Zbylut J. Twardowski

Clinical Value of Standardized Equilibration Tests in CAPD Patients

Peritoneal transport rates, a critical determinant of peritoneal dialysis efficiency, vary widely among patients and may be easily categorized by standardized peritoneal equilibration test. Measurements of creatinine and glucose transfer are particularly useful in selecting optimal dialysis prescription. Patients with high-average peritoneal solute transport do well on standard CAPD even after losing residual renal function. Patients with high peritoneal solute transfer rates are likely to have inadequate ultrafiltration on standard CAPD. These patients do much better on dialysis regimens with short-dwell exchanges, such as nightly peritoneal dialysis or daytime ambulatory peritoneal dialysis. Patients with low-average and particularly with low peritoneal transport rates are likely to develop symptoms and signs of inadequate dialysis on standard CAPD as residual renal function becomes negligible, and may require high-dose peritoneal dialysis prescriptions.

Cross-sectional assessment of weekly urea and creatinine clearances in patients on continuous ambulatory peritoneal dialysis.

In 55 patients on continuous ambulatory peritoneal dialysis, the authors determined daily renal and dialysate clearances of urea nitrogen (CUN) and creatinine (CCr). Results are expressed as weekly CUN in liters (Kt) divided by liters of total body water determined from a nomogram (V). The authors calculated weekly CCr as the weekly dialysis clearance plus the average of renal CUN and CCr (to correct for creatinine secretion); they normalized total weekly CCr to 1.73 m2 body surface area. Mean weekly Kt/V and CCr were 2.1 and 65.2, respectively. Mean dietary protein intake by dietary survey was 0.85 g/kg body weight. Protein catabolic rate (PCR) calculated from urea kinetics was 0.94 g/kg standardized weight (V/0.58); PCR was significantly (p < 0.01) correlated with Kt/V (r = 0.53). The authors used linear regression to determine PCR, as follows: PCR = 0.80 [weekly Kt/V]/3 + 0.39. This slope is nearly 1.5 times that reported for the relationship of PCR to [weekly Kt/V]/3 in hemodialysis patients. Eighty-two percent of patients on continuous ambulatory peritoneal dialysis had more than the targeted minimum weekly Kt/V of 1.7, 71% had a weekly CCr more than the targeted minimum of 50, and 75% had a PCR > 0.8 g/kg/day. In support of the hypothesis that Kt/V requirements are related to peak concentration control rather than to time averaged blood urea nitrogen, patients on continuous ambulatory peritoneal dialysis have a higher PCR at given Kt/V values compared to hemodialysis patients. These patients are more likely to have a PCR > 0.8 if weekly Kt/V > 1.7.

Intraabdominal Pressures during Natural Activities in Patients Treated with Continuous Ambulatory Peritoneal Dialysis

Intraabdominal pressures were measured during natural activities in 6 men, age 24-62 years, treated with continuous ambulatory peritoneal dialysis. The pressures were measured with a pressure transducer secured at the level of the umbilicus in the supine, sitting, and upright positions with 0-3 liters intraperitoneal fluid during talking, coughing, straining, changing position, walking, jogging, exercycling, jumping and weight lifting. Coughing and straining generated the highest intraabdominal pressures in every position. The pressures with weight lifting were proportional to the magnitude of the weight lifted up to 50 lbs, but were lower than those during coughing and straining. The pressures were generally higher with greater intraabdominal fluid volumes, especially with jumping and coughing. Exercycling was associated with lower intraabdominal pressure than was jogging, and the pressures were only minimally influenced by intraperitoneal fluid volumes. The results of this study can be used as a guide in establishing preventive measures in patients with intraperitoneal fluid to decrease complication rates related to raised intraabdominal pressures such as dialysate leaks, hernias and hemorrhoids.

Hyperbaric Oxygen Therapy in Calciphylaxis-Induced Skin Necrosis in a Peritoneal Dialysis Patient

A 58-year-old white woman on continuous ambulatory peritoneal dialysis for 2 years developed calciphylaxis-induced necrotic skin lesions over both lower extremities. Despite subtotal parathyroidectomy and other conventional measures, skin lesions continued to worsen. Mapping of transcutaneous oxygen pressure showed markedly low values in involved areas. Skin ulcers completely healed after 38 sessions of hyperbaric oxygen therapy. The results in our case indicate that hyperbaric oxygen therapy may be useful in the treatment of skin ulcers secondary to calciphylaxis.

