CA1124952A - Method and apparatus for continuous, ambulatory peritoneal dialysis - Google Patents

Abstract

METHOD AND APPARATUS FOR CONTINUOUS, AMBULATORY PERITONEAL DIALYSIS

ABSTRACT

A process for the removal of toxins from the body in a continuous manner while the patient is totally ambulatory.
The process involves the infusion of a dialysate fluid under prescribed conditions into the peritoneal cavity. The toxic solutes are transported across the peritoneum membrane into the dialysate fluid by the natural processes of diffusion and convection. The dialysate fluid and the toxins are then removed after a prescribed residence phase. Apparatus includes an in-dwelling balloon catheter surgically implanted within the peritoneal cavity of a patient, a Dacron TM cuff surgically attached to the abdominal wall, and an external quick connect coupling attached to the catheter. Apparatus may also include a wearable microbiological filter unit for reducing the risk of peritonitis during infusion of dialysate fluid.

Description

METHOD AND APPARATUS FOR CONTINUOUS, AMBULATORY PERITONEAL
DIALYSIS

BACKGROUND OF THE INVENTION

1. Field of the Invention The invention relates generally to the field of Surgery, and more particularly to fluid infusion methods and devices for performing peritoneal dialysis within a patient.

2. Description of the Prior Art Several of the functions performed by human kidneys are the removal of waste metabolites, the maintenance of fluid, electrolyte and acid-base balances, and hormone and enzyme syntheses. The foregoing is discussed by Abbrecht, P.H.,'bn Outline Renal Structure and Function", CEP Symp. Series, 64, 1 ~1968). Abbrecht ~1968) forms the first reference in the appended Bibliography which appears after the disclosure and prior to the claims.
References from the Bibliography are referred to throughout the specification by use of superscripts, for example, Abbrecht (1968)1. Loss of normal kidney function ~acute or chronic renal insufficiency) is generally treated ~. ' llZ4~5Z -through dialysis therapy or transplantation. Transpla~-tation, if successful, restores all the normal functions.
Dialysi3 partially replaces some of the normal kidney functions. For example, it does not replace the hormone or enzyme functions, among others, as evidenced by the greatly reduced blood hemoglobin levels in chronic uremic patients.
Two types of dialysis thereapy are generally employed.
Bemodialysis is most commonly used in which the blood is lo cleansed by passage through an artificial kidney in an extracorporeal membrane system. The waste metabolites diffuse across the membrane and are removed by a washing dialysate solution. Excess fluid is removed by pressure-induced ultrafiltration. The other approach is termed peritoneal dialysis, in which the dialysate solution is infused directiy into the abdominal cavity. This cavity ~B lined by the peritoneaL membrane which is highly vas-cularized. r~etabolites ar~ removed by diffusion from the blood to the dialysate acros ~le peritoneal membrane.
Excess fluid is removed by osmosis induced by a hyper-tonic dialysate solution.
Current dialysis treatments are generally performed interm~ttently under high efficiency conditions. The treatments are usually performed two or three times per week. The length of the treatment depends upon the de-sired reduction in blood waste metabolite levels, but u~ually averages 4-6 hours per hemodialysis and 24-48 hours for peritoneal dialysis. The time difference re-flects the higher efficiency of hemodialysis, which is a primary reason for its greater popularity. Both proced-ures result in partial correction of abnormal metabolite, fluid, electrolyte and pH levels during the treatment.

1124~S~
Blood metabolite levels are greatly reduced followed by a slow concentration buildup between dialyses. ~jellstrand (1976) has hypothesized that the resulting concentration fluctuations may be detrimental to the patient's health.
In fact, high efficiency hemodialyzers are not generally u~ed to their full potential because of a characteristic disorder termed the "disequilibrium syndrome" which devel-Op8 in certain patients. These patients develop headache,nausea, vomiting, and severe blood pressure alterations 0 after two to three hours of dialysis. ThLs conditlon often persists throughout the treatment leaving the patient weak and exhausted. It is hypothesized by Arieff3 et al. (1975) that this syndrome i9 a result of large in~racellular to extracellular concentration ~and osmotic) gradients with concomitant fluid shifts, particularly across the-~blood-brain barrier".
Ihe Arieff hypothesis is supported by the results of Popovich, et al. (1975) who have investigated the conse-quences of physiological resistance on metabolite removal from the patient-artificial kidney system. Vitamin B-12 ~nd inulin were selected as representative middle mole-cules in their investigation. They have shown that very lit~le of the larger test metabolites are cleared from the intracellular body pools during the dialysis treatment.
This is caused by the high resistance to mass transfer across the cellular membranes and results in a large post dialysis concentration rebounds as the pools equilibrate ln the interdialytic period.
The conventional hemodialysis procedures use an ~nordinately large amount of dialysate fluid, approximately 450 liters/week. It is contemplated that the procedure of the present invention will utilize approximately 70 liters/week.

