A comparison of infection rates among older and younger patients on continuous peritoneal dialysis.

OBJECTIVE: To determine if peritoneal dialysis-related infection rates are higher in older patients compared with younger patients. DESIGN: A retrospective review of prospectively collected data. Control adult patients were matched with older study patients for race, sex, insulin dependence, connection device, and time on dialysis. SETTING: A university-based peritoneal dialysis program which includes patients from a Veterans Administration Hospital outpatient dialysis program. PATIENTS: Infection rates of 103 patients 60 years of age (older patients) were compared with 103 matched control patients 18-49 years of age (younger patients). MAIN OUTCOME MEASURES: Rates of peritonitis, exit site and tunnel infection expressed as episodes/patient/year (episodes/year) and the infecting organisms for each were examined. Outcomes, including catheter removal and the cause for removal, transfer to another dialysis modality and the reason for such, death and transplantation were also assessed. RESULTS: Mean time on peritoneal dialysis was the same in each group (20 +/- 21 months in the older and 18 +/- 17 months in the younger patients). The overall peritonitis rates were the same in the two groups (0.95/year in the older and 0.89/year in the younger patients), but the older patients had a higher rate of S. epidermidis peritonitis (0.28/year vs 0.13/year, p = 0.0001). S. aureus peritonitis rates were similar (0.16/year in older and 0.17/year in younger patients). Older patients had fewer exit-site infections (0.80/year versus 1.2/year, p = 0.0001) and, specifically, lower rates of S. aureus exit-site infections (0.23/year vs 0.47/year, p = 0.0001). Tunnel infections were also less common in older patients (0.15/year vs 0.23/year, p = 0.008), but S. aureus tunnel infection rates were similar (0.05/year and 0.09/year). Catheter infection was the most common reason for catheter removal in both patient groups (35% of catheters in the older and 44% of catheters in the younger patients, p = NS). More catheters were removed form older patients because of dementia or the loss of mechanical skills required to perform peritoneal dialysis exchanges (15% vs 5%, p = 0.04). CONCLUSIONS: Older age per se is not associated with higher peritonitis rates, but the use of disconnect systems should be encouraged in older patients and their mental and physical skills monitored to avoid S. epidermidis peritonitis. The lower rates of S. aureus catheter infection in older patients requires further study.

Life-threatening hyperkalemia associated with captopril administration.

Angiotensin converting enzyme (ACE) inhibitors have become commonly used medications for hypertension and congestive heart failure. These agents are noted for their low incidence of adverse effects; but in certain cases, these effects can be life-threatening. Severe hyperkalemia is one of the potentially dangerous effects of the ACE inhibitors. While cases of life-threatening hyperkalemia associated with the use of ACE inhibitors have been described previously, in no instance was dialysis required. Herein, we report a case of acute hyperkalemia in a patient with congestive heart failure and renal insufficiency, the resolution of which required hemodialysis. The hyperkalemia in this case occurred without an increase in the patient's azotemia. In addition, the patient did not respond to attempts to effect the intracellular shift of potassium. This suggested that there may have been a defect in internal potassium homeostasis.

Staphylococcus aureus peritonitis is associated with Staphylococcus aureus nasal carriage in peritoneal dialysis patients.

Although the definition of S. aureus nasal carriage in peritoneal dialysis patients is variable, carriage is often defined as 2 or more positive cultures for S. aureus. We investigated the relationship between S. aureus infections and nasal carriage (defined as 1 or more positive nose cultures) in 138 patients on peritoneal dialysis. By this definition, approximately 50% of the patients were carriers. The rates of S. aureus exit-site infection (0.28/year vs 0.43/year, p < 0.001) and peritonitis (0.08/year vs 0.20/year, p < 0.001) were lower in the noncarriers (patients with no positive nose cultures) than in those patients who had 1 or more positive nose cultures. Patients with only 1 positive nose culture had a similar S. aureus exit-site infection rate (0.31/year vs 0.28/year), but a higher peritonitis rate (0.24/year vs 0.08/year, p < 0.001) compared to those patients with no positive nose cultures. However, patients with 2 or more positive nose cultures were at increased risk for both S. aureus exit-site infections and peritonitis. This relationship held even when only patients with frequent nose cultures were included in the analysis. Thus patients with even 1 positive nose culture for S. aureus are at risk for S. aureus peritonitis and should not be classified as noncarriers.