Computerized tomography with and without intraperitoneal contrast for determination of intraabdominal fluid distribution and diagnosis of complications in peritoneal dialysis patients.

Seven computed tomography scans and 19 computed tomograph peritoneography (CTP) studies performed in 20 peritoneal dialysis patients were analyzed retrospectively as to their diagnostic usefulness in peritoneal dialysis related complications. Computed tomographic peritoneography was found to be superior to computed tomography scans in localizing small leak sites. In seven of nine patients with clinically diagnosed dialysate leakage, computed tomographic peritoneography supported the clinical diagnosis and localized the leak site in six patients. All patients with a conspicuous leak site and/or with leaks through hernias had to have surgical treatment. Computed tomographic peritoneography failed to reveal a leak or identify a fluid tract in patients with intermittent, small leaks. Those leaks responded easily to a dialysis regimen with diminished intraabdominal pressure. Normal intraperitoneal fluid distribution was based on 17 studies after intraperitoneal infusion of 2,000 ml of peritoneal dialysis solution in patients without intraabdominal organomegaly and/or any clinical suspicion of fluid maldistribution, with average peritoneal transport characteristics. As appraised in the supine position, approximate fluid contents in the intraperitoneal spaces were pelvis, 30–55%; paracolic gutter, 15–30%; perisplenic and perihepatic, 10–20% each, and lesser sac, 1–3%. Severe fluid maldistribution on computed tomography peritoneography, particularly a small fluid volume in the pelvic space, is a poor prognostic sign as to the feasibility of peritoneal dialysis; neither of our two patients with no fluid in the pelvic space could be maintained on peritoneal dialysis, while patients with no fluid in the lesser sac, perihepatic and perisplenic spaces could be maintained on peritoneal dialysis. No fluid was seen in the peritoneal cavity after drainage in the vertical position. Computed tomographic peritoneography was also found useful for catheter localization in relation to fluid spaces. Potential uses of CTP include: detection of intraabdominal abcesses and other loculated intraabdominal fluid collections, diagnosis of retroperitoneal and intraperitoneal tumors, organomegaly, renal cysts and carcinomas, pancreatitis, hernias, and other problems.

Peritoneal Dialysis for Psoriasis: An Uncontrolled Study

Remissions of long-standing psoriasis have been reported in patients starting either chronic hemodialysis or peritoneal dialysis for renal failure. To see if dialysis influences the course of psoriasis in the absence of renal failure, we selected three patients with severe, refractory, long-standing psoriasis to undergo weekly peritoneal dialysis treatments. Two began to improve after the first dialysis, with nearly complete resolution after four and nine treatments, respectively. The third patient showed no objective changes after four dialyses. These findings add to increasing anecdotal reports of psoriasis improving with dialysis and extend the observations to patients without renal disease.

Continuous ambulatory peritoneal dialysis with a high flux membrane

The standard peritoneal equilibration test (PET) was performed in 66 patients on CAPD. Patients were classified as low (n=5), low average (n=22), high average (n=27), and high (n=12) transporters based on the dialysate/plasma creatinine (D/P Cr) after 4 hour dwells. After an average time interval of 14 months on CAPD, indices of dialysis adequacy and nutrition were assessed. Based on monitoring of patient chemistries and drain volumes, peritoneal transport was considered stable during the interval. Instilled volumes and exchange tonicity were individualized in each patient to achieve combined renal and dialysis weekly creatinine clearance and KT/V urea that were not significantly different between groups. Overall, there were significant positive correlations of PET D/P Cr with dialysate albumin concentrations (r=0.30, p<0.02) and dialysate albumin losses (g/wk, r=0.27, p<0.04). There were significant inverse correlations with lean body mass (r=—0.26, p<0.03), drain volumes (r=—0.025, p<0.04), and KT urea by dialysis (L/wk, r=-0.24,p<0.05). High transporters had significantly (p<0.05) lower mean serum albumin, net protein catabolic rate (nPCR), lean body mass calculated from creatinine kinetics, and daily creatinine production (and presumably lower muscle mass) compared with one or more lower transport groups. In conclusion, we hypothesize that, in high transporters, use of more hypertonic exchanges with greater glucose absorption may inhibit appetite and nPCR; also, protein losses in drain volumes are increased. High transporters may require increased clearance and protein intake targets compared with other groups to maintain nutrition. Also, high transporters may be better suited for nightly intermittent peritoneal dialysis where short cycles provide more ultrafiltration with less glucose absorption.

