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Peritoneal Dialysis for Patients in Uremia Secondary to Obstructive Disease
THE JoURNAL OF UROLOGY
Copyright© 1972 by The Williams & Wilkins Co.
PERITONEAL DIALYSIS }'OR PATIENTS IN UREMIA SECONDARY TO OBSTRUCTIVE DISEASE ROGEHS N. RIECHERS
.,ND
HERBERT BRENDLER
From the Department of Urology, Mount Sinai School of ]vledicine ancl the Urology Services, Mount Sinai Hospital and Kingsbridge Veterans Administration Hospital, New York, New York
:\!lost patients with uremia secondary to urinary tract obstruction present no problems in management. They can be treated successfully by prompt relief of obstruction and standard hospital practices, such as salt and volume replacement and reversal of electrolyte and acid base abnormalities. However, when obstructive disease is severe or has been prolonged, the degree of renal failure may be marked. The patient's clinical condition may be so precarious and the renal reserve so marginal, that deterioration and death will follow without immediate correction of the uremic state by dialysis. The use of hemodialysis in uremic subjects suffering various types of obstructiv,3 disease has been described previously. 1 • 2 However, not all hospitals possess facilities for hemodialysis and even when available, such facilities may be overtaxed an existing chronic dialysis program is the case in our own center). Furthermore, hemodialysis may be contraindicated, for example in the presence of active bleeding, and peritoneal dialysis may be used to advantage.
cases are described herein in some detail. In each case diagnosis of urinary tract obstruction was suspected but not established at the time of admission to the renal unit. The intermittent exchange method has been used in virtually every instance. This involves placement of a multiholed silastic catheter in the peritoneal cavity under local anesthesia. Two liters of dialysis fluid* are infused as rapidly as possible, then permitted to equilibrate in the peritoneal cavity for 20 minutes with the tubing clamped. The dialysate is then drained which requires from 20 minutes to 2 hours. The cycle is then repeated. Approximately 25 such exchanges are carried out in the course of a single dialysis, which takes 24 to 36 hours to complete. The catheter is removed at the conclusion of the procedure. Dialysis by the intermittent exchange method is adjusted to the individual patient's requirements. In general, this works out to about 1 to 2 times weekly. Hemoglobin and blood chemistry values are monitored before and at the conclusion of the procedure.
MATERIAL AND METHODS
The present chronic peritoneal dialysis program at the Kingsbridge Hospital was established in 1968. During the past 3 years, 3,432 dialyses have been done, most of which have been for chronic renal insufficiency associated with primary renal disease. This series mcludes 12 patients with some form of obstructive disease who required dialysis one or more times. Two Accepted for publication April 15, 1971. 1 Fox, M. and Parsons, F. M.: Indications for haemodialysis in advanced uraemic prostatic obstruction. Brit. J. Urol., 36: 487, 1964. 2 Fox, M. and Parsons, F. l\!I.: Value of dialysis in obstructive lesions of the upper urinary tract. Brit. J. Urol., 41: 197, * Inpersol, Abbott North Chicago, Illinois. Inpersol contains mEq./L sodium, 3.5 mEq./L calcium, 1.5 mEq./L magnesium, 101.0 mEq./L chloride, 44.5 mEq./I lactate and 15 or 70 gm./L dextrose. Inpersol-K also contains 4.0 mEq./L potassium and the chloride is 105.0 mEq./L.