- 3 -1124~52 SUMMARY OF THE INVENTIO~

The Continuous Ambulatory Peritoneal Dialysis (CAPD~
process of the present invention differs in several funda-mental ways from all current conven~ional dialysis processes.
It is totally different from the most popular process (hemo-dialysis) in that it employs a natural body membrane which obviates the need for an artificial kidney or for blood acces~.
The fact that CAPD is continuous results in stable, low blood toxic levels. Current peritoneal dialysis pro-~esseS are intermittent (usually employed extensively two or three times per week). Such intermittent treatment result~ in wide toxin fluctuations at much higher levels than CAPD, which is detrimental to the patient's well-~eing.
The CAPD process obtains optimum use (100% efficiency) of dialysate fluid. Current processes employ short resi-dence times with the intent of minimizing toxin levels in the dialysate to achieve the maximum toxin removal rate.
- The~e inefficient high removal ratès are required because of the short intermittent nature of current processes.
The CAPD process is ambulatory - the patient being free to perform his normal daily duties while being treated.
Patients undergoing conventional peritoneal dialysis pro-cesses are not ambulatory. They must remain by their di-alysate supply (usually by machine) during the entire 24 to 48 hours of their treatment.
The CAPD process i~ economical to use - no machines at all are required. The contemplated usage of dialysate fluid is approximately 70 liters/week compared with 450 liters/week for conventional hemodialysis.
The greatest advantage of all is the overall comfort and well-being of the patient using the CAPD.

_ . . ._. .

The invention comprehends portable apparatus for carrying out continuous, ambulatory peritoneal dialysis, which involves establishing a substantially constant presence of dialysate fluid within the peritoneum of a patient at all times over an extended period of time. The apparatus includes an in-dwelling catheter adapted to be surgically implanted in the peritoneal cavity of a patient and having a supply tube for extending through the abdominal wall of the patient, and a bag adapted to be interconnected with the supply tube and carried by the patient during dialysis for dispensing dialysate fluid through the supply tube to the peritoneal cavity of the patient and for receiving spent dialysate drained from the peritoneal cavity of the patient.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of the components of the CAPD
system of the present invention;
FIG. 2 is a schematic view of the invention as intended to be used on a patient;
FIG. 3 is an exploded perspective view of a wearable microbiological filter unit designed for use as an auxiliary component in the system; appearing with Fig. l; and FIG. 4 is a fragmentary schematic view of an air bubble trap and flow directing valve also adapted for use in the system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIIIENT
The continuous, ambulatory peritoneal dialysis system of the present invention is illustrated in simplest form in FIG. 1 and is designated generally by the numeral 10. The overall sys-tem 10 comprises: an infusion system 11, a catheter system 12, and a cap and drainage system 13.
The infusion system 11 comprises a dialysate bottle or bag 15 having an outlet tube 16 which terminates at one-half of a quick connect coupling 17. An adjustable flow control clamp 18 is attached to the tube 16 for regulating the rate of fluid dis-charge from the bag 15. The bag 15 preferably has a volume capacity of 10 to 12 liters and has graduations at 2 liter inter-vals. The bag 15 may also have a hook 19 at its top for hanging it at some desired elevation above the attachment to a patient.
The catheter system 12 comprises a surgically implanted in-dwelling catheter 20 having a connecting tube 21 which termi-llZ4~5Z
ates at a matin~ half of a quick connect coupling 22, and aDacronTM cuff 23 which is surgically implanted in the abdominal wall of a patient. The peritoneal catheter 20 may be, for example, a Goldberg Balloon type as supplied b~7 the American Medical Products Corporation, or a Tenckhoff catheter. The catheter 20 is formed with a plurality of holes 24 and a flexible rib cage 25 adapted to prevent occlusion of the holes 24 during drainage. The DacronTM cuff 23 is adapted to allow tissue in-growth and thereby provide an effective barrier to the entry of bacteria into the peritoneal cavity. The tube 21 extends through the Dacron cuff 23 and provides external connection by means of the coupling 22.
The cap and drainage system 13 comprises an attachable cap 30 for mounting on the coupling 22 during the ambulatory residence period, a disposable drainage tube 31, and a sterile drainage con-tainer 32 for receiving used dialysate. The tube 31 carries a mating half of a quick connect coupling 33 for attachment to the coupling 22 during the drainage period.
In operation, the CAPD system 10 is utilized as follows:
Dialysate fluid is infused into a patient by attaching the coupling 17 to the coupling 22 and allowing approximately 2 liters to pass through the tube 16 to the catheter 20. The rate of flow of the fluid is controlled in a conventional manner by adjustment of the flow control clamp 18. The coupling 17 is then disconnected and the cap 30 placed on the coupling 22 for the ambulatory residence period which may last for approximately

