Simplification of an erythropoiesis model for design of anemia management protocols in end stage renal disease.

Many end stage renal disease (ESRD) patients suffer from anemia due to insufficient endogenous production of erythropoietin (EPO). The discovery of recombinant human EPO (rHuEPO) over 30 years ago has shifted the treatment of anemia for patients on dialysis from blood transfusions to rHuEPO therapy. Many anemia management protocols (AMPs) used by clinicians comprise a set of experience-based rules for weekly-to-monthly titration of rHuEPO doses based on hemoglobin (Hgb) measurements. In order to facilitate the design of an AMP based on formal control design methods, we present a physiologically-relevant erythropoiesis model, and show that its nonlinear dynamics can be approximated using a static nonlinearity, a step that greatly simplifies AMP design. We demonstrate applicability of our results using clinical data.

Withdrawal from dialysis: a palliative care perspective.

A retrospective chart review was conducted in this pilot study of 35 patients who withdrew from dialysis and were followed by a palliative care team. Data included etiology of end-stage renal disease, comorbid illnesses, mode of dialysis and duration, survival time after withdrawal, reason for withdrawal, mental competency, symptom management, and the nature of death. Mean survival time was 10 days. The most frequent symptoms following withdrawal were confusion, agitation, pain and dyspnea. 1/3 of the sample were cognitively impaired at the time of the withdrawal decision. 17% experienced suffering during the withdrawal period, 24% had unrelieved symptoms, 19% psychological distress, while just over 1/3 of patients died alone. With the provision of palliative care, symptom prevalence in the last 24 hours dropped from 53 to 20% for pain, 68 to 33% for agitation and 46 to 26% for dyspnea. Opioids and benzodiazepines were used in the treatment of over 90% of patients. Palliative medicine has the potential to improve the care of patients who discontinue dialysis.

The effects of lipid-lowering agents on acute renal allograft rejection.

BACKGROUND: Preliminary results from clinical trials suggest that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors may help prevent acute renal allograft rejection. However, the mechanism for this putative effect of 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors, and whether it is independent of lipid-lowering per SE are unknown. METHODS: Immediately after renal transplantation we randomly allocated (proportioned 2:1:2) patients to: 1) simvastatin (10 mg/day, n=53), 2) simvastatin placebo plus gemfibrozil (dose adjusted for renal function, n=36), and 3) simvastatin placebo (n=52). RESULTS: Simvastatin, but not gemfibrozil, reduced total and low density lipoprotein cholesterol during the first 90 days posttransplant. There were no major adverse effects of therapy. However, there were no effects of treatment on acute rejection. Indeed, survival free of acute rejection at 90 days was 72% in the simvastatin group, 72% in the gemfibrozil group, and 77% in the placebo control group (P=0.771). A post hoc power analysis suggested that there was only a 7.5% chance that a true effect of simvastatin on acute rejection (versus placebo) was not detected, and a 2.5% chance that an effect of gemfibrozil on acute rejection (versus placebo) was not detected in this study. CONCLUSION: Lipid-lowering agents may not reduce the incidence of acute renal allograft rejection. However, additional studies are needed to confirm this observation. In the mean time, many if not most renal transplant recipients should be treated with HMG-CoA reductase inhibitors starting early posttransplant to prevent cardiovascular disease complications. The results of this study suggest that starting lipid-lowering therapy immediately after renal transplantation is both safe and effective in lowering total and low density lipoprotein cholesterol.

Completely reversed acute rejection is not a significant risk factor for the development of chronic rejection in renal allograft recipients.