CASE REPORTS
Case 1. A. B., KVAH 111-07-5141, a old man with a known history of urethral stricture and previously normal renal function, was admitted to the hospital in a semicornatose state. According to the family, he had manifested progressive difficulty in voiding associated with increasing mental confusion. The patient was quite tachypneic and thought to have pulmonary. edema. Blood chemistry studies revealed the blood urea nitrogen (I3UN) to be 224 mg. per cent, creatinine 18 mg. per cent, carbon dioxide 7.6 mEq. per L and potassium 5.6 per L. The patient was too agitated to obtain satisfactory plain films of the abdomen. The bladder was markedly distended. Catheterization was impossible because of an impenetrable urethral stricture. Therefore, emergency punch cystostomy was performed. Because of the 341
342
RIECHERS AND BRENDLER
patient's extremely critical condition, peritoneal dialysis was begun immediately. With drainage plus dialysis, the BUN fell during the first day to 148 mg. per cent and the patient's mental status improved. A daily diuresis of 5 to 6 L resulted during the first few days. By 7 days the BUN had fallen to 45 mg. per cent (fig. 1). The patient continued to improve clinically. N ephrotomography at the end of the first week disclosed a branched calculus in a shrunken right kidney and 3 lower ureteral stones on the same side. Hydronephrosis and massive ureteral dilatation were noted on the left side. The cause of this condition could not be ascertained from the nephrotomograms and cystoscopy was technically impossible because of the urethral stricture. The patient continued to improve and by 20 days the BUN had decreased to 35 mg. per cent. The patient's condition now was considered satisfactory for an operation. The following day, 3 weeks after initial punch cystostomy and dialysis, the bladder was opened and the left ureter was catheterized. A retrograde ureteropyelogram effectively ruled out the presence of additional stones or stricture on that side. The 3 ureteral CASE I A.B. ( 111-07-5141 l
DIALYSIS ( 24hrs.l 175-
BUN
150125-
mg% 100-
7550-
•
QR
·. ···-·-·-·-·---.--...-·-·-· i -·
250I
3
5 7 9 II
13 15 17 19 21 23 25 DAYS
Fm. 1
calculi were removed by right ureterolithotomy. A large cystostomy tube was left indwe,lling.
Convalescence was uneventful, no further dialysis being required. Followup BUN values have ranged from 30 to 35 mg. per cent. No decisions have been made as to further management of the right renal calculus and urethral stricture. Case 2. G. P., KVAH 107-20-1805, a 42-yearold man, had had documented pulmonary sarcoidosis 10 years in duration and had been hypercalcemic for at least 4 years prior to hospitalization. Two years before entering the hospital the patient had been gainfully employed and feeling well. At that time the BUN was only slightly elevated (26 mg. per cent) and serum calcium was 11.4 mg. per cent (normal 8.5 to 10.5). In the ensuing 2 years he had experienced progressive clinical deterioration, marked in the last few months by anorexia, weight loss, weakness and, ultimately, lethargy. He was admitted to another hospital in a uremic state. Initial laboratory studies revealed BUN 196 mg. per cent, serum creatinine 8.3 mg. per cent and serum calcium 11.3 mg. per cent. Plain films of the abdomen were interpreted as showing bilateral nephrocalcinosis (later proved incorrect). No excretory urogram (IVP) was obtained because of the azotemia. The patient was treated with saline infusions, protein-restricted diet and corticosteroids but renal function continued to worsen. The serum creatinine value rose to 21 mg. per cent. Peritoneal dialysis resulted in a rapid fall in the BUN and serum creatinine (fig. 2). The patient's general condition improved at first but during the next 3 weeks he gradually lost ground. Therefore, he was transferred to our hospital for enrollment in a chronic dialysis program. The presumptive diagnosis was chronic renal CASE 2
G.P. (107-20·1805 l
225-a: DIALYSIS 220 _~-"'2,,(24hrs.)
ADMISSION
§§
_DIALYSIS
t./ ( 24hrs.l
~ ~
~
BUN mg%
~..-7
I 00-
:
7550-
_________ •
lJ 0.R
i---.--·--~"--·-~· _._, ,. . .-·~·-·-· ~i :
0 25;'.: o-,....._......_......_......_......_......_......_....._......_......_;W,WWWWc...L..l2;"'-''--'-'WW~*~~~~70
3wks.
r--1 wk.
