Peritoneal catheter

A peritoneal catheter for introducing and withdrawing fluid from an abdominal cavity which catheter has a plurality of ingress and egress ports spaced about the circumference and along the length of the intra-abdominal portion, which ports are arranged to decrease in size from the proximal to the distal end and, further which has a body portion formed into at least a one-half turn. The catheter tubing and the ports therein are coated with Ultra-low Temperature Isotropic carbon.

BACKGROUND OF THE INVENTION 
This invention resides in the field of catheters implantable within the 
human body and more particularly, relates to peritoneal catheters. 
Peritoneal catheters are used in a method of treatment for kidney disease 
or failure known as peritoneal dialysis. The purpose of the treatment is 
the same as hemodialysis, that is, to remove the waste products or toxins 
from the blood by solute and fluid diffusion out of circulation. In 
hemodialysis, this is accomplished by circulating the blood outside the 
body through an artificial kidney in which toxins and excess fluids 
migrate through specific permselective membranes. In peritoneal dialysis, 
a solution or dialysate is introduced into the space between the abdominal 
wall and the thin membrane known as the peritoneum which covers the entire 
abdominal cavity and visceral organs. The peritoneum will act as a 
diffusion selective membrane for toxin removal when a proper dialysate is 
artificially placed in the above mentioned space. Once there, the fluid is 
allowed to dwell for a period of time, come to chemical equilibrium with 
circulating blood over several hours, and then the fluid is drained. 
The cycle is repeated on a regular basis, the duration and frequency of 
which depends upon the patient's medical condition and the treatment 
regimen adopted. A catheter inserted into and extending outside the body 
is used for the introduction and removal of the dialysate. 
A variety of peritoneal catheters exist in the prior art. Their design 
format is basically a flexible, straight or slightly bent tube having exit 
ports in the intra-abdominal portion and one or more unique design 
features. Such are described in Peritoneal Dialysis Bulletin, 1983 Vol. 3, 
No. 3, published by Peritoneal Dialysis Bulletin Inc., Toronto Western 
Hospital, Toronto, Ontario, Canada. These include cuffs or flanges which 
communicate with the walls of the body tunnel to block bacterial 
ingression (Tenckhoff); intra-abdominal immobilizers such as an inflatable 
balloon (Goldberg and Hill) or flanges (Toronto Western Hospital) to 
prevent catheter tip migration; and a dual columnar disc fluid 
distribution head positioned at the end of the intra-abdominal portion 
(Lifecath). 
By way of background, United States Patents directed to or disclosing 
catheter devices include U.S. Pat. Nos. 1,626,839, Kallmeyer; 3,828,767, 
Spiroff; 4,173,981, Mortensen; 4,184,497, Kolff et al; 4,256,102, Monaco; 
4,278,092, Borsanyi et al; 4,681,570, Dalton; and 4,687,471, Twardowski et 
al. 
This invention disclosed herein is directed to the problem of limiting 
trauma to abdominal structures during dialysate introduction and to 
reducing the likelihood of blockage during fluid withdrawal. This may be 
accomplished by providing a generally flexible catheter arranged to 
introduce and withdraw dialysate in a smooth and uniform manner. The 
present invention functions to produce the above-desired result by 
providing in combination a catheter having a formed half helical turn 
arranged to be disposed within the body and a plurality of ports of 
decreasing size from the proximal to the distal end in the intra-abdominal 
portion in combination with an Ultra-low Temperature Isotropic carbon 
coating on the ports and the tubing. 
This configuration, which consists of a structure not disclosed in the 
prior art known to the applicant, results in an even and wide spread 
distribution of fluid flow. The structure eliminates forceful streaming 
and catheter whip that is common in the prior art. The dialysate flowing 
through the bent portion of the catheter into the body undergoes a 
transformation from laminar flow to a spiral, rotary flow that has a 
radial component. Upon reaching the spatially distributed size graded 
ports in the intra-abdominal portion of the catheter, the fluid exits in a 
plurality of directions in what may be described as a gentle manner rather 
than with the strong directional force that will occur when either a 
single end port or series of in line ports are employed. 
When the dialysate is removed after a dwell period, the same spacial and 
size graded configuration of ports results in an even, distributed 
withdrawal with a reduced likelihood of clogging, a problem which is of 
substantial concern in the use of many presently existing devices. 
SUMMARY OF THE INVENTION 
The invention may be summarized as a peritoneal catheter arranged to 
provide an evenly, distributed, low velocity ingress and egress of fluids 
to and from the abdominal cavity employing a plurality of radially and 
longitudinally positioned ports of graded diameter in the intra-abdominal 
portion and further having at least a one-half helical turn formed in the 
body portion. The flow characteristics are facilitated by longitudinal 
gradation of the port diameters, the small ports located at the 
intra-abdominal tip or the distal end and the largest nearest the body 
portion or the proximal end. The end port is similar in diameter to the 
adjacent side ports. 
Dialysate entering the catheter during the initial stage of peritoneal 
dialysis is altered from a laminar flow to a spiral rotary flow that has a 
radial component after passing through the bent portion. As the fluid 
reaches the series of ports in the catheter's intra-abdominal portion, it 
is evenly distributed in a swirl about the interior of the tube and flows 
out of the catheter proportionally about its circumference. 
This action continues down the length toward the tip where the additional 
distal port improves the flow characteristics. It has been observed that a 
further benefit is obtained by grading the ports such that the largest is 
away from the catheter tip. In this manner, the flow velocity is 
progressively reduced and more evenly distributed as the fluid travels to 
the end of the catheter. 
Upon fluid withdrawal, the multiplicity of ports allows for an evenly 
distributed ingress into the catheter preventing any strong localized flow 
which would tend to draw the omentum against the wall of the tube. 
