U.S. patent application number 13/598476 was filed with the patent office on 2012-12-27 for self-contained portable apparatus for administration of a drug solution.
Invention is credited to Erik Andreen, Martin NILSSON.
Application Number | 20120330272 13/598476 |
Document ID | / |
Family ID | 38846870 |
Filed Date | 2012-12-27 |
United States Patent
Application |
20120330272 |
Kind Code |
A1 |
NILSSON; Martin ; et
al. |
December 27, 2012 |
SELF-CONTAINED PORTABLE APPARATUS FOR ADMINISTRATION OF A DRUG
SOLUTION
Abstract
A self-contained portable apparatus for administration of a drug
solution includes a housing having an enclosure for receiving a
flexible pouch containing a drug solution, the output of which is
connectable to a conduit for delivering the drug solution to a
recipient. A pressurization system is arranged for providing a
constant and controllable gas pressure to the housing in order to
obtain a controllable delivery of the drug solution. The
pressurization system includes a pressure source for delivering
positive pressure gas; a pressure accumulation tank connected to
the source and the second chamber; a one-way valve arranged between
the pressure source and the pressure accumulation tank; and a
mechanical pressure regulator arranged between the pressure
accumulation tank and the housing. Hereby, an extremely stable and
well controllable output pressure and output flow is
obtainable.
Inventors: |
NILSSON; Martin; (Hovas,
SE) ; Andreen; Erik; (Torslanda, SE) |
Family ID: |
38846870 |
Appl. No.: |
13/598476 |
Filed: |
August 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12285700 |
Oct 10, 2008 |
8267894 |
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13598476 |
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60960770 |
Oct 12, 2007 |
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Current U.S.
Class: |
604/500 ;
604/141; 604/182 |
Current CPC
Class: |
A61M 5/1486 20130101;
A61M 5/14244 20130101; A61M 5/16877 20130101 |
Class at
Publication: |
604/500 ;
604/182; 604/141 |
International
Class: |
A61M 5/155 20060101
A61M005/155; A61M 5/142 20060101 A61M005/142 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2007 |
EP |
07118365.1 |
Claims
1. A self-contained portable apparatus for administration of a drug
solution, said apparatus comprising: a housing having an enclosure
for receiving a flexible pouch containing a drug solution, wherein
said enclosure has a first chamber within said pouch and a second
chamber arranged outside said pouch, the chambers being arranged in
a pressure-transmitting relation within said enclosure; an output
from said first chamber connectable to a conduit for delivering
said drug solution to a recipient; and a pressurization system for
providing a constant and controllable gas pressure to said second
chamber, wherein a controllable pressure is obtained in said first
chamber for a controllable delivery of the drug solution, wherein
said pressurization system comprises: a pressure source for
delivering positive pressure gas; a pressure accumulation tank
connected to said source and to said second chamber, arranged to
provide a positive pressure reservoir; a one-way valve arranged
between said pressure source and said pressure accumulation tank,
enabling gas to flow solely in the direction from the pressure
source to the pressure accumulation tank; and a mechanical pressure
regulator arranged between said pressure accumulation tank and said
second chamber.
2. The apparatus of claim 1, wherein the pressure source comprises
a hand-operated pump.
3. The apparatus of claim 1, wherein the pump comprises an air
compression cup which is slideably arranged over the pressure
accumulation tank.
4. The apparatus of claim 1, wherein the pressure source comprises
a liquefied gas container.
5. The apparatus of claim 4, wherein the liquefied gas container is
a liquefied CO.sub.2 container.
6. The apparatus of claim 1, wherein the drug solution is an
anesthetic.
7. The apparatus of claim 1, wherein it is arranged to provide an
output flow rate of the drug solution in the range 1-200 ml/h.
8. The apparatus of claim 7, wherein it is arranged to provide an
output flow rate of the drug solution in the range 1-20 ml/h.
9. The apparatus of claim 8, wherein it is arranged to provide an
output flow rate of the drug solution in the range 4-12 ml/h.
10. The apparatus of claim 1, wherein it is arranged to provide an
essentially constant output flow rate for at least 1 hour.
11. The apparatus of claim 10, wherein it is arranged to provide an
essentially constant output flow rate for at least 12 hours.
12. The apparatus of claim 11, wherein it is arranged to provide an
essentially constant output flow rate for at least 24 hours.
13. The apparatus of claim 1, wherein it is arranged to provide an
essentially constant output pressure for the drug solution.
14. The apparatus of claim 13, wherein said essentially constant
output pressure is in the range 0.1-1.0 bar.
15. The apparatus of claim 14, wherein said essentially constant
output pressure is in the range 0.3-0.6 bar
16. The apparatus of claim 1, wherein the pressure accumulation
tank is capable of accumulating a pressure exceeding 1 bar.
17. The apparatus of claim 16, wherein the pressure accumulation
tank is capable of accumulating a pressure exceeding 2 bar.
18. The apparatus of claim 1, wherein the pressure accumulation
tank is provided with a high-pressure relief valve, arranged to
release pressure from the accumulation tank if the pressure exceeds
a certain threshold limit.