A comparison of peritoneal dialysis-related infections in short- and long-term peritoneal dialysis patients.

OBJECTIVE: We hypothesized that the infection rates and organisms would differ in long-term peritoneal dialysis (PD) patients versus those who died or transferred to hemodialysis during the first 4 years on PD. DESIGN: Data on PD-related infections and outcome were collected from 1979 to 1991 (prospectively since 1982). SETTING: The patients were followed at University and Veterans Administration dialysis centers. PATIENTS: All patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) for 4 years or more (n = 43) were compared to those patients who died or transferred to hemodialysis prior to 4 years on PD (n = 213). MAIN OUTCOME MEASURES: Infection rates due to various microorganisms and reasons for transfer to hemodialysis were examined. RESULTS: Peritonitis rates were 1.2/year versus 0.8/year (p < 0.001) in patients on peritoneal dialysis less than 4 years compared to those on 4 years or more, respectively, a difference due to S. epidermidis (0.32/year vs 0.20/year, p = 0.0001) and gram-negative rods other than P. aeruginosa (0.15/year versus 0.06/year, p < 0.001). Exit-site infection rates were 1.2/year versus 0.7/y (p < 0.0001) in the patients on less than 4 years compared to those on 4 years or more, respectively, a difference in part due to S. aureus (0.45/year vs 0.3/year, p < 0.001) and other gram-positive organisms (0.28/year vs 0.10/year, p < 0.001). The rates of infections that were similar in the two groups were tunnel infections (0.2/year), P. aeruginosa infections, and S. aureus peritonitis (0.18/year vs 0.14/year, p = 0.09). S. aureus was the most common cause of exist-site and tunnel infections in both groups. Forty-two percent of the patients on PD 4 years or more subsequently transferred to hemodialysis, most often due to infections, especially S. aureus. CONCLUSIONS: Although infection rates are lower in patients on peritoneal dialysis 4 years or more, S. aureus and P. aeruginosa continue to account for a high proportion of the infections. Improvement in technique survival will require prevention of these infections.

Increased risk of Staphylococcus epidermidis peritonitis in patients on dialysate containing 1.25 mmol/L calcium.

Peritoneal macrophage function is decreased in vitro in the presence of dialysate with 1.25 mmol/L calcium compared with that containing 1.75 mmol/L calcium. Theoretically, patients using this dialysate may have a higher risk of peritonitis. Nineteen patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) were converted from dialysate with 1.75 mmol/L calcium (mean time, 33 +/- 26 months) to that with 1.25 mmol/L calcium, for some or all exchanges (mean time, 10 +/- 4.7 months). Peritonitis rates were compared with 19 control patients who remained on dialysate with 1.75 mmol/L calcium. The two groups were matched for the proportion of diabetics, sex, age, use of the Y-set, and dialysis modality (CAPD, CCPD). Peritonitis rates were similar in the study patients before conversion to 1.25 mmol/L calcium dialysate and in the control patients (0.49 v 0.58 episodes/patient-year, respectively). After conversion to dialysate with 1.25 mmol/L calcium, the peritonitis rate was 0.82 episodes/patient-year contrasted to 0.58 episodes/patient-year in the control patients (P = 0.09). The peritonitis rate due to Staphylococcus epidermidis was 0.51 episodes/patient-year when 1.25 mmol/L calcium dialysate was used, and 0.19 episodes/patient-year for the comparable period in the control patients on 1.75 mmol/L calcium dialysate (P = 0.005). The proportion of peritonitis episodes due to S epidermidis increased from 20% to 61% after conversion to 1.25 mmol/L calcium (P = 0.01). The increased risk of peritonitis due to S epidermidis in patients using dialysate with 1.25 mmol/L calcium is consistent with a previous study demonstrating that clearance of S epidermidis by peritoneal macrophages is less effective with a decrease in the dialysate calcium content.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemoperitoneum complicating chronic peritoneal dialysis: single-center experience and literature review.

