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Biomedical subjects

A M Kaufman

Publications and source records attributed to A M Kaufman.

At least 19 recordsLinked to original sources
PubMed2001

ANCA-associated vasculitis in Greek siblings with chronic exposure to silica.

We present the case of two siblings with similar environmental exposure to silica. Both of them developed perinuclear antineutrophil cytoplasmic antibody (p-ANCA)-associated vasculitis with pulmonary-renal syndrome. p-ANCAs were present with antimyeloperoxidase specificity on capture enzyme-linked immunosorbent assay. Treatment with corticosteroids and cyclophosphamide resulted in resolution of the clinical picture. Chronic exposure to silica is the leading environmental factor associated with ANCA-positive vasculitis. Several clusters of systemic vasculitis have been described. Positive and negative human leukocyte antigens (HLA) have been reported in systemic vasculitis. Affected brothers in our case shared one parental HLA haplotype. To the best of our knowledge, this is the first report of a family cluster of silica-induced, ANCA-associated systemic vasculitis with members sharing some of their HLA antigens.

Adult↗
PubMed2000

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis.

UNLABELLED: Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis. BACKGROUND: Commonly used bioimpedance analysis (BIA) is insensitive to changes in peritoneal fluid volume. The purpose of this study was to show, to our knowledge for the first time, that a new segmental approach accurately measures extracellular fluid changes during peritoneal dialysis (PD). METHODS: Fourteen stable PD patients were studied during a standard exchange with fluids of known conductivity. Bioimpedance was continuously measured in the arm, trunk, and leg and from wrist to ankle. Volume changes were calculated using both a newly developed sum of segmental BIA (SBIA) and current wrist-to-ankle BIA (WBIA) and were compared with actual volume changes measured gravimetrically. RESULTS: When 2.19 +/- 0.48 L were removed from the peritoneal cavity during draining, 95.2 +/- 13.8% of this volume was detected by SBIA compared with only 12.5 +/- 24. 3% detected by WBIA. When 2.11 +/- 0.20 L of fresh dialysate was infused into the peritoneal cavity during filling, 91.1 +/- 19.6% of this volume was detected by SBIA compared with only 8.8 +/- 21.1% detected by WBIA. CONCLUSION: The good agreement between measured and calculated data using SBIA was due to: (a) improved placement of electrodes, (b) estimation of trunk extracellular volume based on a new algorithm, and (c) consideration of changes in dialysate conductivity. Correct estimation of fluid volume in the trunk is a prerequisite for applications in which direct analysis of fluid changes cannot be performed such as with peritoneal equilibration tests and continuous flow PD.

Adult↗
PubMed2000

Sensitivity and specificity of the thermodilution technique in detection of access recirculation.

BACKGROUND/AIM: Recirculation measured by thermodilution includes effects caused by access and cardiopulmonary recirculation. The aims of this study were to illustrate the accuracy of thermodilution in measurement of hemodialysis recirculation and also to identify a sensitive and specific threshold to detect access recirculation. METHODS: 110 studies were performed in 19 patients. Recirculation obtained directly by the blood temperature monitor (BTM) was compared to that calculated from access blood flow, pump blood flow, and cardiac output determined by ultrasound dilution using the hemodialysis monitor (HDM). RESULTS: A highly significant linear correlation was obtained between repeated BTM recirculation measurements (R(BTM, 2) = 0.99.R(BTM, 1) - 0.22%, r(2) = 0.99). There were no significant differences between repeated BTM recirculation measurements with correct placement (11.4+/-7.1 vs. 10.9+/-7.4%, p = NS) or reversed placement (30.0+/-15.6 vs. 30.2 +/-15.9%, p = NS) of blood lines. A strong linear relationship was obtained between the recirculation determined by thermodilution and the recirculation calculated from HDM measurements (R(calc) = 0.98. R(BTM) - 1.49%, r(2) = 0.95). The mean recirculation obtained by BTM was not significantly different from the recirculation calculated by HDM with correct placement (9.5+/- 2.2 vs. 8.6+/-2.5%, p = NS) or with reversed placement (25.4+/-7.8 vs. 23.8+/-7.7%, p = NS) of blood lines. When a recirculation greater than 15% measured by the BTM was considered as the threshold at which true access recirculation occurred, sensitivity and specificity of the thermodilution method to detect access recirculation were 93 and 98%, respectively. CONCLUSIONS: Recirculation measurements made by the BTM are accurate and precise. Even though BTM thermodilution includes effects of cardiopulmonary recirculation, so that low levels of access recirculation might not be detected, a BTM recirculation >15% represents a highly significant access recirculation.

