Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~3~
PERITONEAL INJECTION CATHETER APPARATUS AND METHODS
BACKGROUND
1. The ~ield of the Invention
_ _ . _ _
This invention relates to peritoneal access devices
and, more particularly, to novel apparatus and methods
for injecting a drug into the peritoneal cavity in a
direction toward the mesenteric peritoneal membrane.
2. The Prior Art
A large proportion of the various chemical
reactions that occur in the body are concerned with
making energy in foods available to the various
physiological systems in the cells. Metabolism of
glucose is particularly important in many of these
chemical reactions, and the body has a very
sophisticated regulatory system adapted to maintain
blood glucose levels at an optimum level so that
adequate amounts of glucose will be available as
needed.
One of the most important elements in the glucose
regulatory system is the hormone "insulin." Insulin is
a relatively small protein, having a molecular weight
of only 5743 daltons; it is comprised of two amino acid
chains connected by a pair of disulfide linkages.
Insulin has the ability to regulate glucose
metabolism in two ways. First, insulin has the ability
~3~ 9
to increase the rate of glucose transport through the
cell membrane of many types of cells in the body. In
the absence of insulin, the rate of glucose transport
into these cells is reduced to less than one-fourth of
the normal rate. On the other hand, excessive levels
of insulin can increase the rate of glucose transport
to nearly five times normal. Adjustments in the level
of insulin in the body can thus be seen to have the
capability of adjusting the rate of glucose absorption
by twenty fold.
In addition to its role in glucose transport,
insulin also acts as a regulatory hormone. Normally,
when digestion results in rising levels of glucose in
the body, certain cells in the pancreas, known as "beta
cells" of the "islets of Langerhans," commence
secreting insulin into the portal vein. About half of
the secreted insulin is immediately absorbed by the
liver, with the remaining portion being distributed
through most of the rest of the body.
In response to the rising level of insulin, the
liver produces large quantities of an enzyme known as
glucokinase, which causes conversion of glucose in
glycogen which is then stored. Importantly, a large
portion of the excess glucose entering the blood system
as a product of digestion is rapidly removed by the
liver in order to maintain relatively normal
concentrations of glucose in the bloodstream. --
Later, when the blood glucose level commences to
drop below normai, the pancreas reduces its secretion
of insulin, and the "alpha ceLls" of the islets of
Langerhans commence to secrete a hormone known as
"glucagon." Glucagon stimulates the conversion of
glycogen in the liver into glucose by activating
another enzyme known as liver phosphorylase. Th-is, in
turn, results in release of glucose into the
bloodstream for transport throughout the bod~.
From the foregoing, it will be appreciated that
the pancreas and the liver play a major role in
regulating the level of glucose in the bloodstream.
Unfortunately, the delicate balance between the actions
of the pancreas and the liver can be easily upset. For
example, it is not uncommon for the pancreas to suffer
damage so that it no longer secretes adequate levels of
insulin. This condition is known as "diabetes
mellitus," or more commonly, simply "diabetes."
Serious cases of diabetes often exhibit a total
cessation of insulin secretion.
As would be expected, insufficient secretion of
insulin substantially reduces the transport of glucose
into most tissues of the body. (The most notable
exception is the brain; glucose transport across the
blood-brain barrier is dependent upon diffusion rather
than insulin-mediated transport.) Further, the glucose
regulatory function is also impaired since, in the
absence of insulin, little glucose is stored in the
liver during times of excess and, hence, is not
available for subsequent release in times of glucose
need.
3L~3~
One result of the lack of sufficient quantities of
insulin in the body is a rise in the blood glucose
concentration. This causes the osmotic pressure in
extracellular fluids to rise above normal, which in
turn often results in - significant cellular
dehydration. This problem is exacerbated by the action
of the kidneys which act to remove excessive quantities
of glucose from the blood; the increase in glucose
concentration in the kidneys causes yet additional
fluids to be removed from the body. Thus, one of the
significant effects of diabetes is the tendency for
dehydration to develop.
However, an even more serious effect occurs
because of the failure of body tissues to receive
adequate levels of glucose. In the absence of adequate
levels of glucose, the metabolism of body cells
switches from carbohydrate metabolism to fat
metabolism. When the body is required to depend
heavily upon fat metabolism ~or its energy, the
concentration of acetoacetic acid and other keto acids
rises to as much as thirty times normal, thus causing a
reduction in the pH of the blood below its normal pH
level of 7.4.
Again, this problem is exacerbated by the
kidneys. Substantial quantities of the keto acids
combine with the basic ion sodium. Then, as the
kidneys remove the various keto acids from the blood,
substantial amounts of sodium are also lost, thereby
resulting in even further decreases in blood pH. If
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the blood pH is ~reduced to below about 7.0, the
diabetic person will enter a state of coma; and this
condition is usually fatal.
