Idiopathic retroperitoneal fibrosis: a role for mycophenolate mofetil.

PURPOSE: Idiopathic retroperitoneal fibrosis (IRPF) is an unusual progressive illness for which consistent therapeutic recommendations have not been devised. The present report describes a collaborative nephrology and urology approach to distinguish IRPF from secondary disease and then combine necessary acute surgical or radiological intervention with short-term corticosteroid and with mycophenolate mofetil (MM) to facilitate steroid tapering and long-term management. MATERIALS AND METHODS: 21 patients have been evaluated and followed over a 7-year period, 16 with characteristic IRPF and 5 with secondary retroperitoneal disease. IRPF patients initially received high-dose corticosteroid and MM. We report clinical follow-up along with imaging studies of the retroperitoneum and related organs, serologic markers for systemic disease, and nonspecific acute-phase reactants as indicators of ongoing disease activity. RESULTS: Among IRPF patients, uniform success in stabilizing clinical signs and symptoms, radiological disease in the retroperitoneum and associated organs, and inflammatory indicators have been observed. Corticosteroid therapy can be limited to 6 months or less and MM to approximately 2 years, all with substantial impact on the natural history of IRPF. CONCLUSIONS: This is not a randomized, controlled trial, and patients were often referred with prior complications and/or treatments, however, the systematic approach and consistent results support the utility of MM as a safe and effective choice for long-term stabilization in IRPF.

Renal replacement therapy for severe acute renal failure.

Acute renal failure (ARF) is a sentinel event that signals increased complexity and risk during the course of any general hospital admission. The initial diagnosis and specific treatment of the ARF already pose a daunting challenge, but the stakes are even higher when ARF is severe and renal replacement therapy (RRT) is needed. This paper addresses the onset and diagnosis of ARF only briefly and then turns to the specific choice and design of RRT modality that will optimize the ultimate outcome. Some guidelines are proposed since definitive standards for the treatment of severe ARF in critically ill patients are still evolving.

Estimating the impact of renal replacement therapy choice on outcome in severe acute renal failure.

BACKGROUND: Mortality in severe acute renal failure (ARF) requiring renal replacement therapy (RRT) approximates 50% and varies with clinical severity. Continuous RRT (CRRT) has theoretical advantages over intermittent hemodialysis (IHD) for critical patients, but a survival advantage with CRRT is yet to be clearly demonstrated. To date, no prospective controlled trial has sufficiently answered this question, and the present prospective outcome study attempts to compare survival with CRRT versus that with IHD. METHODS: Multivariable Cox-proportional hazards regression was used to analyze the impact of RRT modality choice (CRRT vs. IHD) on in-hospital and 100-day mortality among ARF patients receiving RRT during 2000 and 2001 at University of Michigan, using an "intent-to-treat" analysis adjusted for multiple comorbidity and severity factors. RESULTS: Overall in-hospital mortality before adjustment was 52%. Triage to CRRT (vs IHD) was associated with higher severity and unadjusted relative rate (RR) of in-hospital death (RR = 1.62, p = 0.001, n = 383). Adjustment for comorbidity and severity of illness reduced the RR of death for patients triaged to CRRT and suggested a possible survival advantage (RR = 0.81, p = 0.32). Analysis restricted to patients in intensive care for more than five days who received at least 48 hours of total RRT, showed the RR of in-hospital mortality with CRRT to be nearly 45% lower than IHD (RR = 0.56, n = 222), a difference in RR that indicates a strong trend for in-hospital mortality with borderline statistical significance (p = 0.069). Analysis of 100-day mortality also suggested a potential survival advantage for CRRT in all cohorts, particularly among patients in intensive care for more than five days who received at least 48 h of RRT (RR = 0.60, p = 0.062, n = 222). CONCLUSION: Applying the present methodology to outcomes at a single tertiary medical center, CRRT may appear to afford a survival advantage for patients with severe ARF treated in the ICU. Unless and until a prospective controlled trial is realized, the present data suggest potential survival advantages of CRRT and support broader application of CRRT among such critically ill patients.