Although acute rejection (AR) has been shown to correlate with decreased long-term renal allograft survival, we have noted AR in recipients who subsequently had stable function for more than 5 years. We reviewed 109 renal graft recipients with a minimum of 1 year graft survival and follow-up of 5-8 years. Post-transplant sodium iothalamate clearances (IoCI) measured at 3 months and yearly thereafter were used to separate recipients into 2 groups. In 61 patients (stable group), there was no significant decrease ( > 20 % reduction in IoCl over 2 consecutive years) in IoCl. Forty-eight patients had significant declines in IoCl (decline group). Groups were compared for incidence, severity, timing, and completeness of reversal of AR. Rejection was considered completely reversed if the post-AR serum creatinine (Scr) returned to or below the pre-AR nadir Scr after anti-rejection therapy. The incidence of AR was not significantly different between groups (47% vs 52%). A trend toward a lower mean number of AR episodes per patient was noted in the stable group (0.69 vs 1.04, P = 0.096), but the timing of AR was not different. Steroid-resistant AR occurred in approximately 25 % of both groups. A striking difference was seen in complete reversal of AR, with the stable group having 100% (42/42 episodes of AR in 29 patients) complete reversal whereas only 32 % (8/25) of the patients in the decline group had complete reversal (P < < 0.001). Of 8 declining patients with complete reversal, graft loss was due to chronic rejection (CR) in only 3. Seventeen declining patients had incomplete reversal of AR, and 82 % (14/17) lost their grafts to CR. Overall, only 8% (3/37) of the recipients with complete reversal of AR developed CR. No patients with incompletely reversed AR had stable long-term function as measured by IoCl. AR is not invariably deleterious to long-term renal graft function if each episode of AR can be completely reversed.

Dying well after discontinuing the life-support treatment of dialysis.

BACKGROUND: Cessation of life-prolonging treatments precedes death in an increasing number of cases, but little attention has been accorded to the quality of dying. OBJECTIVE: To examine the quality of dying following dialysis termination. PATIENTS AND METHODS: A prospective cohort, observational study involved 6 dialysis clinics in the United States and 2 clinics in Canada, and 131 adult patients receiving maintenance dialysis who died after treatment cessation. Sixty percent (n = 79) underwent patient (n = 23) and/or family (n = 76) interviews and follow-up with caretakers. A quality of dying tool quantified duration, pain and suffering, and psychosocial factors. RESULTS: The sample was 59% female, the age was 70.0+/-1.2 years old, the duration of dialysis was 34.0+/-2.8 months, and death occurred 8.2+/-0.7 days after the last dialysis treatment. (Data are given as mean +/- SE.) Thirty-eight percent of the subjects who completed the protocol were judged to have had very good deaths, 47% had good deaths, and 15% had bad deaths. During the last day of life, 81% of the sample did not suffer, although 42% had some pain and an additional 5% had severe pain. According to the psychosocial domain of the quality of dying measure, patients who died at home or with hospice care had better deaths than those who died in a hospital or nursing home. CONCLUSIONS: Most deaths following withdrawal of dialysis were good or very good. The influence of site of death and physician attitudes about decisions to stop life support deserves more research attention. Quality of dying tools can be used to establish benchmarks for the provision of terminal care.

Changing incidence of glomerular diseases in adults.

