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Biomedical subjects

J A Delmez

Publications and source records attributed to J A Delmez.

16 recordsLinked to original sources
PubMed1992

Hyperphosphatemia: its consequences and treatment in patients with chronic renal disease.

Control of phosphorus accumulation in chronic renal insufficiency is crucial to the prevention of secondary hyperparathyroidism and metastatic calcification. In early renal failure, calcitriol levels are normal and parathyroid hormone levels are elevated. The phosphorus levels are maintained in the normal range by the phosphaturia induced by hyperparathyroidism. In this situation, dietary phosphorus restriction increases calcitriol levels and suppresses parathyroid hormone secretion. As renal failure progresses into late stages, hyperphosphatemia is evident along with low levels of calcitriol and worsening hyperparathyroidism. Phosphorus restriction will not affect calcitriol concentrations, yet parathyroid levels may decline. During long-term dialysis, urinary excretion of phosphorus is usually minimal. Therefore, phosphorus balance is determined primarily by the net amount absorbed by the bowel and the quantity removed during dialytic therapy. Given an adequate diet, no form of conventional dialysis is able to fully compensate for the gastrointestinal absorption of phosphorus. Hence, compounds that bind phosphorus in the bowel are often necessary. With the realization that the use of phosphorus binders containing aluminum leads to aluminum accumulation and its sequelae: osteomalacia, dementia, myopathy, and anemia, other phosphorus binders have been evaluated. Calcium carbonate has been investigated the most thoroughly and is in wide use. It is inexpensive and contains a high percent of elemental calcium. However, it is only modestly potent in the binding of phosphorus, and large doses are often necessary to attain satisfactory control of phosphorus. This may lead to hypercalcemia. One approach to this problem is to decrease the concentration of calcium in the dialysate. Alternatively, a more effective phosphorus binder may be used. Calcium acetate has been shown in acute studies to have twice the binding capacity of phosphorus per calcium absorbed than calcium carbonate. Whether use of this compound decreases the incidence of hypercalcemia is unproven. Calcium citrate increases the gastrointestinal absorption of aluminum and offers no advantage over calcium carbonate. Other compounds, such as calcium ketoacids and calcium alginate, have not been extensively studied and are not generally available. The use of phosphorus binders containing magnesium in conjunction with a dialysate low in magnesium may be efficacious. Large doses of magnesium will cause diarrhea and thus limit its use as a single agent. Reasons for failure to control hyperphosphatemia include poor compliance, improper prescription of binders, poor dissolution rates seen with some generic brands of calcium carbonate, and the presence of severe hyperparathyroidism. Optimal control of serum phosphorus in dialysis patients should always be viewed in the context of adequate nutrition and protein intake.

Aluminum↗
PubMed1992

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)

Age Factors↗
PubMed1992

Hemodialysis prescription and delivery in a metropolitan community. The St. Louis Nephrology Study Group.

The National Cooperative Dialysis Study attempted to determine adequacy of hemodialysis based on kinetic modeling of urea. Based on this study, it has been recommended that a dimensionless term quantitating the amount of dialysis delivered (KT/V) be greater than 1.0 to avoid adverse outcomes. With the declining duration of dialysis treatments in the United States, there has been concern that a significant proportion of patients may be receiving inadequate therapy. The purpose of this study was to survey hemodialysis practices and treatment outcomes in our metropolitan area. Sixteen area nephrologists volunteered to study their outpatient hemodialysis patients (N = 617). Demographic data and urea kinetic modeling results were then analyzed at the lead center. The mean length of dialysis was 3.2 +/- 0.4 (SD) hours with dialysis blood flow rates of 333 +/- 74 ml/min. The mean KT/V was 1.03 +/- 0.25 with nearly half of patients failing to attain a KT/V of 1.0. In 55% of patients the reason for a low KT/V was the prescription of an insufficient amount of dialysis treatment. In the remainder, insufficient delivery of prescribed dialysis contributed to the low KT/V. Only 1 of 33 patients undergoing dialysis twice a week achieved the recommended quantity of treatment on a weekly basis. Patients undergoing dialysis in non-profit units had a higher KT/V than those treated in proprietary units (1.1 +/- 0.26 vs. 0.92 +/- 0.22, P less than 0.001). In addition, patients dialyzed in units that performed urea kinetic modeling on all or selected patients had a higher KT/V compared to those in units where urea kinetics were not done (1.12 +/- 0.25 vs. 0.95 +/- 0.23, P less than 0.001). If these findings reflect practices elsewhere in the United States, many hemodialysis patients fail to receive the current recommended quantity of treatment.