The generally accepted treatment for diabetes is
to administer enough insulin so as to restore
carbohydrate metabolism. Tradit`ionally, administration
of insulin has been made by injections into the
peripheral circulation, either from an intramuscular or
subcutaneous injection. Although widely used, this
form of treatment has several disadvantages.
First, using peripheral insulin administration,
only about ten percent of the administered insulin
reaches the liver, as compared to approximately Eifty
percent in normal persons. As a consequence, hepatic
glucose production is not first reduced; rather, blood
glucose is lowered by increased utilization by other
tissues (such as muscle and fat), due to the presence
of high levels of insulin in the peripheral
circulation. Hence, normal levels of blood sugar are
achieved only by carefully matching any increased
peripheral utilization of blood sugar to an increased
hepatic production. This is inherently much more
difficult than simply decreasing hepatic glucose
production.
Additionally, these traditional administration
methods fail to provide the type of control over the
blood glucose concentration that occurs in a normal
person. Clearly, once- or twice-daily injections of
insulin cannot supply controlled variable amounts of
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insulin in response to changing metabolic demands
during the course of the day. ~ence, when using
traditional insulin administration methods, the blood
glucose content tends to fluctuate between abnormally
high and low concentrations. Significantly, there are
some indications that such periodic rise and fall of
glucose concentrations between hyperslycemia and
hypoglycemia contributes to devastating vascular and
neurological complications over a period of time. (It
is not uncommon, for example, for a long-term diabetic
to experience atherosclerosis, arteriosclerosis,
hypertension, severe coronary heart disease,
retinopathy, cataracts, chronic renal disease, or loss
of the extremities.)
Another consequence of massive injections of
insulin on a periodic basis is that excessive amounts
of insulin occasionally enter the bloodstream, thereby
causing glucose to be rapidly transported into the
cells and decreasing the blood glucose to substantially
below normal levels. ~nfortunately, diabetic patients
already have little glucose reserve, since the liver,
in its state of underinsulinization, is already
releasing glucose. Consequently, the blood sugar level
will plummet despite adeyuate levels of
counterregulatory hormones (such as glucagon,
epinephrine, norepinephrine, and growth hormones),
which normally would increase iver production of
glucose in emergency situations.
~;~3~132~
Importantly, if the blood glucose level is reduced
too much, there will be insufficient glucose to diffuse
across the blood-brain barrier, and the brain and
central nervous system will begin to suffer from
depressed metabolism. This hypoglycemic reaction
(having a progression of symptoms from nervousness,
sweating, stupor, and unconsciousness to occasionally
irreparable brain damage), will occur until sugary
substances are taken either by mouth or intravenously.
The resulting ongoing cycle between hyperglycemia
and hypoglycemia has created a basic rift in the
philosophy of diabetic control. The "tight control"
philosophy claims that the long-term devastations of
diabetes (that is, blindness, heart attacks, kidney
failure, and loss of extremities), are due to
abnormally elevated sugar levels. Those ascribing to
this "tight control" philosophy strive to keep blood
sugar within the normal range even at the risk of
frequent (more than once a week) hypoglycemic
reactions. The converse "loose control" philosophy is
based upon the presumption that the basic premise of
the "tight control" philosophy has yet to be proved and
that the considerable risks of hypoglycemic reactions
are not worth an unproved benefit.
In an effort to avoid the undesirable effects of
the traditional insulin administration methods, various
closed and open loop control delivery systems have been
developed. Closed loop delivery systems are synonymous
with prolonged hospitalization. Additionally, they are
~ ~ 3~ 2~
awkward to wear, they require tubing sets and implanted
needles and, in spite of claims made to the contrary,
they can malEunction ("surge"), usually at the most
inconvenient hours.
Open loop delivery systems, on the other hand,
actually produce a more sustained, if somewhat better
regulated, hyperinsulinemic state. ~owever, the
therapists involved still persist in using both open
and closed loop systems to deliver insulin
peripherally, thereby giving rise to many of the
difficulties already mentioned.
Consequently, due to the problems and difficulties
set forth above, those skilled in the art of treating
diabetes have sought to find improved methods for
administering therapeutic insulin to diabetic
individuals. Perhaps one of the most promising insulin
administration methods which is currently being
investigated comprises the administration of insulin
via the peritoneum.
The peritoneum is the largest serous membrane in
the body and consists (in the male) of a closed sac, a
part of which is applied against the abdominal
parietes, while the remainder is reflected over the
contained viscera. (In the female, the peritoneum is
not a closed sac, since the free ends of the uterine
tubes open directly into the peritoneal cavity.)
The part of the peritoneum which lines the
abdominal wall is named and the parietal peritoneum and
that which is reflected over the contained viscera
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constitutes the mesenteric (visceral) peritoneum. The
space between the parietal and mesenteric layers of the
peritoneum is called the peritoneal cavity. However,
under normal conditions, this "cavity" is merely a
potential one, since the parietal and mesenteri¢ layers
are typically in contact.
