Is CAPD the Panacea for Chronic Renal Failure?

Is CAPD the Panacea for Chronic Renal Failure? Christina M. Comty, M.D.

D

URING the past four years continuous ambulatory peritoneal dialysis (CAPD) has become accepted as a method of treating the patient with end-stage renal disease, and at the International Symposium on CAPD in Berlin in June, 1981, it was estimated that more than 7000 patients throughout the world may be on this form of treatment. Many advantages have been reported for CAPD, including decreased cost, promotion of home dialysis, an increase in the weekly clearance of small and middle molecules, few dietary and fluid restrictions, and a decreased incidence of thirst, anemia, and hypertension. 1-3 The Regional Kidney Disease Program at Hennepin County Medical Center in Minneapolis provides all forms of therapy for patients with chronic renal failure from North and South Dakota, Minnesota, and upper Michigan. Transplantation is encouraged in suitable patients, and approximately 400 patients are maintained on dialytic therapy at any time, including 120 to 130 patients on home dialysis. In October 1979, we introduced CAPD as an alternative to chronic hemodialysis or peritoneal dialysis, the only selection criteria being that the patient had vision and manual dexterity to change the bags and that a functioning Tenckhoff double cuffed chronic catheter could be established. Training was performed by home dialysis personnel, and all patients were trained to obtain samples for peritoneal cell counts and bacteriology and to add antibiotics and heparin to the dialysate in the event of peritonitis. Diabetic patients who required insulin continued to use a mixture of regular and NPH insulin subcutaneously twice daily. Between October 1979 and November 1981, 46 patients ranging in age from 22 to 84 yr were trained to perform CAPD, and one CAPD patient was transferred from another program. The outcome of these 47 patients is shown in Table 1. The

From the Regional Kidney Disease Program at Hennepin County Medical Center, Minneapolis, Minn. Reprint requests should be addressed to Christina M. Comty, M.D., Regional Kidney Disease Program, Hennepin County Medical Center, 701 Park Al'enue, Minneapolis, Minn. 55415. © 1982 by The National Kidney Foundation, Inc. 0272-6386/82/030386-04$01.00/0

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duration of CAPD ranged from 1 to 30 mo (total exposure 420 patient-months). Twelve patients (26%) died after 1'-12 mo on CAPD, but no deaths were caused by CAPD. Only 19 patients (40%) are still on CAPD, representing about 5% of our total dialysis popUlation. Our results thus far do not confirm the enthusiastic reports of other centers, and CAPD in our hands at present is not overwhelmingly successful in the treatment of patients with end-stage renal disease, The reasons for this are unclear. To the patient, the attractiveness of CAPD is the relative simplicity, the lack of blood, and the absence of awesome equipment. Furthermore, patients have relative freedom and independence and can return to their home environment without the expense of prolonged training, Although all patients are told of the dangers and seriousness of peritonitis, they appear to be relatively undaunted, at least until they experience their first episode of peritonitis, However, a 22-yr-old female and a 60-yr-old male were unwilling to accept the chronic abdominal distention of CAPD and returned to hemodialysis. Other patients have declined CAPD on the grounds that they prefer not to be involved with dialysis every day of the week. Our experience with peritonitis is similar to that of other centers; namely, one episode every 10'- 11 patient-months of treatment. The majority of episodes have been caused by Staph epidermidis, On several occasions other organisms have been implicated in association with urinary tract infection in patients with polycystic kidney disease or when peritonitis was secondary to a tunnel infection. No deaths have occurred from peritonitis, unlike the experience reported by Khanna et ai, , 3 but 50% of patients required hospitalization because of the severity of their illness. Although we discontinued CAPD in two patients because of severe peritonitis, four other patients have each had three episodes of peritonitis without apparent ill effect on peritoneal function, Other problems have included the development of herniae in 25% of patients, worsening of hiatal hernia symptoms, worsening of chronic backache, and severe constipation. The high incidence of ab-