Arteriovenous Shunt, Surgical↗
PubMed1998

Effects of controlled blood cooling on hemodynamic stability and urea kinetics during high-efficiency hemodialysis.

Although the use of cooled dialysate during hemodialysis is associated with stabilization of intradialytic BP, the effects of blood cooling on hemodynamics and urea kinetics in high-efficiency hemodialysis have not been completely studied. In particular, the effects of blood cooling have not been elucidated in very short-time, high K/V dialysis treatments, in which postdialysis urea rebound is maximized. In theory, blood cooling could increase urea compartmentalization during treatment and decrease dialysis efficacy. Measurements of cardiovascular hemodynamics and urea kinetics were performed in 15 patients (56 studies) during dialysis, using a blood temperature monitor with control of dialysate temperature. Dialysate temperature was adjusted to either lower the core temperature or raise the core temperature by, respectively, producing negative heat-energy exchange (cooled dialysis) or keeping heat-energy exchange in the extracorporeal circuit neutral (thermoneutral dialysis) so that energy was not transferred to or from the patient. Each subject was studied on both protocols, thereby allowing each individual to act as his own control. In cooled dialysis, heat-energy exchange in the extracorporeal circuit was -266+/-15 kJ per treatment, and dialysate temperature averaged 35.7+/-0.02 degrees C. In thermoneutral dialysis, heat-energy exchange in the extracorporeal circuit averaged 5+/-31 kJ per treatment, and dialysate temperature averaged 37.1+/-0.02 degrees C. Dialysate cooling resulted in a reduction in mean body temperature compared with thermoneutral therapy (-0.22+/-0.04 versus +0.31+/-0.05 degrees C). Cooling resulted in a greater increase in peripheral vascular resistance index (+515+/-160 versus + 114+/-92 dyn.sec/cm5 per m2), an increase in mean arterial pressure (+4+/-3 versus -4+/-4 mmHg), a reduction in the maximum intradialytic fall in mean arterial pressure (-10+/-2 versus -18+/-3, mmHg), and a reduction in staff interventions for hypotension or dialytic symptoms (6 of 28 versus 12 of 28 studies). These differences occurred without differences in the change in blood volume (-14.3+/-1.8% versus -13.9+/-2.2%) or cardiac index (-0.4+/-0.1 versus -0.4+/-0.2, L/min per m2). Urea rebound (37+/-4% versus 38+/-3%) and effective Kt/V (1.29+/-0.05 versus 1.32+/-0.06) were not different between groups. Thus, body temperature cooling can be used to stabilize BP and reduce intradialytic events requiring staff intervention without compromising the efficacy of treatment in high-efficiency dialysis.

Blood↗
PubMed1996

High flux dialysis membranes improve plasma lipoprotein profiles in patients with end-stage renal disease.