Of particular significance, a portion of the blood
circulation of the peritoneum leads directly into the
portal venous system. Hence, any insulin absorbed by
the peritoneum would potentially have nearly direct
access to the liver. As a result, such insulin would
first be available to reduce hepatic glucose
production, and the insulin could, therefore,
potentially function more effectively in its glucose
regulatory capacity.
For a number of years, it has been well-known that
the peritoneal membrane will function fairly
effectively as an exchange membrane for various
substances. Thus, as early as 1923, peritoneal
dialysis was first applied clinically. At the present
time, peritoneal dialysis is being used with increasing
frequency to treat individuals suffering from end-stage
renal disease.
In a typical peritoneal dialysis treatment,
approximately two liters of dialysate is infused into
the peritoneal cavity. Then, after the dialysate has
remained within the peritoneal cavity for a period of
time, thereby permitting the necessary diffusion across
the peritoneal membrane, the dialysate is removed.
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This procedure is typically repeated a number of times
during each dialysis treatment. Thus, in simple terms,
the peritoneal cavity, together with the dialysate,
functions as an artificial kidney.
The performance of peritoneal dialysis necessarily
requires some type of peritoneaI access device. The
first peritoneal access device was a piece of rubber
tubing temporarily sutured in place. By 1960,
peritoneal dialysis was becoming an established form of
artificial kidney therapy; and, in order to lessen the
discomfort of repeated, temporary punctures into the
peritoneal cavity, various access devices permitting
the painless insertion of acute or temporary peritoneal
catheters were developed.
The most common peritoneal access device is of the
Tenckhoff type in which a capped, percutaneous,
silastic tube passes through the abdominal wall into
the peritoneal cavity. Another peritoneal access
device ~the "Gottloib" prosthesis) consists of a short,
"golf tee" shaped device which is adapted to be placed
under the skin with a hollow tubular portion extending
just into the peritoneal cavity. This device is
designed specifically to allow the insertion of an
acute peritoneal catheter (or trocar) through the skin
and down through this access tubing directly into the
peritoneal cavity.
Another device consists of a catheter buried
underneath the skin and extending into the peritoneal
cavity via a long tubing. Peritoneal dialysis is
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performed by inserting a large needle in the
subcutaneous portion of the catheter.
When using such access devices, a variety of drugs
or other fluids have sometimes been added to the large
volumes of peritoneal dialysis solutions and instilled
into the peritoneal cavity for various therapeutic
reasons. Some examples of these drugs are antibiotics,
amino acids, and insulin. However, such therapeutic
maneuvers are merely fortuitous, in that the clinician
is simply taking advantage of a particular situation,
that is, a peritoneal access device implanted in a
particular group of patients. Importantly, there are
cogent reasons for not using existing, permanent
peritoneal access devices for simple drug injections in
a wide variety of patients not suffering from end-stage
renal disease.
First, the majority of prior art peritoneal access
devices are long, clumsy, percutaneous, infection-prone
silastic tubes. EIence, it is undesirable that any
patient would wear such a device on a permanent or
semi-permanent basis, unless it is absolutely
necessary.
In addition, most of the prior art peritoneal
access devices have a relatively large internal volume,
that is, relatively large volumes of fluid are required
in order to fill the devices. As mentioned above,
during a typical dialysis treatment, approximately two
liters of dialyzing fluid is injected into the
peritoneal cavity at one time. Thus, when existing
~34~2~3
devices are used for purposes o~ peritoneal dialysis,
the relatively large internal volume of the device is
of little consequence. However, when injecting small
quantities of fluid or drugs into the peritoneal
cavity, this volume is a very real hindrance since the
injected fluid may simply remain within the device
itself instead of entering the peritoneal cavity.
Further, it has been found that bacteria will
sometimes accumulate and grow within the prior art
access devices. Also the prior art peritoneal access
devices often become obstructed by body cells and/or
bacteria after they are implanted in a patient. In
many cases, such obstruction cannot be eliminated
without damaging the device, and the access device
must, therefore, be removed.
Accordingly, it would be an improvement in the art
to provide a novel subcutaneous peritoneal injection
catheter which may be readily implanted underneath the
skin and provide direct access into the peritoneal
cavity. It would also be an improvement in the art to
provide a subcutaneous peritoneal injection catheter
having a relatively small internal volume while
providiny a relatively enlarged target area. In
addition, it would be an improvement in the art to
provide a peritoneal catheter apparatus which can be
used to inject small volumes of fluid into the
peritoneal cavity and which would minimize the-
opportunity for catheter obstruction. It would also be
an improvement in the art to provide a peritoneal
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injection catheter apparatus and method which minimizes
the accumulation or growth of body cells on the
catheter. In addition, it would be an improvement in
the art to provide an apparatus and method for
minimizing the occurrence of bacterial growth-on or in
a peritoneal injection catheter. Further, it would be
an improvement in the art to provide an apparatus and
method for minimizing the occurrence of peritoneal
injection catheter obstruction which would preserve the
structural integrity of the catheter. Such devices and
methods are disclosed and claimed herein.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The present invention relates to a novel
subcutaneous peritoneal injection catheter apparatus
and methods which minimize catheter obstruction during
use.