Fm. 2
~---Gwks.~
343
PERITONEAL DIALYSIS
demonstrated the hypercalcemia to be due to the sarcoidosis and not to secondary hyperparathyroidism. DISCUSSION
Fm. 3
insufficiency secondary to sarcoidosis with hypercalcemia and nephrocalcinosis. On admission the BUN was 66 mg. per cent and serum creatinine 8.6 mg. per cent. An infusion IVP with tomographic cuts demonstrated bilaterally shrunken kidneys with multiple, small, caliceal stones but no evidence of medullary calcification. 'J'he right side functioned promptly but there was delayed excretion on the left side associated with a dilated collecting system down to the level of an obstructing stone in the mid ureter. A large, nonobstructing stone was present at the left ureteropelvic junction (fig. 3). In view of the patient's precarious condition, an operation was delayed until 24-hour peritoneal dialysis could be done. At operation the left ureteral calculus was removed without difficulty. Pyelolithotomy was then performed, along with removal of all caliceal stones. A post-obstructive diuresis then occurred but was handled without incident. Therefore, convalescence was uneventful. The serum creatinine stabilized at about 7 mg. per cent. No further dialysis was required. The patient was discharged from the hospital on salt supplements and a moderately restricted protein diet. A dexamethasone suppression test performed subsequently
In renal failure secondary to obstructive disease, peritoneal dialysis serves 3 purposes: 1) Lifesaving: Acidosis, hyperkalemia, hyponatremia and volume depletion are common imbalances in the uremic patient which can be corrected by dialysis. Drainage alone or in combination with salt and volume replacement may not suffice in patients with severe depletion of renal reserve. In such patients the addition of dialysis substitutes for the essential regulatory functions of the kidneys until the latter have recovered sufficiently. 2) Diagnostic: It is essential that the nature of the obstruction be defined without delay in order to institute appropriate drainage. Routine IVP is usually of little help in severely uremic subjects, except perhaps to visualize the kidney outlines on the plain film and identify radiopaque calculi. Cystoscopy and retrograde pyelography may not be possible, either for technical reasons (as in case I) or because general anesthesia is required with its attendant risks. Preliminary peritoneal dialysis reverses the agitation and confusion of uremia, thus rendering the patient more cooperative for cystoscopic procedures. Therefore, general anesthesia may not be required. The procedure also improves the patient's general condition to the point at which, should anesthesia be necessary, he will tolerate it better. Finally, there is recent evidence suggesting that vigorous dialysis immediately prior to infusion IVP can appreciably improve visualization of the collecting systems in advanced uremia. 3 Brown and associates reported on the successful use of peritoneal dialysis prior to single-injection high-dose IVP in the diagnosis of obstruction in 21 oliguric subjects. 4 3) Preoperative: The severely uremic patient is a poor candidate for a major operation. He is malnourished, in poor general health and suffers from impaired resistance to infection and delayed wound healing. Even after extended periods of 3 Matalon, R. and Eisinger, R. P.: Successful • mtravenous pyelography in advanced uremiavisualization in the post:dialytic state. New Engl. J. Med., 282: 835, 1970. 4 Brown, C. B., Glancy, J. J., Fry, I. K. and Cattell, W.R.: High-dose excretion uroo-raphy in oliguric renal failure. Lancet, 2: 952, 1970.
344
RIECHERS AND BRENDLERS
drainage and vigorous corrective measures, some of these patients never improve sufficiently to undergo an operation with safety. Furthermore, the increased protein breakdown following a major operation may prove too much of a load for an already compromised renal reserve. Preoperative dialysis can be beneficial in such situati~ns. Considerable improvement can be expected within 24 to 48 hours. Not only may an operation be undertaken sooner and with less risk but there is a better chance for an uncomplicated and smooth recuperative period (case 2). Indications for dialysis. The specific indications for peritoneal dialysis in patients with urinary obstruction are difficult to describe categorically. Much depends on individual circumstances. It certainly should be done when the patient is hospitalized with symptoms of uremia, regardless of the BUN levels. Patients with marked elevations of BUN (greater than 150 mg. per cent) who do not show a drop of at least 50 per cent following 24 to 48 hours of catheter drainage also should undergo dialysis promptly. The presence of infection increases the risk of overloading the kidneys, which are damaged severely with the products of protein catabolism, and constitutes still another indication for early dialysis. Because hemodialysis is capable of more rapid reversal of biochemical abnormalities, the usefulness of peritoneal dialysis in obstructive urologic emergencies generally is not appreciated. However, rapid improvement in BUN levels and the patient's general condition can be expected if it is carried out early enough. Even in highly catabolic patients with extreme degrees of azotemia, peritoneal dialysis regularly lowers urea levels effectively. 5 Obviously, in such situations, the more rapid clearances achieved by hemodialysis make it the method of choice, provided it is available. Sometimes, even if it is available, 5 Pr!ngle A,. and Smit~, E. K. M.: Daily perito1 neal drnlys1s m renal failure. Brit. J. Urol., 36: 493, 1964.
