Biomedical subjects

Michael A Kraus

Publications and source records attributed to Michael A Kraus.

6 recordsLinked to original sources

PubMed2005

Subcutaneous terbutaline use in CKD to reduce potassium concentrations.

BACKGROUND: Acute hyperkalemia is a frequent and potentially life-threatening medical problem in patients on maintenance hemodialysis therapy. beta-Adrenergic receptor (betaAR) stimulation causes potassium cellular influx and a decline in plasma potassium concentrations. Therefore, betaAR agonists are used in the treatment of patients with hyperkalemia. The goal of this study is to evaluate the utility of weight-based subcutaneous terbutaline dosing to reduce plasma potassium concentrations in a group of subjects with chronic kidney disease (CKD) requiring hemodialysis. METHODS: Fourteen subjects with CKD receiving long-term hemodialysis were administered terbutaline, 7 microg/kg, subcutaneously. Heart rate measurements and blood samples for potassium concentration determinations were made serially for 420 minutes. Effects of terbutaline on heart rate and potassium responses were determined in each subject. RESULTS: Terbutaline significantly reduced plasma potassium concentrations and significantly increased heart rates during the time course of the study (P < 0.001, repeated-measures analysis of variance). Mean reduction in peak potassium concentration (-1.31 +/- 0.5 [SD] mEq/L) and increase in peak heart rate (25.8 +/- 10.5 beats/min) were significantly different from baseline (P < 0.001, baseline versus peak for both responses). No subject reported significant adverse effects. CONCLUSION: Administration of subcutaneous terbutaline obviates the need for intravenous access and should be considered as an alternative to nebulized or inhaled beta-agonists to treat acute hyperkalemia in patients with CKD. As with the use of any beta-adrenergic agonist, close cardiovascular monitoring is necessary to avoid or minimize toxicity during therapy.

Adrenergic beta-Agonists↗

PubMed2004

Rituximab for reduction of anti-HLA antibodies in patients awaiting renal transplantation: 1. Safety, pharmacodynamics, and pharmacokinetics.

BACKGROUND: Preformed HLA antibodies (Ab), reported as panel-reactive antibody (PRA), prolong patient waiting time for kidney transplantation. We hypothesized that rituximab (RTX) could reduce PRA via B-cell depletion. This initial study reports the safety, pharmacokinetics, and pharmacodynamics of RTX in patients with end-stage renal failure. METHODS: The study was an investigator-initiated single-dose, dose-escalation phase I trial of RTX in chronic dialysis patients (PRA >50%). It was approved by the Institutional Review Board and the Food and Drug Administration. Nine subjects were treated with a single dose of RTX (n=3 per group) at 50, 150, or 375 mg/m. Peripheral lymphocyte cell surface markers and HLA Ab levels (%PRA and titers) were tested using flow cytometry. RESULTS: There were four significant adverse events: a suspected histoplasmosis infection; two Tenchkoff dialysis catheter infections; and fever (38.7 degrees C) during infusion. At 2 days after RTX therapy, there was depletion of CD19 cells (pre-RTX 181+/-137 vs. post-RTX 12+/-5.6, P =0.006). In 2 (22%) of 9 subjects, there was no appreciable change in PRA. Among the other seven patients, one had a decrease in PRA from 87% to 51% with a concurrent decrease in fluorescence intensity; five patients had changes in histogram architecture suggesting loss of antibody specificity; and one patient had a fourfold decrease in PRA titer from 1:64 to 1:16 at 6 months after treatment. In addition, one of the seven patients converted a donor-specific crossmatch to negative and underwent a successful living donor kidney transplantation. CONCLUSIONS: RTX can be safely administered and may be an effective agent to reduce high-titer anti-HLA Abs in subjects awaiting kidney transplantation.

Adult↗

PubMed2003

Internal jugular vein thrombosis associated with hemodialysis catheters.

PURPOSE: To determine the prevalence of internal jugular vein thrombosis among patients undergoing hemodialysis in whom tunneled dialysis catheters were placed by interventional radiologists and to evaluate potential risk factors for thrombosis, such as the number of catheters inserted per patient through the right internal jugular vein, catheter type and material, total catheter days, and catheter-associated infection. MATERIALS AND METHODS: Ultrasonographic (US) evaluation of the right internal jugular vein was performed by interventional radiologists in 143 patients with a history of dialysis catheter placement. The examination focused on the detection of right internal jugular vein thrombosis, with or without occlusion. Total catheter days, catheter type, and catheter-related complications, most notably infection, were evaluated with database analysis for possible association with subsequent development of thrombosis. Statistical analysis of potential risk factors was performed with logistic regression models and chi2 tests. RESULTS: Evidence of right internal jugular vein thrombosis was present in 25.9% of the patients enrolled in the study. Among the veins with thrombosis, 62% were occluded. Only the mean number of catheters placed in the right internal jugular vein per patient was significant below the level of P =.20; therefore, a multivariate logistic regression model was not used. CONCLUSION: Prevalence of internal jugular thrombosis, both complete and incomplete, was higher in the study population than previously reported. The risk factors that were analyzed demonstrated no statistically significant association with development of thrombosis.

Catheters, Indwelling↗

PubMed2003

Kinetic comparison of different acute dialysis therapies.

Recent clinical data indicate both ultrafiltration rate (Qf) and timing of treatment initiation in continuous renal replacement therapy (CRRT) and therapy frequency in intermittent hemodialysis (HD) influence survival in critically ill patients with acute renal failure (ARF). In this study, kinetic modeling is used to compare effective dose delivery by three acute dialysis therapies: continuous venovenous hemofiltration (CVVH), daily HD, and sustained low-efficiency dialysis (SLED). A modified equivalent renal clearance (EKR) approach to account for the initial unsteady-state stage during dialysis is employed. Effective small solute clearance in CVVH is found to be 8% and 60% higher than in SLED and daily HD, respectively. Differences are more pronounced for middle and large solute categories, and EKR in CVVH is approximately 2-fold and 4-fold greater than the corresponding values in daily HD and SLED, respectively. The superior middle and large solute removal for CVVH is due to the powerful combination of convection and continuous operation. In CVVH, a decrease in the initial BUN from 150 to 50 mg/dL is predicted to decrease TAC and, therefore, increase EKR by approximately 35%. After clinical validation, the quantification method presented in this article could be a useful tool to assist in the dialytic management of critically ill ARF patients.

Acute Kidney Injury↗

PubMed2003

Dose determinants in continuous renal replacement therapy.

Increasing attention is being paid to quantifying the dose of dialysis prescribed and delivered to critically ill patients with acute renal failure (ARF). Recent trials in both the intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) realms have suggested that a direct relationship between dose and survival exists for both of these therapies. The purpose of this review, first, is to analyze critically the above-mentioned dose/outcome studies in acute dialysis. Subsequently, the factors influencing dose prescription and delivery are discussed, with the focus on continuous venovenous hemofiltration (CVVH). Specifically, differences between postdilution and predilution CVVH will be highlighted, and the importance of blood flow rate in dose delivery for these therapies will be discussed.

Acute Kidney Injury↗

PubMedDate not supplied

Patterns of interdialytic weight gain during the first year of hemodialysis.

This retrospective study describes patterns of interdialytic weight gain (IWG) over the first year of hemodialysis in 27 individuals. IWG increased over the first 12 weeks and appeared to reverse after 12 weeks, increasing again after 32 weeks. Interventions may need to occur after the individual has been receiving treatment for 12 weeks; booster interventions may be indicated after 32 weeks. Variability in the two measures used (mean daily interdialytic weight gain and mean daily percent above dry weight) suggests a need for further study.

Adult↗