer periphery of 
that portion of the body which supports the cylinder.

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, an inlet portion 5, and an outlet portion 6. 
In this tubular main body 1, a flow path 11 extends 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 side as viewed in FIG. 1) of the 
tubular main body 1, the change-over valve 4 is provided at an 
intermediate portion of the body 1, and the cylinder 3 with its bottom 
directed outwardly is connected slidably to the other end (at the 
left-hand side as viewed in FIG. 1 at the tubular main body 1). 
Although the inlet portion 5, the change-over valve 4, and the outlet 
portion 6 may be formed unitarily with the tubular main body 1, they may 
be made of separate parts, as shown in the drawings, for convenience in 
the manufacturing and handling thereof. 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 allows the solution of 
medicine to flow in a direction indicated by arrow 511 but not in the 
opposite direction, or serves to open or close the flow path 11. 
The change-over valve 4 serves to selectively place the inlet portion 5 and 
the cylinder 3 in communication, the cylinder 3 and the outlet portion 6 
in communication, the inlet portion 5 and the outlet portion 6 in 
communication, or all three in communication. For example, the valve 4 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 surrounds the connection portions of the same. As shown 
in FIG. 1 or 5, one circumferential portion 21 of the balloon 2 is 
air-tightly secured to the outer periphery of the body 1 at a given 
position and the other circumferential portion 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 covers the open end of the tubular main 
body 1 or the open end of the cylinder 3 and the holes 31 or 12. 
With the structure described above, the solution of medicine which leaks 
from the connected portions of the tubular main body 1 and the cylinder 3 
or the holes is enclosed in the balloon 2 and cannot flow out of the 
infuser. 
It is desirable that this balloon 2 be 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. Commercially available silicon rubber, latex 
rubber and so forth can be used as an optimal material for the balloon. 
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 the solution of medicine is 
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 circumferential portions 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 in 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 be 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 FIGS. 7(A)-7(F). 
FIGS. 7(A) to (E) show 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 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 move freely 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 fills 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 are important factors in 
establishing time during which the solution of medicine is allowed to flow 
out. 
Referring to FIGS. 1 and 4, an example of the use 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 from the outlet 6 by 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 both the flow path 11 and holes 
31 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. 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 
needs to be prevented, a 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 is oriented to locate the inlet portion 5 at 
the top thereof. This allows air in the balloon 2 to enter the flow path 
11 via the holes 31, and the 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 indwelling retainer 
8 for the human body, such as an injecting needle, is fitted to the outlet 
portion 6 (FIG. 6). 
Next, the cylinder 3 is placed in communication with the outlet portion 6 
by operating the change-over valve 4 (FIG. 5(B)). Then, the inlet portion 
4 may either communicate with the outlet portion 6 or be shut off from 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 by virtue of the 
contracting action of the balloon 2. 
Finally, a normal air bleeding operation is carried out. In order to 
confirm whether air has been completely bled, 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 owing to 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 are always uniform in comparison with 
outflow characteristics A of the infuser according to the prior art 
(PCT-JP-89-00515). 
FIGS. 6(A)-(C) shows main examples of indwelling retainers 8 for 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 of any shape depending on the infusing site of 
the human body. For instance, a flat elliptical balloon may be utilized. 
A transparent cover 81 [FIGS. 9(A) or (B)] covering the exterior of the 
balloon 2 may be detachably mounted on the tubular main body 1 to prevent 
the balloon from being ruptured by 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 has a simple 
structure and is easy to handle. The infuser of the present invention does 
not restrict the action and movement of the patient, and reduces the 
labour and actual working hours of the operator. Moreover, once air is 
bled, the ingress of air is not allowed until the balloon is completely 
contracted. 
Furthermore, the infuser in accordance with the present invention has 
uniform outflow characteristics for the solution of medicine.