dialysis by the peritoneal route may be preferable. This is true in patients with severe chronic renal failure due, for example, to long-standing prostatic obstruction in whom too rapid correction of metabolic abnormalities may lead to hypotension or hypokalemia. Also, as previously mentioned, active bleeding constitutes a contraindication to hemodialysis because of the heparinization required. In addition to its availability and effectiveness, peritoneal dialysis enjoys the advantages of relative ease and simplicity. Complications are uncommon but may include localized peritoneal infection, transient hypotension, loss of protein which is easily remedied, significant bleeding at times and leakage around the tube which can be somewhat troublesome. SUMMARY AND CONCLUSIONS
Not all patients with renal insufficiency secondary to urinary obstruction require, or would benefit from, peritoneal dialysis. Most of these patients can be handled satisfactorily with drainage and correction of metabolic abnormalities. Such patients usually enjoy a relatively rapid return of renal function paralleled by generalized clinical improvement. In addition, they tolerate anesthesia and major operative procedures without difficulty. However, there are other patients who enter the hospital in such extreme renal decompensation that the foregoing measures may prove inadequate to support life. It is in this type of patient that peritoneal dialysis has its best application. The procedure facilitates and improves the quality of diagnostic evaluation and permits needed surgical procedures to be carried out sooner and with less risk. It should be considered of potential benefit in all patients with severe uremia owing to obstructive disease. Two illustrative cases have been described and the specific indications for dialysis are discussed.
Copyright© 1972 by The Williams & Wilkins Co.
PERITONEAL DIALYSIS }'OR PATIENTS IN UREMIA SECONDARY TO OBSTRUCTIVE DISEASE ROGEHS N. RIECHERS
.,ND
HERBERT BRENDLER
From the Department of Urology, Mount Sinai School of ]vledicine ancl the Urology Services, Mount Sinai Hospital and Kingsbridge Veterans Administration Hospital, New York, New York
:\!lost patients with uremia secondary to urinary tract obstruction present no problems in management. They can be treated successfully by prompt relief of obstruction and standard hospital practices, such as salt and volume replacement and reversal of electrolyte and acid base abnormalities. However, when obstructive disease is severe or has been prolonged, the degree of renal failure may be marked. The patient's clinical condition may be so precarious and the renal reserve so marginal, that deterioration and death will follow without immediate correction of the uremic state by dialysis. The use of hemodialysis in uremic subjects suffering various types of obstructiv,3 disease has been described previously. 1 • 2 However, not all hospitals possess facilities for hemodialysis and even when available, such facilities may be overtaxed an existing chronic dialysis program is the case in our own center). Furthermore, hemodialysis may be contraindicated, for example in the presence of active bleeding, and peritoneal dialysis may be used to advantage.
cases are described herein in some detail. In each case diagnosis of urinary tract obstruction was suspected but not established at the time of admission to the renal unit. The intermittent exchange method has been used in virtually every instance. This involves placement of a multiholed silastic catheter in the peritoneal cavity under local anesthesia. Two liters of dialysis fluid* are infused as rapidly as possible, then permitted to equilibrate in the peritoneal cavity for 20 minutes with the tubing clamped. The dialysate is then drained which requires from 20 minutes to 2 hours. The cycle is then repeated. Approximately 25 such exchanges are carried out in the course of a single dialysis, which takes 24 to 36 hours to complete. The catheter is removed at the conclusion of the procedure. Dialysis by the intermittent exchange method is adjusted to the individual patient's requirements. In general, this works out to about 1 to 2 times weekly. Hemoglobin and blood chemistry values are monitored before and at the conclusion of the procedure.