19. The apparatus of claim 18, wherein the high-pressure relief
valve is arranged to maintain a pressure below about 3 bar in the
accumulation tank.
20. The apparatus of claim 1, wherein the enclosure in the housing
is provided with a high-pressure relief valve, arranged to release
pressure from enclosure if the pressure exceeds a certain threshold
limit.
21. The apparatus of claim 1, wherein said second chamber is
provided in an expandable bladder, said bladder being arranged
adjacent to said flexible pouch within said enclosure.
22. The apparatus of claim 1, wherein the housing is made of
relatively rigid material.
23. The apparatus of claim 1, wherein the housing is made of
relatively rigid plastic material.
24. The apparatus of claim 1, wherein the apparatus forms a
disposable product for one time use.
25. The apparatus of claim 1, wherein the enclosure of the housing
is arranged to receive a pouch of drug solution which is a standard
disposable pre-filled medicament container.
26. The apparatus of claim 1, wherein a manometer is arranged on
the pressure accumulation tank, for providing an indication of the
current pressure in said tank.
27. The apparatus of claim 1, wherein the housing is further
provided with a manually controllable valve for releasing the
pressure of the second chamber.
28. The apparatus of claim 1, wherein the mechanical pressure
regulator arranged between said pressure accumulation tank and said
second chamber is controllable to provide different pressures to
the second chamber.
29. A method for administration of a drug solution, comprising the
steps: providing a flexible pouch containing a drug solution in a
housing; and providing a pressure in a second chamber arranged
outside said pouch within said housing, said pressure thereby
acting on the flexible pouch for delivering said drug solution to a
recipient; wherein said pressure in the second chamber is provided
by the additional steps: providing a positive pressure from a
pressure source; forwarding at least part of said pressure from the
pressure source to a pressure accumulation tank connected to said
source through in a non-returnable way; and forwarding at least
part of said pressure from the pressure accumulation tank to the
second chamber through a mechanical pressure regulator arranged
between said pressure accumulation tank and said second
chamber.
30. A self-contained portable apparatus for administration of a
drug solution, said apparatus comprising: a housing having an
enclosure for receiving a flexible pouch; an inflatable bladder,
said inflatable bladder being wrapped around the flexible pouch
containing the drug solution in a pressure-transmitting relation
within said enclosure; a pressurization system for providing a
constant and controllable gas pressure to said inflatable bladder,
wherein a controllable pressure is obtained in said pouch for a
controllable delivery of the drug solution, wherein said
pressurization system is integrated on or within the housing, and
comprises: a pressure accumulation tank connected to the inflatable
bladder, arranged to provide a positive pressure reservoir; a
mechanical, hand-operated pump, comprising an air compression cup
which is slideably arranged over the pressure accumulation
tank.
31. A self-contained portable apparatus for administration of a
drug solution, said apparatus comprising: a housing having an
enclosure for receiving a flexible pouch; an inflatable bladder,
said inflatable bladder being wrapped around the flexible pouch
containing the drug solution within said enclosure; a pressure
accumulation tank connected to the inflatable bladder and being
integrated on or within the housing; and a mechanical,
hand-operated pump, comprising an air compression cup which is
slideably arranged over the pressure accumulation tank.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of copending application
Ser. No. 12/285,700 filed on Oct. 10, 2008, which claims the
benefit of U.S. Provisional Application No. 60/960,770 filed on
Oct. 12, 2007 and to Patent Application No. 07118365.1 filed in the
European Patent Community, on Oct. 12, 2007. The entire contents of
all of the above applications are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a self-contained portable
apparatus for administration of a drug solution, and in particular
an apparatus which is usable for administration of liquid
medicaments to a patient, e.g. for use in post-operative pain
relief. The apparatus is arranged to provide a very uniform and
controllable flow rate.
BACKGROUND OF THE INVENTION
[0003] The administration of medical liquids is largely carried out
by gravity-induced hydrostatic pressure infusion of the liquid from
a bottle or other container suspended above the recipient an
acceptable distance. The liquid empties by gravity at a rate of
flow which can be regulated by what is known as a drop-by-drop
device which reduces the rate of flow by restriction or compression
of the flexible tube carrying the liquid which is to be injected.
Although this equipment is used in hospitals, it is however bulky,
difficult to move, clumsy and slow to set up. Further, the flow
rate is not easily controlled since variations in relative
positions of the receiving portion of the patient and the
dispensing bottle may occur with time as the patient or bottle may
be shifted about.
[0004] Moreover, previously available pressure-assisted
administration devices are often quite complicated and expensive,
and also often lack portability. Further, these known apparatuses
are often unable to provide, as well as continuously maintain for a
long time, a desired flow rate.
[0005] Still further, most known administration devices require
that the drug solution is discharged from its original container,
i.e. from the prepackaged, disposable, standard medical containers,
and into a administration reservoir of the administration
apparatus. This is normally a rather tedious and cumbersome task,
and also invokes a risk for contamination, since the solution must
pass through additional handling steps in the preparation and
transfer process, prior to being introduced to a patient.