The apparatus includes a receiving chamber or
reservoir having a relatively small internal volume
while employing a penetrable membrane and relatively
enlarged target surface area. The reservoir is
interconnected with the peritoneal cavity by a hollow
stem. The penetrable rnembrane accommodates a hollow
needle being inserted into the receiving reservoir and
is configurated with a dome-like profile so that the
membrane may also be depressed to expel insulin from
the receiving reservoir into the peritoneal cavity in a
di ection generally toward the mesenteric peritoneal
membrane.
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The distal end of the hollow stem (which is
situated inside the peritoneal cavity), is constructed
so as to minimize the likelihood of catheter
obstruction during use by a patient. For example, in
one presently preferred embodiment of the i~vention,
the distal end of the stem is-provided with two,
parallel, diametrally enlarged flanges. The two
flanges are unequal in size, and they are positioned on
the stem such that the larger flange resides against
the peritoneal membrane and the smaller flange is
located i~nediately adjacent the distal opening of the
stem. In addition, an antibacterial aqent may be
placed within the device, and the device may also be
formed of or coated with a substance which inhibits
body cell and bacterial growth.
It is, therefore, a primary object of this
invention to provide improvements in implantable
injection catheters.
Another object of this invention is to provide an
improved method for injecting fluids into the
peritoneal cavity.
Another object of this invention is to provide a
novel subcutaneous peritoneal injection catheter having
a relatively small fluid capacity while presenting a
relatively large target surface area.
Another object of this invention is to provide a
novel peritoneal catheter having a receiving reservoir
and a dome-like cover for the receiving reservoir, the
dome-like cover serving as an expulsion membrane for
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lZ3~2~
forcing Eluids from the receiving reservoir into the
peritoneal cavity.
Another object of this invention is to provide an
implantable injection catheter having securement means
for securing the catheter subcutaneously.
A further object of this invention is to provide
an improved implantable peritoneal injection catheter
which minimizes the possibility of catheter obstruction
due to body cell adhesion, accumulation, and/or
ingrowth.
It is also an object of the present invention to
provide an improved, subcutaneously implantable
peritoneal injection catheter which minimizes the
likelihood of bacterial growth within the subcutaneous
reservoir of the catheter.
It is a further object of this invention to
provide a method for minimizing or eliminating
peritoneal injection catheter obstruction which will
maintain the structural integrity of the peritoneal
catheter.
Further, it is an object of this invention to
provide an improved implantable subcutaneous peritoneal
injection catheter which may be used by a single
patient over a relatively long period of time without
interruption or malfunction.
These and other objects and features of the
present invention will become more fully apparent from
the following description and appended claims, taken in
conjunction with the accompanying drawings.
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BRIEF DESCRI~TION OF THE DRAWINGS
_
Figure 1 is a schematic illustration of a
subcutaneous peritoneal injection catheter shown
implanted in the abdominal wall of a torso;
Figure 2 is a vertical cross-sectional view of one
presently preferred embodiment of the present
invention;
Figure 3 is a vertical cross-sectional view of a
second preferred embodiment of the present invention;
Figure 4 is a bottom perspective view of the
embodiment depicted in Figure 3;
Figure 5 is a vertical cross-sectional view of a
third preferred embodiment of the present invention;
Figure 6 is a vertical cross-sectional view of a
fourth preferred embodiment of the present invention;
Figure 7 is a horizontal, cross-sectional view
taken along lines 7-7 of Figure 6;
Figure 8 is a bottom perspective view of the
embodiment depicted in Figure 6; and
Figure 9 is a cross-sectional, schematic
illustration of the embodiment of Figure 6 implanted in
an abdominal wall and which i5 shown in cooperation
with a trocar which is being used to break out a
frangible portion of the base of the catheter.
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1~341PZ9
DETAILED DESCRIPTI~N OF T~E PREFER~ED EMBODIr~ENTS
. .
General Discussion
As an alternative to both intravenous and
intramuscular insulin delivery, portal venous
administration of insulin has given highly encouraging
results in experimental animals: less insulin is
required to achieve normoglycemia and hyperinsulinemia
is avoided. Long-term access directly into the portal
system, however, carries several severe risks, all of
which are lethal.
Nevertheless, there is a secondary and much safer
route leading directly into the portal venous system --
the mesenteric (visceral) peritoneal membrane.