Studies performed at large metropolitan medical centers have reported an increasing incidence of idiopathic focal segmental glomerulosclerosis (FSGS) in adults. To determine whether a similar trend occurs in small urban and rural communities and to determine the role of race in these observations, we reviewed the patient records of all adults who underwent renal biopsies at our institution over the 20-year period from 1974 to 1994. The patients were grouped for analysis in 5-year intervals, 1975 to 1979, 1980 to 1984, 1985 to 1989, and 1990 to 1994, for the following diagnoses: FSGS, membranous nephropathy (MN), minimal change nephropathy (MCN), membranoproliferative glomerulonephritis (MPGN), immunoglobulin A (IgA) nephropathy, chronic glomerulonephritis, diabetic nephropathy, hypertensive nephrosclerosis, and chronic interstitial nephritis. Patients with secondary causes for these lesions were excluded. The relative frequency of FSGS increased from 13.7% during 1975 to 1979 to 25% during 1990 to 1994 (P < 0.05). The relative frequency of MN decreased from 38.3% during 1975 to 1979 to 14.5% during 1990 to 1994 (P < 0.01). There were no changes in the frequencies of MCN, MPGN, IgA nephropathy, chronic glomerulonephritis, diabetic nephropathy, hypertensive nephrosclerosis, or chronic interstitial nephritis over the 20-year period. However, there was a significant increase in the percentage of blacks with FSGS, from 0% in 1975 to 1979 to 22.6% in 1990 to 1994, and an increased percentage of Hispanics with FSGS, from 0% in 1975 to 1979 to 21.3% in 1990 to 1994 (P < 0.05). The modest increase in whites with FSGS did not reach statistical significance. The incidence of MN in blacks and whites decreased over the 20-year period. In the last 5 years, 15 patients per year had FSGS compared with 7 patients per year with MN (P < 0.05). No changes in age or sex between groups or over time accounted for these results. We conclude that FSGS is now diagnosed twice as often as MN and is the most common idiopathic glomerular disease at our hospital. Reasons for this increase include the emergence of FSGS in both Hispanics and blacks, with a modest increase of FSGS in whites. The increase in FSGS in the three most common races in our community suggests that factors other than genetic, perhaps environmental, have a role in the pathogenesis of FSGS.

Transplantation and 2-year follow-up of kidneys procured from a cadaver donor with a history of lupus nephritis.

BACKGROUND: Two patients underwent cadaver transplantation with kidneys from a donor with a history of World Health Organization Class IV/V lupus nephritis, and we report their clinical and pathological outcome. METHODS: The donor had a diagnosis of lupus nephritis made by renal biopsy 5 years before donation. At the time of donation, a biopsy was performed on the donor and on one of the recipients at 2 months and 1 year after the transplant. RESULTS: Both recipients underwent uneventful renal transplantation. On the first postoperative day, the donor's final pathological results became available. Although the frozen section seemed to be quite benign, the permanent sections revealed World Health Organization Class II/V lupus nephritis, with full house immunofluorescence and multiple electron dense deposits. Biopsies were performed on recipient #2 at 8 weeks and 1 year after the transplant. These revealed marked diminution followed by complete resolution of all tubular reticular structures and deposits as well as immunofluorescent activity. Both recipients remain with normal renal function and urinalysis at 3 years after the transplant. CONCLUSION: Although a history of clinically significant renal disease has been considered an absolute contraindication to kidney donation, with appropriate workup and caution, select patients may still be considered, which would increase the potential donor pool.

Hemodynamic, cardiac, and electrolyte effects of low-dose aerosolized terbutaline sulfate in asthmatic patients.

STUDY OBJECTIVE: Aerosolized beta2-agonists have been associated with increased morbidity in asthmatics. These drugs cause transient increases in heart rate and decreases in serum potassium levels after these drugs are first utilized. This study is designed to elucidate whether beta-adrenergic tolerance to the hemodynamic, cardiac, and electrolyte effects of inhaled terbutaline occurs during 14 days of maintenance therapy. DESIGN: Eight patients with stable asthma weaned off beta2-agonist therapy were studied in a randomized, double-blinded, placebo-controlled study utilizing aerosolized terbutaline, 400 microg q6h. Hemodynamic measurements and M-mode echocardiography were performed before and 15 and 30 min after the initial dose of terbutaline or placebo and after a dose of aerosolized terbutaline after 14 days of aerosolized terbutaline maintenance therapy. Holter monitors were worn on the first day of placebo or terbutaline therapy and on day 14 of terbutaline therapy. Plasma potassium, bicarbonate, and glucose levels, pH, renin activity, and serum insulin and aldosterone levels were measured before and after 24 and 48 h after terbutaline or placebo therapy and after 14 days of aerosolized terbutaline maintenance therapy. RESULTS: Terbutaline increased cardiac index and decreased systemic vascular resistance greater after 14 days of therapy compared with the first dose (5.2+/-0.5 vs 4.4+/-0.6 L/min/m2; p<0.05; and 760+/-62 vs 1,016+/-118 dyne x s x cm(-5), p<0.01). After 14 days of terbutaline therapy, the mean maximum heart rate and number of episodes of heart rate > 100 beats/min were higher compared with the other study day (p<0.05). Plasma potassium level decreased from 4.29+/-0.09 to 3.65+/-0.16 mmol/L after 24 h of terbutaline and to 3.90+/-0.11 mmol/L after 48 h. Plasma potassium level returned to baseline after 14 d of terbutaline therapy. Plasma glucose and serum insulin levels rose significantly 24 h and 48 h after terbutaline and returned to baseline after 14 d of terbutaline therapy. Serum aldosterone level decreased significantly as serum potassium level decreased in the first 48 h of terbutaline therapy but returned to baseline levels after 14 d of terbutaline. CONCLUSIONS: Cardiovascular beta2-receptors in patients with stable asthma do not develop tolerance to the effects of low-dose aerosolized terbutaline after 14 days of maintenance therapy. In contrast, the homeostatic mechanisms regulating serum potassium develop tolerance to low-dose terbutaline maintenance therapy. Lack of cardiovascular tolerance to maintenance doses of aerosolized beta2-agonists may be important in increased morbidity if excessive amounts of these drugs are administered during asthma exacerbations.

