Flow in hemodialysis grafts after angioplasty: Do radiologic criteria predict success?

BACKGROUND: The anatomic success of percutaneous angioplasty of venous stenosis is determined by the improvement in cross-sectional diameter of the vessel. A successful outcome is defined as a residual stenosis of <30%. The purpose of this study was to determine whether the angiographic assessment of a venous stenosis correlates with the change in graft blood flow following angioplasty. METHODS: Twenty-two hemodialysis patients with decreased intragraft blood flow (<700 mL/min) underwent diagnostic fistulography and angioplasty. All grafts were patent at the time of the procedure. Intragraft blood flow was measured before and after angioplasty using the ultrasonic dilution technique. Change in graft blood flow after angioplasty was correlated to the morphologic changes of the treated stenosis. RESULTS: The mean preangioplasty and postangioplasty graft blood flows were 457 +/- 136 and 818 +/- 202 mL/min, respectively. The mean degree of stenosis before angioplasty was 74 +/- 15% and 18 +/- 14% after dilation (P < 0.001). The only variable that significantly correlated with postangioplasty blood flow was preangioplasty flow (r2 = 0.22, P < 0.001). The postangioplasty blood flow was not significantly different than the highest recorded blood flow measured in that graft (798 +/- 213 mL/min, P = NS). There was no significant correlation between the change in blood flow and the change in percentage of stenosis. CONCLUSION: Following angioplasty of a venous stenosis, the graft blood flow is most closely predicted by the preprocedural blood flow and is similar to the highest recorded blood flow ever measured in that graft. Angiographic criteria to assess the success of angioplasty are not predictive of changes in blood flow.

Impaired delivery of hemodialysis prescriptions: an analysis of causes and an approach to evaluation.

Serial kinetic modeling is commonly used in hemodialysis to assess the adequacy of dialysis. A variety of problems lead to declining Kt/V in previously stable patients. These include noncompliance, vascular access recirculation, and dialyzer dysfunction. The purpose of this study was to find the relative frequencies of these problems in a group of patients undergoing routine hemodialysis. Simultaneous urea kinetic modeling and access recirculation were tested during 3 consecutive months. The baseline Kt/V was defined as the average of each patient's Kt/V values obtained during the previous 4 mo. A clinically important fall in Kt/V was defined as a decline of > or =0.2 if the baseline Kt/V was > or =1.2, or a decline of > or =0.1 if the baseline Kt/V was <1.2. Ninety-three of 375 (25%) sessions met the criteria for a significant decline in urea kinetic modeling. The baseline Kt/V in this group was 1.33 +/- 0.20 (mean +/- SEM) and declined to 1.02 +/- 0.18 in the abnormal month (P < 0.05). In 42% of instances with a decline of Kt/V, reduced blood processing due to a lower blood flow or shorter time than prescribed was responsible. Recirculation of >12% was found in 25% of sessions with a decrease in Kt/V. These patients most often had access dysfunction or reversed needles. The remaining one-third of patients with decreases in Kt/V had no problem identified, and subsequent monthly kinetic modeling results returned to baseline. These results suggest that analysis of falling urea kinetic modeling results should include a careful review of the dialysis record for reductions in prescribed time or blood flow rates followed by vascular access testing. If these evaluations are unrevealing, urea kinetic modeling results usually return to baseline in the next month.

Effects of antiplatelet drugs on dialysis-associated platelet deposition in polytetrafluoroethylene grafts.

Hemodialysis is associated with platelet deposition in polytetrafluoroethylene (PTFE) graft fistulas. We determined whether aspirin or ticlopidine would modify this response. Patients on chronic hemodialysis with forearm loop PTFE fistulas were studied. Platelets labeled with 111indium were injected and a baseline scan of the fistula arm was made with a large field of view gamma camera. After a routine dialysis treatment, a second scan was performed within 1 hour. Four weeks later, a repeat labeled platelet study was conducted after taking either aspirin 325 mg/d or ticlopidine 250 mg/d orally for 7 days. Images were computer analyzed by drawing seven standardized regions along each graft. The counts per second per pixel in postdialysis images were compared with predialysis images for each region and a percent uptake compared with the predialysis image was calculated. Regions with dialysis-induced uptake of more than 1.5-fold compared with the predialysis image before antiplatelet drug therapy were compared with these same regions after therapy. Six patients were studied before and after aspirin therapy. Uptakes larger than 1.5-fold over predialysis images were found in 12 of 40 regions and were 292% +/- 50% (+/-SEM) before and 193% +/- 25% of predialysis values after aspirin (P = 0.02, paired t-test). Uptakes in the remaining regions were 107% +/- 4% before and 115% +/- 6% after aspirin (P = NS). A second group was studied before and after ticlopidine (n = 5). Uptakes increased by more than 1.5-fold compared with predialysis images in 19 of 30 regions and had a median of 286% increased uptake (mean, 785% +/- 374%) before and 160% (153% +/- 10%) after drug therapy (P < 0.001, Wilcoxon). Uptakes in the remaining regions were 116% +/- 5% before and 134% +/- 13% after drug therapy (P = NS). Platelet aggregation studies suggested compliance with both drugs. These studies show that these antiplatelet drugs reduce, but do not completely prevent, dialysis-associated radiolabeled platelet deposition in PTFE grafts.