MATERIAL AND METHODS
The present chronic peritoneal dialysis program at the Kingsbridge Hospital was established in 1968. During the past 3 years, 3,432 dialyses have been done, most of which have been for chronic renal insufficiency associated with primary renal disease. This series mcludes 12 patients with some form of obstructive disease who required dialysis one or more times. Two Accepted for publication April 15, 1971. 1 Fox, M. and Parsons, F. M.: Indications for haemodialysis in advanced uraemic prostatic obstruction. Brit. J. Urol., 36: 487, 1964. 2 Fox, M. and Parsons, F. l\!I.: Value of dialysis in obstructive lesions of the upper urinary tract. Brit. J. Urol., 41: 197, * Inpersol, Abbott North Chicago, Illinois. Inpersol contains mEq./L sodium, 3.5 mEq./L calcium, 1.5 mEq./L magnesium, 101.0 mEq./L chloride, 44.5 mEq./I lactate and 15 or 70 gm./L dextrose. Inpersol-K also contains 4.0 mEq./L potassium and the chloride is 105.0 mEq./L.
CASE REPORTS
Case 1. A. B., KVAH 111-07-5141, a old man with a known history of urethral stricture and previously normal renal function, was admitted to the hospital in a semicornatose state. According to the family, he had manifested progressive difficulty in voiding associated with increasing mental confusion. The patient was quite tachypneic and thought to have pulmonary. edema. Blood chemistry studies revealed the blood urea nitrogen (I3UN) to be 224 mg. per cent, creatinine 18 mg. per cent, carbon dioxide 7.6 mEq. per L and potassium 5.6 per L. The patient was too agitated to obtain satisfactory plain films of the abdomen. The bladder was markedly distended. Catheterization was impossible because of an impenetrable urethral stricture. Therefore, emergency punch cystostomy was performed. Because of the 341
342
RIECHERS AND BRENDLER
patient's extremely critical condition, peritoneal dialysis was begun immediately. With drainage plus dialysis, the BUN fell during the first day to 148 mg. per cent and the patient's mental status improved. A daily diuresis of 5 to 6 L resulted during the first few days. By 7 days the BUN had fallen to 45 mg. per cent (fig. 1). The patient continued to improve clinically. N ephrotomography at the end of the first week disclosed a branched calculus in a shrunken right kidney and 3 lower ureteral stones on the same side. Hydronephrosis and massive ureteral dilatation were noted on the left side. The cause of this condition could not be ascertained from the nephrotomograms and cystoscopy was technically impossible because of the urethral stricture. The patient continued to improve and by 20 days the BUN had decreased to 35 mg. per cent. The patient's condition now was considered satisfactory for an operation. The following day, 3 weeks after initial punch cystostomy and dialysis, the bladder was opened and the left ureter was catheterized. A retrograde ureteropyelogram effectively ruled out the presence of additional stones or stricture on that side. The 3 ureteral CASE I A.B. ( 111-07-5141 l
DIALYSIS ( 24hrs.l 175-
BUN
150125-
mg% 100-
7550-
•
QR
·. ···-·-·-·-·---.--...-·-·-· i -·
250I
3
5 7 9 II
13 15 17 19 21 23 25 DAYS
Fm. 1
calculi were removed by right ureterolithotomy. A large cystostomy tube was left indwe,lling.