[0006] In many situations, a patient may also require a very slow
and continuous introduction of medicament liquid into the patient's
system, such as a few milliliters per hour for several hours, or
sometimes even a day or more. It is therefore very important that
these medicament liquid or pharmaceutical solution doses be
administered with a highly accurate introduction rate (flow rate),
which is maintained very stable during the entire process.
[0007] To this end, many of today's administration apparatuses
comprises complex electronic systems. For example, such systems may
include complex valve arrangement by which the fluid is introduced
into the chamber and withdrawn there from, and controlled by a
electronic circuitry which includes pressure sensors and logic
circuitry which controls fluid pumps which move the liquid. While
relatively compact and accurate, these systems are also highly
complex, expensive and requires a great deal of electrical power to
operate. Further, these apparatuses are solely intended for
multi-time use, which necessitates cumbersome and tedious cleaning
and sterilization of the apparatuses before re-use, and also
invokes a risk for contamination of the patient.
[0008] Further, it is known from the prior art to produce portable
and mechanical administration devices. For example, U.S. Pat. No.
3,460,277 discloses a self-contained portable administration
apparatus using CO2 cartridges to obtain a relatively precisely
regulated gas flow to displace a medical arranged in a pressure
collapsible container. To this end, the pump device comprises a
casing comprising a collapsible bladder holding the fluid to be
driven (the medical liquid) and a second inflatable bladder to be
filled with a driving fluid, whereby expansion of the second
bladder causes the medical liquid to be controllably expelled.
However, this device is still relatively complicated and expensive
to produce, and there is also a problem of obtaining a sufficiently
continuously stable and controllable pressure acting of the
pressure collapsible container holding the medical liquid. Similar
problems are also encountered in the apparatus disclosed in U.S.
Pat. No. 5,954,696 and U.S. Pat. No. 4,673,392, which are both
related to similar types of administration apparatuses.
[0009] Consequently, there is still a need for administration
apparatuses which are both capable of providing a sufficiently
stable and controllable flow rate, and at the same time are safe
and inexpensive to produce and use.
SUMMARY OF THE INVENTION
[0010] It is therefore an object of the present invention to
provide a self-contained, portable apparatus for administration of
a drug solution, which at least alleviates the above-discussed
problems of the prior art.
[0011] This object is achieved with an administration apparatus
according to the appended claims.
[0012] According to the invention, there is provided a
self-contained portable apparatus for administration of a drug
solution, said apparatus comprising: [0013] a housing having an
enclosure for receiving a flexible pouch containing a drug
solution, wherein said enclosure has a first chamber within said
pouch and a second chamber arranged outside said pouch, the
chambers being arranged in a pressure-transmitting relation within
said enclosure; [0014] an output from said first chamber
connectable to a conduit for delivering said drug solution to a
recipient; and [0015] a pressurization system for providing a
constant and controllable gas pressure to said second chamber,
wherein a controllable pressure is obtained in said first chamber
for a controllable delivery of the drug solution.
[0016] Further, the pressurization system comprises: [0017] a
pressure source for delivering positive pressure gas; [0018] a
pressure accumulation tank connected to said source and to said
second chamber, arranged to provide a positive pressure reservoir;
[0019] a one-way valve arranged between said pressure source and
said pressure accumulation tank, enabling gas to flow solely in the
direction from the pressure source to the pressure accumulation
tank; and [0020] a mechanical pressure regulator arranged between
said pressure accumulation tank and said second chamber.
[0021] The administration apparatus according to the invention is
relatively simple, and can be produced relatively cost-effectively.
Hereby, it is possible to provide this administration apparatus as
a disposable, for one-time use, and the like, which makes it very
safe and secure from a contamination point of view. Further, the
inventive pressurization system, involving inter alia an
accumulation tank, enables a multitude of various pressure sources
to be used, and at the same time the provision of a very stable and
controllable system, where the pressure acting on the flexible
pouch containing the drug solution in the enclosure of the housing
is extremely stable over time, and essentially constant even when
the flexible pouch is full or nearly empty. Accordingly, the
present invention provides a very stable and constant outgoing
pressure for the drug solution. Further, the pressure in the
pressurization system may always be kept below 3 bar, which reduces
the safety risks of the system, and also reduces the safety
requirements of the system. The only exception to this is,
possibly, the pressure source, where higher pressures may provided.
However, in that case the accumulation tank functions as a buffer
to the rest of the system, thereby ensuring adequate safety of the
overall system.
[0022] The present administration apparatus may be equipped with
any type of flexible pouch for holding the drug solution, such as
prepackaged, disposable, standard medical containers of flexible
materials.
[0023] The invention is particularly useful for administration of
e.g. pain relieving agents such as anesthetics during
post-operation treatment of a patient at a low administration rate
during a prolonged time. For example, the apparatus may be arranged
to provide an output flow rate of the drug solution in the range
1-200 ml/h, and preferably in the range 1-20 ml/h, and most
preferably in the range 4-12 ml/h. Further, the apparatus may be
arranged to provide an essentially constant output pressure and
output flow rate for at least 1 hour, and preferably for at least
12 hours, and most preferably for at least 24 hours.