Kinetics, dynamics, and bioavailability of bumetanide in healthy subjects and patients with chronic renal failure.

Six patients with chronic renal failure (CRF group) and four healthy subjects (HS group) were given 5 mg oral and intravenous doses of bumetanide in a random, crossover design. The CRF group had significantly lower plasma and renal clearances, resulting in a five-to sixfold reduction in the fractional urinary excretion of the drug. The percent free drug in plasma for the CRF group was more than double that for the HS group, and significant correlations were observed for volume of distribution at steady state vs. percent free (r = 0.661; P less than 0.05), nonrenal clearance vs. percent free (r = 0.796; P less than 0.01), and renal clearance vs. creatinine clearance (r = 0.995; P less than 0.001). Although bioavailability was relatively consistent among the HS (0.664 +/- 0.112) and CRF (0.689 +/- 0.149) groups, the absorption-time profiles were more irregular for both groups. Cumulative sodium excretion and overall efficiency of response to bumetanide did not differ significantly between the two routes of administration in either group.

Racial group differences in plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients.

Approximately 50% of the mortality in hemodialysis patients is due to cardiovascular disease. Antioxidant vitamins and carotenoids may be protective because oxidation of low-density lipoproteins appears to be a necessary prerequisite for the development of atherogenesis, and hemodialysis itself may stimulate the generation of oxygen reactive species. African Americans comprise a substantial proportion of dialysis patients because they have higher rates of hypertension, glomerulonephritis, and diabetic end-stage renal disease than do whites. The purpose of this cross-sectional study was to determine the plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients and to investigate whether differences in these concentrations in the major racial or ethnic groups exist. Plasma concentrations of alpha- and gamma-tocopherol, carotenoids, and retinol were measured with HPLC and plasma vitamin C was measured with a spectrophotometric method in 109 white and African American hemodialysis patients. Dietary intakes of selected micronutrients were also compared by using data from a food-frequency questionnaire. Overall, plasma vitamin C and alpha-tocopherol concentrations were comparable but plasma carotenoid concentrations were lower than those reported for other populations. African American patients had significantly higher mean plasma concentrations of retinol (P < 0.04), lutein (P < 0.02), and total carotenoids minus lycopene (P < 0.04); whites had significantly higher mean plasma concentrations of alpha-tocopherol (P < 0.02), independent of age and plasma lipid concentrations. Diabetes comorbidity had an independent negative association with plasma beta-carotene concentration but was not associated with other measures.

Long-term intraperitoneal deferoxamine for hemochromatosis.

Intraperitoneal deferoxamine is a well established treatment for aluminum accumulation syndrome in patients with end-stage renal disease receiving peritoneal dialysis, but the use of intraperitoneal deferoxamine has not been described outside of the setting of chronic renal failure. We present here a case of secondary hemochromatosis, complicated by cirrhosis and cardiomyopathy, in which a chronic peritoneal dialysis catheter was used both to treat ascites and to deliver parenteral deferoxamine for iron overload. Daily urinary iron excretion was similar to that achieved when using standard routes of deferoxamine administration. Over a 2-year period, reversal of both the biochemical indicators and the clinical manifestations of iron overload was accomplished.

Redefining the incidence of clinically detectable atheroembolism.

