Note: Descriptions are shown in the official language in which they were submitted.
96A-076
This invention relates to infusion apparatus. It
relates especially to such apparatus which can be
implanted and refilled and recharged periodically so that
it can remain in the patient's body for a prolonged
period.
Background Df the Invention
Relatively recently infusion apparatus has been
developed which can be implanted in the body and remain
there for a prolonged period. The apparatus can be
refilled with infusate without having to remove the
apparatus from the body. This refilling is accomplished
by injecting additional infusate through a penetrable
septum in the apparatus which septum is located directly
under the patient's skin. In some cases, the act o~
refilling the apparatus with infusate also recharges the
apparatus's power source so that the device can operate
uninterruptedly to dispense infusate such as insulin,
heparin or a chemotherapeutic agent at a very small rate
over a long time. ~xamples of infusion apparatus of this
2~ general type are disclosed in U.S. Patents 3,951,147 and
4,258,711, both owned by the assignee of the present
application.
Some infusion apparatus of this type such as the one
described in the latter patent have the capability of
dispensing a continuous basal dose of infusate to the
patient as well as larger bolus doses when the occasion
demands it. For example, a patient may receive a
continuous dose of insulin based on the average glucose
level in his blood. Then, right after mealtimes, when
the glucose level usually rises, the pump can be made to
dispense a bolus dose of insulin to compensate for that
increased glucose level due to the ingestion of food. In
order to provide such dual dosage capability for any
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reasonable length of time, the pump must have a large infusate
reservoir to provide both the basal and bolus requirements or two
smaller reservoirs, one o:E which contains the infusate at the basal
concentration and the other of which contains infusate at a higher
bolus concentration. In either event, the inclusion of the bolus
dispensing capability inc.reases the overall size of the pump
envelope.
In some instances, however/ a supplement to the basal
infusate flow is required relatively infrequently. For example,
it may only be introduced to add an angiographic solution to the
infusate so that the area distribution in the body being infused
can be monitored from time to time. It would be desirable in
such cases to provide this capability in a pump having a minimum
overall size or envelope. It is also essential that this added
capability be provided without adversely affecting the basal
infusate contained in the apparatus or its flow to the patient.
Summary of the Invention
Accordingly, the present invention provides implantable
infusion apparatus comprising: A. an infusate reservoir; B. an
entry port into said infusate reservoir; C. a self-sealing
penetrable sep-tum closing said entry port; D. a small fixed-
volume chamber; E. an entry port into said chamber; F. a second
self-sealing penetrable septum closing -the entry port in-to said
chamber, the exposed surfaces of both septa being located near one
another in substantially the same plane or in parallel planes so
that, when the apparatus is implanted in -the body, both said
septa are access:ible extracorporeally by transcutaneous injection
at nearby locatlons on the body surface; G. means defining a
Fluid i.n]et passacJe extending :from said reservoir -to said
chamber; ~1. means for mov:ing the contents of said reservoir to
said chamber; and I. means defining a substan-t.ially unres-trie-ted
fluid outlet passage crom saicl chamber ~or connec-t,ion to a conduit
leading to an intusion si-te so tha-t an injection of inEusate i.nto
said chamber flows substan-t:ially immecliately -to the infusion site.
The invention also provides infusion apparatus cornprising
A. a housing; B. a container moun-ted inside the housing, said
container defining along with the housing (1) a first chamber
inside the container, and (2) a second chamber outside the eon-
tainer, but inside the housing; C. an entry port into one of said
ehambers; D. a self-sealing penetrable septum elosing said en-try
por-t; E. a third small fixed-volume chamber; F. an en-try por-t
into the third chamber; G. a seeond self-sealing penetrable septum
closing the entry port into the third ehamber; H. means defining
a fluid inlet passage extending from said one ehamber to the third
chamber; I. means in -the other of said first and second ehambers
for moving the eontents of said one chamber -to said third ehamber;
and J. means defining a substan-tially unrestricted fluid outlet
passage from the third chamber for conneetion to a eannula leading
to an infusion site so tha-t an injeetion of infusate into the third
chamber flows substantially immediately to the infusion si-te.
In general, -the present pump ean be situated ou-tsi.de or
inside the body. Basieally, it eomprises an infusate reservoir, a
pump for eonduc-ting infusa-te from that reservoir to a catheter
positioned at an infusion site in the patient and a septum-sealed
por-t in fluid communication with -the flow path from the reservoir
downstream frorn-the pump whieh allows the fluid output from the
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pump to be supplementecl by ~luid injected into the por-t -thxough
its septum. 'i'he invention has par-ticular applicat:ion to implant-
able infusion apparatus. Accordingly, it will be clescribed in tha-t
con-tex-t. :Lt should be unders-tood, however, that it can also be
applied -to external infusion devices.