Aged↗
PubMed1992

Calcium acetate as a phosphorus binder in hemodialysis patients.

Much interest is currently centered on the use of calcium acetate as a phosphorus binder in patients with renal failure. Therefore, this compound in subjects previously stable on calcium carbonate and undergoing high-efficiency hemodialysis with a dialysate calcium of 2.5 mEq/L was evaluated. Twenty subjects were switched from generic calcium carbonate to a single calcium carbonate preparation for a period of 2 months. This was followed by a phase (1 month) in which calcium acetate was substituted for calcium carbonate at a dose containing half the amount of elemental calcium. Subjects then continued calcium acetate for 6 months. It was found that calcium acetate allowed comparable control of immunoreactive parathyroid hormone, calcium, and phosphorus levels compared with calcium carbonate. This occurred with half the amount of elemental calcium ingested in the form of calcium acetate (349 +/- 25 versus 699 +/- 75 mmol/day; P less than 0.001). With this lower dose, the overall incidence of hypercalcemia was the same with each formulation. In the eight subjects concurrently receiving i.v. calcitriol, the incidence of hypercalcemia was significantly higher during the first month of calcium acetate compared with that in those not receiving this compound (P less than 0.05). Of those four subjects receiving the high dose of calcitriol (2 micrograms thrice weekly), all required either reduction in the dose or discontinuation of the drug. Thus, mineral metabolism could be controlled adequately with calcium acetate despite using half as much elemental calcium compared with calcium carbonate. This, however, did not result in a lower incidence of hypercalcemia, particularly in those receiving i.v. calcitriol.

Acetates↗
PubMed1991

The short-term effects of a low-protein diet in stable renal transplant recipients.

The short-term effects of a low-protein diet were assessed in eight stable renal transplant recipients on maintenance immunosuppression 38 +/- 7 months following transplantation. Two-week baseline protein and caloric intakes derived from daily food records were 0.97 +/- 0.08 g/kg.d and 25.3 +/- 1.6 kcal/kg.d. A diet containing 0.6 g protein/kg.d and greater than or equal to 30 kcal/kg.d was then prescribed. Nitrogen balance was assessed for 3 weeks and final measurements were taken at 4 weeks. Body weight decreased from 76.4 +/- 3.8 to 74.8 +/- 3.5 kg (P = 0.028). Baseline inulin clearance was 40.9 +/- 6.2 mL/min.1.73 m2 and did not change following the dietary modification. There were no significant changes in plasma proteins, lipids, or in white blood cell counts. During the low-protein diet, mean protein intake was 0.62 +/- 0.02 g/kg.d (P less than 0.001 v baseline) and the mean caloric intake decreased to 20.8 +/- 1.2 kcal/kg.d (P = 0.036 v baseline). Mean baseline nitrogen balance was -62.8 +/- 81.4 mmol/d (-0.88 +/- 1.14 g/d) and remained negative, -113.5 +/- 35.7 mmol/d (-1.59 +/- 0.50 g/d), after 3 weeks of the protein-restricted diet. A positive correlation between caloric intake and nitrogen balance combining all periods was seen (r = 0.61, P less than 0.01, n = 32) with predicted neutral nitrogen balance occurring at a caloric intake of 28 kcal/kg.d. There was also a weak correlation (r = 0.42, P less than 0.05, n = 32) between protein intake and nitrogen balance.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Proteins↗
PubMed1990

Optimization of high-efficiency hemodialysis by detection and correction of fistula dysfunction.

Recirculation studies were performed in 103 patients treated with high-efficiency dialysis over a 14 month period. Fistulograms were performed on 22 out of 25 patients with greater than 0.15 fractional recirculation at a 400 ml/minute blood pump setting. Clinically significant abnormalities were found in 82% (N = 18) and treated in 17. Two patients had second episodes of elevated recirculations and were treated again within the period of follow-up. Treatment with angioplasty (N = 11) or surgical revision (N = 8) resulted in a fall in recirculation from 0.33 +/- 0.04 to 0.12 +/- 0.02 (P = 0.001). The fractional reduction of urea clearance due to recirculation fell from 0.20 +/- 0.03 to 0.08 +/- 0.02 (P = 0.001) and the effective urea clearance of the dialysis treatment rose by 16% from 193 +/- 7 ml/min to 224 +/- 6 ml/min (P = 0.001). Pre-dialysis BUN fell from 72 +/- 4 mg/100 ml to 62 +/- 3 mg/100 ml (P = 0.012). There was no correlation between venous pressure (VP) at 400 ml/min blood pump setting and recirculation (R2 = 0.04), although VP changed significantly comparing values before and after fistula repair (211 +/- 10 vs. 186 +/- 7 mm Hg, P = 0.012). Venous pressures in 20 of the patients in our dialysis unit with recirculations of less than 0.10 were 201 +/- 6 mm Hg (P = NS compared to patients with recirculation greater than or equal to 0.15 at 400 ml/min blood flow).(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriovenous Shunt, Surgical↗
PubMed1989

Severe dialyzer dysfunction undetectable by standard reprocessing validation tests.