Enhanced fluid removal guided by blood volume monitoring during chronic hemodialysis.

Fluid overload predisposes chronic hemodialysis patients to cardiovascular disease, a significant cause of morbidity and mortality in these patients. We evaluated the efficacy of monitoring changes in blood volume during routine hemodialysis to detect fluid overload. Intradialytic changes in blood volume were monitored by continuously measuring hematocrit in all 56 patients in a single dialysis unit over 7 weeks. After Week 1, patients were categorized into 2 separate groups depending on their maximum intradialytic decreases in blood volume. In Group 1, 46 of 56 or 82% had greater than a 5% decrease in blood volume while in Group 2, 10 of 56 or 18% had less than a 5% decrease in blood volume. During Weeks 2-7, dialytic fluid removal was intentionally increased in Group 2 patients by 0.80 +/- 0.62 L (mean +/- SD) or 47 +/- 43%. This intervention resulted in a larger (p < 0.02) intradialytic decrease in body weight (2.7 +/- 0.9 kg versus 2.0 +/- 0.8 kg) and a larger (p < 0.02) intradialytic decrease in blood volume (15 +/- 5% versus 4 +/- 1%) than experienced during Week 1 with a low incidence of symptoms. We conclude that there is a significant percentage of chronic hemodialysis patients who can tolerate additional fluid removal without hypovolemic symptoms even though they are considered to be at dry weight by routine physical examination and that the identification of these patients can be facilitated by intradialytic blood volume monitoring.

Ritodrine- and terbutaline-induced hypokalemia in preterm labor: mechanisms and consequences.

