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Biomedical subjects

J Burkart

Publications and source records attributed to J Burkart.

22 records · Page 2Linked to original sources
PubMedDate not supplied

Comparison of intraperitoneal and subcutaneous epoetin alfa in peritoneal dialysis patients.

OBJECTIVE: To compare the efficacy of intraperitoneal (i.p.) and subcutaneous (s.c.) administration of epoetin alfa in patients receiving peritoneal dialysis (PD). DESIGN: A 32-week prospective, randomized, cross-over experimental design. SETTING: Two university-based outpatient PD centers. PATIENTS: Twenty adult PD patients receiving stable doses of s.c. epoetin alfa enrolled in the study. Thirteen patients completed 32 weeks of follow-up. INTERVENTION: Patients were randomly assigned to receive either s.c. or i.p. epoetin alfa at the start of the study. Dose adjustments were made to maintain baseline hematocrit +/- 3 percentage points. Following 16 weeks of treatment, patients crossed over to the other route of administration for an additional 16 weeks. Intraperitoneal epoetin alfa was administered into an empty peritoneal cavity for approximately 8 hours before resuming dialysis. End-of-study i.p. epoetin alfa doses required to maintain target hematocrit were given twice weekly (n = 1), once weekly (n = 11), or once every other week (n = 1). All patients received iron supplements to maintain or exceed prestudy iron parameters. MAIN OUTCOME MEASURE: Prior to the study, the primary outcome measure was defined as the difference in epoetin alfa dose between i.p. and s.c. administration. RESULTS: Thirteen patients completed the study. The area under the dosing-requirement curve for i.p. epoetin alfa was larger than for s.c. administration (p = 0.0029), and the slope of the 16-week dose-requirement curve was greater for i.p. administration (p = 0.017), suggesting greater dose stability for s.c. administration. Paired analysis indicated greater i.p. intrapatient dose requirements (p < 0.0001). The mean difference in s.c. versus i.p. doses was 5000 +/- 1510 units per week. Some patients required escalating i.p. doses to maintain target hematocrit values. Iron administration and iron stores were similar in both groups. CONCLUSION: Intraperitoneal epoetin alfa may be a suitable alternative for some patients for whom s.c. dosing is undesirable. Large i.p. versus s.c. dosing differences noted in a few patients are unexplained, but may result from interpatient variability in i.p. epoetin alfa absorption. Intraperitoneal dosing into an empty peritoneum can be done safely and effectively.

Absorption↗
PubMedDate not supplied

Quantitative gas transfer into and out of circulating venous blood by means of an intravenacaval oxygenator.

The volume of O2 and CO2 transferred into/out circulating venous blood by various sized IVOX devices has been assessed by ex vivo and in vivo animal experiments and by reviewing the gas transfer data collected from the first 20 human ARDS patients studied during Phase I of the IVOX clinical trials. Data from these assessments indicate that oxygen transfer through the size 5 IVOX ranges from 15.4 to 18.0 cc/min; through the size 6 IVOX ranges from 22.8 to 35.5 cc/min; through the size 7 IVOX ranges from 28.5 to 66.7 cc/min; through the size 8 IVOX ranges from 34.9 to 66.3 cc/min; through the size 9 IVOX ranges from 45.9 to 115.7 cc/min; through the size 10 IVOX ranges from 52.9 to 133 cc/min. Quantitative carbon dioxide transfer through the various size IVOX devices closely follows the quantitative oxygen transfer achieved by IVOX. These quantitative data provide valuable information to clinicians considering using IVOX to augment the inadequate gas transfer existing in patients with acute, potentially reversible respiratory failure. They indicate IVOX transfers clinically significant quantities of O2 into and CO2 out of circulating venous blood in an intact subject without involving the subjects natural lungs.

Animals↗
PubMedDate not supplied

Peritoneal dialysis kinetic modeling: validation in a multicenter clinical study.

OBJECTIVE: To clinically validate the use of a computer-based kinetic model for peritoneal dialysis (PD) by assessing the level of agreement between measured and modeled values of urea and creatinine clearances and ultrafiltration (UF). DESIGN: An open multicenter observational study. PATIENTS: There were 111 adult continuous ambulatory peritoneal dialysis (CAPD) patients (47 female, 64 male) in four centers. All patients underwent a four-hour peritoneal equilibration test (PET) using 2.5% dextrose but with variable fill volumes (range: 1-3 L). Patients with a residual renal function greater than 10 mL/min were excluded. MAIN OUTCOME MEASURES: Correlations and limits of agreement between measured and modeled values of total weekly urea KT/V, total weekly normalized creatinine clearance (L/week/1.73 m2), daily drain volume (L), net ultrafiltration (L), daily peritoneal urea clearance (L/day), and daily peritoneal creatinine clearance (L/day). Measured values were obtained from 24-hour urine and dialysate collections while modeled values were based on results from the PET in combination with the PD ADEQUEST kinetic program. RESULTS: The results show there is excellent agreement between measured and modeled urea KT/V and creatinine clearances, with concordance correlations of 0.94 and 0.92, respectively. Given the excessive variation and limited range in ultrafiltration values, the concordance correlation between measured and modeled UF was only 0.50. In terms of daily peritoneal clearances and ultrafiltration, the level of precision (i.e., standard deviation) in the differences between modeled and measured values is +/- 1.05 L/day for urea clearance +/- 1.03 L/day for creatinine clearance, and +/- 0.919 L/day for ultrafiltration. By contrast, the level of precision (i.e., standard deviation) in the differences between two measured values is estimated to be +/- 0.979 L/day for urea clearance, +/- 0.802 L/day for creatinine clearance, and +/- 0.707 L/day for ultrafiltration. Defining the limits of clinical agreement to be +/- 2 standard deviations of the differences between two clinically measured 24-hour clearances (or ultrafiltration), we find that 94% of the modeled urea clearances, 87% of the modeled creatinine clearances, and 86% of the modeled ultrafiltration values fall within the limits of clinical agreement. CONCLUSION: Data for a carefully performed PET and overnight exchange can, in combination with a scientifically validated kinetic model, provide clinicians with a powerful mathematical tool for use in CAPD dialysis prescription management. Although not intended to replace actual measurements, kinetic modeling can prove useful as a means for predicting clearances for various alternative prescriptions and perhaps also as a means for checking certain types of noncompliance.

Adult↗