It is generally accepted that careful monitoring of total cell volume and ultrafiltration rates will ensure adequate function of reprocessed dialyzers. During routine urea kinetic measurements we noted that the percent of patients with clearances less than 200 ml/min increased from 5% to 48% despite adherence to these validation tests. As these patients did not have evidence of recirculation in the vascular access, possible causes of dialyzer dysfunction were investigated. Injection of methylene blue into the dialysate port revealed non-uniform flow of dialysate in dialyzers from patients with markedly reduced clearances. In vitro studies of dialyzers subjected to sequential daily reprocessing, without patient exposure, demonstrated that in vitro clearances declined in one lot but not another. The initial clearances of 218 +/- 4 ml/min fell progressively to 112 +/- 18 (P less than 0.001) after 15 reuses. No effects of reprocessing were found in a different lot (230 +/- 2 vs. 226 +/- 4 ml/min). Soaking the dialyzers from the affected lot in either the disinfectant or dialysate solution caused a decline in the clearances which was less than that of serial reuse. Although the magnitude of the problem of dialyzer malfunction with reuse is unknown, careful attention to dialyzer function is warranted in patients treated with reprocessed dialyzers.

Creatinine↗
PubMed1989

Control of mineral metabolism in CAPD patients.

The purpose of this article is to review the basic pathophysiological events leading to renal osteodystrophy and how continuous ambulatory peritoneal dialysis may alter these processes. This form of therapy has significant effects on mineral homeostasis and may, under some circumstances, alter vitamin D and parathyroid hormone metabolism. Some short-term studies suggest that there may be an improvement in bone histology during treatment. Although much remains to be learned about renal osteodystrophy and continuous ambulatory peritoneal dialysis, enough information is currently available to allow implementation of a rational plan of therapy that should optimize mineral metabolism.

Aluminum↗
PubMed1989

Parathyroid hormone suppression by intravenous 1,25-dihydroxyvitamin D. A role for increased sensitivity to calcium.

Numerous in vitro studies in experimental animals have demonstrated a direct suppressive effect of 1,25-dihydroxyvitamin D (1,25(OH)2D) on parathyroid hormone (PTH) synthesis. We therefore sought to determine whether such an effect could be demonstrated in uremic patients undergoing maneuvers designed to avoid changes in serum calcium concentrations. In addition, the response of the parathyroid gland in patients undergoing hypercalcemic suppression (protocol I) and hypocalcemic stimulation (protocol II) before and after 2 wk of intravenous 1,25(OH)2D was evaluated. In those enlisted in protocol I, PTH values fell from 375 +/- 66 to 294 +/- 50 pg (P less than 0.01) after 1,25(OH)2D administration. During hypercalcemic suppression, the "set point" (PTH max + PTH min/2) for PTH suppression by calcium fell from 5.24 +/- 0.14 to 5.06 +/- 0.15 mg/dl (P less than 0.05) with 1,25(OH)2D. A similar decline in PTH levels after giving intravenous 1,25(OH)2D was noted in protocol II patients. During hypocalcemic stimulation, the parathyroid response was attenuated by 1,25(OH)2D. We conclude that intravenous 1,25(OH)2D directly suppresses PTH secretion in uremic patients. This suppression, in part, appears to be due to increased sensitivity of the gland to ambient calcium levels.

Anuria↗
PubMed1987

The effects of intraperitoneal calcitriol on calcium and parathyroid hormone.