Comparison of survival of an expanded polytetrafluoroethylene graft designed for early cannulation to standard wall polytetrafluoroethylene grafts.

BACKGROUND: Placement and maintenance of a well-functioning vascular access are essential for delivery of adequate hemodialysis. Newly placed polytetrafluoroethylene (PTFE) arteriovenous grafts require a period of wound healing and incorporation of fibrous tissue before use, a period typically lasting two to three weeks. An ideal PTFE graft would be one that can be used for vascular access immediately, obviating the need for temporary dialysis catheters. Recently an expanded PTFE (ePTFE) graft with a mesh cannulation segment (Diastat graft) has been proposed for early cannulation. STUDY DESIGN: This is a retrospective single-center study comparing ePTFE graft survival to contemporaneously placed standard wall PTFE (GORE-TEX) grafts. RESULTS: Forty-seven consecutive new or established patients receiving chronic hemodialysis had grafts (25 ePTFE, 22 standard PTFE) placed between November 1994 and July 1995. There were no significant differences between the groups in age, race, gender, incidence of diabetes mellitus, or peripheral vascular disease. By the end of the study, 21 of 25 ePTFE grafts had clotted, compared with 11 of the 22 patients receiving a standard PTFE graft. Median time to first clotting was 53 days for the ePTFE grafts and 164 days for the standard PTFE grafts (p < 0.0001). Nine patients with ePTFE grafts required a temporary catheter after their first clotting episode. CONCLUSIONS: The ePTFE grafts thrombosed at a significantly higher rate than standard wall PTFE grafts. Further experience with the Diastat graft might improve graft survival. However, early experience does not suggest that the avoidance of short-term temporary access outweighs the problem of high clotting rate, and its attendant morbidity.

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 $2,906 and the medial professional fee was $3,156 for a medial total cost of $6,062. The median technical cost for surgical thrombectomy was $2,449 and the median surgical fee was $2,100, but these patients incurred an additional anesthesia fee (median, $1,031) bringing the total median cost to $5,580. CONCLUSIONS: These two competing procedures were comparable in cost, and the technical success and patency rates were also similar.

The effects of hemodialysis on platelet activation with new and reprocessed regenerated cellulose dialyzers.

Biocompatibility of dialysis membranes is defined, in part, by the tendency to activate the coagulation system. Methods for evaluating stimulation of the coagulation include analyses of markers of platelet activation. The purpose of these studies was to ascertain the effects of high blood flow rates and reprocessing on platelet activation during routine hemodialysis with regenerated cellulose membranes. The platelet alpha-granule protein, beta-thromboglobulin (BTG), was measured in patients undergoing routine chronic hemodialysis with regenerated cellulose dialyzers. Initial studies showed BTG levels to increase from 24 +/- 2 IU/mL at the baseline to 30 +/- 3 IU/mL at 120 minutes and postdialysis, respectively (P < 0.05). In contrast, BTG levels corrected for hemoconcentration with plasma protein concentrations showed no significant changes compared with baseline values. Further studies assessed the effects of two types of new and reprocessed regenerated cellulose dialyzers during four different treatments. Platelet counts at 10 and 30 minutes did not change compared with the baseline, while white blood cell counts decreased significantly. No significant changes in BTG levels occurred when corrected for hemoconcentration with either dialyzer. Additional studies with new and reprocessed regenerated cellulose dialyzers comparing 450 and 220 mL/min blood flow rates at 10 minutes showed no change in BTG. In summary, these studies show no evidence for platelet activation by routine hemodialysis with regenerated cellulose membranes. Differences from previous studies include correction of BTG for hemoconcentration due to ultrafiltration and pre-rinsing of dialyzers. Methods for assessment of cellular activation by dialysis membranes must account for hemoconcentration.

Impaired delivery of dialysis: diagnosis and correction.

Hemodialysis treatments yielding inadequate amounts of dialysis, as defined by urea kinetic modeling, are partially responsible for considerable mortality and morbidity in the United States. In almost 50% of dialysis treatments resulting in a Kt/V of < 1.0, the culprit is impaired delivery of the prescribed amount of dialysis. The factors involved in impaired delivery of dialysis are many and often elusive. If present and widespread, a search for the cause of the problem entails careful examination of the equipment and nursing procedures. If impaired delivery is a sporadic and infrequent event, a patient-specific investigation should be undertaken. In either circumstance, a clear understanding of the principles and practical aspects of hemodialysis greatly assists the nephrologist as a sleuth.