4 to 5 hours. The cap 30 is then removed and the drain coupling 33 attached to the coupling 22. The spent dialysis fluid is drained from the patient's peritoneal cavity by gravity through the tube 31 into the drainage container 32. The cycle just described is thenrepeated so as to maintain a substantially constant presence of the dialysate fluid within the patient and thereby provide for continuous dialysis.

, ~,, 11'~495Z
A ~lightly modified e~bod.iment of the invention is illustrated in FIG. 2 which shows the CAPD system as in-tended to be used on a patient. The system illustrated includes a wearable millipore filter unit 40 intended to minimize the introduction of bacteria into the peritoneal cavity during infusion of dialysate fluid. The filter unit 40 i5 interposed in the supply line 16 between the supply bottle 15 and the indwelling catheter 20. The filter unit 40 comprises a relatively flat filter body 41, 10 . a fluid inlet conduit ~2, and an outlet tube or conduit 43.
The lnlet tube 42 has a quick connect ~coupling 44 adapted to be attached to the coupling 17. The outlet tube 43 i8 attached to one branch of a "T" connector 45. A second branch of the "T" connector is att,ached to a tube 46 leading to the catheter ~0, and the third branch is con-hected to a tube 47 which leads to the drainage bottle 32.
The tube 47 carries a quick connect coupling 48 adapted to be attached to the coupling 33 of th~ drain tube 31.
Fluid cut-off clamps 49 and 50 are attached to the tubes 43 and 47, respectively. The clamps 49 and 50 are re-lea~ed alternately during infusion and drainage, respectively.
The wearable microbiological filter unit 40 is shown ln exploded form in FIG. 3. The unit comprises the rela-.
t~vely flat and flexible body or housing 41, a central leaf-type filter 51, the inlet tube 42, and outlet tube 43.
The outer shell or housing 41 preferably is made of two halves 54 and 55 cast from flexible, medical grade sili-cone elastomer bonded together into a ~hape that can con-form to body curvature. The halves 54 and 55 also may be ~formed with raised longitudinal spines 56 and 57, respec-tively, adapted to prevent collapse of the outer shell against the filter Si. The fllter 51 preferably is formed 4~.5~
of two sheet~ 58 and 59 of 0.22~ pore size membrane mater-ial bonded together at their edges. The inlet tube 42 and outlet tube ~3 preferably are made of standard, commercially aYailable silicone elastomer. tubing.
It is deemed desirable, if not imperative, to minimize ~he risk of introducing air into the peritoneal cavity during infusion of the dialysate fluid. To this end, a device such as the bubble trap and flow directing val~e 60, lllustrated schematically in FIG. 4, may also be included 0 to advantage wi~hin the system 10. The valve structure 60 shown can supplement or substitute for the "T" connector 45 and clamps 49 and 50. The valve 60 comprises a rela-tively flat valve body 61, preferably made of clear plas-tic, and a rotatable valve core 62, also preferably made of clear plastic.~ The valve body 61 i9 formed with an inlet channel 63, an ou~let channel 64, a drain channel 65, and an air bleed channel 66. The valve core 62 is formed with interconnected radial channels 67, 68, 69, and 70, as illustrated. The inlet channel 63 and outlet channel 64 are constructed so as to form an inverted "U"
configuration. The inlet channel 63 is connected to the outlet tube 43 of the filter unit 40. (Alternatively, the entire valve structure 60 may be constructed as an integral part of the filter unit 40). The outlet channel 64 is connected to the catheter 20, and the drain channel 65 is adapted to be connected to the drainage bottle 32.
With the valve structure 60 oriented in a vertical plane, and with the valve core 62 turned to the "A" posi-tion,~(as shown in FIG. 4A), any air trapped in the chan-nels 63 and 64 can be bled through the air bleed channel66 to atmosphere.
Once all the air has been bled from the line, the valve core 62 is turned to the "I" position (as shown in 1~4~5Z
FIG. 4B) for infusion of dialysate fluid through channels 63, 68, 67, and 64 to the catheter 20. ~en the desired amount of fluid has been infused, the coupling 17-44 is di~connected and a cap placed on the coupling 44 for the period of residency. The coupling half 48 is also capped during the residency period.
After the desired period of residency within the peritoneal cavityj the spent dialysate fluid is drained by uncapping the coupling half 48, connecting the coupling 33 to 48, and turning the valve core 62 to the "D" position ~as shown in FIG. 4C). In this position, the inlet channel 63 is cut off, and fluid is drained backwards through the outlet channel 64, through channels 70 and 68 to the drain channel 65. When drainage has been completed, the valve core 62 is returned to the "I" position, the drain bottle 32 disconnected, and the supply bottle 15 recon-nected for infusion to the,inlet tube 42. The cycle is then repeated as described above.
' It is contemplated that the filter unit 40 and valve ~tructure 60 may be flushed periodically with a formalin solution, or the like, to prevent the growth of bacteria within the filter and related conduits. To accomplish this, the valve core 62 is turned to the "Fn~position (as shown in FIG. 4D), and communication to the outlet channel 64 is cut off. The formalin solution is passed through the inlet tube 42, filter unit 40, through inlet chan'nel 63j valve core channels 70 and 68 to the drain channel 65.
, m e formalin solution is cleared by passing through a portion of dialysate fluid the,reafter, before turning the valve core 62 to the "I" position for,infusion.

