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T Buur

Publications and source records attributed to T Buur.

13 recordsLinked to original sources
PubMed1991

Pharmacokinetics of felodipine in chronic hemodialysis patients.

Five chronic hemodialysis patients (1 woman and 4 men, aged, 46-68 yr) were given an oral dose of 10 mg felodipine followed by 0.057 mg [3H] felodipine IV. After 5 hours, a hemodialysis treatment lasting 4 hours was performed. Blood and dialysate flows were 200 mL/min and 500 mL/min, respectively. Capillary dialyzers with 1.3 m2 cellulose acetate membrane were used. The pharmacokinetic characteristics and reduction in diastolic BP were similar to those in hypertensive patients with normal renal function and in uremic patients who were not treated with dialysis. There was no measurable removal of felodipine by hemodialysis. Dialyzer clearance of radioactive metabolites was about 10 mL/min, and only 8.9% of the dose was eliminated by the treatment. The half-life of radioactive metabolites was 10 days (6-14 days) in three patients dialyzed thrice weekly. Since the metabolites are biologically inactive, no adjustment of dose is required in hemodialysis patients.

Administration, Oral↗
PubMed1991

Precision of hemodialysis urea kinetic modeling: empirical data and Monte Carlo simulation.

To examine the precision of variable volume urea kinetic modeling (UKMv) 15 stable hemodialysis patients were followed with repeated sampling for 5 weeks. Samples were frozen and later submitted to careful batch analysis. On average, the index for dialysis adequacy (Kt/V) varied 6.1% and normalized protein catabolic rate (pcr) varied 10.5%. Immediate routine analysis correspondingly rendered 8.6% and 13.2%. A simpler, fixed volume model (UKMf) had an almost similar variation and results correlated highly with UKMv. The duration of the preceding interval does not affect Kt/V, but per is lower during longer intervals. Computer simulation demonstrated that most of the variation of calculated pcr could be explained by fluctuations of urea generation, i.e., secondary to dietary changes. Fluctuations in the efficiency of dialysis may cause most variation of Kt/V, but the imprecision of the urea analysis also contributes. Precise knowledge of effective dialyzer clearance is not important for the calculation of Kt/V and pcr. It is concluded that calculating these variables with a simple model, employing a reasonable estimate of dialyzer clearance will suffice for routine use. The slightly higher accuracy of a more sophisticated model is overshadowed by day-to-day variations.

Adult↗
PubMed1991

Accuracy of hemodialysis urea kinetic modeling. Comparison of different models.

To test the accuracy of urea kinetic modeling (UKM), the classic fixed-volume model UKMf, two variable-volume models (UKMvb and UKMvd), direct dialysis quantification (DDQ) and a partial dialysate collection method (PDC) were evaluated in 15 stable, high-hematocrit patients. Urea generation rate (G) was also determined from a 1-week collection of total dialysate and urine (OWC). The results, except distribution volumes, were highly correlated. However, Kt/V, the normalized whole-body urea clearance, was about 8% higher with UKMvb and UKMvd. Two of three simple equations for Kt/V rendered grossly deviating, but highly correlating, results. The normalized protein catabolic rate was 8% higher with UKMvd. With OWC as reference, UKMvb and UKMvd overestimated G by 19 and 15%, respectively. All results of PDC closely followed those of DDQ. This method may be an alternative for exact quantification. Before using a new UKM method it should be compared to an established reference method.

Adult↗
PubMed1991

Medical reasoning and patient requests in decision-making for female genitourinary infections.

The aim of this study was to investigate General Practitioners' (GPs') collection and analysis of data on women presenting with lower genitourinary (GU) complaints, also taking into account patient preferences. For 135 patients seen after nurse triage, eleven GPs recorded the clinical data they had explored, an evaluation of the patient's desire (or not) for medical interventions, a preliminary diagnosis with certainty estimate, and management actions. Whether a clinical data item was explored varied between 97% of the patients for fever to 15% for pelvic examination. Decisions regarding diagnosis followed to a large extent results from screening laboratory tests. For prescription of antibiotics the patient's desire (or not) for medical interventions was a significant discriminant. The GPs reported the lowest diagnostic certainty for diagnosis of urethritis, the highest for cystitis. Factors contributing to physicians' uncertainty in their decision-making were assumed patient reluctance for medical interventions and negative screening tests. In conclusion, patient requests and preferences significantly influenced the GPs, even though results from screening laboratory tests were mainly used as the basis for decisions. The high reliance on screening tests may often cause other clinical information to be neglected. Thus, the uncertainty regarding patients with negative laboratory test results may reflect that important information is not included in the clinical analysis.