Hemoperitoneum is a well-recognized, if uncommon, complication of chronic peritoneal dialysis. In this review of 424 patients maintained on peritoneal dialysis at a single center during an 11-year period, 26 patients (6.1%) developed one or more episodes of hemoperitoneum. Three patients had hemoperitoneum on two separate occasions with different etiologies. One additional patient was seen on a hospital consultative service. Three types of bleeding episodes were observed. Twenty-one of 30 (70%) were benign, consisting of pink-tinged dialysate with little clinical consequence (group 1). Three (10%) consisted of minor hemoperitoneum associated with significant intra-abdominal pathology (group 2), and six (20%) required active intervention (group 3). The most frequent cause of hemoperitoneum was bleeding related to menstruation or ovulation; hemoperitoneum was more common in women than in men. Two patients had hemoperitoneum occurring after more than 6 years on dialysis. In both, the etiology was sclerosing peritonitis, an association not previously noted. The less common etiologies of hemoperitoneum encountered in our patients were similar to those in reports from other centers and are compiled here.

Calcium mass transfer in peritoneal dialysis patients using 2.5 mEq/l calcium dialysate.

Standard peritoneal dialysate has a relatively high calcium concentration of 3.5 mEq/l. Peritoneal dialysis patients thus gain calcium from the dialysate which contributes to the risk of hypercalcemia. Dialysate with 2.5 mEq/l calcium is now available. Theoretically, using dialysate with this calcium content, calcium transfer should be negative (from the patient into the dialysate) when the patient is hypercalcemic, and positive when the patient is normocalcemic or hypercalcemic. Thus, 2.5 mEq/l calcium dialysate may allow larger doses of calcium carbonate to be prescribed. We compared calcium mass transfer (CMT) in 17 stable peritoneal dialysis patients using 3.5 and 2.5 mEq/l calcium dialysate. A solution of 2.05 l, 1.5 g/dl dextrose was dwelled for 4 hours. Calcium was measured in the drained dialysate and serum (total and ionized). Mean CMT was 0.7 +/- 0.5 mEq/exchange using 3.5 mEq/l calcium dialysate and -0.9 +/- 0.9 mEq/exchange using 2.5 mEq/l calcium dialysate (p less than 0.0001). At the time of the CMT studies, the mean serum ionized calcium levels were identical for the two groups (2.6 mEq/l). CMT correlated inversely with serum total calcium, serum ionized calcium, and drained dialysate volume. During hypercalcemia calcium transfer was from the dialysate to the patient when 3.5 mEq/l calcium dialysate was used, but from the patient to the dialysate when 2.5 mEq/l calcium dialysate was used. We conclude that 2.5 mEq/l calcium dialysate is effective in removing calcium and will be helpful in preventing hypercalcemia when large doses of oral calcium compounds are prescribed as a phosphate binder.

An analysis of ten-year trends in infections in adults on continuous ambulatory peritoneal dialysis (CAPD).

Infectious complications are the Achilles heel of CAPD. To determine trends in these events, we analyzed the CAPD related infections of 303 adults on CAPD at a single university center between 1979 and 1989. During this decade the percentage of insulin-dependent diabetics increased from 14% to 39% (p less than 0.005). Peritonitis rates fell from 2.4 episodes/y in 1979 to 0.8 episodes/y in 1989. The proportion of patients with multiple episodes of peritonitis decreased (40% of the patients in 1979-1982 vs 15% in 1983-1989, p = 0.0001) while the proportion of patients with no episodes of peritonitis increased during the same periods (29% vs 49%, p = 0.005). The proportion of peritonitis episodes due to S. aureus rose over the 10-year period (p = 0.005), while those due to S. epidermidis decreased (p less than 0.10). The overall incidence of S. aureus peritonitis remained unchanged. Catheter infection rates initially increased and then fell during the decade; S. aureus remained the predominant cause. The proportion of peritonitis episodes associated with catheter infection rose (13% in 1982 vs 24% in 1989, p = 0.025), and in 1989, 80% of these episodes were caused by S. aureus. Catheter loss was also primarily due to S. aureus infections in 1989 (80%). Infections due to P. aeruginosa were a persistent problem. The proportion of patients transferring to hemodialysis each year paralleled catheter loss rates, which in turn appeared to be more related to catheter infection rates than to peritonitis rates. We conclude that control of S. aureus and P. aeruginosa will be the key to future reductions in the infectious complications of CAPD patients.