[0024] The administration apparatus may be used for any type of
drug solution, such as liquid medicaments for post-surgery pain
relief, such as solutions of ropivakain and other local
anesthetics, for instance Narop.RTM. and Naropin.RTM., both
produced by AstraZeneca. However, the administration apparatus may
also be used to deliver intravenous fluids and solutions for a wide
variety of medical therapies including chemotherapy, antiviral and
antibiotic therapy, and also include intravenous introduction of
saline solutions, glucose solutions and various other solutions
comprising pharmaceuticals. In e.g. post-surgery use of anesthesia,
the drug solution may be administered through a catheter after
surgery and after closing of the surgical incision.
[0025] The present invention is an entirely mechanical
construction, which does not need any electronics or the like for
its operation. Further, the apparatus may be made very compact, and
thereby portable and self-contained. Still further, the drug
solution is at all times maintained separated from the
pressurization system, which makes the apparatus very safe, and
significantly reduces the risk for contamination of the drug
solution, and also makes it possible to use less expensive
materials in the pressurization system, since these materials need
not be compatible for the drug solution, etc.
[0026] Due to the extremely accurate pressure provided by the
pressurization system and acting on the flexible pouch holding the
drug solution, no flow regulation or the like are in principle
needed in the conduit transferring the drug solution to the
patient. However, in most cases flow control means may still be
advantageous in the conduit system. For example, it may be
advantageous to provide a branched conduit system, with one branch
providing a continuous drug administration to the patient, and a
second branch with a liquid reservoir providing the possibility of
bolus doses. Typically, the continuous drug administration can e.g.
be 1-20 ml/h, and preferably 2-14 ml/h, and the batch-wise (bolus)
dosages can be e.g. 5-30 ml extra every 1-6 hour. Further, since
the pressurization system provides an essentially constant pressure
on the flexible pouch holding the drug solution, it also becomes
possible to control the output liquid flow from the apparatus with
great accuracy, and by relatively simple means.
[0027] The pressure source is preferably a hand-operated pump.
Hereby, the pump may be used to manually fill the accumulation tank
with an adequate pressure before starting the drug administration,
and may also be used during use, for increasing the pressure in the
accumulation tank. Most preferably, the pump comprises an air
compression cup which is slideably arranged over the pressure
accumulation tank. Hereby, a very compact product is obtainable.
However, other alternative pressure sources may also be used for
filling the accumulation tank, such as a liquefied gas container,
and preferably a liquefied CO.sub.2 container, or a container with
pressurized air.
[0028] The one-way valve ensures that pressurized gas is only
transferred in the direction from the pressure source to the
accumulation tank, and not in the reverse direction. This makes it
possible only to activate the pressure source temporarily or
intermittently, such as only initially, before starting the drug
administration to the patient, or only when the pressure in the
accumulation tank becomes lower than a predetermined threshold
value.
[0029] The mechanical pressure regulator guarantees that a stable
and constant gas pressure is provided from the accumulation tank to
the second chamber, and that the pressure in the enclosure is
automatically adjusted during the emptying of the flexible pouch
holding the drug solution. Such mechanical pressure regulators are
per se previously known.
[0030] The apparatus is preferably arranged to provide an
essentially constant output pressure for the drug solution, said
output pressure preferably being in the range 0.1-1.0 bar, and most
preferably 0.3-0.6 bar.
[0031] The pressure accumulation tank is preferably capable of
accumulating a pressure exceeding 1 bar, and preferably exceeding 2
bar. Further, as a safety measure, the pressure accumulation tank
is preferably provided with a high-pressure relief valve, arranged
to release pressure from the accumulation tank if the pressure
exceeds a certain threshold limit, such as a threshold limit of 3
bar. Similarly, the enclosure in the housing may be provided with a
high-pressure relief valve, arranged to release pressure from
enclosure if the pressure exceeds a certain threshold limit.
[0032] The second chamber is preferably arranged as an expandable
bladder, said bladder being arranged adjacent to said flexible
pouch within said enclosure. However, alternatively, the second
chamber may be provided in the enclosure by means of a flexible
membrane arranged between a compartment holding the first chamber
and a compartment forming the second chamber. Still further, the
second chamber may be the entirety of the enclosure being
exteriorly from the flexible pouch holding the drug solution,
whereby the gas acts directly on the flexible pouch.
[0033] The housing is preferably made of relatively rigid material,
and preferably a rigid plastic material.
[0034] A manometer is preferably arranged on the pressure
accumulation tank, for providing an indication of the current
pressure in said tank. This can be used for monitoring the present
pressure of the tank, and also for monitoring the operation of the
drug administration.
[0035] Further, the housing is preferably further provided with a
manually controllable valve for releasing the pressure of the
second chamber. Hereby, the pressure of the second chamber can at
all times be released to atmosphere pressure, for e.g. for exchange
of the flexible pouch or other maintenance operations.
