David W. Windus

Calcium Carbonate as a Phosphate Binder in Patients with Chronic Renal Failure Undergoing Dialysis

Phosphate binders that contain aluminum are frequently prescribed to treat hyperphosphatemia in patients with chronic renal failure, but an accumulation of aluminum can lead to osteomalacia. To evaluate the efficacy of calcium carbonate as an alternative phosphate binder, we studied 20 patients maintained on dialysis during three consecutive periods. In period 1, the patients took aluminum hydroxide for a month (mean dose, 5.6 g per day; range, 1.5 to 14.0). In period 2, they took no phosphate binders for a month, and in period 3, they took calcium carbonate (Os-Cal) for two months (mean dose, 8.5 g per day; range, 2.5 to 17). The mean (+/- SE) serum calcium level during period 1 was 9.6 +/- 0.2 mg per deciliter; this decreased slightly (to 9.3 +/- 0.1) during period 2 and increased to 10.0 +/- 0.2 during period 3. The mean (+/- SE) serum phosphorus level during period 1 was 4.8 +/- 0.1 mg per deciliter; this increased to 7.3 +/- 0.3 during period 2, but returned to the control value (4.8 +/- 0.2) during period 3. Six of the 20 patients continued to need aluminum hydroxide during period 3 for satisfactory control of hyperphosphatemia. Calcium carbonate successfully lowered serum phosphorus levels and raised serum calcium levels in the majority of our patients, thereby confirming that this agent may be a satisfactory substitute for traditional phosphate binders that contain aluminum. The possibility that long-term treatment could cause such side effects as metastatic calcification will require further investigation.

Permanent vascular access: a nephrologist's view.

Vascular access complications are the greatest cause of morbidity in hemodialysis patients in the United States. Although arteriovenous fistulas have been recommended as the preferred mode of vascular access, recent data indicate that the majority of patients on hemodialysis in the United States have prosthetic graft fistulas. The most frequent complications of prosthetic graft fistulas are thrombosis and stenosis. Hospitalization rates for fistula complications are higher in patients with diabetes mellitus and of black race. Pathogenesis of intimal hyperplasia may include elaboration of platelet-derived growth factor and mechanical endothelial injury. Screening for stenosis and impaired blood flow in fistulas can be carried out with recirculation measurements, venous and intra-access pressure measurements, and Doppler ultrasound. A combination of the techniques is probably the best current strategy for fistula screening and further evaluation. Surgical thrombectomy and fistula revision remain the standard for comparison of newer approaches to management of complications. Percutaneous angioplasty with or without stent placement, thrombolysis, and use of atherectomy devices may play an increasing role in the treatment of complications, although comparative trials of these modalities need to be performed. No satisfactory long-term pharmacologic means of preventing thrombosis, stenosis, or restenosis have been found for graft arteriovenous fistulas. It is hoped that future directions in the field of vascular access placement and management will include better strategies for allowing primary arteriovenous fistula development, advances in graft materials, improved understanding of the pathogenesis of thrombosis and stenosis, and development strategies to prevent complications.

Factors Affecting Delivery of High-Efficiency Dialysis Using Temporary Vascular Access

The effectiveness of hemodialysis depends, in part, on the delivery of the prescribed rate of blood flow and the amount of blood recirculation. Studies evaluating the magnitude of recirculation in double-lumen catheters at blood flow rates > or = 300 mL/min have not been performed. We therefore examined the effects of prescribed blood flow rate and placement site on measure blood flow, recirculation and effective clearance using double-lumen catheters in 17 patients. Double-lumen catheters were placed in the internal jugular (12.5 cm), subclavian (20 cm), and femoral veins (15 cm and 24 cm). Recirculation studies were performed in triplicate with a two-needle method at blood flow rates of 250, 300, 350, and 400 mL/min. Blood flow rate was measured with an ultrasonic flow meter placed on the venous line. The arterial line pressure was continuously monitored. Mean arterial line pressure was -105 +/- mm Hg at 250 mL/min and -231 +/- mm Hg at 400 mL/min prescribed blood flow rates in the internal jugular, subclavian, and 15-cm femoral vein catheters. Patients with 24-cm femoral catheters had a mean arterial line pressure of -196 +/- mm Hg at 250 mL/min and -327 +/- mm Hg at 400 mL/min. In spite of the change in arterial line pressure, measured blood flow rate increased appropriately at all set blood flows and with all catheter sites studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Prosthetic Fistula Survival and Complications in Hemodialysis Patients: Effects of Diabetes and Age

Current trends in hemodialysis include increases in patient age, prevalence of diabetes, and use of high-efficiency dialysis. These patients often require prosthetic fistulas for vascular access. Little is known about fistula survival and complications in this setting. Hemodialysis patients at our center receiving new prosthetic fistulas between January 1, 1988 and January 1, 1991 were studied. Sixty-five prosthetic fistulas were placed in 50 nondiabetic and 73 in 51 diabetic patients. There were no differences in age, sex, race, or access type or location in patients with or without diabetes. Seventeen percent of fistulas were lost in nondiabetic compared with 32% diabetic patients (P less than 0.05). Life-table analysis showed 1- and 2-year graft survivals of 88% and 77% in nondiabetic patients and 70% and 67% in diabetic patients. A significant difference in graft survivals was found for the time interval from 100 to 600 days after fistula placement. There were 188 complications in 92 of the grafts. There was no difference in the distribution of thromboses, elevated recirculations, or infections causing the first complication in patients with or without diabetes, but complications occurred earlier in diabetic patients (175 +/- 26 v 286 +/- 36 days, P less than 0.01). Nondiabetic patients with prosthetic fistula complications were significantly older than those without complications (64 +/- 4 and 56 +/- 2 years, respectively, P less than 0.05). No impact of age on complications was found in diabetic patients. The probability of a first thrombosis at 6 and 12 months was 29% and 49% in nondiabetic and 55% and 72% in diabetic patients (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Fatal Rhizopus Infections in Hemodialysis Patients Receiving Deferoxamine