BACKGROUND AND OBJECTIVES: Atheroembolism, caused by peripheral embolization of small cholesterol crystals that fracture off of ruptured atherosclerotic plaques in the major vessels, leads to multifocal ischemic lesions and progressive tissue loss. The end result is often ischemic injury in the skin, kidney, brain, myocardium, and intestine, but any organ distal to the culprit lesion may be affected. The precise incidence of this serious clinical syndrome has been difficult to ascertain from the available literature, but it appears to be much more common than has been assumed. The objective of the present study is to clarify the incidence of atheroembolism among inpatients in an acute hospital setting. PATIENTS AND METHODS: We surveyed inpatient nephrology consultations during a 7-month period from January through July 1994. From a pool of 402 consultation charts, 99 were identified with two or more substantive risk factors for atheroembolism. The records of 85 of these patients were available for careful review. More than 300 additional patients were found to have ICD-9 discharge codes for other vascular conditions, but we were unable to confirm that any of these were in fact cases of atheroembolism, since there is no specific ICD-9 discharge code for this entity. In the 85 cases reviewed, a diagnosis of atheroembolism was made only if the patient had identifiable substantive risk factors, suggestive physical findings, and supporting laboratory results. RESULTS: Eleven of the 85 surveyed records documented strong evidence supporting a "probable" diagnosis of atheroembolism. Tissue was examined in 4 of these 11, resulting in definitive histologic confirmation in 3. Another 5 of the 85 surveyed records were "suggestive" of atheroembolism. Altogether, atheroembolism was a likely diagnosis in a total of 16 cases during this 7-month period, or 1 case in every 2 weeks. These cases comprised 19% of nephrology consultations in which 2 or more risk factors were present, or 4% or all nephrology consultations. The patients' records confirmed the serious implications of clinically detectable atheroembolism. Several patients underwent lower extremity amputation, nearly half required acute or chronic dialysis, and more than half died within several months of diagnosis CONCLUSIONS: The present study suggests that at least 4% of all inpatient nephrology consultations, representing approximately 5% to 10% of the acute renal failure encountered, involve clinically significant atheroembolism. Patients with atheroembolism appear at a rate of at least 1 case every 2 weeks. They often have identifiable substantive risk factors at initial consultation, and probably represent only the most severe cases of atheroembolism. In view of the serious implications of this basically untreatable syndrome, heightened awareness and preventive maneuvers in the population at risk are essential.

Renal failure following major angiography.

Acute renal failure following angiography with contrast agents is known to occur, but the circumstances and frequency of its occurrence are not well described. A retrospective review of consecutive angiographic procedures performed over a six month interval revealed a 12 per cent incidence of renal failure following angiography. The degree of failure was severe in approximately 30 per cent of these cases and was associated with a significant mortality even though renal function usually recovered. The occurrence of renal failure was associated with the presence of renal insufficiency, impaired liver function, diabetes mellitus, hypoalbuminemia and proteinuria at the time of angiography to a statistically significant level. Furthermore, combinations of these factors, particularly preexisting combined renal insufficiency and impaired liver function, were associated with an increased incidence of acute renal failure. It is concluded that angiography poses a significant hazard to patients with underlying medical problems, particularly those involving the excretory routes of the contrast agent.

Intraleukocytic sequestration as a cause of persistent Staphylococcus aureus peritonitis in continuous ambulatory peritoneal dialysis.

Peritonitis caused by Staphylococcus aureus in four patients undergoing continuous ambulatory peritoneal dialysis failed to respond to, or relapsed immediately after cessation of, intraperitoneal antibiotic therapy with vancomycin or cephalothin and tobramycin. Sequestration of viable staphylococci within polymorphonuclear leukocytes in the peritoneal fluid was suspected for two reasons: (1) staphylococci could still be grown after treatment of the dialysate cell fraction with lysostaphin, a procedure that kills only extracellular staphylococci, and (2) diminished polymorphonuclear leukocyte bactericidal activity was demonstrated in peritoneal dialysis effluent. Addition of rifampin, which readily penetrates polymorphonuclear leukocytes, to the treatment regimen of all patients led to prompt resolution of peritonitis without relapse.

Amelioration of chronic renal allograft dysfunction in cyclosporine-treated patients by addition of azathioprine.