[0036] Still further, the mechanical pressure regulator is
preferably arranged between said pressure accumulation tank and
said second chamber is controllable to provide different pressures
to the second chamber. Hereby, the pressure in the second chamber
becomes controllable, and can be set for different pressure levels
by means of controlling the pressure regulator. This may e.g. be
used for set-up of the administration apparatus for various types
of use, or for controlling the pressure of the second chamber
during use, for controlling the output flow of the drug
solution.
[0037] According to another aspect of the invention, there is
provided a method for administration of a drug solution, comprising
the steps: [0038] providing a flexible pouch containing a drug
solution in a housing; and [0039] providing a pressure in a second
chamber arranged outside said pouch within said housing, said
pressure thereby acting on the flexible pouch for delivering said
drug solution to a recipient; [0040] wherein said pressure in the
second chamber is provided by the additional steps: [0041]
providing a positive pressure from a pressure source; [0042]
forwarding at least part of said pressure from the pressure source
to a pressure accumulation tank connected to said source through in
a non-returnable way; and [0043] forwarding at least part of said
pressure from the pressure accumulation tank to the second chamber
through a mechanical pressure regulator arranged between said
pressure accumulation tank and said second chamber.
[0044] By means of this aspect of the invention, similar advantages
are obtainable and corresponding preferred embodiments are feasible
as discussed above in relation to the corresponding first aspect of
the invention.
[0045] These and other aspects of the invention will be apparent
from and elicidated with reference to the embodiments described
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] For exemplifying purposes, the invention will be described
in closer detail in the following with reference to embodiments
thereof illustrated in the attached drawings, wherein:
[0047] FIG. 1 is a schematic view of the principal construction of
an administration apparatus according to a first embodiment of the
present invention;
[0048] FIG. 2 shows a second embodiment of an administration
apparatus according to the present invention;
[0049] FIG. 3 is an exploded view of the administration apparatus
of FIG. 2;
[0050] FIG. 4 is a diagram illustrating the deviation in the
average output flow over the entire operation cycle for the present
invention and a number of comparative examples; and
[0051] FIG. 5 is a diagram illustrating the measured pressure in
the second chamber and the accumulation tank, as well as the
resulting flow for the second chamber, of the administration
apparatus of FIGS. 2 and 3 during operation.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0052] The invention will now be discussed in more detail by means
of embodiments. Unless otherwise is specifically mentioned, the
different features are mutually exchangeable between the
embodiments, and further, the same reference numerals are used to
denominate similar or corresponding parts throughout the drawings
and the specification.
[0053] An administration apparatus for administration of a drug
solution according to a basic first embodiment, as illustrated in
FIG. 1, comprises a housing 1 having an enclosure 2 for receiving a
flexible pouch (not shown) containing a drug solution. In this
context "flexible" indicates that the pouch forms a
pressure-collapsible container, whereby the liquid arranged in the
pouch is releasable by compression operating thereon. The enclosure
forms a first chamber within said pouch and a second chamber
arranged outside said pouch, wherein the chambers are arranged in a
pressure-transmitting relation within said enclosure. Hereby, the
pressure provided in the second chamber is transferred to the first
chamber, and consequently the pressure provided in the second
chamber is essentially equal to the pressure obtained in the drug
solution contained in the flexible pouch.
[0054] Thus, the housing forms separate chambers for the driving
gas and the driven drug solution, formed by separate and abutting
collapsible containers, respectively, having a large common
interface. The housing forms a rigid container or frame. Part of
the housing is formed by a lid or removable wall section, to permit
insertion of a new medical container of drug solution, and removal
of an emptied container.
[0055] The housing is preferably made at least partly of a
transparent plastic material in order to permit immediate visual
monitoring of the condition of the inner bag. Further, the housing
may be injection molded, pressure formed, or the like.
[0056] An output from the first chamber is connectable to a conduit
(not shown) for delivering said drug solution to a recipient, and
in particular to a patient. For example, the conduit may comprise
tubing leading from the first chamber, a valve for opening and
closing the conduit and a catheter for introduction of the drug
solution into the patient. For example, it may be advantageous to
provide a branched conduit system, with one branch providing a
continuous drug administration to the patient, and a second branch
with a reservoir of drug solution providing the possibility of
bolus doses. Such conduits are per se known in the art, and will
not be discussed in any detail in this application.
[0057] Further, the administration apparatus comprises a
pressurization system for providing a constant and controllable gas
pressure to said second chamber. The pressurization system
comprises a pressure source 3 for delivering positive pressure gas.
In this embodiment, the pressure source is a hand-actuated pump,
but other pressure sources, such as a liquid gas cartridge, are
also feasible. A pressurized driving fluid supply meeting these
requirements is e.g. a cartridge in which is stored liquefied
CO.sub.2, fluorocarbons or hydrocarbons contained under pressures
required to maintain liquid-gas equilibrium, or gases such as
N.sub.2 or air under high pressure. Another alternative would be to
use an external pressure source, which could then be used for
loading the accumulation tank before use of the apparatus, and
possible even for subsequent reloading during use.