Parathyroid suppression by intraperitoneal calcitriol (1,25(OH)2D3) during peritoneal dialysis. The purpose of this study was to determine if parathyroid hormone (PTH) suppression could be achieved by increasing calcium mass transfer (Ca MT) with high dialysate Ca (4 mEq/liter) or via intraperitoneal (i.p.) 1,25(OH)2D3 in patients undergoing continuous ambulatory peritoneal dialysis. Eleven patients were dialyzed for two months with standard Ca dialysate (3.5 mEq/liter) followed by two months with 4.0 mEq/liter Ca, then by three months of i.p. 1,25(OH)2D3. During the latter period, patients were randomized to groups whose dialysate contained either 3.5 mEq/liter or 4.0 mEq/liter Ca. We found that 4.0 mEq/liter Ca dialysate more than doubled Ca MT (37 +/- 17 mg/day to 84 +/- 6 mg/day) leading to a modest fall (P less than 0.05) in PTH levels (84 +/- 5.5% of controls). Ionized calcium levels did not change. With i.p. 1,25(OH)2D3, however, ionized calcium rose significantly (P less than 0.001) leading to a decline in PTH levels to 53.9 +/- 7.9% of control values. Serum 1,25(OH)2D3 levels rose from undetectable to 47.7 +/- 7.2 pg/dl (normal range 20 to 35). These studies indicate that increasing Ca MT using a 4.0 mEq/liter Ca dialysate leads to a small reduction in PTH concentrations. On the other hand, i.p. 1,25(OH)2D3 is well absorbed into the systemic circulation, raises ionized calcium levels, and leads to a marked suppression of PTH. Thus, i.p. 1,25(OH)2D3 may be a simple and effective means to suppress secondary hyperparathyroidism in patients undergoing CAPD.

Adult↗
PubMed1986

Continuous ambulatory peritoneal dialysis and bone.

We studied the effects of continuous ambulatory peritoneal dialysis (CAPD) on the histological manifestations of uremic bone disease. Twelve patients underwent bone biopsy immediately prior to and after one year of such treatment. Those with larger quantities of non-mineralized bone matrix (osteoid) experienced a reduction in relative osteoid volume, mean osteoid seam width, and total osteoid surface. Moreover, the use of time-spaced kinetic markers of mineralization (tetracycline) enabled us to demonstrate that CAPD usually decreased the amount of non-mineralized bone matrix by shortening mineralization lag time (that is, the interval from organic matrix deposition to its mineralization). The changes in the histomorphology appeared to occur independently of bone aluminum. These data indicate that CAPD generally enhances the mineralizing capacity of individual osteoblasts and suggests that such therapy is beneficial to the uremic skeleton.

Biopsy↗
PubMed1979

Prevention of thrombosis in patients on hemodialysis by low-dose aspirin.

Since platelet cyclo-oxygenase is much more sensitive to inactivation by aspirin than is the enzyme in the arterial wall and low doses of aspirin may prevent thrombosis by blocking thromboxane synthesis, we conducted a randomized, double-blind trial of aspirin (160 mg per day) vs. placebo in 44 patients on chronic hemodialysis. The study was continued until there were 24 patients with thrombi and both groups had been under observation for a mean of nearly five months. Thrombi occurred in 18 of 25 (72 per cent) of patients given placebo and 16 of 19 (32 per cent) of those given aspirin (P less than 0.01). The incidence of thrombosis was reduced from 0.46 thrombi per patient month in the placebo group to 0.16 thrombi per patient month in the aspirin group (p less than 0.005). A dose of 160 mg of aspirin per day is an effective, nontoxic antithrombotic regimen in patients on hemodialysis.

Acetylation↗
PubMedDate not supplied

Effects of prazosin in the control of blood pressure in hypertensive dialysis patients.

Twenty-two chronic hemodialysis patients with hypertension were treated with prazosin. Eight patients had volume-responsive hypertension, 11 volume-indpendent, and 3 high-renin hypertension. Blood pressure fell in all volume-responsive patients from a predialysis level of 175 +/- 5/100 +/- 3 to 148 +/- 4/75 +/- 3 mm Hg (p less than 0.001) after 3 months of therapy. Prazosin alone was effective in volume responsive patients at a dose of 5 +/- 1.0 mg daily. The blood pressure fell in volume-indpendent patients from 192 +/- 7/105 +/- 2 mm Hg predialysis to 155 +/- 6/80 +/- 3 after 3 months (p less than 0.001). Two were controlled on prazosin alone at a dose of 12 +/- 2 mg daily. Nine required 27 +/- 5 mg of prazosin daily as well as additional antihypertensive treatment. The blood pressure fell from 183 +/- 3/109 +/- 6 mm Hg predialysis to 173 +/- 17/85 +/- 3 mm Hg in high-renin patients after 3 months. One patient was controlled on 40 mg of prazosin daily. Two required 40 mg of prazosin daily as well as additional antihypertensive medication. Eleven patients described transient dizziness within the first month of therapy. One patient had recurrent syncope necessitating prazosin withdrawal; Prazosin is an effective antihypertensive agent which can be used in all types of hypertensive dialysis patients either alone or in combination with minimal side effects.

Blood Pressure↗