Convalescence was uneventful, no further dialysis being required. Followup BUN values have ranged from 30 to 35 mg. per cent. No decisions have been made as to further management of the right renal calculus and urethral stricture. Case 2. G. P., KVAH 107-20-1805, a 42-yearold man, had had documented pulmonary sarcoidosis 10 years in duration and had been hypercalcemic for at least 4 years prior to hospitalization. Two years before entering the hospital the patient had been gainfully employed and feeling well. At that time the BUN was only slightly elevated (26 mg. per cent) and serum calcium was 11.4 mg. per cent (normal 8.5 to 10.5). In the ensuing 2 years he had experienced progressive clinical deterioration, marked in the last few months by anorexia, weight loss, weakness and, ultimately, lethargy. He was admitted to another hospital in a uremic state. Initial laboratory studies revealed BUN 196 mg. per cent, serum creatinine 8.3 mg. per cent and serum calcium 11.3 mg. per cent. Plain films of the abdomen were interpreted as showing bilateral nephrocalcinosis (later proved incorrect). No excretory urogram (IVP) was obtained because of the azotemia. The patient was treated with saline infusions, protein-restricted diet and corticosteroids but renal function continued to worsen. The serum creatinine value rose to 21 mg. per cent. Peritoneal dialysis resulted in a rapid fall in the BUN and serum creatinine (fig. 2). The patient's general condition improved at first but during the next 3 weeks he gradually lost ground. Therefore, he was transferred to our hospital for enrollment in a chronic dialysis program. The presumptive diagnosis was chronic renal CASE 2
G.P. (107-20·1805 l
225-a: DIALYSIS 220 _~-"'2,,(24hrs.)
ADMISSION
§§
_DIALYSIS
t./ ( 24hrs.l
~ ~
~
BUN mg%
~..-7
I 00-
:
7550-
_________ •
lJ 0.R
i---.--·--~"--·-~· _._, ,. . .-·~·-·-· ~i :
0 25;'.: o-,....._......_......_......_......_......_......_....._......_......_;W,WWWWc...L..l2;"'-''--'-'WW~*~~~~70
3wks.
r--1 wk.
Fm. 2
~---Gwks.~
343
PERITONEAL DIALYSIS
demonstrated the hypercalcemia to be due to the sarcoidosis and not to secondary hyperparathyroidism. DISCUSSION
Fm. 3
insufficiency secondary to sarcoidosis with hypercalcemia and nephrocalcinosis. On admission the BUN was 66 mg. per cent and serum creatinine 8.6 mg. per cent. An infusion IVP with tomographic cuts demonstrated bilaterally shrunken kidneys with multiple, small, caliceal stones but no evidence of medullary calcification. 'J'he right side functioned promptly but there was delayed excretion on the left side associated with a dilated collecting system down to the level of an obstructing stone in the mid ureter. A large, nonobstructing stone was present at the left ureteropelvic junction (fig. 3). In view of the patient's precarious condition, an operation was delayed until 24-hour peritoneal dialysis could be done. At operation the left ureteral calculus was removed without difficulty. Pyelolithotomy was then performed, along with removal of all caliceal stones. A post-obstructive diuresis then occurred but was handled without incident. Therefore, convalescence was uneventful. The serum creatinine stabilized at about 7 mg. per cent. No further dialysis was required. The patient was discharged from the hospital on salt supplements and a moderately restricted protein diet. A dexamethasone suppression test performed subsequently
In renal failure secondary to obstructive disease, peritoneal dialysis serves 3 purposes: 1) Lifesaving: Acidosis, hyperkalemia, hyponatremia and volume depletion are common imbalances in the uremic patient which can be corrected by dialysis. Drainage alone or in combination with salt and volume replacement may not suffice in patients with severe depletion of renal reserve. In such patients the addition of dialysis substitutes for the essential regulatory functions of the kidneys until the latter have recovered sufficiently. 2) Diagnostic: It is essential that the nature of the obstruction be defined without delay in order to institute appropriate drainage. Routine IVP is usually of little help in severely uremic subjects, except perhaps to visualize the kidney outlines on the plain film and identify radiopaque calculi. Cystoscopy and retrograde pyelography may not be possible, either for technical reasons (as in case I) or because general anesthesia is required with its attendant risks. Preliminary peritoneal dialysis reverses the agitation and confusion of uremia, thus rendering the patient more cooperative for cystoscopic procedures. Therefore, general anesthesia may not be required. The procedure also improves the patient's general condition to the point at which, should anesthesia be necessary, he will tolerate it better. Finally, there is recent evidence suggesting that vigorous dialysis immediately prior to infusion IVP can appreciably improve visualization of the collecting systems in advanced uremia. 3 Brown and associates reported on the successful use of peritoneal dialysis prior to single-injection high-dose IVP in the diagnosis of obstruction in 21 oliguric subjects. 4 3) Preoperative: The severely uremic patient is a poor candidate for a major operation. He is malnourished, in poor general health and suffers from impaired resistance to infection and delayed wound healing. Even after extended periods of 3 Matalon, R. and Eisinger, R. P.: Successful • mtravenous pyelography in advanced uremiavisualization in the post:dialytic state. New Engl. J. Med., 282: 835, 1970. 4 Brown, C. B., Glancy, J. J., Fry, I. K. and Cattell, W.R.: High-dose excretion uroo-raphy in oliguric renal failure. Lancet, 2: 952, 1970.