Management of chronic renal allograft dysfunction in cyclosporine-prednisone treated renal allograft recipients remains problematic. We therefore initiated a protocol of azathioprine addition (1.0-1.5 mg/kg/day) to ongoing CsA/Pred therapy. Three groups were treated. Group A (n = 21) had chronic progressive renal dysfunction (serum creatinine greater than or equal to 2.5 mg/dl or more than 15% above baseline) four or more months after transplantation. Group B (n = 8) had frequent or severe rejection episodes occurring despite adequate CsA levels. Group C (n = 7) had constitutional side effects of CsA with or without renal dysfunction persisting despite drug taper or financial difficulty in affording CsA. Aza was initiated 17.8 +/- 2.8 months after transplantation in group A, the mean serum creatinine having risen from 2.55 +/- 27 mg/dl to 3.04 +/- .20 mg/dl (P = .07) over the six months preceding Aza initiation, despite stable and low therapeutic range HPLC whole-blood CsA levels (118 +/- 10 ng/ml vs. 133 +/- 11 ng/ml, P = NS). Renal function declined at a rate of -0.20 +/- .06 Cr1/year in the six-month period before addition of Aza, and then improved at a rate of 0.09 +/- .04 Cr-1/year after addition of Aza (P = .002). These changes in renal function occurred without a decrease in CsA levels (118 +/- 10 six months before Aza vs. 126 +/- 26 six months after Aza, P = NS). In group B Aza was initiated at 58 +/- 8 days after transplantation when mean sCr was 3.56 +/- .29 mg/dl and mean CsA level was 222 +/- 17 ng/ml. At least follow-up 12.7 +/- 2.0 months after addition of Aza, all group B grafts were functioning, mean sCr was 2.69 +/- .31 mg/dl (P = .09 compared with baseline), and mean CsA level was 128 +/- 34 ng/ml (P = .07 compared with baseline). Group C patients had addition of Aza at 43 +/- 19 months after transplantation when mean sCr was 2.97 +/- .60 and mean CsA level was 125 +/- 30 ng/ml; addition of Aza had no influence on the rate of decline in renal function in this group. Of these 36 patients, 6 received therapy for acute rejection over the entire follow-up period of 12.3 +/- 1.4 months after addition of Aza; 4 of these retain graft function. Infectious complications consisted of 2 urinary tract infections, 1 bacterial pneumonia, and one case of otitis media.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparing continuous hemofiltration with hemodialysis in patients with severe acute renal failure.

Continuous venovenous hemofiltration (CVVH) or CVVH with additional diffusive dialysis (CVVH-D) has theoretical advantages in treating severe acute renal failure (ARF), but no prospective clinical trials or restrospective comparison studies have clearly shown its superiority over intermittent hemodialysis (HD). To evaluate this question, all 349 adult patients with ARF receiving renal replacement therapy (RRT) at our medical center during 1995 and 1996 were analyzed using multivariate Cox proportional hazards methods. Initial univariate analysis showed the odds of death when receiving initial CVVH to be more than twice those when receiving initial HD (risk for death, 2.03; P < 0.01). Progressive exclusion of patients in whom the RRT modality might not be open to choice and the risk for death was very high (systolic blood pressure < 90 mm Hg; total bilirubin level > 15 mg/dL; or total RRT < 48 hours) for total RRT left 227 patients in whom the risk for death was 1.09 (95% confidence interval [CI], 0.67 to 1.80; P = 0.72) for initial CVVH, virtually equivalent to the risk for initial HD. Comorbid indicators significantly associated with death or failure to recover renal function included: older age; medical rather than surgical diagnosis; preexisting infection or trauma and liver disease as primary diagnoses; and abnormal bilirubin level or vital signs at initiation of RRT. These results show that the high crude mortality rate of patients undergoing CVVH was related to severity of illness and not the treatment choice itself. With the addition of more inclusive comorbidity data and a broader spectrum of interim outcomes, this type of analysis is a practical alternative to what would almost assuredly be a cumbersome and costly prospective, controlled trial comparing traditional HD with CVVH.

Analysis of variable flow Doppler hemodialysis access flow measurements and comparison with ultrasound dilution.