Adult↗
PubMed1990

Urea kinetics and clinical evaluation of the haemodialysis patient.

Urea kinetic modelling (UKM) was performed on 62 patients in a haemodialysis unit not normally using kinetic methods. Without knowledge of the results, four nephrologists, four nurses and the patients themselves evaluated adequacy of dialysis (eAD) and daily protein intake (eDPI). Thirty-two patients had Kt/V less than 1.0, and 17 patients had Kt/V less than 0.9. Estimated improvement of the efficacy of treatment after the intervention of a physician was minor. Seven patients had a protein catabolic rate (pcr) at less than 0.8 g/kg per day. On average physicians identified five of these. Both nurses and doctors exhibited highly significant correlations between Kt/V and eAD, and between pcr and eDPI, but the correlation coefficients were generally modest (typically below 0.4). When patients evaluated themselves, no significant correlations were found. Examined individually, all four physicians' decisions about eAD correlated better with model-generated decisions than with eAD stated by their colleagues. It is concluded that UKM should be used to secure adequate and more uniform treatment prescription. There is no 'clinical standard' competing with UKM. Nurses make satisfactory evaluations compared to doctors, but the patients are unable to assess the adequacy of their dialysis or diet.

Adult↗
PubMed1990

Audit of decision-making regarding female genitourinary infections in outpatient practice.

Patient data, diagnosis, work-up measures, and prescriptions were collected from 63 consultations by general practitioners (GPs) to study day-to-day management of women with complaints suggestive of genitourinary (GU) infections. The collected patient data were thereafter presented to a panel of 9 specialist physicians for their individual recommendations. On drug prescriptions, the panel supported 81% of the decisions, did not support 14%, and remained undecided on 5% of the cases. In all but one of the unsupported cases, the GP had prescribed antibiotics. On diagnoses, the panel supported 62% of the decisions, did not support 13%, and was undecided on 25% of the cases. The most frequent discordance concerned diagnosis of urethritis. On collection of medical data by history and physical examination, the panel found 22% of the consultations unsatisfactory. Discordance in both diagnosis and drug prescription were related to remarks about data collection. The results suggest that the body of knowledge available for GPs for management of female GU infections in outpatient practice is incomplete.

Adolescent↗
PubMed1990

Inter-observer variation in decision-making regarding patients on chronic hemodialysis: a study using the kappa index.

To examine inter-observer variation in the monitoring of patients with chronic disease, four nephrologists independently assessed 62 patients on maintenance hemodialysis. Deviation from normal was determined for adequacy of dialysis, protein intake, and metabolic state. The kappa-index, which allows to adjust for chance agreement, was used to analyze each monitoring diagnosis. Low agreement was found on decisions concerning adequacy of dialysis (kappa 0.12-0.26), while agreement was higher about protein intake (kappa 0.21-0.46), and metabolic state (kappa 0.24-0.52). Two physicians classified no patient as overdialyzed, while 16-18% were thus categorized by the other two. Routines for review of recent medical history also differed significantly between the physicians. Measures are needed to increase the reliability of decisions regarding the monitoring of chronic hemodialysis. A long lasting physician-patient relationship is not a sufficient prerequisite for diminishing decision variation. Medical audit as part of the clinical routine, and use of additional sources of information, exemplified by urea kinetic modeling, are discussed.

Adult↗
PubMed1990

Secondary effects of erythropoietin treatment on metabolism and dialysis efficiency in stable hemodialysis patients.

To test the possible effect of erythropoietin (EPO) induced higher hematocrit on dialysis efficacy and metabolism, 14 metabolically stable hemodialysis patients were evaluated with various kinetic methods, including total dialysate collection. Tests were performed twice before EPO treatment and twice when hemoglobin had stabilized in the targeted range. Samples were frozen and batch analyzed for each patient after completion of the study. During this period, dialysis regimens were fixed. EPO treatment caused several significant changes. Hematocrit increased from 21.5% to 34.3%. Pre- and postdialysis serum potassium increased 0.3-0.4 mmol/l, and 56% more potassium binder was given. Serum phosphate concentrations were unchanged, but the aluminum hydroxide dose had been raised 44%. Dialyzer clearance decreased for urea (4.8%), creatinine (14.7%), phosphate (16.5%) and potassium (8.6%). The ratio of postdialysis/predialysis measurements changed for calcium, creatinine and uric acid. Five patients experienced enhanced appetite, but average dry weight did not change, nor could changes be demonstrated for protein catabolism, generation rate of urea and creatinine, or their distribution volumes. Estimated sodium intake remained unchanged. The findings indicate that EPO treatment reduces dialysis efficiency slightly for a number of substances, but in the metabolically stable patient there are no impressive dietary changes. Problems can be overcome by appropriate changes of dialysis regimen and medication.