The effects of ritodrine and terbutaline on potassium homeostasis, renal function, and cardiac rhythm were assessed in women treated with these drugs for preterm labor. Timed blood and urine samples were obtained for two hours before and during six hours of intravenous ritodrine (N = 5) and terbutaline (N = 5) administered in pharmacologically equivalent doses. No differences were found in any parameters affecting potassium homeostasis or renal function between these drugs. A decrease in mean plasma potassium of 0.9 mEq/liter occurred after 30 minutes of drug infusion (4.2 +/- 0.1 to 3.3 +/- 0.1 mEq/liter, P < 0.005) before any significant changes in plasma glucose (75.0 +/- 4.7 to 93.7 +/- 6.1 mg/dl, P = NS) or plasma insulin (12.4 +/- 6.0 to 28.4 +/- 5.1 mU/ml, P = NS). The mean plasma potassium after four hours of drug infusion was 2.5 +/- 0.1 mEq/liter. Plasma insulin rose to a level known to induce cellular potassium uptake (39.2 +/- 7.7 mU/ml) after 60 minutes of drug therapy and remained at this level for four hours. Hyperlactatemia occurred at four hours (4.7 +/- 0.8 mmol/liter) and the plasma lactate/pyruvate ratio increased in a 10:1 ratio. Both drugs significantly reduced glomerular filtration rate, sodium, potassium, and chloride excretion and urinary flow rate. Changes in acid-base homeostasis, plasma aldosterone, or renal potassium excretion did not contribute to ritodrine-or terbutaline-induced hypokalemia. In 83 women with preterm labor randomly assigned to ritodrine (N = 42) or terbutaline (N = 41), the maximum decrease in plasma potassium occurred after six hours of drug infusion. During Holter monitoring, 3 of 14 women treated with ritodrine or terbutaline developed symptomatic cardiac arrhythmias at the lowest plasma potassium while no women treated with saline and morphine (N = 12) developed cardiac arrhythmias (P = 0.14). We conclude that ritodrine and terbutaline induce profound hypokalemia by stimulating cellular potassium uptake and both drugs cause significant renal sodium and fluid retention and cardiac arrhythmias. Careful monitoring of electrolytes, fluid balance, and cardiac rhythm should occur during tocolytic therapy with ritodrine or terbutaline.

Capsulectomy: a cure for the page kidney.

Hypertension is a known complication after renal trauma. The cause of posttraumatic hypertension can be renal scarring, infarction, hydonephrosis, infection, vascular injury, and parenchymal compression. The authors report on the case of a 16-year-old boy who experienced hypertension after blunt renal trauma. He had a dense fibrous pseudocapsule causing renal parenchymal compression, which lead to hypertension, a Page kidney. Evaluation with computed tomographic (CT) scan, radioisotope renal scan, renal Doppler, and angiogram confirmed the diagnosis. Removal of the renal capsule and the constricting fibrous pseudocapsule was curative.

Trough serum vancomycin levels predict the relapse of gram-positive peritonitis in peritoneal dialysis patients.

We reviewed 31 episodes of gram-positive peritonitis that occurred in our peritoneal dialysis population between 1990 and 1993 in an attempt to identify the risk factor(s) for peritonitis relapse. All patients were treated with 4 weekly doses of intravenous vancomycin. Vancomycin doses no. 1 and 2 were based on body weight (15 mg/kg with a 1-g minimum); vancomycin doses no. 3 and 4 were adjusted in an attempt to maintain the trough serum vancomycin level at greater than 12 mg/L. Nine peritonitis episodes complicated by a relapse were identified. Peritonitis episodes preceding a relapse were similar to relapse-free episodes with respect to patient age, diabetes, peritoneal dialysis modality, duration of peritoneal dialysis treatment, residual urea clearance, peritoneal fluid cell count, causative organism, and weekly vancomycin dose. However, cumulative 4-week mean trough vancomycin levels were consistently lower during peritonitis episodes preceding a relapse (7.8 +/- 0.6 mg/L during relapse-prone episodes v 13.7 +/- 0.9 mg/L during relapse-free episodes; P = 0.0004). Furthermore, relapses developed during nine of 14 peritonitis episodes demonstrating a 4-week mean trough vancomycin level less than 12 mg/L compared with zero of 17 episodes with a 4-week trough level greater than 12 mg/L (P < 0.05). The detection of a low initial 7-day trough vancomycin level also was a useful marker for subsequent peritonitis relapse. In 13 peritonitis episodes associated with an initial trough level less than 9 mg/L, nine were complicated by a relapse.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of post-renal transplant erythrocytosis and microalbuminuria: response to angiotensin-converting enzyme inhibition.