The variable flow (VF) Doppler method determines access blood flow from the pump speed-induced change in Doppler signal between the arterial and venous needles. This study evaluated 35 patients in two analyses to assess VF Doppler measurement reproducibility (54 paired measurements) and compared VF Doppler and ultrasound dilution flow measurements (24 paired measurements). VF Doppler measurement variations were 4% for access flow less than 800 mL/min (n = 17), 6% for access flow of 801 to 1,600 mL/min (n = 22), and 11% for access flow greater than 1,600 mL/min (n = 15). The mean measurement coefficient of variation was 7% for VF Doppler compared with 5% for ultrasound dilution. Correlation coefficients (r) between VF Doppler and ultrasound dilution access flow measurements were 0.79 (n = 24; P < 0.0001), 0.84 for access flow less than 2,000 mL/min (n = 20; P < 0.0001), and 0.91 for access flow less than 1,600 mL/min (n = 18, P < 0.0001). VF Doppler measurements using indicated versus measured pump flow rates correlated highly (r = 0.99; P < 0.0001). VF Doppler therefore yields reproducible access volume flow measurements that correlate with ultrasound dilution measurements. The VF Doppler method is dependent on the pump-induced change in access Doppler signal and therefore is inherently most accurate and reproducible at lower access blood flow rates. This method appears capable of determining access flow rates in the clinically useful range.

Continuous arteriovenous hemofiltration: improved survival in surgical acute renal failure?

Continuous arteriovenous hemofiltration (CAVH) is an effective method for renal failure management that has the potential to decrease mortality rates. This hypothesis has not been comparatively studied. Fifty six patients with acute oliguric renal failure complicating multiple organ failure had measurements of resting energy expenditure by indirect calorimetry, caloric and protein intake, energy balance, and outcome. Two management protocols included hemodialysis, full calories, and low protein (phase I) or CAVH, full calories, and high protein (phase II). The survival rate in phase I was 12% and 28% in phase II (not a statistically significant difference); CAVH did facilitate parenteral feeding. Patients with positive energy balance had improved survival compared with those with significant energy deficit (37.5% versus 9.4%, p less than 0.025). We conclude that full nutritional support improves survival in acute renal failure. The method of renal replacement therapy is of secondary importance, but CAVH has distinct advantages in the nutritional management of surgical patients.

Continuous arteriovenous filtration: an effective treatment for surgical acute renal failure.

Continuous arteriovenous hemofiltration (CAVH) is a new method of renal replacement therapy that has several advantages in the surgical treatment of acute renal failure. We initially learned the technique in laboratory testing and then developed a management protocol. Since 1983 we have used CAVH to treat 61 patients with acute renal failure. This extracorporeal technique consists of arteriovenous cannulation of the femoral vessels, which provides continuous blood flow through a hollow-fiber membrane. Hydrostatic pressure (systole greater than 80 mm Hg) creates an ultrafiltrate at a typical rate of 12 L/day. Volume is replaced with an intravenous solution at a rate to achieve the desired fluid balance, usually a net loss of 1 to 2 L/day. This extracellular fluid exchange typically results in removal of 15 gm of urea nitrogen and 50 mEq of potassium per day. The technique can be used in most intensive care units and has relatively few complications. In addition to being a safe and effective means of renal replacement therapy for acute renal failure, CAVH is particularly advantageous for managing conditions of fluid overload in hemodynamically unstable patients.

Epoprostenol (PGI2, prostacyclin) during high-risk hemodialysis: preventing further bleeding complications.