344
RIECHERS AND BRENDLERS
drainage and vigorous corrective measures, some of these patients never improve sufficiently to undergo an operation with safety. Furthermore, the increased protein breakdown following a major operation may prove too much of a load for an already compromised renal reserve. Preoperative dialysis can be beneficial in such situati~ns. Considerable improvement can be expected within 24 to 48 hours. Not only may an operation be undertaken sooner and with less risk but there is a better chance for an uncomplicated and smooth recuperative period (case 2). Indications for dialysis. The specific indications for peritoneal dialysis in patients with urinary obstruction are difficult to describe categorically. Much depends on individual circumstances. It certainly should be done when the patient is hospitalized with symptoms of uremia, regardless of the BUN levels. Patients with marked elevations of BUN (greater than 150 mg. per cent) who do not show a drop of at least 50 per cent following 24 to 48 hours of catheter drainage also should undergo dialysis promptly. The presence of infection increases the risk of overloading the kidneys, which are damaged severely with the products of protein catabolism, and constitutes still another indication for early dialysis. Because hemodialysis is capable of more rapid reversal of biochemical abnormalities, the usefulness of peritoneal dialysis in obstructive urologic emergencies generally is not appreciated. However, rapid improvement in BUN levels and the patient's general condition can be expected if it is carried out early enough. Even in highly catabolic patients with extreme degrees of azotemia, peritoneal dialysis regularly lowers urea levels effectively. 5 Obviously, in such situations, the more rapid clearances achieved by hemodialysis make it the method of choice, provided it is available. Sometimes, even if it is available, 5 Pr!ngle A,. and Smit~, E. K. M.: Daily perito1 neal drnlys1s m renal failure. Brit. J. Urol., 36: 493, 1964.
dialysis by the peritoneal route may be preferable. This is true in patients with severe chronic renal failure due, for example, to long-standing prostatic obstruction in whom too rapid correction of metabolic abnormalities may lead to hypotension or hypokalemia. Also, as previously mentioned, active bleeding constitutes a contraindication to hemodialysis because of the heparinization required. In addition to its availability and effectiveness, peritoneal dialysis enjoys the advantages of relative ease and simplicity. Complications are uncommon but may include localized peritoneal infection, transient hypotension, loss of protein which is easily remedied, significant bleeding at times and leakage around the tube which can be somewhat troublesome. SUMMARY AND CONCLUSIONS
Not all patients with renal insufficiency secondary to urinary obstruction require, or would benefit from, peritoneal dialysis. Most of these patients can be handled satisfactorily with drainage and correction of metabolic abnormalities. Such patients usually enjoy a relatively rapid return of renal function paralleled by generalized clinical improvement. In addition, they tolerate anesthesia and major operative procedures without difficulty. However, there are other patients who enter the hospital in such extreme renal decompensation that the foregoing measures may prove inadequate to support life. It is in this type of patient that peritoneal dialysis has its best application. The procedure facilitates and improves the quality of diagnostic evaluation and permits needed surgical procedures to be carried out sooner and with less risk. It should be considered of potential benefit in all patients with severe uremia owing to obstructive disease. Two illustrative cases have been described and the specific indications for dialysis are discussed.