Paul M. Zabetakis

A multicenter study of noncompliance with continuous ambulatory peritoneal dialysis exchanges in US and Canadian patients

Recent evidence suggested that noncompliance (NC) with continuous ambulatory peritoneal dialysis (CAPD) exchanges may be more common in US than in Canadian dialysis centers. This issue was investigated using a questionnaire-based method in 656 CAPD patients at 14 centers in the United States and Canada. NC was defined as missing more than one exchange per week or more than two exchanges per month. Patients were ensured of the confidentiality of their individual results. Mean patient age was 56 +/- 16 years, 52% were women, and 39% had diabetes. The overall admitted rate of NC was 13%, with a rate of 18% in the United States and 7% in Canada (P < 0.001). NC was more common in younger patients (P < 0.0001), those without diabetes (P < 0.001), and employed patients (P < 0.05). It was also more common in black and Hispanic than in Asian and white patients (P < 0.001). NC was more common in patients prescribed more than four exchanges daily (P < 0.0001) but was not affected by dwell volume. On multiple regression analysis, the independent predictors of NC, in order of importance, were being prescribed more than four exchanges per day, black race, being employed, younger age, and not having diabetes. Being treated in a US unit did not quite achieve significance as a multivariate independent predictor. These findings suggest that NC is not uncommon in CAPD patients and is more frequent in US than in Canadian patients. However, country of residence is less powerful as a predictor of NC than a variety of other demographic and prescription factors.

Idiopathic Retroperitoneal Fibrosis: A Systemicconnective Tissue Disease?

AbstractAbstractRenal histology of a patient with idiopathic retroperitoneal fibrosis demonstrated a proliferative crescentic glomerulonephritis with intramembranous electron-dense deposits. These findings were interpreted as being consistent with an immune complex glomerulonephritis. Serologic studies revealed a positive antismooth muscle antibody titer of 1:80 and a weakly positive antinuclear antibody titer of 1:40. No distinct systemic disease was identified.While fibrosis of the retroperitoneum can occur in association with a number of distinct pathologic conditions and pharmacologic agents, the mechanism responsible for the development of the idiopathic variety of retroperitoneal fibrosis remains unclear. Our observation of an immune complex glomerulonephritis and the cumulative data on idiopathic retroperitoneal fibrosis are consistent with the concept that the fibrosis may be a local expression of an immunologically mediated systemic disease.

ASSESSMENT OF RENAL OSTEODYSTROPHY IN HEMODIALYSIS PATIENTS

We performed a prospective study of 30 patients undergoing chronic hemodialysis to determine which of 6 generally available diagnostic procedures provided the most useful information for the assessment of bone disease in hemodialysis patients. The 6 procedures were: routine biochemical measurements, N-terminal parathyroid hormone (N-PTH), radiographic analysis of hands and clavicles, bone density determination by dual photon absorptiometry (DPA), deferoxamine stimulation test, and iliac crest bone biopsy. Serum N-PTH was elevated in 83% of patients but was not significantly associated with abnormalities of other biochemical parameters. No significant relationship was demonstrated between biochemical data and radiographic findings or between biochemical data and bone density by DPA. All patients with abnormal DPA had an elevation of N-PTH; therefore, DPA did not reveal any unsuspected disease. Bone biopsies were done in 20 patients and findings in each were consistent with uremic osteodystrophy, including osteitis fibrosa cystica in 11 patients and aluminum-associated bone disease in 2 patients. Six patients had mixed disease, and 1 patient had osteoporosis. Despite 11 positive deferoxamine tests, bone biopsy revealed aluminum deposition in only 7 of these patients, suggesting extraosseous aluminum accumulation in the remaining 4. Evaluation of the positive and negative predictive accuracies of DPA, x-ray analysis, N-PTH levels, and aluminum bone deposition revealed that normal DPA or x-ray findings do not exclude bone disease, that N-PTH level is a good marker for secondary hyperparathyroidism, and that a negative deferoxamine test excludes aluminum-associated bone disease. Discriminant analysis also reinforced these conclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