Although access to the intraperitoneal site is more
difficult, it has the potential advantages of avoiding
peripheral hyperinsulinemia, insulinizing the liver via
direct portal venous system insulin absorption, and
more rapid absorption than subcutaneously delivered
insulin.
As alluded to above, when administering insulin
via the peritoneum, it is most desirable that the
insulin be substantially absorbed by the mesenteric,
rather than the parietal, peritoneal membrane. If the
insulin is absorbed by the parietal peritoneal
membrane, the insulin enters the body's general
systemic venous system. The effect is thus the same as
if the insulin had been injected intramuscularly; that
is, the insulin is gradually absorbed into the
peripheral circulatory system and only a portion of the
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1;~3~2~
insulin reaches the liver. As a result, control of
glycemia is not significantly better than that achieved
by conventional intramuscular injections. If the
injected insulin is absorbed by the mesenteric
peritoneal membrane, on the other hand, the insulin is
absorbed into the portal venous system and made readily
available to the liver.
Preliminary results of experiments using
intraperitoneal delivery of insulin appear favorable.
Insulin delivery into the peritoneum is reported to
have resulted in a rapid rise in circulating peripheral
insulin concentration, which peaked at 30-45 minutes
following the initiation of insulin delivery.
Furthermore, when the infusion rate of intraperitoneal
insulin was reduced to the background rate, a gradual
decline in peripheral insulin concentration to normal
fasting values resulted. (This free insulin response
is a marked contrast to the continuing high levels
following intramuscular insulin injection.)
It was, therefore, concluded that normalization of
plasma insulin profiles was achievable with intraperi-
toneal infusion of insulin and, further, that meal-
related hyperglycemia (elevated blood glucose) is well-
controlled with intraperitoneal insu]in, yet hypoglyce-
mic episodes are reduced compared to subcutaneous
delivery. See, D. S. Schade, R. P. Eaton, N. M.
Friedman, & W. J. Spencer, "Normalization of Plasma~~
Insulin Profiles With Intraperitoneal Insulin Infusion
in Diabetic Man," 19 DIABETOLOGI~ 35-39 (1980).
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1~3~29
Intraperitoneal delivery of insulin has been
performed in ketosis-prone diabetic human subjects on a
short-term basis (i.e., a matter of hours). Such
intraperitoneal delivery achieves comparable glycemic
control to that achieved with intramuscular insulin,
with only approximately half the- integrated blood
levels of plasma insulin. Intraperitoneal insulin has
also been utilized long term in patients with ketosis-
prone diabetes and end-stage renal disease who were
being treated by continuous ambulatory peritoneal
dialysis. Adequate control was achieved in the three
patients reported.
There appears to be no conclusive documentation
substantiating the thesis that the intraperitoneal
delivery of drugs is primarily absorbed into the protal
venous system (mesenteric peritoneum) rather than the
general systemic venous system (parietal peritoneum).
However, there is a considerable amount of indirect
evidence for this hypothesis: (1) in laparatomy one's
field of vision is virtually totally obscured by the
mesenteric peritoneum; (2) the work of other
researchers indicates that control of glycemia by
intraperitoneal insulin administration is good, even
though there was a 50% "loss" of insulin -- presumably
picked up by the liver before reaching the peripheral
circulation; and (3) intraperitoneal administration of
sodium nitroprusside (for the purpose of causing
intraperitoneal vasodilation) results in no detectable
levels of peripheral plasma thiocyanate. (It is
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assumed that metabolism of nitroprusside by the liver
accounted for the lack of peripheral thiocyanate.)
The Preferred Embodiments
This invention is best understood by reference to
the drawings wherein like parts are designated with
like numerals throughout.
Referring now more particularly to Figure 1,
peritoneal catheter 10 is shown implanted in the
abdominal wall 90 of a torso 92 and provides fluid
communication from peritoneal catheter 10 with the
peritoneal membrane 94 surrounding peritoneal cavity
96. It should be noted that peritoneal cavity 96 is
shown somewhat distended as though infused with
dialysate, in order to more clearly set forth the
environment of peritoneal catheter 10.
Referring now more particularly to Figure 2, one
presently preferred embodiment of the peritoneal
catheter apparatus of this invention, designated
generally as 10, includes a body 12, a cap 14, and a
stem 16. Body 12 serves as the basal member for the
peritoneal catheter 10 and is con~igurated with a
funnel-like section 20 having a relatively shallow
depth in comparison with the relatively enlarged
diameter. The depth of funnel section 20 is
selectively predetermined so as to contain a
predetermined body of insulin which may be suitably
retained momentarily or expelled~ as desired.
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Funnel section 20 is surrounded at its upper edge
by an upstanding rim 22 and terminates downwardly
toward its center in a throat 24. Body 12 is
fabricated from a suitable, puncture resista~t plastic
material such as, for example, a conventional,
biocompatibIe polyurethane. Body 12 is aIso provided
with sufficient thickness so as to preclude inadvertent
puncture by a needle.