[0058] The pressure source 3 is connected to a pressure
accumulation tank 5, which provides a positive pressure reservoir.
The accumulation tank is preferably arranged to be pressurized up
to a positive pressure during initialization of the administration
apparatus, e.g. up to 1-2 bar, or even up to 3 bar. However, it is
in many cases an advantage to have an accumulation tank having a
pressure below 3 bar connected to the administration system, since
this provides lower safety risks, and therefore requires less
safety requirements. In many applications, the initial loading of
the accumulation tank will be sufficient for the whole
administration process. However, it is also possible to reload the
accumulation tank during operation. Between the pressure source 3
and the accumulation tank 5 a one-way valve 4 is provided, which
allows gas to flow from the pressure source to the accumulation
tank, but prevents gas from flowing in the opposite direction.
[0059] The accumulation tank is connected to the second chamber
within the enclosure 2 via a mechanical pressure regulator 6,
arranged to control the pressure within the second chamber to a
predetermined pressure level, said pressure level being lower than
the pressure of the accumulation tank. The pressure regulator is
arranged to mechanically and automatically control the output
pressure to a predetermined value. Optionally, this predetermined
value may be manually controllable, in order to enable adjustment
of the predetermined value during operation, or for adjustment
between various types of operations. Thus, the pressure regulator 6
reduces the pressure of the driving fluid from a lever p.sub.1 to a
level p.sub.2, and the latter may be varied within limits by
adjustment of a regulator control (not shown). Normally, p.sub.2 is
much less than p.sub.1. The regulator control for adjustment of the
output pressure may e.g. adjust a spring tension in the regulator.
Several pressure regulators, both of spring and diaphragm type, are
per se known in the art, and are commercially available.
[0060] The administration apparatus is preferably arranged as a
self-contained and portable device. Even though this goal may be
achieved by means of the apparatus discussed above in respect of
FIG. 1, the embodiment illustrated in FIGS. 2 and 3 illustrate an
even more compact, portable and self-contained apparatus.
[0061] The housing 1 receives a flexible pouch 10 for holding the
drug solution, such as prepackaged, disposable, standard medical
containers of flexible materials, said pouch forming the first
chamber. In practice, any one of a number of standard drug solution
containers may be used with the administration apparatus of the
present invention, but solution containers in the range 50-500 ml
are preferred, and most preferably in the rage 100-300 ml.
[0062] An inflatable bladder 11 is wrapped around the flexible
pouch 10 and also arranged within the housing 1, thereby forming
the second chamber.
[0063] The housing 1 forms a receptacle with an openable lid 13.
After insertion of the flexible pouch 10, the lid 13 is closed.
Preferably, the lid is arranged with a snap lock, such as flexible
locking arms 15. However, the lid may be attached to the housing
bottom by any of a variety of conventional mechanical fasteners,
such as push-pins, screws, snap-fit posts and detents, and the
like.
[0064] Further, the lid is preferably arranged with an inner wall
14 to be inserted into the housing 1. Hereby, the lid stabilizes
the housing, and thereby aids in the resistance against the
positive pressure building up within the housing during operation.
Still further, the lid is preferably arranged with an output
opening 16, which is connectable to a conduit (not shown) for
delivering said drug solution to a recipient, and in particular to
a patient. The conduit for delivering the drug solution to the
patient may comprise a needle or other device, such as a catheter,
for administering fluids, and tubing connecting the output opening
16 to the needle or catheter end. The conduit may also comprise
filters, such as air elimination filters and particle elimination
filters, bisections for enabling both bolus doses and continuous
administration, flow controlling resistive lumen or orifices etc.
Such conduits are per se known in the art.
[0065] The output opening may be connected to an internal needle or
spike, which penetrates a membrane of the flexible pouch during
insertion of the pouch into the housing and closing of the lid.
Hereby, fluid connection between the flexible pouch and the
administration conduit is obtained automatically during arrangement
of the flexible pouch within the housing. The drug spike may be of
the type which is per se well known in the art. However, other type
of access means are feasible. For example, the output opening may
simply be an opening, through which a connection part of the
flexible pouch is accessible.
[0066] The pressurization system is arranged on the side of the
housing, and formed as integrated parts on or within the housing 1.
In this embodiment, the accumulation tank 5 is arranged at the side
of the housing, and essentially extending over the whole length of
the housing. A gap is formed between the accumulation tank and the
housing in one end of the tank, so that the accumulation tank is
only connected to the housing in one end. Further, the accumulation
tank has a uniform cross-section at least in the part not connected
to the housing, and preferably an essentially circular
cross-section. Further, an opening with a non-return valve 4 is
arranged at the end side of the non-connected end of the tank. A
hand-actuated pump, functioning as a pressure source 3, is arranged
outside the accumulation tank 5, and in particular outside the part
of the tank which is not connected to the housing, and is
displaceable or slideable in the length direction of the tank.