The renin-angiotensin system is not responsible for hypertension following coronary artery bypass grafting

Systemic hypertension following coronary artery bypass graft (CABG) procedures has been reported to occur in 15% to 80% of cases. Previous reports have implicated the renin-angiotensin system as being responsible, at least in part, for this phenomenon. In this prospective study, 18 previously normotensive subjects were studied before, during, and after CABG. In 4 patients (22%), paroxysmal postoperative hypertension developed (systolic blood pressure greater than 150 mm Hg). There were no differences between the normotensive and hypertensive groups in plasma renin activity, angiotensin II level, or aldosterone level. Despite the trend toward elevation of these variables during cardiopulmonary bypass (CPB), all had returned to control levels within two hours after CPB, whether or not hypertension developed. Serum norepinephrine levels were elevated (.10 greater than p greater than .05) in the hypertensive group at the time hypertension developed. No other relationship or pattern could be defined to distinguish the hypertensive from the normotensive group. The renin-angiotensin system does not appear to be responsible for paroxysmal hypertension following CABG.

Percentage body fat determination in hemodialysis and peritoneal dialysis patients: A comparison

OBJECTIVE To evaluate percentage body fat in hemodialysis (HD) and peritoneal dialysis (PD) patients. DESIGN A prospective study of 20 HD patients and 20 PD patients. SETTING Sol Goldman Renal Therapy Center, Lenox Hill Hospital, New York, NY; Baumritter Kidney Center Albert Einstein College of Medicine, Bronx, NY; Body Composition Unit, St Lukes Roosevelt Hospital, Columbia University, New York, NY. PATIENTS Twenty HD (10 men, 10 women) patients, mean age 41.8 +/- 2.4 years and 20 PD (12 men, 8 women) patients, mean age 48.6 years +/- 3.0 years. INTERVENTION This is a noninterventional study. PATIENTS signed consent to undergo dual-energy x-ray absorptiometry, total body potassium counting bioelectrical impedance analysis, total body water determination, and anthropmetric evaluation. MAIN OUTCOME MEASURES Present and compare percentage body fat between HD and PD patients as determined by the methods used. RESULTS Percentage fat is not different between HD and PD patients. Differences in absolute values of percent fat between techniques exist. CONCLUSION HD patients and PD patients may be evaluated by the methods of body composition used. Percentage body fat will vary among techniques; therefore the same method should be used to follow a patient over time.

Renin-aldosterone system can respond to furosemide in patients with hyperkalemic hyporeninism

Thirty-four patients (65.3+/-3.3 years of age, mean+/-SEM) with hyperkalemia (serum potassium >5.0 mEq/L) had measurement of their renin-aldosterone system. Nineteen patients (56%) had plasma renin activity (PRA) >1.5 ng/mL/h, which was not low, while 15 (44%) had PRA <1.5. Twelve of the 15 hyporeninemic hyperkalemic patients were studied to determine whether their renin-aldosterone system responded to 2 weeks of furosemide, 20 mg daily. Four were nonresponders: PRA averaged 0.3+/-0.1 ng/mL/h, and it did not increase with furosemide or respond to captopril before or after furosemide. Eight patients were responders: PRA averaged 0.6+/-0.2 ng/mL/h and increased with furosemide to 5.5+/-3.4 ng/mL/h. Captopril failed to increase PRA before furosemide, but PRA increased to 15.3+/-8.4 ng/mL/h after furosemide. Plasma aldosterone was low in both nonresponders and responders (3.5+/-1.2 ng/dL vs 5.8+/-2.5 ng/dL) and did not increase significantly with furosemide (4.3+/-1.7 ng/dL vs 8.7+/-2.5 ng/dL). Serum potassium did not fall and therefore did not limit the rise in aldosterone. Renin responders had greater body weight, were predominantly female (6/8 vs 2/4) and were more likely to have diabetes mellitus (7/8 vs 0/4). Plasma atrial natriuretic peptide (ANP) fell with furosemide in 8 of 8 responders and in 1 of the 2 nonresponders in whom it was measured. Neither group had suppressed plasma prorenin levels, indicating no suppression of renin gene expression. These results indicate that many hyperkalemic patients do not have suppressed PRA. Further, a majority of patients with suppressed PRA have high levels of ANP and can respond to diuretic therapy with a rise in PRA and a fall in ANP, suggesting physiologic suppression of the renin system by volume expansion. A minority of hyperkalemic patients with suppressed PRA had PRA that did not increase under these study conditions.