A major cause of the morbidity and mortality of patients with end-stage renal disease (ESRD) is related to disorders of large blood vessels, especially coronary heart disease. Atherosclerosis, the most common form of this disease, is known to result from abnormalities in plasma lipoproteins, as well as from factors that damage the vessel wall. Two well-known risk factors for coronary heart disease are elevated plasma concentrations of LDL and reduced concentrations of HDL. This latter disorder is often accompanied by elevated triglycerides. Low HDL and elevated triglycerides are commonly associated with ESRD. Dialysis with high flux membranes differs from conventional dialysis in a number of ways. These include better biocompatibility and increased flux of larger molecules. Although several previous studies had suggested that dialysis with high flux membranes improves plasma lipoprotein profiles, a definitive cross-over designed study to assess the roles of high flux versus biocompatibility in altering lipoprotein profiles had not been done. Preliminary data from such a study are presented. These data confirm the beneficial effects of high flux membranes to reduce plasma triglycerides and suggest that this effect is primarily due to the high flux, and not the biocompatible, feature of the membranes.

Humans↗
PubMed1996

Decreased bladder compliance in patients with myelomeningocele treated with radiological observation.

PURPOSE: Recently others advocated frequent radiological surveillance to detect upper urinary tract deterioration in children with neurogenic bladder secondary to spina bifida. We reviewed the consequences of such expectant management on bladder compliance and urinary continence. MATERIALS AND METHODS: We retrospectively reviewed the records of 214 children presenting to our spina bifida clinic in a 13-year period. Follow-up is available for 95 girls and 86 boys. Imaging studies of the kidneys were repeated at 6 to 12-month intervals. Urodynamics were performed when upper urinary tracts deteriorated or in incontinent school age children. RESULTS: On radiographic study there was evidence of upper urinary tract deterioration in 79 children, including hydronephrosis in 34, hydronephrosis and vesicoureteral reflux in 19, and reflux only in 26. Follow up studies performed after clean intermittent catheterization and pharmacological therapy were instituted revealed resolution or improvement of upper tract deterioration in 52 patients (69%), while bladder compliance improved in only 42%. Surgical intervention was required in 34 children, despite improvement of upper tract changes in many of these patients on follow up radiographic studies. CONCLUSIONS: Although radiological surveillance of patients with myelomeningocele allows recognition of upper tract changes, the effects of elevated outlet resistance on bladder compliance are not as readily reversible as the initial radiographic findings. The incidence of enterocystoplasty exceeds that reported for patients treated prospectively based on urodynamic findings, which should be considered in the treatment of these children.

Female↗
PubMed1995

Solute disequilibrium and multicompartment modeling.

Mathematical models that simulate the exchange of solute between multiple body compartments have been used to study the distribution, elimination, and transport of urea, water, electrolytes, and other substances in the dialysis patient. Within a compartment, such substances are assumed to be uniformly distributed while exchange between compartments or with the environment may occur in a number of different ways. Diffusion in response to concentration gradients between, for example, intracellular and extracellular spaces, and convection due to blood flow have been identified as the most important transport mechanisms. Any system with more than one compartment may develop nonuniform solute distribution or solute disequilibrium between compartments. The minimum number of compartments required to model a kinetic process such as urea removal during hemodialysis depends on the accuracy and temporal resolution required, with higher resolution calling for more compartments. A two-compartment model is adequate for most clinical purposes. The physiological meaning or anatomic counterparts of the mathematical compartments remain uncertain as both flow and diffusion transport mechanisms contribute to the disequilibrium. Processes such as access and cardiopulmonary recirculation may be represented as additional compartments with small distribution volumes and high mass transport rates. Failure to recognize the effect of multiple compartments will result in an inaccurate measurement of dialysis dose and an inadequate hemodialysis prescription with a predictably poor clinical outcome. Allowance for compartment effects is particularly important in patients receiving treatment with a high ratio of dialyzer clearance to total body water, now commonly encountered during short-time, high-efficiency dialysis.

Biological Transport↗
PubMed1995

The use of heated citric acid for dialyzer reprocessing.