Hereby, the pump forms a cylinder, or a compression cup, with an
internal cross-section which generally corresponds to the external
cross-section of the corresponding part of the accumulation tank,
whereby a relatively tight seal is formed between the pump and the
accumulation tank. However, other alternative pressure sources may
also be used for filling the accumulation tank, such as a liquefied
gas container, and preferably a liquefied CO.sub.2 container or a
container of pressurized air.
[0067] The accumulation tank 5 is connected to the inflatable
bladder 11 within the enclosure 2 via a mechanical pressure
regulator 6, arranged to control the pressure within the inflatable
bladder to a predetermined pressure level, lower than the pressure
of the accumulation tank.
[0068] During operation, the pump 3 is displaced up and down on the
accumulation tank, whereby air is forced through the one-way valve
4 into the accumulation tank 5, whereby a pressure is built up in
the tank. This positive pressure is gradually released to the
inflatable bladder 11 through the exact control of the regulator 6,
whereby a very exact and constant pressure is applied on the liquid
medicine arranged in the flexible pouch 10.
[0069] The volume of the pressure accumulation tank as well as the
initial pressure as provided by the pressure source are preferably
selected in dependence of the total volume of the drug to be
administered, and the desired output pressure in the second chamber
of the housing. Preferably, the volume of the accumulation tank is
relatively small, in order to reduce the overall size of the
apparatus. For example, it is preferred that the accumulation tank
has an internal volume V.sub.acc that is less than the internal
volume V.sub.pouch of the pouch (first chamber) holding the drug
solution, and preferably less than 70% of this volume, and most
preferably less than 50% of this volume. Further, it is preferred
that the pressure source is operable to provide an initial pressure
to the accumulation tank that is sufficient to completely empty the
pouch. Accordingly, the pressure source is preferably operable to
provide a pressure P.sub.acc,initial to the accumulation tank that
fulfills the following condition:
P.sub.acc,initial.gtoreq.P.sub.reg*(V.sub.acc+V.sub.pouch)/V.sub.acc
where P.sub.reg is the regulated pressure of the second chamber,
acting on the first chamber (i.e. the pouch), V.sub.pouch is the
volume of the pouch, i.e. the volume of the drug to be
administered, and V.sub.acc is the volume of the accumulation
tank.
[0070] The administration apparatus is particularly useful for
administration of e.g. pain relieving agents such as anesthetics
during post-operation treatment of a patient at a low
administration rate during a prolonged time. For example, the
apparatus may be arranged to provide an output flow rate of the
drug solution in the range 1-200 ml/h, and preferably in the range
1-20 ml/h, and most preferably in the range 4-12 ml/h. Further, the
apparatus may be arranged to provide an essentially constant output
pressure and output flow rate for at least 1 hour, and preferably
for at least 12 hours, and most preferably for at least 24 hours.
Further, an essentially constant output pressure for the drug
solution can hereby be provided, e.g. in the range 0.1-1.0 bar, and
most preferably 0.3-0.6 bar.
[0071] Further, as a safety measure, the pressure accumulation tank
is preferably provided with a high-pressure relief valve 12,
arranged to release pressure from the accumulation tank if the
pressure exceeds a certain threshold limit. Similarly, the
enclosure in the housing may be provided with a high-pressure
relief valve, arranged to release pressure from enclosure if the
pressure exceeds a certain threshold limit. The high-pressure
relief valve may also be arranged to provide an alarm sound or the
like, such as a whistle tone, when it is activated. Manometers
(e.g. 17 in FIG. 3) and the like may also be provided to indicate
the present pressure in e.g. the accumulation tank or the second
chamber during use. Such a manometer may also be used for
monitoring the flow of drug solution out of the administration
apparatus, and/or as a measure of the amount of drug solution
remaining in the flexible pouch.
Experimental Results
[0072] An administration apparatus as discussed above with
reference to FIG. 2 was used for experimental measurements. The
output of the apparatus was connected to a flow regulator, which
allowed a flow of 4 ml/h at an overpressure of 0.4 bar. The output
of the flow regulator was forwarded through a catheter, and the
drug administered through the catheter was collected and weighed.
Further, manometers were used to measure the pressure in the first
and second chamber of the housing.
[0073] For the experiments, a pouch holding a drug solution was
arranged in the housing, and administered by means of the
administration apparatus. The weight of the administered drug was
continuously measured, together with the pressure in the first and
second chamber, until the nominal volume was delivered from the
pouch.
[0074] The result of this measurement is presented in the diagram
of FIG. 5. In this diagram, the x-axis represents the time,
extending from close to 0 minutes to about 1500 minutes (25 hours),
which is the time when the nominal volume was delivered from the
pouch. On the y-axis, flow and pressure are represented. FIG. 5
illustrates the pressure in the second chamber (dashed line) and
the corresponding pressure in the accumulation tank (full line).
Further, the resulting flow rate (dash dotted line) is illustrated.
Accordingly, it is clearly discernible how the pressure in the
accumulation tank constantly falls from a relatively high pressure
level to a pressure level only slightly above the pressure in the
second chamber, whereas the pressure in the second chamber, as well
as the output flow rate, remain essentially constant and extremely
stable during the entire process.
