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Biomedical subjects

E G Lowrie

Publications and source records attributed to E G Lowrie.

At least 19 recordsLinked to original sources

Race and diabetes as death risk predictors in hemodialysis patients.

Case mix and laboratory predictors of death risk were evaluated in 17,185 hemodialysis patients. The laboratory variables most closely associated with the increased death risk borne by diabetic patients (relative to non-diabetics) and White patients (relative to non-Whites) were identified. The analyses of laboratory death risk predictors were similar to those previously reported. Serum albumin concentration is the most powerful death risk predictor among all of the variables, both case mix and laboratory. Statistical models including only case mix variables reveal both race (RRWhites = 1.42) and diabetes (RRdiabetes = 1.43) as significant predictors. Adding creatinine, albumin, and BUN concentrations to the model eliminated diabetes as a significant predictor. Creatinine and albumin accounted for most of the change. Adding only creatinine eliminated race. The data suggest that reduced visceral and somatic protein mass and/or metabolism may be important determinants of mortality in dialysis patients. Because differences in the concentrations of creatinine and albumin explain much of the risk associated with being White or diabetic, differences in nutritional status may explain the reduced survival observed in those groups. Therefore, clinicians should not simply accept without question the notion that diabetics and Whites are doomed to inferior survival.

Adult

Increased serum aluminum. An independent risk factor for mortality in patients undergoing long-term hemodialysis.

The annual mortality rate among patients receiving long-term hemodialysis has been rising over the past decade. The prevalences of known risk factors such as older age, male sex, duration of dialysis, presence of diabetes, coronary artery disease, or hypertension do not seem to have changed during this time. However, evidence suggests that an increased body aluminum level may have an adverse effect on survival even in the absence of overt aluminum toxic reaction. Therefore, we evaluated the correlation between serum aluminum levels and mortality in 10 646 patients undergoing long-term hemodialysis. Mortalities were 18% higher for patients with serum aluminum levels between 1520 and 2220 nmol/L and progressively increased to 60% higher for patients with aluminum levels above 7410 nmol/L. Serum aluminum level was an important predictor of survival even after other known risk factors had been controlled. These data strongly suggest that patients undergoing long-term hemodialysis should have periodic surveillance of the serum aluminum levels, and in those patients who have plasma levels of 1520 to 2220 nmol/L or higher, one should seriously consider discontinuing aluminum salts and giving therapy to decrease body aluminum level if it is found to be increased.

Age Factors

Death risk in hemodialysis patients: the predictive value of commonly measured variables and an evaluation of death rate differences between facilities.

Logistic regression analysis was applied to a sample of more than 12,000 hemodialysis patients to evaluate the association of various patient descriptors, treatment time (hours/treatment), and various laboratory tests with the probability of death. Advancing age, white race, and diabetes were all associated with a significantly increased risk of death. Short dialysis times were also associated with high death risk before adjustment for the value of laboratory tests. Of the laboratory variables, low serum albumin less than 40 g/L (less than 4.0 g/dL) was most highly associated with death probability. About two thirds of patients had low albumin. These findings suggest that inadequate nutrition may be an important contributing factor to the mortality suffered by hemodialysis patients. The relative risk profiles for other laboratory tests are presented. Among these, low serum creatinine, not high, was associated with high death risk. Both serum albumin concentration and creatinine were directly correlated with treatment time so that high values for both substances were associated with long treatment times. The data suggest that physicians may select patients with high creatinine for more intense dialysis exposure and patients with low creatinine for less intense treatment. In a separate analysis, observed death rates were compared with rates expected on the basis of case mix for these 237 facilities. The data suggest substantial volatility of observed/expected ratios when facility size is small. Nonetheless, a minority of facilities (less than or equal to 2%) may have higher rates than expected when compared with the pool of all patients in this sample. The effect of various laboratory variables on mortality is substantial, while relatively few facilities have observed death rates that exceed their expected values. Therefore, we suggest that strategies designed to improve the overall mortality statistic for dialysis patients in the United States would be better directed toward improving the quality of care for all patients, particularly high-risk patients, within their usual treatment settings rather than trying to identify facilities with high death rate for possible regulatory intervention.

Adult

Bacteremic infection in hemodialysis.

This is a retrospective study of 133 episodes of bacteremic infection in 112 hemodialysis patients. The frequency of bacteremic infection was 9.5% in patients with chronic renal failure and 10.9% in patients with acute renal failure. In patients with acute renal failure, pneumonia and intra-abdominal abscess were the most frequent sources of septicemia. Sepsis was usually due to Gram-negative organisms and mortality was high. In patients with chronic renal failure, infection of the shunt or fistula was the most common cause, was frequently due to Staphylococcus organism, and had a more favorable survival rate. Gram-negative septicemia from a nonaccess source in patients with chronic renal failure was associated with a higher mortality. Bacterial endocarditis and septic pulmonary emboli occurred in 3.6% of septic episodes and 0.35% of patients at risk and had very low mortality. A low threshold for obtaining blood cultures and early antibiotic treatment are believed to be important in the treatment of bacteremic infections in patients undergoing long-term hemodialysis.

Acute Kidney Injury

Vestibular toxicity of gentamicin. Incidence in patients receiving long-term hemodialysis therapy.