The effects of hemodialysis on platelet deposition in prosthetic graft fistulas.

The effects of hemodialysis on the coagulation system are not completely understood. The purpose of these studies was to determine the effects of hemodialysis on platelet deposition in prosthetic graft fistulas. Nine patients with polytetrafluoroethylene graft fistulas and two with native vein fistulas were studied. Dialysis was performed thrice weekly with blood flow rates of 400 to 450 mL/min and regenerated cellulose hollow-fiber dialyzers. Platelets were labeled with oxine-111indium. Images of the fistula were obtained immediately after injection (baseline study), postdialysis the same day, the following morning, and before and after the next two routine treatments. Images were analyzed by drawing regions of interest, and activities were expressed as counts per pixel and percent baseline after correction for background and biologic clearance and physical decay. There was a marked dialysis-associated enhancement of platelet deposition in sites along the graft. More than a twofold increase in uptake was noted most frequently in the arterial anastomosis, arterial loop, midloop, venous loop, and venous anastomosis regions. The arterial loop and midloop regions were most consistently affected. The arterial side of the loop during the first dialysis treatment showed an increase from 15 +/- 3 counts/pixel (+/- SE) predialysis to 46 +/- 14 counts/pixel postdialysis (P = 0.03, Mann-Whitney). The uptake increased with dialysis in the midloop region from 12 +/- 2 counts/pixel to 40 +/- 11 counts/pixel (P = 0.04, paired t-test). The uptake was nearly reversed by the next dialysis treatment. Subsequent treatments had a similar pattern. No significant change in activity was found in the two patients with native vein fistulas.(ABSTRACT TRUNCATED AT 250 WORDS)

Dialysis access grafts: anatomic location of venous stenosis and results of angioplasty.

PURPOSE: To determine the distribution of stenoses and results of angioplasty in patients with similar forearm dialysis grafts made of polytetrafluoroethylene (PTFE). MATERIALS AND METHODS: Diagnostic radiographs of the fistula obtained in 215 patients were reviewed; 90 patients had similar, unrevised forearm PTFE loop dialysis grafts. The location, morphology, and results of angioplasty were reviewed for each measurable stenosis. Surgical, radiologic, and dialysis records were reviewed to document the subsequent patency rate of each patient's dialysis access. RESULTS: On the initial diagnostic fistulogram, 93 stenoses were identified. The anatomic distribution included 47% at the venous anastomosis and 11% within 1 cm of the anastomosis. Life table analysis revealed a 6-month patency rate of 63% and a 1-year patency rate of 41% for the first angioplasty in a given graft, and a 6-month patency rate of 44% and a 1-year patency rate of 22% [corrected] for the second angioplasty. CONCLUSION: Performance of serial venous angioplasty procedures may help prolong the life of a graft, but the patency rates diminish with subsequent interventions.

The effect of comorbid conditions on hemodialysis access patency.

Vascular access complications are a continuing source of hospitalization and morbidity in chronic dialysis patients. Several factors have been identified that are associated with complications in patients with native vein and prosthetic bridge arteriovenous graft fistulas. Early failure of native vein arteriovenous fistulas most consistently are related to small blood vessels. It remains unclear whether other comorbid factors play a role in complications of this fistula type. Prosthetic bridge fistulas are frequently placed in the United States and are associated with frequent complications. Factors most consistently associated with higher complication rates are diabetes mellitus, older age, and black race. Antiphospholipid antibody-associated syndromes and erythropoietin therapy have also been suggested as contributing factors. In addition, elevated lipoprotein(a) and hypoalbuminemia have been found to be associated with an increase of prosthetic graft thrombosis in white and Hispanic dialysis patients. This information strongly suggests that fistula complications are multifactorial. An improved understanding of the mechanisms of these associations may aid in the delineation of the pathogenesis and an improvement in the outcome of this important problem.

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)

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.

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.

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)

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.

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.

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)

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)

Comparison of culture and serology for the diagnosis of cytomegalovirus infection in kidney and liver transplant recipients.

This study compared culture, including the shell vial procedure, with serology, including IgM cytomegalovirus (CMV) antibody testing, for the diagnosis of CMV infection in 42 subjects undergoing cadaveric renal or liver transplantation. Of 35 subjects who developed active CMV infection, 31 had positive cultures, while IgM CMV antibodies were detected in 29. Subjects with symptomatic CMV infection were more likely than asymptomatic subjects to have positive cultures of leukocytes (17/18 vs. 9/17, P = .01). In contrast, symptomatic and asymptomatic subjects did not differ in their IgG or IgM CMV antibody test responses. In subjects with symptomatic infection, viral shedding typically began early in the course of infection, often preceding symptoms, while the serologic response usually followed the appearance of symptoms. With the use of the shell vial procedure to facilitate detection of positive cultures, symptomatic CMV infections following kidney or liver transplantation can be recognized earlier and more reliably using viral culture than by serologic testing.