The pump includes a housing containing an inEusate
reservoir, preferably in -the form of a metal bellows capsule. An
entrance port into the interior of the bellows is closed by a
pene-trable septum mounted in the housing wa]l so that, when the
apparatus is implanted, the septum is located directly under the
patient's skin. An outlet port leading from the in-terior of the
bellows capsule communicates with an outle-t conduit which extends
exteriorly of the housing. The bellows capsule is filled with
infusate by percutaneous injection through the penetrable septum.
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96A-076
Means are provided inside the housing and outside
the bellows for compressing the bellows, thereby to expel
the infusate therein through the outlet conduit. One
preferred means for exerting compressive force on the
bellows capsule is a fluid pressure power cell such as
disclosed in the aforesaid patents. Of course, various
other battery-operated or mechanical devices may be
employed to progressively compress the bellows. Flow of
infusate from the capsule is maintained constant by a
l~ flow restriction in the outlet conduit.
Instead of leading directly to a catheter at the
infusion site as described in those prior patentsl the
restricted outlet conduit from the bellows reservoir
connects to the catheter by way of a small chamber
located inside or outside the housing. The chamber is
formed with an entry port containing a septum which is
also located directly under the patient's skin when the
apparatus is properly implanted. Various types oE
liquids can be introduced into this chamber by
percutaneous injection through its septum. Those fluids
will mix with the infusate being dispensed from the
bellows reservoir and be conducted by the catheter to the
same infusion site in the patient's body. These additive
liquids may comprise radio-opaque material, higher
concentrations of infusate or various other types of
liquids depending upon the particular patient's medical
problem. Since the chamber is located downstream from
the flow restriction leading from the infusate reservoir,
in practice almost all liquid injected into that chamber
3~ flows through the catheter to the infusion site.
Thus, the present pump has the capability of
dispensing infusate for a prolonged period, with that
infusate being supplemented when needed by slugs of other
liquids which might be desirable for proper patient
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. ~
96A-076
s
treatment. Yet this capability is achieved by a single
device which is contained in a small envelope so that its
implantation in the patient does not cause undue patient
discomfort.
~rief 4es~criptiP-n~-p-f~the D~awing
For a fuller understanding of the nature and objects
of the invention, reference should be had to the
following detailed description, taken in connection with
the accompanying drawing, in which:
FIG. 1 is a diagrammatic view illustrating the
infusion apparatus implanted in the body; and
FIG. 2 is a sectional view on a much larger scale
illustrating the elements of the FIG. 1 apparatus in
greater detail.
Des~riptiPn~-p~the~pFeferFed ~mbPdiment
Referring to FIG. 1 of the drawing, the present
apparatus indicated generally at 10 is shown implanted
into a subcutaneous pocket in the abdominal wall of a
patient P. The apparatus includes a generally
cylindrical housing 12 which contains a supply of
infusate. That infusate is dispensed from the apparatus
through an unrestricted delivery cannula 14 leading from
the housing 12 to an infusion site. In this case the
cannula is shown implanted into the hepatic artery H via
the gastroduodenal artery G.
When the supply of infusate in the housing 12 is
exhausted, the apparatus can be refilled by subcutaneous
injection through a self-sealing septum 16 in housing 12.
When the apparatus is properly implanted, that septum is
located directly under the patient's skin and is thus
accessible to a syringe needle. In some pumps of this
general type, that refilling operation also recharges the
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96A~076
power source which expels the infusate from the
housing 12 to the patient.
For some patients, the physician may wish to deliver
a bolus dose of infusate to the patient or momentarily
infuse another substance into the patient such as a
radio-opaque material for an angiogram, tracer dye
microspheres which are opaque to X-rays or gamma rays.
In the present apparatus, this is accomplished by
subcutaneous injection through a second septum 18 located
in an extension 12a of housing 12. Septum 18 is spaced
from septum 16 on the same side of housing 12.
Accordingly, it is also located directly under the skin
and is equally accessible to penetration by a syringe
needle.
The substance injected through septum 18 does not
mix with the infusate in housing 12. Rather, i~ is
delivered directly to cannula 14 so it flows immediately
to the infusion site through the cannula. Accordingly,
the patient receives the benefit of that substance
immediately after its injection. The inclusion of the
additional septum 18 gives the apparatus 10 the ability
to deliver a slug of infusate or other liquid when needed
without materially increasing the overall size of the
apparatus. Accordingly, it makes the apparatus quite
useful for those cases where it is desirable to deliver a
second substance to a patient on an occasional basis.