Four hemodialysis patients receiving deferoxamine for metal overload had fatal rhinocerebral rhizopus infections. Serious fungal infections are not commonly seen in patients on dialysis, and none of these patients had the usual risk factors for rhizopus infection. Deferoxamine is being used with increased frequency in dialysis patients for aluminum and iron overload states. We propose that there is a link between the deferoxamine therapy and this unusual infection. Deferoxamine may serve as a specific growth factor for Rhizopus species or may alter host immune function. We suggest searching for fungal organisms in patients with unexplained illnesses receiving deferoxamine.

RENAL TRANSPLANTATION FOR SYSTEMIC LUPUS ERYTHEMATOSUS AND RECURRENT LUPUS NEPHRITIS: A SINGLE-CENTER EXPERIENCE AND A REVIEW OF THE LITERATURE

Prior to 1975 patients with systemic lupus erythematosus were generally not considered candidates for renal transplantation because of concern that immune complex deposition would rapidly destroy the allograft. However, recent evidence suggests that good patient and graft survival rates can be achieved comparable to other renal diseases. Between September 23, 1963 and July 31, 1990, 1070 renal transplants were performed at Washington University Medical Center (WUMC). During this period, 14 patients with SLE (12 female and 2 male) received 16 renal transplants (7 living-related donor [LRD], 1 living-unrelated donor [LURD], and 8 cadaver [CAD]). The mean age at the time of the first transplant was 32.5±10.3 years. The duration of disease prior to transplant was 88.0±45.9 months and the duration of hemodialysis prior to transplant was 36.0± 33.7 months. Of these patients, 7/14 (50%) had negative and 3/14 (21%) positive SLE serology pre- and post-transplant, 3/14 (21%) had negative serology pretransplant that became positive posttransplant, and 1/14 (2%) was positive pretransplant and became seronegative posttransplant. Patient survival was 92.8% (13/14), and of the 16 kidneys transplanted 62.5% (10/16) are still functioning with a mean follow-up period of 43.7±45 months. The current mean serum creatinine was 1.4± 0.26 mg/dl. One noncompliant patient developed recurrent lupus nephritis bringing the total number of cases reported in the literature to seven. The present study demonstrates that patients with SLE can be transplanted with excellent patient and graft survival and function and a low rate of recurrent lupus nephritis. From a review of the literature, there appears to be an association between positive SLE serology pre- and posttransplant and recurrent lupus nephritis.

Effects of Phosphate Binder Therapy on Vascular Stiffness in Early Stage Chronic Kidney Disease

Background/Aims: Cardiovascular disease (CVD) is increased in chronic kidney disease (CKD), and contributed to by the CKD-mineral bone disorder (CKD-MBD). CKD-MBD begins in early CKD and its vascular manifestations begin with vascular stiffness proceeding to increased carotid artery intima-media thickness (cIMT) and vascular calcification (VC). Phosphorus is associated with this progression and is considered a CVD risk factor in CKD. We hypothesized that modifying phosphorus balance with lanthanum carbonate (LaCO3) in early CKD would not produce hypophosphatemia and may affect vascular manifestations of CKD-MBD. Methods: We randomized 38 subjects with normophosphatemic stage 3 CKD to a fixed dose of LaCO3 or matching placebo without adjusting dietary phosphorus in a 12-month randomized, double-blind, pilot and feasibility study. The primary outcome was the change in serum phosphorus. Secondary outcomes were changes in measures of phosphate homeostasis and vascular stiffness assessed by carotid-femoral pulse wave velocity (PWV), cIMT and VC over 12 months. Results: There were no statistically significant differences between LaCO3 and placebo with respect to the change in serum phosphorus, urinary phosphorus, tubular reabsorption of phosphorus, PWV, cIMT, or VC. Biomarkers of the early CKD-MBD such as plasma fibroblast growth factor-23, Dickkopf-related protein 1 (DKK1), and sclerostin were increased 2- to 3-fold at baseline, but were not affected by LaCO3. Conclusion: Twelve months of LaCO3 had no effect on serum phosphorus and did not alter phosphate homeostasis, PWV, cIMT, VC, or biomarkers of CKD-MBD.

Thrombolysis versus Surgical Thrombectomy for the Treatment of Dialysis Graft Thrombosis: Pilot Study Comparing Costs☆

PURPOSE This preliminary investigation was designed to compare the cost of pharmacomechanical thrombolysis and angioplasty with that of surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. PATIENTS AND METHODS This prospective, randomized study consisted of 20 patients with unrevised, polytetrafluoroethylene forearm dialysis grafts of similar configuration in which graft thrombosis occurred for the first time. Ten patients underwent pulse-spray thrombolysis plus angioplasty, and 10 patients underwent surgical thrombectomy. The technical costs, professional fees, and all other associated costs were obtained. Procedural data, graft patency rates, and demographic information were analyzed. RESULTS The technical success rate was 70% for thrombolysis and 80% for surgical thrombectomy. The duration of patency, including the technical failures, was 81.6 days for thrombolysis and 93.9 days for surgery. For the thrombolysis and angioplasty procedure, the median technical cost was

The Effect of Comorbid Conditions on Hemodialysis Access Patency

2,906 and the medial professional fee was

Effects of Antiplatelet Drugs on Dialysis-Associated Platelet Deposition in Polytetrafluoroethylene Grafts

3,156 for a medial total cost of