The opposite edge of rim 22 is formed as a
retainer shelf 26 for the purpose of retaining an edge
or lip 44 of cap 14. The lower portion of body 12
includes a neck 28 having a coaxial counterbore 30.
The internal diameter of counterbore 30 is selectively
predetermined so that column 50 may be telescopically
received into abutment with throat 24, as will be set
forth more fully below.
Cap 14 is configurated with an outwardly curved
dome-like puncture zone shown as dome 40. The outer
circumference of cap 14 includes an inwardly directed
circumferential lip 44 adapted to be received in snap-
fit relationship with shelf 26 for the purpose of
mounting cap 14 to body 12. The height of rim 22, as
well as the d ameter and the depth of funnel section 20
in combination with the hemispherical radius of cap 14,
selectively predetermine the volume of the resulting
receiving reservoir 18.
Cap 14 is fabricated from a suitable biocompatible
material (such as silicone rubber) having the desired
characteristics of being: (a) resilient~ (b) readily
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~3~ 2~
penetrable, and (c) resealable to accommodate being
flexed and punctured numerous times wlthout degradation
of the structural integrity of cap 14. A reinforcing
material 42 is preferably embedded in the biocompatible
material of-cap 14. Also, a portion of cap 14 and body
12 may be covered with a suitable, biocompatible velour
material 43 to accommodate tissue ingrowth.
Stem 16 is configurated as a hollow tubular column
50 having a hollow lumen 52 extending therethrough. As
previously mentioned, stem 16 is telescopically
received into abutment with throat 24. The diameter of
lumen 52 matches the diameter of throat 24 so as to
provide a continuous, smooth flow channel through
peritoneal catheter 10.
The distal end 54 of tubular column 50 is provided
with a diametrally enlarged flange 56. As shown,
flange 56 is located immediately adjacent distal end 54
of tubular column 50. Thus, flange 56 is adapted to
rest against peritoneal membrane 94, as will be
described n~ore fully below.
In use, peritoneal catheter 10 is first surgically
implanted in a patient. This is accomplished by making
an incision in the patient's abdominal wall 90 and
peritoneal membrane 94 (see Figure 1). The peritoneal
catheter is then placed in the patient such that distal
end 54 of stem 16 extends into peritoneal cavity 96
with flange 56 being against peritoneal membrane 94.
Peritoneal catheter 10 is then secured in place by
means of sutures.
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1~34~9
Once peritoneal catheter 10 is in place, the user
injects insulin into receiving reservoir 18 by pene-
trating dome 40 with a conventional, hollow needle.
Advantageously, the insulin in receiving reservoir 18
may be allowed to slowly percolate through lumen 52
into peritoneal cavity 96 or, upon demand, the user may
depress dome 40 with a finger to forcibly expel insulin
from receiving reservoir 18 through lumen 52 into peri-
toneal cavity 96.
From the foregoing, it will be appreciated that
the peritoneal injection catheter of the present
invention has, inter alia, the following features: (1)
the internal volume of the device is minimal; (2) it
presents a large surface area (consistent with the
first constraint) to allow for injection of various
drugs; (3) it is designed purely and simply for one-way
flow, i.e., drug injection is inward only; (4) it is
designed so that a variety of drugs may be injected
into the peritoneal cavity toward the mesenteric
peritoneal membrane; (5) it has a resilient, dome-
shaped surface above the receiving reservoir so that
the dome may be depressed to expel insulin from the
receiving reservoir into the peritoneal cavity; and (6)
it is not designed for peritoneal dialysis and, in
fact, would not function if used for this purpose.
This peritoneal injection catheter has been quite
successful for use in administering insulin to diabetic
patients. However, in spite oE this success, some
difficulties have been observed.
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First, it has been noted that this catheter
occasionally becomes obstructed after it is implanted
in a patient. At present, the chief causes of such
catheter obstruction appear to be the accumulation of
body cells in the peritoneal opening, tissue growth
over or within the peritoneal opening, and total or
partial occlusion by the greater omentum. Such
obstruction, of course, interrupts catheter use, and
the obstruction may be difficult to remove. Addition-
ally, when attempting to dislodge the obstruction from
the peritoneal catheter, the peritoneal catheter may
occasionally rupture, thereby necessitating complete
removal of the catheter.