Peritonitis in Continuous Ambulatory Peritoneal Dialysis: Analysis of an 8-Year Experience

Experiences with peritonitis in a continuous ambulatory peritoneal dialysis (CAPD) program at a single center over 8 years were reviewed. Home-acquired peritonitis rates have been less than 1 episode per patient year since 1982. Gram-positive organisms continue to account for most episodes in a similar proportion. Actual known contamination could be pinpointed in only 7.4% of cases, but was strongly suspected in 35.8% of episodes. Exit site and/or tunnel infections were thought to have caused 20% of the cases. Intrinsic peritonitis probably accounted for 10.5%. Recurrence of peritonitis with the same organisms following cessation of antibiotics represented only 2.1% of cases.

Effects of Intraperitoneal Nitroprusside on Peritoneal Clearances in Man with Variations of Dose, Frequency of Administration and Dwell Times

Clinical studies with intraperitoneal nitroprusside were designed to examine drug effects on peritoneal clearances as a function of dose, frequency of administration and dwell times. Increases in clearances and protein losses were seen with 1 mg of nitroprusside per liter of dialysis solution, with progressively greater effects up to maximum doses of 4.5 mg/1. Maximum effects were seen at the high dose after 3 or more consecutive exchanges. Clearance effects promptly returned toward control during postdrug exchanges and, in some studies, even during alternate exchanges. Proportional effects on solute clearances appeared independent of dwell time, supporting previous studies suggesting area permeability alterations. Series of 12 or more consecutive exchanges showed little change in blood pressure. Increases in serum thiocyanate were not detected after multiple exchanges. Dialysate cell counts showed no evidence of chemical irritation.

Dialyzer reuse--part II: advantages and disadvantages.

Although single dialyzer use and reuse by chemical reprocessing are both associated with some complications, there is no definitive advantage to either in this respect. Some complications occur mainly at the first use of a dialyzer: a new cellophane or cuprophane membrane may activate the complement system, or a noxious agent may be introduced to the dialyzer during production or generated during storage. These agents may not be completely removed during the routine rinsing procedure. The reuse of dialyzers is associated with environmental contamination, allergic reactions, residual chemical infusion (rebound release), inadequate concentration of disinfectants, and pyrogen reactions. Bleach used during reprocessing causes a progressive increase in dialyzer permeability to larger molecules, including albumin. Reprocessing methods without the use of bleach are associated with progressive decreases in membrane permeability, particularly to larger molecules. Most comparative studies have not shown differences in mortality between centers reusing and those not reusing dialyzers, however, the largest cluster of dialysis‐related deaths occurred with single‐use dialyzers due to the presence of perfluorohydrocarbon introduced during the manufacturing process and not completely removed during preparation of the dialyzers before the dialysis procedure. The cost savings associated with reuse is substantial, especially with more expensive, high‐flux synthetic membrane dialyzers. With reuse, some dialysis centers can afford to utilize more efficient dialyzers that are more expensive; consequently they provide a higher dose of dialysis and reduce mortality. Some studies have shown minimally higher morbidity with chemical reuse, depending on the method. Waste disposal is definitely decreased with the reuse of dialyzers, thus environmental impacts are lessened, particularly if reprocessing is done by heat disinfection. It is safe to predict that dialyzer reuse in dialysis centers will continue because it also saves money for the providers. Saving both time for the patient and money for the provider were the main motivations to design a new machine for daily home hemodialysis. The machine, developed in the 1990s, cleans and heat disinfects the dialyzer and lines in situ so they do not need to be changed for a month. In contrast, reuse of dialyzers in home hemodialysis patients treated with other hemodialysis machines is becoming less popular and is almost extinct.