11~4~SZ
~THE~TICAL MODEL

The blood metahollte levels of patients are governed by a balance between the generation rate and the removal rate of the particular toxin ln question. Theoretical re-lationships have been deri~ed which predict the predialysis metabolite concentrations under discontinuous hemodialysis and peritoneal dialysis situations5 7 Similar expressions ~ave been derived which predict the ln~tantaneous blood ~nd dialysate metabolite concentration levels during peri-toneal dialysis infusions. These analyses result in equations which are fairly complex for the general case.
If steady state conditions can be assumed, ~he equations can be greatly simplified. Under these conditions, the steady state blood metabolite level CB is given by:
.
- CB ~ ~
where G is the net generation rate and K is the total ~olute clearance (the sum of the dialysis clearance plus the residual renal clearance).
Alternatively, the net solute clearance necessary to maintain a prescribed blood metabolite level may also be computed. For example, equation (1) predicts that a total - clearance of 7.1 ml/min is required assuming that a steady state blood urea nitrogen (BUN) concentration level of 70 mg/dl is desired with a BU~J generation rate of 5.0 mg/min ~15.4 g urea/day). This corresponds to a total clearance . ..... , _ .
of approximately 10 liters per day.
Thls result is routinely employed by nephroiogists.
Patients are generally p~aced on some dialysis regimen when their residual renal clearance diminishes signifi-cantly below 7 ml/min.

l~Z4~5Z
The mathemati~al model also presents a simplification whlch i~ possible if the dialysate fluid totally equili-brates with the blood, i.e., CD = C~. For these conditions, the dialysance clearance equals the dialysate flow rate, QD, and equation (1) can be rewritten as:
G

2) ~here KR = residual renal clearance. For the anuric case (RR ' 0), and equation (2) further simpli~ies to:

.
CB D G (3) QD
This analysis yields the hypothesis that a patient c~n be adèquately dialyzed with acceptable B~l levels if only 10 liters of dialysate fluid per day are allowed to continuously equilibrate with body fluids (i.e. a dialysis clearance of 7.0 ml/min and a steady state BUN level of approximately 70 mg/dl).