Dialyzer reprocessing with heated water (100 to 105 degrees C) for 20 h can be used safely in lieu of chemical methods for disinfection. All infective agents including spores are destroyed and depyrogenation may occur. However, these temperatures may result in structural damage to the dialyzer, limiting reuse. Dialyzer reprocessing by using 1.5% citric acid heated to 95 degrees C for 20 h is an alternative method that produces equivalent microbiologic effects. Citric acid is well known as a disinfecting agent used for dialysis equipment. Because there is little structural damage to dialyzer components at 95 degrees C, reuse statistics are improved (mean reuse increased to 12.8). Both small and large molecule clearances and the sieving coefficient for protein are insignificantly altered by the process. Whereas the procedure is relatively simple, quality-assurance indicators are essential. The method has appeal because it avoids the use of chemical germicides. However, at present it has only been tested thoroughly in polysulfone dialyzers with heat-resistant polycarbonate casings and polyurethane resin. The clinical experience is favorable.

Citric Acid↗
PubMed1994

Reactive glycosylation endproducts in diabetic uraemia and treatment of renal failure.

In diabetes and ageing, glucose-derived advanced glycosylation endproducts (AGEs) cross-link proteins and cause vascular tissue damage. Elimination of circulating low-molecular weight AGE-modified molecules (LMW-AGEs) by the kidney is impaired in diabetic patients with end-stage renal disease, a group subject to accelerated atherosclerosis. We determined the effectiveness of current renal replacement treatments on elimination of serum LMW-AGEs in diabetic and non-diabetic patients with end-stage renal disease. Although diabetic patients receiving high-flux haemodialysis achieved 33% lower steady-state serum LMW-AGE than did those in conventional haemodialysis (p < 0.005), LMW-AGE concentrations remained 3.5-6 fold above normal, whether high-flux dialysis, conventional haemodialysis, or chronic ambulatory peritoneal dialysis were used. High-flux haemodialysis markedly reduced AGE during each treatment session (47.9% in the diabetic, p < 0.001 and 60.6% in the non-diabetic group, p < 0.001) but concentrations returned to pre-treatment range within 3 hours. In contrast, normal LMW-AGE concentrations were maintained in patients with functioning renal transplants. We found that LMW-AGEs with an apparent molecular weight of 2000-6000 circulate and retain strong inherent chemical reactivity--when exposed to collagen in vitro, up to 77% attached covalently to form AGE-collagen, and the AGE-crosslink inhibitor aminoguanidine completely inhibited this reaction. The results suggest that LMW-AGEs comprise a set of chemically-reactive molecules that are refractory to removal by current dialysis treatments. Through covalent reattachment onto vascular matrix or serum components, LMW-AGEs may exacerbate vascular pathology associated with end-stage renal disease.

Adult↗
PubMed1993

Intradialytic parenteral nutrition: a practical approach.

Intradialytic parenteral nutrition (IDPN) therapy is becoming more prevalent in the malnourished patient undergoing maintenance hemodialysis. This is of particular concern to the nephrology nurse in that additional time is required to administer the solution, monitor the patient, and document the process. The IDPN monitoring flowsheet described in this article was developed to promote continuity of care from treatment to treatment, especially during initiation of IDPN, and to assist the nephrology nurse in administering and monitoring the therapy.

Aged↗
PubMed1990

The role of fantasy in the treatment of a severely disturbed child.

This case study demonstrates the psychodynamic role of a system of fantasies that dominated the emotional life of a severely disturbed child. Transformations in these fantasies revealed her development of a more stable sense of reality and the capacity for object relations.

Anxiety, Separation↗
PubMed1988

Complementary role of citrate and bicarbonate excretion in acid-base balance in the rat.