Angiotensin-converting enzyme (ACE) inhibitor therapy has recently been shown to be effective in the treatment of post-renal transplant erythrocytosis (PTE). In an attempt to assess the effect of drug treatment on serum erythropoietin level, glomerular filtration rate, and urinary protein excretion, we prospectively evaluated 8 consecutive cadaveric renal transplant recipients with PTE treated with ACE inhibitor therapy for 3 months. In response to ACE inhibition, the mean hematocrit (HCT) value decreased from 53.7 +/- 0.6% before treatment to 42.7 +/- 2.2% at the conclusion of the study (p = 0.03). However, 1 patient failed to respond to ACE inhibition (HCT > 50%), and 2 patients with PTE developed anemia (HCT < 35%) while maintained on drug treatment. Although the mean serum erythropoietin level decreased during ACE inhibition (from 22.8 +/- 8.4 to 9.4 +/- 5.3 mU/ml; p = 0.06), a consistent change in individual erythropoietin levels was not identified. At the conclusion of the study, the serum erythropoietin levels were undetectable in 4 patients, decreased in 1, unchanged in 2, and increased in the only patient with PTE who failed to respond to drug treatment. All patients tolerated the ACE inhibitor therapy without developing cough or hyperkalemia. In addition, serum creatinine levels, 125I-iothalamate clearances, and mean arterial blood pressures were unchanged throughout the study. Microalbuminuria (spot urinary albumin/creatinine ratio between 30 and 200 mg/g) developed in 5 patients with PTE and coincided with the onset of erythrocytosis (25.2 +/- 7 mg/g before PTE and 76.3 +/- 36.7 mg/g at the time of PTE detection).(ABSTRACT TRUNCATED AT 250 WORDS)

Increased osmolal gap in alcoholic acidosis.

We studied a patient with alcoholic acidosis and an increased osmolal gap. Ethyl alcohol and other compounds that are known to increase serum osmolality in alcoholics were not detected. However, the levels of glycerol, acetone, and the acetone metabolites acetol and 1,2-propanediol were increased in the serum of this patient. On admission and 3 and 7 hours after admission, the combined serum osmolality of glycerol, acetone, acetol, and 1,2-propanediol accounted for 48%, 92%, and 62% of the increase in the osmolal gap above the highest normal level of 10 mOsm/kg H2O. The disappearance of the osmolal gap correlated with the correction of the acidosis and the concomitant reduction in serum glycerol and acetone levels. Elevations of endogenous glycerol, acetone, and acetone metabolite levels should now be added as causes for an increased osmolal gap in the alcoholic patient. Ingestion of toxic alcohols can no longer be assumed to be the only cause for an increased osmolal gap in alcoholic patients.

Predictive value of Doppler ultrasonography in renal transplantation.

During a 17-month period, 268 Doppler sonography studies were performed on 46 consecutive renal transplant patients. There were 35 episodes of acute rejection in 10 patients, 8 episodes of delayed function and 47 episodes of high cyclosporine levels (greater than 800 ng/dl by TDX method) in 21 patients. Defining an abnormal resistive index (RI) as greater than 0.8 or a 20% increase above baseline, the test has a specificity of 99% and a sensitivity of 94% in the 1st month post-transplant and had an overall predictive value of 99%. Episodes of high cyclosporine levels ranging from 800 to 1650 ng/dl did not correlate with a high RI except in one circumstance with concurrent acute rejection. Within the 1st month post-transplant, only 1 false-negative study occurred. An additional 8 false-negative studies occurred beyond 1 month post-transplant. Patients with delayed function are separated into three groups based on the Doppler ultrasounds: Group I, patients with an accelerated acute rejection with high RI (N = 2); Group II, patients with true ischemic acute tubular necrosis with normal RI (N = 2); and Group III, patients with possible immunologically-mediated delayed function with intermediate RI between 0.6 and 0.8 (N = 4). Doppler ultrasound is a useful ancillary test to confirm the clinical suspicion of acute rejection. Since high cyclosporine levels do not cause an increase in RI, Doppler ultrasound may help to avoid confusion between acute rejection and cyclosporine toxicity. Additionally, this test may offer insight into the cause of early post-transplant renal dysfunction.