CLINIC~L TECHNIQUE . ~

The desired equilibration of meta~olite between blood ~nd dialysate fluid can be readily accomplished with inter-mlttent peritoneal dialysis utilizing the system 10 descri-bed above. Normal peritoneal dialysis procedure is to infuse 2 liters of dialysate with a re~idence time of lS
to 60 minutes. I have discovered that if the residence time 1s extended to approximately 4~ hours, a patient can perform 5 exchanges per day with sufficient time for in-fusion and drainage. Thi~ long residence period has been found to be sufficient for equilibration between plasmn and the dialysate for urea and creatinine. Five exchanges per day at two liters per exchange yields the 10 liters/day which has been hypothesized to be required to maintain the ' ~ llZ4,95Z
patient with acceptable B~N levels. Steady state may be a~sumed since five exchanges are performed each day with relatively long residence times which compares favorably wlth the usuàl three hemodialysis trea~ments per week.
Thig equilibrium peritoneal dialysis technique is funda-mental to the Continuous, Ambulatory Peritoneal Dialysis procedure of the invention de~cribed and claimed herein.

.
' EXAMPLE

Equilibrium peritoneal dialyQis according to the present invention was aonducted on a 40-year old, 190 lb.,

5 ~ 9 n male over a five-month period through use of an in-dwelling Tenc~hoff catheter. The patient had a history of surgical removal of his right kidney at an early age s~condary to a traumatic injury. He had developed neph-rotic syndromé approximately 18 months prior to reaching end stage renal disease. He had well established athero-~clerotic coronary artery disease with angina pectoris.
Caxdiac catheterization and coronary arteriography revealed atherosclerotic changes of the left circumflex coronary ~rtery and a 90% occlusion of small obtuse marginal branch on that side. The right coronary artery revealed stenosis 1 cm. long in the mid portion with approximately 50% ob-struction. ~e was said to have had Buerger's disease at ~ge 28 and had previously had a surgical procedure on the ,left iliac area at that age. A gastric mucosal biop~y demonstrated Menetrier's disease at age 39. ~e had hyper-cholestolemia and hypertriglyceridemia ~nd had been diag-nosed as having mild adult onset diabetes for approximately four years. Both his father and mother had diabetes, the mother requiring insulin. ~is glomerular filtration rate in September, 1974, was 14 ml/min, with a creatinine level ~ 124~5~
of 9.9 mg/dl. He had 8 gram~ of protein ln the urine per 24 hours at that time.
On eight separate occasions, efforts were made to establish a subcutaneous arteriovenous fistula, or the establishment of a Quintin-Schribner shunt. All of these ~ttempts were unsuccessful because of thrombosis; only on one occasion was a fistual utiiized for a ~ingle dialysis.
It wa~ recommended to the patient that he be transferred to a center where chronic peritoneal dialysis could be lnstituted. This the patient was unwilling or unable to do. In view of these circumstances, the equilibrium-peritoneal dialysis technique defined herein was undertaken ~8 a llfe-saving necessity.
After obtaining appropriate ~nformed consent, the procedure of peritoneal dialysis using S two-liter exchanges per 24 hours was instituted. Infusion required 10 minutes, relying only on hydrostatic pressure, and was followed by nn equilibration period averaging 260 minutes. Drainage o~ the dialysate averaged fifteen minutes. Three minutes wer¢ required for tubing connection yielding 288 minutes per exchange. The procedure was originally conducted with Dianeal~ 1.5% solution in the hospital. This did not allow for adequate water removal, so 4.25% solution was substituted on a variable schedule until it was determined that alternate 1.5% and 4.25~ solutions could be used to remove approximately 2000 cc. of fluid per day in excess of that instilled into the peritoneum; the patient was un-cooperative in maintaining fluid restrictions. The pro-oe dure was carried out on an experimental basis by the patient in the hospital for approximately one month. After ~tabilization of the patient on the new procedure, he was trained to conduct the procedure in his home. Within the first month at home ne had an episode of peritonitis which ~ 1~24~952 subsequently resulted in obstruction of the chronic peri-' toneal catheter. The catheter was replaced and, subsequentto that, no obstructive problems developed.
The patient complained of intermittent abdominal pain whlch was felt to be related to the 4.25~ hypertonic solu-tion or to the pH of the solutions. The pH was adjusted w~th sodium bicarbonate, but he continued to exhibit inter-mittent abdominal pain. This did ~o't, however, prevent him from carrying out normal physical activity, including 10, making several trips to distant cities by carrying his dia,lysate solutions with him in the back of his car.
The patient also complained of intermittent difficulty ln sleeping because of abdominal distension.
The patient was oliguric during the course of the study. He had an estimated creatinine residual renal clearance of'5.0 ml/min and was anorexic with nausea and vomiting at the ihitiation of the study on June 30, 1975.
His B~1 was '70 mg/dl while under strict dietary protein restriction. Immediately after commencçment of treatment in the hospital his diet restrictions were removed and his B~l's remained at 70 mg/dl with a significant increase in patient well-being. The BUN levels then diminished and stahilized in the 35 to 45 mg/dl range with creatinines in the 7,to 10 mg/dl range. The alleviation of the symtom~
of chronic uremia in the patient was comparable to parients on hemodialysis. A creatinine residu~l clearance of 3.0 ml/min was measured on 10/20j75. The treatment was contin-ued by the patient in his homè until 12/9/75 at which time he was successfully transplanted with a cadaveric C-match kidney. ~le currently has a glomerular filtration rate of 96 ml/min.