Studies were performed to evaluate whether alterations in the excretion of citrate, a metabolic precursor of bicarbonate, play a quantitatively important role in acid-base balance during bicarbonate feeding in the rat. Potassium depletion (K-DEPL), chloride depletion (Cl-DEPL), or potassium plus chloride depletion (KCl-DEPL) was produced by eliminating potassium, chloride, or potassium chloride from the diet. After 3 days of depletion, sodium bicarbonate (4,000 mueq/24 h) was added to the diet for 7 days. In all groups plasma bicarbonate concentration increased minimally during bicarbonate administration and was similar to normal controls receiving bicarbonate. In K-DEPL, citrate excretion was less than normal but bicarbonate excretion was greater than normal. In Cl-DEPL, bicarbonate excretion was less than normal but citrate excretion was greater than normal. In KCl-DEPL, bicarbonate and citrate excretion were similar to normal. Sodium bicarbonate was also administered to K-DEPL and KCl-DEPL rats in which plasma bicarbonate concentration averaged 32.9 meq/1. The reciprocal relationship between citrate and bicarbonate excretion was not altered by the profound metabolic alkalosis. Again, plasma bicarbonate concentration changed little with sodium bicarbonate administration. These studies suggest that the ability to excrete a base load remains intact despite potassium or chloride depletion or metabolic alkalosis. Complementary alterations of citrate and bicarbonate excretion play an important role in acid-base balance under these conditions.

Acid-Base Equilibrium↗
PubMed1988

Potassium-depletion alkalosis in the rat.

Studies were performed to investigate the role of concomitant chloride depletion in potassium-depletion alkalosis in the rat and the relationship between potassium depletion, plasma bicarbonate (PHCO3), and net acid excretion. 1) Selective potassium depletion (K-DEPL), potassium plus chloride depletion (KCl-DEPL), or selective chloride depletion (Cl-DEPL) was produced by administering a selectively potassium-, potassium and chloride-, or selectively chloride-deficient diet. In K-DEPL and KCl-DEPL rat, PHCO3 increased progressively and similarly during a 38-day period of restriction, whereas net acid excretion was similar and not elevated in either group. Cl-DEPL did not result in alkalosis. Chloride administration without potassium in alkalotic KCl-DEPL rats did not result in a sustained significant decrease in PHCO3. Potassium administration without chloride in alkalotic KCl-DEPL rats decreased PHCO3. Thus concomitant chloride depletion plays a minimal role in the alkalosis produced by dietary-induced potassium depletion. 2) Administration of a chronic acid load to alkalotic K-DEPL rats did not decrease PHCO3, and net acid excretion increased similarly as in normals. In K-DEPL rats after PHCO3 was reduced toward normal levels with acetazolamide, net acid excretion increased sharply above base-line values and PHCO3 increased markedly. Thus the alkalotic K-DEPL rat maintains the ability to excrete a chronic acid load, and a reduction in PHCO3 elicits an increase in acid excretion to restore the initial acid-base condition. These studies suggest that potassium depletion alters the set-point at which the kidney maintains PHCO3.

Acetazolamide↗
PubMed1986

Congestive heart failure with hypernatremia.

A patient presented with hypernatremia (plasma sodium level equals 171 mEq/L), marked congestive heart failure, and fluid retention. A high-salt intake and an inappropriate lack of thirst in this patient with poor cardiac function resulted in hypernatremia accompanied by edema. Hypertonic salt intake may have been due, in part, to zinc deficiency.

Heart Failure↗
PubMed1985

The effect of diuretics on systemic and renal hemodynamics in patients with renal insufficiency.

Diuretics have been used in acute renal failure in an attempt to increase urine flow and ameliorate the reduction in glomerular filtrate rate. A beneficial response occurs in some experimental models of acute renal failure when diuretics are administered prophylactically or very early in the course of renal failure and may require a renal vascular bed capable of responding partially, at least, to vasodilating stimuli. In chronic renal insufficiency the most important indications for diuretic use are for the treatment of systemic hypertension and for the correction of the congested state. However, the precise effect of diuretic therapy under these conditions is unpredictable and dependent on the functional state of the renal vessels. Diuretic administration may at times prove detrimental, resulting in a deterioration of glomerular filtration rate. In hemodynamically unstable conditions the slow removal of extracellular fluid by continuous arteriovenous hemofiltration may prove preferable to diuretic administration or standard forms of dialysis.

Acute Kidney Injury↗