Turning now to FIG. 2, the housing 12 is a generally
cylindrical container which is about the size of a small
hockey puck. The container is made of a suitable
material such as titanium which is compatible with the
human system. Positioned in the container is a bellows
capsule 24 having an open end mounted to a header 12b at
the top of the container 12, the opposite end of the
bellows capsule being closed. Thus the bellows defines a
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96A-076
first chamber 26 inside the bellows and a second
chamber 28 outside the bellows, but inside the
housing 12.
Formed in header 12~ is an entry port 32 which
extends from chamber 26 through header 12b. The outer
end of port 32 is closed by the septum 16. A porous
needle stop 33 is positioned at the inner end of port 32.
Also formed in the header is an exit port 34 containing a
filter 36. That port communicates with an outlet tube 38
containing a fluid restricter 38a and whose opposite end
communicates with an inlet tube 40 leading to a small
chamber 42 in the housing extension 12a. An exit tube 43
leads from the chamber 42 to cannula 14. Also, an entry
port 44 is formed in the top of chamber 42 which port is
closed by septum 18. Additionally, a needle stop 46 is
positioned at the bottom of chamber 42.
Normally, chamber 26 is filled with infusate by
injection of the infusate through septum 16. Chamber 28,
on the other hand, is filled with a two-phase fluid which
vaporizes at physiological temperatures so that it exerts
a pressure on the bellows capsule 24 tending to collapse
it, thereby expelling the infusate through the exit
port 34 and the restrictive outlet tube 38 to chamber 42.
From that chamber the infusate flows through the
cannula 14 to the infusion site, to wit, artery H
(FIG. 1).
When the supply of infusate in chamber 26 is
exhausted, it can be refilled by injecting additional
infusate through septum 16 using a hypodermic syringe.
The extension of the bellows capsule 24 during this
refilling operation exerts a pressure on the two-phase
fluid in chamber 28 which condenses that fluid thereby
recharging the fluid power cell. The operation of such a
fluid power cell is fully described in the aforesaid two
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96A-076
patents as well as in patent 3,731,681. Thus the
infusate in chamber 26 can be dispensed to the patient at
a very low flow rate to meet his long term requirements,
the apparatus being refilled periodically, e.g. every
thirty days, as needed.
In those situations where it would be desirable to
infuse a larger concentration of the same infusate or a
different liquid altogether into the patientls artery H,
this is accomplished by injecting that additional liquid
through septum 18 directly into chamber 42 using a
standard hypodermic syringe shown in dotted lines at N in
FIG. 2. That liguid then flows without restriction
through outlet tube 43 and cannula 14 directly to the
infusion site. Since chamber 42 is located downstream
from restriction 38a, that additional substance is forced
to flow directly through the cannula. Very little
upstream flow through the restricted tube 38 into
infusate chamber 26 will occur. Accordingly,
substantially the entire volume (i.e. 99.99%) of the
substance injected into chamber 42 flows immediately to
the infusion site as a slug, rather than being dispensed
to the pa-tient over a longer term along with the infusate
from chamber 26.
In those apparatus 10 having a very low
restriction 38a in the outlet tube 38, such backflow from
chamber 42 into chamber 26 may be prevented by a check
valve in the outlet tube upstream from chamber 42. Such
a valve is indicated in dotted lines at 48 in FIG~ 2.
It can be seen therefore that the incorporation of
chamber ~2 with its septum 18 into the apparatus
downstream from the restrictive outlet tube from the
infusate reservoir 26 provides a convenient means for
injecting additional liquids directly into the patient's
arterial system whenever that is required. The
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incorporation o r that adcli-tional chamber in-to the appara-tus does
no-t materially increase the vo:lume of housing 12 or the overall
cos-t or complexity of the apparatus. Ye-t it makes the appara-tus
much more versatile.
I-t will thus he seen tha-t the objec-ts set forth above,
among those made apparent from the preceding description, are
efficiently at-tained. Also, cer-tain changes may be made in the
above construction withou-t departing from the scope of the inven-
tion. For example, a mechanical pump such as a peristaltic pump
may be employed in lieu of -the vapor pressure pump to conduct
infusate from chamber 26 -to ca-theter 16. Therefore, it is intended
-that all matter contained in the above descrip-tion or shown in the
accompanying drawing be interpreted as illustrative and not in a
limiting sense.
It is also to be ~nderstood that -the following claims
are intended to cover all of the generic and specific features of
the invention herein described.