Second, it has alsG been noted that bacterial
growth may occur within the catheter. When using the
subcutaneous peritoneal injection catheter, the patient
injects insulin into the device, and the fluid
thereafter disperses into the peritoneal cavity. Until
recently it has been assumed, probably correctly, that
any bacteria driven through the skin by the needle and
then transported into the peritoneal cavity would
probably cause very little harm. The basis of this
assumption is that the peritoneal cavity has some very
effective defense mechanisms against invading
microorganisms and the number that could be forced into
the cavity with the head of a 25 g needle (0.51 mm in
diameter) would not represent an overwhelming
invasion. Unfortunately, however, the small
subcutaneous reservoir inherent in the device itself is
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1234~29
not so protected. The omentum in the peritioneal
cavity cannot reach into this region, and mesenteric
lymph glands are remote. Thus, the only possible means
of combating microorganisms that may be residing in the
reservoir would be with microbiocidal chemicals and the
few white ~ells which free peritoneal fluid contains.
Accordingly, it would be advantageous to form
peritoneal catheter 10 in such a way that the
possibility of cell growth in or on the catheter is
minimized. This may be accomplished in a number of
ways, as set forth more fully below.
One preferred embodiment of a peritoneal catheter
which is configurated so as to minimize catheter
obstruction is depicted in Figure 3. As with the first
embodiment, this embodiment also includes a body 112, a
cap 114, and a stem 116. The body 112 and the cap 114
of this embodiment are in all respects identical to
those described in connection with the first
embodiment. However, the distal end oE tubular column
150 is configurated somewhat differently. As shown,
the distal end 154 of tubular column 150 is provided
with two, diametrally enlarged flanges 156 and 158. As
shown, flange 158 is somewhat smaller than flange 156
and is located immediately adjacent distal end 154 of
tubular column 150. Advantageously, the outer edges of
flange 158 are somewhat rounded, as shown, such that
flange 158 has no sharp edges which could injure
adjacent tissue.
1~3~i~3~
Tubular column 150, together with ~langes 156 and
158, may be formed as a single unit, as shown
Alternatively, tubular column 150 and flange 156 may be
formed as a single unit, with flange 158 being attached
to a smaller tubular column which is adapted to be
snugly received within lumen 152.
Peritoneal catheter 110 is surgically implanted in
a patient in exactly the same manner as the first
embodiment, with the flange 156 resting against the
peritoneal membrane 94 (see Figure 1). However, in the
event that body tissue or cells should begin to grow or
accumulate adjacent flange 156 of peritoneal catheter
110, the cel:Ls would grow along the surface of flange
156 so as to grow into the space between flange 156 and
flange 158. Thereafter, the tissue would be forced to
double back on itself in order to continue its
growth. It is well known that, unless the growth is
cancerous, cell growth will cease as soon as the tissue
doubles back on itself. In any event, it is highly
unlikely that the cells would thereafter grow outward
and upward over the top of flange 158, thereby
occluding the distal end of 154 of tubular column 150.
Experimental catheters having substantially the
same configuration as the catheter depicted in Figures
2 and 3 have been implanted in six diabetic patients to
date. Each of these catheters has remained free from
any obstruction during the period of implantation
(approximately six months). Significantly, when two of
these catheters were subsequently removed (due to
--2D--
~23~32~
unrelated, accidental, ~raumatic injuries to the
patien~'s abdominal area), it was noted that body
tissue had, in fact, grown over flanse 156 of the
catheters. However, such overgrowth had stopped once
the tissue reached column 50, and no tissue growth over
flange 158 had occurred.
Figure 5 depicts a third embodiment of the
peritoneal catheter 210 of this invention. As with the
previous embodiment, this embodiment also includes a
body 212, a cap 214, and a stem 216. The body 212 and
cap 214 of this embodiment are in all respects
identical to those described in connection with the
first embodiment. Similarly, stem 216 is also
configurated as a hollow, tubular column 250 having two
parallel, diametrally enlarged flanges 256 and 258
adjacent the distal end 254 thereof. However, in this
embodiment, flange 256 and flange 258 are substantially
the same size.
The third embodiment is implanted in a patient in
a similar manner as the first embodiment, with flange
256 being secured in place against peritoneal membrane
94 inside peritoneal cavity 96 (see Figure 1). Should
tissue growth or body cell accumulation commence around
flange 256, flange 258 acts as a restraining member to
inhibit the cells from growing over and obstructing
distal end 254.
It will also be appreciated that, while only one
opening in distal ends 154 and 254 is illustrated in
Figures 3-5, both the second and third embodiments of
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12~ 9
the present invention could have several such
openings. Such a configuration would additionally
serve to minimize the possibility of catheter
obstruction.
Figures 6-9 depict a fourth embodiment of the
peritoneaL catheter 310 of this invention. The fourth
embodiment also comprises a body 312, a cap 314, and a
stem 316. Like the second and third embodiments, the
fourth embodiment differs from the first embodiment
only in the construction and configuration of stem
316. In the fourth embodiment, tubular column 350 has
a diametrally enlarged flange 356 at the distal end 354
thereof. Attached to flange 356 is a generally
circular disc 368 having a plurality of radial spacing
members 360. As shown best in Figure 7, disc 368 has a
frangible circular area 362 at its center; and each
radial spacing member 360 is a narrow strip which is
secured along a radius of disc 368 and extends from
frangible area 362 to the outer edge oE disc 368.