Twenty-three patients on long-term hemodialysis regimens who received gentamicin sulfate were reviewed retrospectively to assess the incidence of ototoxicity and to identify potential risk factors. Dosage of gentamicin sulfate was 1.0 to 1.5 mg/kg intravenously three times weekly. Serum gentamicin levels were monitored in 21 cases. Seven patients developed signs and symptoms of vestibular dysfunction. Statistically significant differences were found between the ototoxic and nonototoxic groups with respect to age (P less than .001), total dose (milligrams per kilogram) (P less than .001), and duration of therapy (P less than .001). The total dose per kilogram of body weight contributed most heavily to ototoxicity, and regression analysis suggests that the critical cumulative dose is about 17.5 mg/kg. The two groups did not differ with respect to mean peak and valley serum levels. We conclude that this population is at high risk of developing gentamicin-related vestibular dysfunction specifically when the cumulative dose exceeds 17.5 mg/kg.

Adult

High Rates of controlled ultrafiltration combined with optimal diffusion: recent advances in hemodialysis technique.

A system which permits high rates of middle molecule removal while preserving the removal of low molecular weight substances is described. It consists of a high fluid flux hollow fiber artificial kidney and an ultrafiltration controller. When used in combination, high rates of convective transport can be achieved through rapid ultrafiltration and reconstitution of blood with physiologic salt solutions. The theoretical impact of changing from conventional dialysis to this form of therapy on the body burden of middle molecules is estimated.

Diffusion

A longitudinal study of bone disease after successful renal transplantation.

A retrospective study of 100 patients followed for 1-4 years after successful renal transplantation was undertaken to assess the amelioration of previously present metabolic bone disease and to determine the risk factors associated with the development of osteonecrosis. 42% of patients showed some evidence of bony abnormality. Following transplantation, there was slow but progressive resolution in the X-ray changes of hyperparathyroidism but not of osteoporosis. 14% of patients developed osteonecrosis in the posttransplant period with the femoral head the most common site involved (72% of patients). Osteonecrosis could not be related to average steroid dose, number of steroid pulses, or the preexistence of metabolic bone disease.

Adult

Initial clinical evaluation of the Hospal artificial kidney system.

A high flux artificial kidney system, which permits control over ultrafiltration, has been developed and patients are now being treated with it at a large outpatient kidney center. The basic operating characteristics have been described and some preliminary clinical results mentioned. Characteristics of the Hospital Artificial Kidney System are: 1. Higher clearances for middle molecules than conventional systems; 2. Adequate clearances for small solutes such as urea; 3. Predictable control of ultrafiltration with discrepancies between actual weight loss and theoretical weight loss on the order of 0.7 to 1.3 ml/min, when the system is operated in the designated manner.

Evaluation Studies as Topic

Controlled ultrafiltration (UF) with hemodialysis (HD): analysis of coupling between convective and diffusive mass transfer in a new HD-UF system.

A convertible and versatile dialysis system consisting of a PMMA hollow fiber unit and UFR controller is shown to be useful for evaluating the effect of solute and fluid removal rates on adequacy of dialysis. Post-dilution mode where high UFR is applied to the patient with matching or comparable dilution rate is concluded to be most effective modification for enhancing the clearance for "middle molecules", without sacrificing the removal rates for the small solutes.

Creatinine

Hyperlipidemia after renal transplantation in children.

A cross-sectional survey of 32 children who received renal allografts was undertaken to evaluate lipid profiles in a pediatric transplant population. Ages ranged from 8 to 18 years, and serum creatinine concentrations varied from 0.5 to 5.6 mg/100 ml (mean, 1.4 mg/100 ml). Fifty percent of patients showed an abnormal lipoprotein electrophoresis, and these were evenly divided between type II and type IV patterns. The data suggest that patients with type II pattern tend to be receiving higher doses of prednisone, and increasing levels of cholesterol and triglyceride are also associated with higher corticosteroid dosages. In contrast to the observations of others in dialysis patients, measurements of glucose metabolism such as fasting blood sugar and fasting insulin levels were not associated with lipid abnormalities in this population. Lipid abnormalities following renal transplantation in children are similar to those described in adults, and may contribute to morbidity in the years following successful renal transplantation.

Adolescent

Factors in the dialysis regimen which contribute to alterations in the abnormalities of uremia.

While hemodialysis therapy in its present form is capable of sustaining life, dialysis patients are not metabolically normal and we are unable to say what technical factors contribute adequate therapy. Recent efforts to resolve these problems have led to the assumption that substances in the molecular weight range of 800 to 3000 daltons may be pathogenic in uremia and these may not be effectively removed by dialysis. Accordingly, four groups of patients (ten each) underwent changes in their routine which were theoretically designed to alter independently the concentration of small (urea) and "middle" molecules in the blood. In two groups, the concentration of urea was theoretically increased or decreased while the concentration of so-called middle molecules was maintained unchanged. In the remaining two groups, middle molecule concentration was theoretically increased or decreased while small molecule concentration was unchanged. Patients were evaluated prior to and after completing altered dialysis therapy. The results suggest three related conclusions. First, the uremic syndrome may be viewed as a constellation of abnormalities which can be subgrouped by association so that azotemia may be correlated with neuropathic disease and hypertension with weight gain or body size, for example. Second, those physiologic variables which changed after altered dialysis tended to deteriorate with increasing concentration of small molecules in the blood and remained independent of theoretical changes in middle molecules. Finally, when patients are relatively under-dialyzed, they may spontaneously modulate the reduced removal of metabolites such as urea by decreasing the dietary intake of nutrients.

Adult