The frequency of hemodialysis-associated hemorrhage was studied prospectively in two successive, parallel, heparin-controlled studies using epoprostenol (PGI2; average dose, 4.1 ng/kg.min) as the sole antithrombotic agent. Sixty-three patients with active or recently active bleeding underwent 163 hemodialysis treatments in each of which prospective bleeding risk was assessed. PGI2 was associated with up to 50% overall reduction in the frequency of bleeding, particularly in the highest risk circumstances. PGI2 also allowed successful completion of the full, prospectively prescribed hemodialysis time in the most treatments (82% versus 93% with heparin). Furthermore, the efficiency of hemodialysis using PGI2, as indicated by the reduction in concentration of blood urea nitrogen and serum creatinine, was equal to that using heparin, even though there was a tendency toward modest reduction in residual volume of the hollow fiber dialyzer and slightly more frequent early termination of treatment from dialyzer clotting with PGI2. No severe vasodilatory side effects of PGI2 were observed during these studies. Hypotension was equally frequent during hemodialysis with heparin as with PGI2. The current results suggest that PGI2 should be considered as a substitute for heparin during high-risk hemodialysis because PGI2 may reduce the incidence of dialysis-associated bleeding without severe adverse side effects.

Pharmacokinetics of quinapril and its active metabolite quinaprilat during continuous ambulatory peritoneal dialysis.

The pharmacokinetics of quinapril, a novel angiotensin converting enzyme (ACE) inhibitor, and its active metabolite, quinaprilat, were determined following a single 20-mg oral dose of quinapril in six patients with chronic renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD). Overall, quinapril was well tolerated by these CAPD patients, with mild and transient side effects, not unexpected in this clinical setting, which included pruritus, headache, nausea, and cough. Blood pressure reduction was observed in four of six patients, with onset reliably two to four hours after dosing and duration up to 48 hours, associated with quinaprilat concentrations in plasma above 90 ng/mL for at least 33 hours postdose. Two patients experienced significant hypotension, systolic blood pressure below 90 mm Hg, which responded promptly to oral fluid administration and/or reduction in dialysate tonicity. The pharmacokinetic profile of quinapril in these CAPD patients was not significantly different from that previously observed in healthy subjects with normal renal function and in patients with moderate to severe renal dysfunction not yet requiring dialysis (RDND). The apparent elimination half-life of quinapril was approximately one hour, with negligible dialysate excretion. The pharmacokinetic profile of quinaprilat in these CAPD patients was similar to that previously observed in patients with RDND. The elimination half-life of quinaprilat was markedly prolonged when compared to that in healthy subjects and averaged 20 hours, with only a small amount of quinaprilat excreted in dialysate (mean = 2.6% of total dose).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic hormone secretion in patients with renal failure.

To study the effects of volume overload and renal failure on plasma levels of immunoreactive atrial natriuretic hormone (IR-ANH), we measured levels of this hormone in normal subjects, in patients with advanced chronic renal failure (CRF) with and without clinically evident volume overload, and in patients with end-stage renal disease (ESRD) treated with chronic hemodialysis. The levels were 13 +/- 2 pmol/l in normal volunteers, 77 +/- 24 pmol/l in patients with CRF without volume overload, and 219 +/- 50 pmol/l in patients with CRF and clinically evident volume overload (analysis of variance, p less than 0.001, alpha = 0.05 compared to normals). In patients with ESRD, the levels of IR-ANH were 145 +/- 46 pmol/l before dialysis and decreased to 87 +/- 31 after dialysis (p less than 0.025). No correlation was found between the decrease in IR-ANH levels and the decrease in weight during dialysis. A significant positive correlation was found between the IR-ANH levels and blood urea nitrogen in patients with CRF (r = 0.658, p less than 0.01). Volume overload appears to be the most important stimulatory factor for ANH secretion in renal failure patients but other mechanisms, especially a decrease in metabolic clearance, may also contribute to elevated plasma levels. The increased secretion of ANH in patients with renal failure may be an important adaptive response to volume overload and hypertension.

Comparison of 3 vancomycin dosage regimens during hemodialysis with cellulose triacetate dialyzers: post-dialysis versus intradialytic administration.