Importantly, frangible area 362 has a diameter which is
approximately equal to that of lumen 352. Thus, radial
support members 360, together with flange 356 and disc
368, form a plurality of fluid communicating channels
364, which may communicate fluid into the peritoneal
cavity through a plurality of openings 366 (see Figure
8) around the circumference of flange 356.
The fourth embodiment of catheter 310 is implanted -
in a patient in the same manner as the second and third
embodiments. Should body cells thereafter be~in to
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~ ~ 3 L~ , 9
accumulate near flange 356 of peritoneal catheter 310,
it is unlikely that all openings 366 will become
occluded so as to prevent fluid flow. Thus, this
embodiment of peritoneal catheter 310 also minimizes
the possibility of peritoneal injection catheter
obstruction.
Referring now more particularly to Figure 9, the
fourth embodiment of the peritoneal catheter 310 of
this invention is shown implanted in abdominal wall
90. A trocar 98 is shown inserted through cap 31~ into
peritoneal catheter 310 so as to extend down lumen 352
in order to break out frangible area 362. Thus, in the
unlikely event that all openings 366 ~o become
obstructed, frangible circular area 362 provides an
emergency "bail-out" which serves two primary
functions.
First, as shown in Figure 9, frangible circular
area 362 provides a means whereby trocar 98 may be
pushed into peritoneal cavity 96 in order to push the
Z0 obstruction away from openings 366 of peritoneal
catheter 310. By using trocar 98 in this manner, it
may be possible to dislodge an obstructing body from
peritoneal catheter 310 so as to free openings 366 for
fluid flow. Second, frangible circular area 362
provides an alternate opening into peritoneal cavity 96
in the event that all openings 366 become permanently
obstructed.
It will be appreciated that the above-described
configurations for the peritoneal catheter of the
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4~ 9
present invention will significantly reduce the
likelihood that the catheter will become obstructed
during use. In addition, however, a portion oE the
catheter may advantageously be formed of or covered
with a suitable cellulicidal material -(that is, a
material which kills growing cells).
Suitable cellulicidal materials include, for
example, silver, platinum-silver, and copper. Each of
these materials has a toxic effect on growing cells,
while remaining safe for internal use. Silver and
platinum-silver, for example, are oligodynamic
materials, that is, they are effective as sterilizing
agents in small quantities. Copper also acts as a
sterilizing agent by leaching a toxic substance into
surrounding fluids. However, it has been found that
the quantity of the toxin leached by the copper is no
greater than the quantity of toxins which are naturally
present in mother's milk. Thus, the use of copper
within the body is considered to be safe.
In order to further deter tissue or bacteria
growth and accumulation, therefore, a portion of the
catheter may be formed of or coated with one of these
cellulicidal materials. For example, one of these
materials could be used to Eorm the distal end of the
hollow stem of the catheter. Alternatively, a plural-
ity of concentric rings could be provided on any or all
of the diametrally enlarged flanges of the catheter,
particularly on those flanges which are immediately
adjacent the peritoneal opening of the catheter.
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~3~ 9
These materials may also be advantageously used
within the peritoneal catheter of the present invention
in order to inhibit the growth of bacteria within the
catheter. Thus, for example, the interior of the
peritoneal catheter could be coated-~with silver by
sputtering the device with silver paint prior to
assembly. Alternatively, silver could be incorporated
into the various plastic materials used in forming the
catheter. In such case, the silver could either be in
the form of a fine powder or as a silver mesh or
screen.
In light of the foregoing, it can be appreciated
that the novel peritoneal injection catheter and the
embodiments described above significantly minimize the
possibility of peritoneal catheter obstruction. Both
the geometrical configuration and the use of
cellulicidal materials on this improved peritoneal
injection catheter minimize the possibility of
obstruction due to omentum overgrowth, tissue ingrowth,
and/or other body cell accumulation. Further, by
providing for a cellulicidal material within the
catheter, this invention also minimizes the likelihood
that bacteria will grow and accumulate within the
subcutaneous reservoir of the peritoneal catheter.
Significantly, this invention comprises a method for
minimizing catheter obstruction while maintaining the
structural integrity of the peritoneal catheter. Thus,
it will be appreciated that the peritoneal catheter of
this invention is an improved implantable subcutaneous
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~a~3~v~
peritoneal injection catheter which may be used by a
single patient over a relatively long period of time
without interruption or malfunction.
The invention may be embodied in other specific
forms without departing from its spiEit-or essential
characteristics. The described embodiments are to be
considered in all respects only as illustrative and not
restrictive. The scope of the invention is, therefore,
indicated by the appended claims rather than by the
foregoing description. All changes which come within
the meaning and range of equivalency of the claims are
to be embraced within their scope.
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