Additionally, the likelihood of clogging is reduced by the spacial 
distribution of the ports. Also from a clinical standpoint, even flow will 
reduce trauma in the patient. 
The catheter is compatible with body tissue and is not encapsulated by 
oementum as a pure silicone rubber catheter would be by virtue of an 
Ultra-low Temperature Isotropic Carbon coating which substantially 
prevents the omentum, for example attempting to adhere to the catheter, 
which would substantially encapsulate the catheter and block the catheter 
holes. 
The features and advantages of the invention will be more clearly 
understood from the description of the preferred embodiment and drawings 
which follow.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1, there is illustrated the catheter of the 
invention comprising a tube generally indicated 10 having a continuous 
bore 11 to the distal end 12. The catheter is divided into three segments 
namely an intra-abdominal portion 15 below line 13, a body portion 16 
between lines 13 and 14, and an external body portion 18 above line 14. A 
plurality of ingress and egress ports 20 are located at the end of 
intra-abdominal portion 15 spaced about the circumference of tube 10. They 
are preferably graded longitudinally from the largest 22 to the smallest 
24. The distal end 12 may also contain an additional port 26 indicated in 
FIG. 4 which is created by installing a plug 25 having a port no larger 
than 1.35 mm. in the distal end 12. 
A one-half helical turn 28 is formed in body portion 16, the configuration 
of which is further shown by reference to top view FIG. 2. By the body 
portion what is meant is that portion of the catheter which will reside in 
the abdominal wall of the patient, i.e. the anatomical structure adjoining 
the peritoneum between the rectus muscle and the skin. It is essential 
that the body portion be formed with a helical turn in a fashion so that 
it will retain its shape after implantation in order that the function of 
the one-half turn be carried out. The helical, rotary motion imparted to 
the fluid by the helical half turn imparts an even distribution of the 
fluid over the many exit ports rather than allowing exit of the fluid 
through one dominant hole. This reduces the force of the fluid flow and 
consequently reduces the trauma inherent in running dialysis fluids into 
the abdominal cavity. Further it is equally important to drain the fluid 
with similarly little trauma that is accomplished by dividing the fluid 
reentrance into the catheter over a large area through many holes which 
limits the flow velocity in any one place. 
Optionally and as is the practice with such catheters, one or two fibrous 
cuffs 30 composed of Dacron, for example, may be positioned over the body 
portion to seal the subcutaneous channel from bacteria by means of 
cellular ingrowth. The outer cuff is positioned so that it may be sutured 
to the subcutaneous tissue while the inner cuff is sutured to the 
posterior rectus sheath. 
In accordance with the above disclosure, a catheter was constructed of 
silicone rubber or other suitable polymeric compound tubing having an 
inside diameter of 2.64 mm., an outside diameter of 4.87 mm. and an 
overall length of 47 cm.. The horizontal distance from the proximal end to 
the beginning of the turn (line 14) is 16 cm. and the vertical distance 
from that point to the distal end is 22-24 cm. 
The vertical length of the turn is on the order of 1.3 cm. with an outside 
radius of 1.4 cm.. The distance from the end of the turn to the first port 
is 7.2 cm., after which 24 holes in four staggered rows of 6 each of a 
diameter of 1.12 mm. were placed a length of 7.0 cm.. These are followed 
by a similar series of 0.61 mm. holes spaced over approximately the same 
remaining length. 
Tests utilizing dyed water gravity fed to the catheter immersed in clear 
water showed a thoroughly uniform dispersion pattern in accordance with 
the object of the invention. The invention shows even distribution of flow 
where the conventional prior art has essentially increased velocity and 
poorly distributed flow at the proximal and distal ends. Tests of 
conventional catheters and the invention illustrate interesting flow data. 
For example, a conventional catheter averages a discharge of 77.6 ml of 
fluid in 60 sec. while the invention discharges 82.8 ml in 60 sec. with a 
hydrostatic head of 13 cm. The invention shows, therefore an average of 
6.7% better inflow and better outflow than the control unit of the prior 
art. 
Clinical studies on humans have been conducted and the catheter has 
performed perfectly for periods of nine up to eighteen months and 
clinically, significantly better inflow and outflow has been noted but 
measurement data was not recorded. These results are to be compared to 
average implant time for standard catheters of eight months. The longevity 
of the implant indicates that there was no attachment by the omentum to 
the catheter of the invention. 
The catheter is preferably composed of silicone elastomer coated with 
Ultra-low Temperature Isotropic (ULTI) carbon, or another non-reactive 
material, which serves to round the edges of the ports and coat the ports 
which reduces or eliminates body reaction to the entire device. The 
particular coating which in essence is applied in molecular layers to the 
surface of the catheter is an important element of the catheter. Carbon 
coatings are generally applied by a sputtering or vacuum vapor process at 
elevated temperature that is not possible with a silicone rubber catheter. 
The ULTI carbon coating is achieved by a hybrid low pressure process where 
isotropic carbon can be deposited from a gaseous precursor at ambient 
temperatures by using a proprietary catalyst and is successful on devices 
having a certain degree of flexibility and a low melting point. 
It will be apparent from the foregoing that the advance in the catheter is 
the curved component section coupled with graduated diameter holes and the 
coating with ultra-low temperature isotropic carbon. The curve imparts 
centrifugal motion to the fluid flowing in which allows the fluid stream 
to exit the catheter through all the holes rather than through only a few 
or one end hole. The distribution of holes also avoids pulling abdominal 
structures into the flow path and drainage can proceed without 
obstruction. 
The method of use and improved and advantageous operation of the apparatus 
are as described above. Variations of the device disclosed herein may 
occur to those skilled in the art. Accordingly, the invention is defined 
by the following claims.