AIMS: Traditionally, vancomycin is administered following dialysis to minimize drug loss when high-flux membranes are employed. Unfortunately, this approach is extremely inconvenient for patients and staff, requiring the patients to remain in the unit for at least 1 hour following dialysis. This study was designed to evaluate the feasibility of administering vancomycin during hemodialysis. Specifically, this study was designed to compare the pharmacokinetics of vancomycin when administered during the last 1-2 hours of dialysis (i.e. intra-dialytic administration) to that administered after completion of dialysis. MATERIALS AND METHODS: In a randomized, 3-way crossover trial, the pharmacokinetics of vancomycin were evaluated in 9 hemodialysis patients, comparing vancomycin 15 mg/kg following dialysis (Phase I), vancomycin 15 mg/kg during the last hour of hemodialysis (Phase II) or vancomycin 30 mg/kg during the last 2 hours of hemodialysis (Phase III). Vancomycin plasma concentrations were obtained over an 8-day period and subsequent comparisons between the treatment approaches were made with paired t-tests or ANOVA, as appropriate. Dialysate vancomycin concentrations determined on Day 1 and Day 3 of Phases II and III were used to calculate the fraction of vancomycin dose removed, and were compared to plasma data using paired t-tests. RESULTS: Vancomycin was significantly removed (33.4 to 39.5%) during a 3- to 4-hour high-flux dialysis session occurring on Day 3 after vancomycin administration. Mean serum concentrations immediately following intradialytic vancomycin administration of 15 mg/kg over the last hour of dialysis or 30 mg/kg over the last 2 hours of dialysis were initially high (77.7 and 95.5 mcg/ml respectively), but fell to 25.9 and 40.5 mcg/ml, respectively, by 4 hours post-dialysis. Predialysis concentrations on Days 3, 5 and 8 were similar for vancomycin 30 mg/kg administered over the last 2 hours of dialysis as compared with a 15 mg/kg dose given after dialysis. Vancomycin 15 mg/kg over the last hour of dialysis resulted in significantly lower subsequent predialysis concentrations than the other dosing schemes. CONCLUSIONS: Vancomycin administration of 30 mg/kg over the last 2 hours of dialysis achieves serum concentrations similar to conventional dosing of 15 mg/kg after dialysis and would allow dosing on a weekly basis.

Variable flow Doppler for hemodialysis access evaluation: theory and clinical feasibility.

Access thrombosis remains an enormous problem for patients on hemodialysis. Current evidence suggests that decreasing access blood flow rate is an important predictor of future access thrombosis and failure. This article describes a method for determining access volume flow and detecting access pathology. The Doppler ultrasound signal downstream from the arterial needle as a function of the variable hemodialysis blood pump flow rate, is used to determine access blood flow. By using this variable flow (VF) Doppler technique compared with duplex volume flow estimates measured in 18 accesses (16 patients with 12 polytetrafluorethylene [PTFE] grafts and 6 autogenous fistulas), the results showed a correlation of 0.83 (p < 0.0001) between these methods. In grafts with lower blood flow rates, aberrant flow patterns were observed, including stagnant or reversed flow during diastole while forward flow was maintained during systole. When reversed diastolic flow was severe, it was accompanied by access recirculation. In conclusion, we report the theory and clinical feasibility of determining access blood flow by using a VF Doppler technique. Measurements are made without the need to determine the access cross sectional area required for duplex volume flow calculations and without the need to reverse the lines required for various indicator dilution techniques. Important information is also obtained about aberrant flow patterns in patients at risk of access failure.

The use of peritoneal dialysis in special situations.

This brief review outlines several situations in which peritoneal dialysis (PD) can be used to address clinical situations that are out of the ordinary for end-stage renal disease (ESRD). For example, PD methodology can be used not only to treat ESRD patients with difficult psychosocial problems that obviate other dialysis options, but also to control ascites accumulation in patients with liver failure, to treat congestive heart failure in azotemic patients with progressive cardiomyopathy, to administer systemic medication via the peritoneal cavity, and to provide additional clearance in demanding circumstances. In discussing these unusual applications for PD, we open the door to extending the indications for PD to a broader spectrum of clinical problems.