Anemia↗
PubMed1988

Pharmacokinetics of chloral hydrate poisoning treated with hemodialysis and hemoperfusion.

In a severe case of chloral hydrate intoxication treated with combined hemodialysis and hemoperfusion the pharmacokinetics of the metabolites trichloroethanol (TCE), trichloroethanol glucuronide (TCE-Glu) and trichloroacetic acid (TCA) were studied. Indications of delayed absorption and some slowing of metabolism were found. At a blood flow rate of 200 ml/min clearances by hemodialysis and hemoperfusion, respectively, in ml/min were estimated to be 188 and 156 for TCE, 184 and 181 for TCE-Glu, 142 and 91 for TCA. Clearance by hemoperfusion declined with time. The half-lives of TCE and TCA were 3.2 and 4.3 hours during combined hemodialysis and hemoperfusion. After termination of treatment the half-life of TCE was 12.8 hours, whereas TCA was metabolized so slowly, that no reliable calculation could be performed. We conclude that hemodialysis and hemoperfusion are equally and highly efficient in the treatment of chloral hydrate poisoning, but hemoperfusion may increase the risk of gastric bleeding more than hemodialysis. Hemodialysis may therefore be preferable and should be tried in spite of low blood pressure.

Adult↗
PubMed1982

Desensitization by terbutaline of beta-adrenoceptors in the guinea-pig soleus muscle: biochemical alterations associated with functional changes.

1 The effects of adrenaline and terbutaline on cyclic adenosine 3',5'-monophosphate (cyclic AMP) content, 22Na-efflux, 42K-influx and subtetanic contractions have been assessed in soleus muscles isolated from guniea-pigs which had been maintained on food with or without terbutaline for 5 days. 2 Terbutaline and adrenaline increased cyclic AMP content and suppressed subtetanic contractions, and regression analysis indicates a statistically significant correlation between these two effects (P less than 0.01). 3 In muscles obtained from terbutaline-treated animals, the effects of terbutaline and adrenaline on cyclic AMP content, active Na-K-transport and subtetanic contractions were all considerably suppressed, but insulin stimulated 22Na-efflux and affected subtetanic contractions to the same extent as in the muscles obtained from the control group. 4 The results suggest that terbutaline treatment leads to a reduction in the number of beta 2-adrenoceptors in skeletal muscle or an impairment of their function. 5 The results provide further support for the idea that the effect of adrenaline or insulin on skeletal muscle contractions is the outcome of stimulation of active Na-K-transport.

Animals↗
PubMedDate not supplied

DiaKin: an integrated program package for hemodialysis kinetics.

A flexible program for the IBM PC performing a number of calculations of relevance for the prescription of hemodialysis treatment has been developed. The program has a 'spreadsheet'-like user-friendly interface, and results may be presented graphically. The present implementation covers 89 algorithms/equations, all based on the assumption of single-pool kinetics. Some of these are detailed for the first time, including considerations on their implementation using a generalizing, structured approach.

Algorithms↗
PubMedDate not supplied

Improvement of decisions regarding hemodialysis patients by urea kinetic modeling.

The potentials for improving decisions about adequacy of dialysis (AD) and daily protein intake (DPI) by urea kinetic modeling (UKM) were examined. Four nephrologists evaluated AD, DPI, and metabolic stability in 62 patients. UKM was done three times; but the results were not revealed. Clinicians' decisions were then compared with UKM measures of effective dialysis (Kt/V) and protein catabolic rate (pcr). Detection of inadequately treated patients by the clinicians was poor (28%, Kt/V less than 1.0; and 40%, Kt/V less than 0.9). Specificities of the clinicians' decisions were 0.96 and 0.92, respectively. Combining pcr and consensus decisions, 59 patients could be assigned a probable DPI. Using this as "gold standard," the average clinician detected 77% of 13 low DPIs. Single or triple pcr determinations alone detected 77% or 62%, respectively. Specificities were 0.91, 0.85, and 1.0. Simulated decision making suggested that combining pcr with clinical evaluation in a logical way would lead to detection of most patients with low DPI. Qualitative data from individual patient cases causing controversies are presented and discussed. It is concluded the UKM should be used routinely to assess the adequacy of dialysis and daily protein intake.

Adult↗