American Journal of Kidney Diseases, Vol. /I, No.3 (November), 1982

SUCCESS OF CAPO -

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Table 1. Outcome In CAPO Patients (47 Patients, April 1982) Remain on CAPO 19 patients (40%) Mean time 15.5 mo (range 6-28) Expired 12 patients (26%) Cancer (1), stopped dialysis (1), sepsis (3), pulmonary fibrosis (1) Mean time 5.5 mo (range 1-12) Changed Therapy: 16 Patients (34%) Patient Preference 2 patients transferred to hemodialysis (1,7 mol Severe Peritonitis 2 patients (8-14 mol Inadequate Dialysis 8 patients Mean time 12 mo (range 6-30) Miscellaneous Reasons Transplantation (1), inflammatory bowl disease (1), pulmonary problems (1) , diabetic neuropathy (1)

dominal herniae is perturbing since herniorrhaphy requires discontinuation of CAPD for 4 wk, and patients without hemodialysis access or hemodialysis facilities have been forced to stay in a hotel at their own expense so as to undergo peritoneal dialysis in the center. Inadequate dialysis is not mentioned a s asignificant problem for CAPD patients in reports from other centers, 1-3 but we have discontinued CAPD in eight patients for this reason, and three of these patients also experienced difficulty with ultrafiltration. None of the patients had problems with recurrent peritonitis. All eight patients developed a variety of complaints including tiredness and lethargy, sleeplessness, depression, pruritus, nausea, anorexia, a metallic taste , and leg cramps. Similar complaints have been described in a high percentage of patients on CAPD in other programs , but inadequate dialysis has not been mentioned . 3 Three patients developed burning dysthesias imd numbness in the feet. Serum creatinine levels had risen progressively in all eight patients and were in excess of 18 mg/dl despite five exchanges daily. Interestingly enough, BUN values increased very little, probably because anorexia caused dietary protein intake to fall in all patients (as shown by urea generation rate), but caloric requirements were maintained from dialysate glucose. All the patients improved dramatically after returning to hemodialysis . A typical example is patient E.L. (Table 2), a

387 Table 2.

Biochemical Results In a Patient With CAPO Failure Prenephrectomy Postnephrectomy January 1980 July 1980 October 1980

WI. (Ib)

Serum BUN mgldl Creatinine mgldl Peritoneal Fluid Total creatinine mg/24 hr Urine Total creatinine mg/24 hr Clearance ml/min

179

75 12.7

191

63 12.0

185

77 18.1

771

858

1562

607

878

0

3.3

5.1

0

heavy, muscular farmer who was very well on CAPD until he underwent bilateral nephrectomy for hypertension in preparation for transplantation. Prior to nephrectomy serum creatinine levels were very stable, with a residual renal clearance of 3- 5 rnl/min. More than 800 mg of creatinine were excreted daily in the urine, and a further 800 mg of creatinine was removed by the peritoneum with four exchanges daily . Following nephrectomy serum creatinine values rose to 18 mg/dl, and on five exchanges daily he was removing 1562 mg creatinine. In February 1981 , after 13 mo on CAPD, he developed symptoms of inadequate dialysis and became very depressed. His serum creatinine rose to 20 mg/dl and he developed peritonitis, at which time he was started on hemodialysis. Although damage to the peritoneal membrane by infection , and possibly by use of hypertonic solutions, is a possible reason for failure of CAPD , the presence of residual renal function may be critical. Serial measurements of renal and peritoneal clearances of creatinine and urea have been performed on all our patients. The peritoneal clearances in many patients are only slightly better than the patients' renal clearance was at .the time that they were considered in need of dialysis . We have observed a tendency for creatinine generation rates to rise in younger, more active individuals as nutrition improves after they start CAPD, at the same time that their residual renal function is dwindling . Our results suggest that CAPD may provide ade-