' llZ4~5Z
CLINIC~L BV~LU~TION

Clinical evaluation of the above example has been conducted and rcported in the technical literature8 In order to quantify the treatmcnt, the concentr~tion levels of urea, creatinine, uric acid, glucose and tritium tagged cyancobalamin were follo-~ed on a single exchange on ll/14/75 and on a multi-day basis. The single exchange study was conducted by inj~cting a loading dose of lOOOyg of cyan-ocobalamin followed 24 hours later by the tagged cyanco-balamin. ~fter an additional 24-hour equilibration period, blood and dialysate sam~les were obtained at 30-mlnute intervals throughout the equilibration period.
Representative dialysate samples were ohtained by m~ing _ situ via withdrawing and reinfusing, 50 ml of dialysate ten times immediately prior to aspiration of ~he sample. Concentration levels of the uremic toxins ~ere det~rmined by use of the TechnicoTMsr~-l2 analyzer, ~hile cyanocobalamin levels were obtained via normal ~lquid scintillation counting tcchniqucs.
The dialysis clearances (KD) of the various substances are normally determined from the average ~lood concentra-tlon (CB), residence time (t), drained dialysate volume (VD) and concentration (CD) by the expression:
CDVD ' ' ' ~ ~ C t t4) For the case of urea and creatinine, the blood and dialy-~ate concentrations equilibrate, CD ~ CB~ such that the equation (4) simplifies to:

RD ~ Dt s QD . ~5) where VD is the drained dialysate volume (the sum of the lnfusion volumc plus ultrafiltration volume).

5~ 5 -llZ~5Z
The xesults for an average residence time of 288 ~lnutcs are prcsented in Table I ~elow. The mean drained dialysate volume for the patient was 2,400 ml.

TABL~ I -uilibriu~ Peritoneal Dialysis Met _olite Clearances Compound Mol. ~t. R, ml/min Urea 60 8.3 Creatinine 113 8.3 Uric ~cid 168 7.7 lQ Cyanocobalamin 1355 5.7 .
The experimental ~ean urea dialysi~ clearance of 8.3 ml~min is slightly greater than the required clearance value predicted in the development of the hypothesis. The increase is caused by the ultra filtered fluid.
The residual creatinine renal clearance was determined to be 3.0 ml/min three weeks prior to the quantative study.
From ~lis the total clearance, R, for urea and creatinine can be estimated to be:
X ~ RD ~ R ~6) R 8.3 + 3.0 ~ ~ ; 11.3 ml/min.
Equation (1) above can be employed to calculate predicted steady state concentration~ of urea and creatinine from this value and the generation rate, G. The results plus the experimental values are presented in Table ~I.