Negative fluid balance and the occurrence of radiocontrast associated acute renal failure

The factors that influence the occurrence and course of radiocontrast associated acute renal failure (RAARF) were evaluated in ten elderly patients who developed postcardiac catheterization renal failure following the use of low osmolar (iohexol) radiocontrast material. Data from these patients was compared to that of ten similar patients who did not develop RAARF. Mean ages (73±1.2 vs. 72±1.7 years, p>0.05), and baseline serum creatinines (1.7±0.1 vs. 1.8±0.1 mg/dl, p>0.05), were not different. The amount of contrast material administered was similar in both groups. Mean fluid balance in patients with RAARF was negative 571±107 ml on the study day, while patients without RAARF were positive 707±222 ml (p<0.05). There were no significant differences between either group in regard to concomitant medications, or associated diseases. Also, no significant differences between the prophylactic use of furosemide infusion or the occurrence of diabetes mellitus were observed in either group. There was, however, an increased risk for RAARF in patients with diabetes mellitus who also developed negative fluid balance (p<0.05). The data suggest that negative fluid balance of relatively small degree (500 ml) in association with the administration of radiocontrast material may be a major factor in the development of RAARF.

Drug use and the elderly in relation to changing etiologies of hyperkalemia

Since there has been an increase in the use of medications known to change renal potassium handling, we reassessed the prevalence of and factors associated with hyperkalemia (potassium ≧ 5.1 mmol L−1) in 100 hospitalized patients. The prevalence of hyperkalemia was 10.4%. Fifty-three patients were receiving one or more medications associated with changes in potassium homeostasis. The medications were potassium supplements (22 patients), converting enzyme inhibitors (12 patients), heparin (12 patients), beta-blocking drugs (9 patients), nonsteroidal anti-inflammatory drugs (3 patients), and potassium-sparing diuretics (2 patients). Beta-blocking drugs, or nonsteroidal antiinflammatory drugs were never the sole associated factor. After medications, the second most important factor associated with hyperkalemia (47 patients) was increased age (≧ 70 yr). Other factors included diabetes mellitus (26 patients), and chronic renal failure (15 patients). Eleven patients were HIV antibody positive. Sixty-seven patients had two or more risk factors. The data suggests that drug therapy may now be the most frequent factor associated with hyperkalemia. Also, patients with advanced age and HIV positivity are now major groups at risk.

Subxiphoid Pericardiotomy-Reply

In Reply.— The experience of Breyer and associates supports our impression that subxiphoid pericardiotomy is a procedure of choice for the treatment of acute cardiac tamponade. It is of particular note that these authors report one patient with a small right ventricular laceration from an attempted, but unsuccessful, pericardiocentesis. No complications from subxiphoid pericardiotomy occurred. The shorter drainage time reported by Breyer et al underscores the need to individualize removal of the catheter based on the quantity of daily drainage. We routinely remove the catheter when less than 30 mL of fluid has been drained during a 24-hour period. It is apparent from the data provided by Breyer et al that our population, which contained more uremic patients, experienced a much greater quantity of drainage fluid of from 300 to 3,400 mL (average, 1,133 ±192 mL). The longer drainage periods were not unexpectedly associated with the cases of highest fluid