[0075] Accordingly, the new drug administration apparatus exhibits
a very stable output flow and output pressure, with a very limited
variation over the entire process. As a comparison, a similar
evaluation was made for some commercially available drug
administration apparatuses. The result of this evaluation is
presented in the diagram of FIG. 4, in which the x-axis represents
the relative amount of delivered drug, extending from 0% of the
nominal value to 100% of the nominal volume. The y-axis indicates
the deviation in percent at each time from the average flow. The
evaluated administration devices were: [0076] the administration
apparatus according to the present invention. (Dotted line); [0077]
comparative example I is an elastomeric balloon infusion system
with a nominal flow rate of 5 ml/h and a nominal volume of 240 ml.
(Dashed line); [0078] comparative example II is an elastomeric
balloon infusion system with a nominal flow rate of 5 ml/h and a
nominal volume of 270 ml. (Full line); [0079] comparative example
III is a spring-operated infusion system with a nominal flow rate
of 4 ml/h and a maximum volume of 100 ml. (Dash dotted line); and
[0080] comparative example IV is an elastomeric balloon infusion
system with a nominal flow rate of 5 ml/h and a nominal volume of
275 ml. (Dash dotted line with double dots).
[0081] From the evaluation in FIG. 4, it is clearly noticeable that
the commercially available comparative examples I-IV all have much
higher deviations from the average flow rate during the process,
and typically with a flow rate much above the average in the
initial phase, when the chamber or pouch containing the drug
solution is full, and with a flow rate much below average during
the final phase, when the chamber/pouch is almost empty.
CONCLUSION
[0082] The drug administration apparatus of the present invention
is a self-contained and portable apparatus, which, by reason of its
convenience and simplicity of use, is well suited for a large
variety of drug administration applications. The apparatus
according to the invention does not require any skill in use. It is
easily and quickly positioned. It can easily be moved and carried
by the injured person or by the medical staff, and thereby causes
no hindrance in handling and transporting the patient. The
simplicity of the constituent parts also guarantees a low
manufacturing cost. Consequently, the apparatus can also be made as
a disposable, for use on only one patient. This, in combination
with the separation of the pressurization system and the drug and
the fact that the drug is allowed to remain in its pre-packed
container, provides an extremely clean and secure drug
administration, which minimizes the risk for contamination for the
patient.
[0083] At the same time, the present invention provides, in a
medical liquid administration system, means for providing an
adequately regulated output pressure from the pressurization
system, acting on the drug to be administered, to selectively,
reliably, and accurately displace the drug and cause the drug also
to flow at a substantially constant flow rate. Hereby, the drug can
be allowed to remain in a pre-packed flexible bag during the whole
administration process, and with the pressurization system fluidly
separated from the drug, and is also usable with standard
manufacturers' drug solution containers to provide efficient,
accurate and low cost administration.
[0084] The administration apparatus of the illustrated embodiment
uses a compact, reliable and cost effective pressure source, such
as a mechanical, hand-operated pump. The administration apparatus
is particularly reliable and cost-effective since it includes
neither electronic components to control or monitor operation, nor
batteries as a primary power source. Because of its compact
construction the administration apparatus according to the
invention is able to function even after having been dropped, and
because of its lack of electronics, the pump is able to operate
even if it comes into contact with water or the like from the
outside. Still further, the pumping means can be made very compact,
as a cup like member arranged around the accumulation tank. Still
further, the present administration apparatus allows easy exchange
of the pouch holding the drug.
[0085] Specific embodiments of the invention have now been
described. However, several alternatives are possible, as would be
apparent for someone skilled in the art. For example, the second
chamber, providing the external pressure on the first chamber, i.e.
the pouch, within the housing may be provided in various ways. One
alternative is to arrange the second chamber within a second pouch,
or a flexible bag, as discussed above. More than one pouch forming
the second chamber may lso be provided, such as two flexible bags
arranged on each side of the pouch holding the drug solution.
Another alternative to make the housing air-tight, whereby the
second chamber may be the part of the housing externally from the
pouch holding the drug solution.
[0086] Further, even though an important application of the present
administration apparatus is to administer a drug solution, such as
anesthetics, directly to a patient, other applications are also
feasible, such as administration of a drug solution to another
apparatus or the like. Further, the administration apparatus may be
used for a large variety of different drugs, such as for use in
open wounds, e.g. for post-surgical treatment, for use during
surgery, for intravenous use, for epidural administration, for
cancer treatment, neurosurgery, etc. In general, the present
administration apparatus is useable for all applications where a
pressure is needed for forwarding the drug from the drug container
to the place where it is needed.
[0087] Still further, the apparatus may be arranged to provide a
predetermined output pressure and output flow from the first
chamber. Alternatively, the output pressure may be controllable,
e.g. by the provision of a controllable pressure regulator between
the accumulation tank and the second chamber. Alternatively or
additionally, a flow regulator or controllable flow restrictor,
such as capillaries of various sizes, may be used for controlling
the output flow from the first chamber.
[0088] Such and other obvious modifications must be considered to
be within the scope of the present invention, as it is defined by
the appended claims.
* * * * *