T-ABLE II
Predicted and ~xperimental Meta~olite Levels Solute G,mg/min X,ml/min C ,predic- C~,experi-~ed,ma~mental,~%
. .
Urea 5.0 11.3 44 35-45 Creatinine 1.4 11.3 12 7-10 Th~ predicted values are in good agreement with the experimental results. It appears that t~e actual genera-tion rates for the patient w~s less than those assumed for the general patient population. This is in line with the diabetic diet of the patient and the restricted activity ; resulting from his cardiovascular complications.
Middle molecule clearances as defined by Vitamin B-12 with this procedure are at acceptable levels. In fact, the steady state middle molecule metabolite concentration-levels of patients with this technique will be considerably less than those undergoiny hemodialysis. For example, 18 hours~
week of hemodialysis at a B-12 clearance of 25 ml/min yields a total clearance-tlme product o 27 liters/week. The cor-responding equilibrium peritoneal dialysis clearance of 5,7 ml/min ~neglecting residual renal clearance) for 168 hours/week yields a total clearance-time product of 57 liters/week. This predicts that the middle molecule concentration level for patients utilizing the new pro-c~dure will be less than one-half of that of patients on hemodialysis. This primarily caused by the increased time factor, i.e., equilibri~m peritoneal dialysis is conducted 24 hours/day. The steady state character of the treatment will also allow for continuous equilibration across the cellular membrane which will circumvent the limitations lmposed by inner body resistances which have been reported for discontinuous hemodialysis techniques4 In summary, the CAPD system of the present invention offers a number of significant advantages over existing dialysis techniques. The fact that toxic solutes are re-~oved continuously eliminates the di~comfort associated with body adjustment to the wide fluctuation in chemical imbalances that-occur before and after conventional dialysis.

.

! 1124952 The cArD process results in lo-~ blood toxic metabolite levels ~hich can be prescribcd within limits by an attend-lng physician by adjusting the dialysate volume infused.
The CA~D proces~ results in lo~er blood levels of larger toxic solutes (so-called "middle molecules") because Of lts contlnuous nature.
The CAPD process does not require blood acce~s as with all conventional hemodialysis processes which constitute approximately 90~ of current dialysis practice. The admin-lstration of an anticoagulant (heparin) is not required.
There is no blood loss in equipment, or contact of blood on foreigll surfaces as is true with all hemodialysis processes.
The c~rD system does not require an artificial kidney or the use of complicated equipment which must be.purchased and maintained.
The CA~D system is wearable and the patient is free to go about his normal activities while the dialysis is being performcd.
The embodiments of the invention shown and described are by way of example only, and it i9 to be understood that many changes and modifications might be made thereto with-out departing from the spirit of the invention.~ The inven-tion ~s not to be construed as limited to the embodiments shown and described, except in-so-far as the claims may be so limited.
BIBLIOGRAPHY

1 Abbrecht P.H., "An Outline Renal Structure and Function", CEP Symp. Series, 64, 1 (19683.
2 Kjellstrand, C.M., "Future Directions for the Ak-CUP
Program", Proceedings Contractors Conference, Artificial Kidney Chronic Uremia Program, NIH, HEW 9, (1976).

3 Arieff, A.I., Guisado, R., Massry, S.G., "Uremic -~ - 18 -4~52 Encephalopathy: Studies on Biochemical Alterations in the Brain", Kidney Intern., 7, S-194 (1975).
4 Popovich, R.P., Hlavinka, D.J.,Bomar, J.B., Moncrief, J.W., and Dechers, J.F., "The Consequences of Physiological Resistances on Metabolite Removal from the Patient-Artificial Kidney System", Trans. Amer. Soc. Artif. Int.
Organs, 21, 108 (1975).
Popovich, R.P., Moncrief, J.W., "The Prediction of Metobolite Accumulation Concomitant with Renal Insufficiency; the Middle Molecule Anomaly". Trans. Amer.
Soc. Artif. Organs, 20:377 (1974).

6 Bomar, J.B., Decherd, J.F., Hlavinka, D.J., Moncrief, J.W., and Popovich, R.P., "The Elucidation of Maximum Efficiency-Minimum Cost E'eritoneal Dialysis Protocols". Trans. Amer.
Soc. Artif, Int. Organs, 20:120 (1974).

7 Sargent, J.A. and Gotch, F.A., "The analysis ofConcentration Dependence of Uremic Lesions in clinical Studies". Kidney International 1 (S-2):35 (1975).

8 Popovich, R.P. and Pyle, W.K., "Preliminary Verification of the Low Dialysis Clearance Hypothesis via a Novel Equilibrium Peritoneal Dialysis Technique". Sec.
Australasian Conf. on Heat and Mass Transfer (1977).

9 Maxwell, M.W., Rockney, R.E., Kleeman, C.R., and Twiss, M.R., "Peritoneal Dialysis I:Technique and Applications", J. Amer. Med. Assoc., 180: 917 (1959).