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quate dialytic therapy only for those patients who maintain a residual renal creatinine clearance of between 2 and 5 ml/min, or for individuals who because of age and bodily build (for example, older women) have a smaller muscle mass and hence a lower creatinine generation rate. In fact, the majority of our patients who have done well and continue on CAPO are older females . The most publicized advantage of CAPO is that it is claimed to be somewhat cheaper than any other form of dialytic treatment. Nonetheless, careful cost accounting in our program suggests that this claim needs clarification. Home hemodialysis is expensive for the first year of treatment because of the cost of 4-6 wk of home dialysis training and the initial cost of establishing the patient at home . It is also expensive to the patient who is responsible for traveling and living expenses if away from home. However, after the first year home hemodialysis is cheaper than CAPO. The cost savings with CAPO are two-fold: training of patients takes between 5 and 15 days in most centers; secondly, because the technique is simple, many more patients can be dialyzed at home, avoiding more expensive outpatient hemodialysis. Nevertheless, the real cost of CAPO has not been fully evaluated , and there are hidden costs with CAPO that have imposed considerable financial hardships to our patients in the midwest. These include the cost of travel to the center for monthly changes of the tubing. Because of this we have allowed many patients to perform their own line changes and to return to be seen every 3 mo. The high cost of oral antibiotic therapy is borne by the patient, since Medicare only reimburses the cost of intraperitoneal antibiotics. Other costs to the patient are incurred in relation to peritoneal catheter malfunction , which is more frequent than are problems with hemodialysis access such as a simple or bovine fistula. Finally, the other major expense of CAPO not included in the quoted cost of dialysis is that of hospitalization which may be necessary for patients with severe peritonitis or where peritonitis has not improved with outpatient administration of intraperitoneal antibiotic therapy . CCPO (continuous cycle peritoneal dialysis) has been described as a method of perfomling CAPO with a lower incidence of peritonitis. Nevertheless , CCPO condemns the patient to treatment with a machine every night and does not improve the ade-

CHRISTINA M. COMTY

quacy of dialysis or eliminate the other disadvantages of CAPO, especially the abdominal distention . CCPO completely negates any financial advantage of CAPO, since the cost of CCPO is very high. In discussing the present role of CAPO, nephrologists must ask themselves which patients (or all patients) should be treated ? Are poor compliance and peritonitis really the major limiting factors in the application of CAPO to a large number of patients? Undoubtedly patients see many advantages in CAPO and are strongly influenced by the enthusiasm with which it is presented. If faced with having to choose either CAPO or death from renal failure, the patient usually will choose CAPO. If CAPO is the only form of dialysis a patient has experienced, they may never know the difference between poor or inadequate dialysis and good dialysis. Even after 22 yr of chronic hemodialysis for end-stage renal disease, rhere is no consensus of opinion as to what constitutes adequate dialysis or the best way to monitor adequacy of dialysis. The great question remains with CAPO, as with other dialysis therapies, in order to determine whether or not a patient is getting adequate dialysis, what are the useful and easy parameters to monitor? Should one ignore blood levels of smaller molecular compounds such as creatinine and wait for a patient to develop peripheral neuropathy ? Should alternative methods of treatment be available at centers offering CAPO? Although CAPO is a useful method of treating end-stage renal disease in selected patients, its future is uncertain. The incidence of peritonitis is associated with considerable morbidity (and mortality in some centers) and is unacceptable for routine dialytic therapy . At the present time little is known about the normal defense mechanisms of the peritoneal cavity, and prevention of peritonitis may not be a question of improving hardware or technique but may be an intrinsic problem with CAPO itself. This is because some patients may have an inadequate peritoneal defense mechanism because of inadequate macrophage function or some other humoral mechanism and may not be suitable for CAPO. The other possibility is that introduction of the unphysiologic CAPO solution into the abdominal cavity may paralyze an otherwise adequate defense mechanism , leaving the patient vulnerable to bacterial, viral, or fungal invasion. The future success of CAPO may well de-

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FACT OR FICTION

pend on whether or not these questions can be answered. Continuous ambulatory peritoneal dialysis, performed as an alternative to hemodialysis or intermittent peritoneal dialysis in a large regional center, has been associated with many problems. These include peritonitis, inadequate dialysis, and herniae formation. Although there are cost savings

associated with the use of CAPD, there are many hidden costs, and often these are the responsibility of the patient. Major costs may be incurred as the result of peritonitis, including antibiotic therapy and hospitalization, costs which may be consid,erable and which may make the cost of CAPD similar to that of center dialysis in some patients.

REFERENCES 1. Popovich RP, Moncreif JW, Nolph KD, et al: Continuous ambulatory peritoneal dialysis. Ann Intern Med 88:449-456, 1978 2. Gokal R, McHugh M, Fryer R, et al: Continuous ambulatory peritoneal dialysis. One year's experience in a UK dialysis unit. Br Med J 474-477, 1980

3. Khanna R, Oreopoulos DG, Dombros N, et al: Continuous ambulatory peritoneal dialysis (CAPD) after three years: Still a promising treatment. Peritoneal Dialysis Bulletin 1:2425, 1981