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Portable apparatus for carrying out continuous, ambulatory peritoneal dialysis, which involves establishing a substantially constant presence of dialysate fluid within the peritoneum of a patient at all times over an extended period of time, said apparatus comprising:
an in-dwelling catheter adapted to be surgically implanted in the peritoneal cavity of a patient and having a supply tube for extending through the abdominal wall of the patient; and a bag adapted to be interconnected with the supply tube and carried by the patient during dialysis for dispensing dialysate fluid through the supply tube to the peritoneal cavity of the patient and for receiving spent dialysate drained from the peritoneal cavity of the patient.

2. Portable apparatus for carrying out continuous, ambulatory peritoneal dialysis, which involves establishing a substan-tially constant presence of dialysate fluid within the peritoneum of a patient at all times over an extended period of time, said apparatus comprising:

an in-dwelling catheter adapted to be surgically implanted in the peritoneal cavity of a patient and having a supply tube for extending through the abdominal wall of the patient; and a bag adapted to be interconnected with the supply tube during dialysis for dispensing dialysate fluid through the supply tube to the peritoneal cavity of the patient and for receiving spent dialysate drained from the peritoneal cavity of the patient.

3. The apparatus of claim 2 which further comprises:

a quick disconnect coupling attached to the end of the supply tube; and a coupling attachment on the bag for interconnection with the coupling on the end of the supply tube.

4. The apparatus of claim 2 which further comprises:

a coupling attached to the end of the supply tube; and a cap for attachment to the coupling on the end of the supply tube to seal the end thereof.

5. The apparatus of claim 2 which further comprises a wearable micrabiological filter interposed between the catheter and the bag for preventing the introduction of bacteria to the peritoneum.

6. Apparatus for performing continuous ambulatory peri-toneal dialysis on a patient, which comprises:

an in-dwelling catheter adapted to be surgically implanted in the patient;

a tube connected to the catheter and extending through the abdominal wall of the patient to terminate externally of the patient for providing fluid communicative access to the patient's peritoneal cavity;

a coupling connector attached to the external end of the catheter tube;

a bag of dialysate fluid;

a tube connected to the bag for providing dialysate fluid flow to and from the bag;

a coupling connector attached to the end of the bag tube;

the catheter tube connector and the bag tube connector being adapted for mating interconnection to provide for an infusion of dialysate fluid into the patient's peritoneal cavity from the bag for residence in the cavity over a period of time during which the patient remains ambulatory and providing for repeated exchange of dialysate fluid several -times per day by draining the spent dialysate fluid from the patient's peritoneal cavity and immediately infusing fresh dialysate fluid.

7. The apparatus of claim 6 which further comprises:

a cap for placement on the catheter tube connector during the period of residence of the dialysate fluid within the patient.

8. The apparatus of claim 6 which further comprises a wearable microbiological filter unit interposed between the catheter and the catheter tube connector for preventing the introduction of bacteria with infused dialysate fluid.

9. The apparatus of claim 6 which further comprises:

a clamp disposed on the bag tube between the bag and the bag tube connector for opening and closing the bag tube to fluid communication therethrough.

10. Apparatus for performing continuous ambulatory peri-toneal dialysis on a patient, which comprises:

an in-dwelling catheter adapted to be surgically implanted in the patient;

a tube connected to the catheter and extending through the abdominal wall of the patient for providing fluid communicative access to the patient's peri-toneal cavity from outside the patient's body;

a T connector attached to the catheter tube providing first and second fluid flow paths in communication with the catheter tube;

a first coupling connector attached to one branch of the T connector;

a second coupling connector attached to the other branch of the T connector;

a bag of dialysate fluid;

a tube connected to the bag for providing a discharge path for the dialysate fluid from the bag;

a coupling connector attached to the end of the dialysate bag tube for mating interconnection with the coupling connector on one branch of the T connector;

(claim 10 cont'd) an empty bag for holding spent dialysate fluid drained from the patient's peritoneal cavity;

a tube connected to the drainage bag for directing drained fluid into the drainage bag;

a coupling connector attached to the end of the drainage bag tube for mating interconnection with the coupling connector on the other branch of the T
connector;

a clamp disposed on one branch of the T connector for opening and closing the branch to fluid communi-cation between the dialysate fluid bag and the patient's peritoneal cavity; and a clamp disposed on the other branch of the T connector for opening and closing the branch to fluid commu-nication between the drainage bag and the patient's peritoneal cavity.