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Biomedical subjects

J M Weller

Publications and source records attributed to J M Weller.

At least 19 recordsLinked to original sources
PubMed2005

Psychometric characteristics of simulation-based assessment in anaesthesia and accuracy of self-assessed scores.

The purpose of this study was to define the psychometric properties of a simulation-based assessment of anaesthetists. Twenty-one anaesthetic trainees took part in three highly standardised simulations of anaesthetic emergencies. Scenarios were videotaped and rated independently by four judges. Trainees also assessed their own performance in the simulations. Results were analysed using generalisability theory to determine the influence of subject, case and judge on the variance in judges' scores and to determine the number of cases and judges required to produce a reliable result. Self-assessed scores were compared to the mean score of the judges. The results suggest that 12-15 cases are required to rank trainees reliably on their ability to manage simulated crises. Greater reliability is gained by increasing the number of cases than by increasing the number of judges. There was modest but significant correlation between self-assessed scores and external assessors' scores (rho = 0.321; p = 0.01). At the lower levels of performance, trainees consistently overrated their performance compared to those performing at higher levels (p = 0.0001).

Anesthesiology↗
PubMed2003

Evaluation of high fidelity patient simulator in assessment of performance of anaesthetists.

BACKGROUND: There is increasing emphasis on performance-based assessment of clinical competence. The High Fidelity Patient Simulator (HPS) may be useful for assessment of clinical practice in anaesthesia, but needs formal evaluation of validity, reliability, feasibility and effect on learning. We set out to assess the reliability of a global rating scale for scoring simulator performance in crisis management. METHODS: Using a global rating scale, three judges independently rated videotapes of anaesthetists in simulated crises in the operating theatre. Five anaesthetists then independently rated subsets of these videotapes. RESULTS: There was good agreement between raters for medical management, behavioural attributes and overall performance. Agreement was high for both the initial judges and the five additional raters. CONCLUSIONS: Using a global scale to assess simulator performance, we found good inter-rater reliability for scoring performance in a crisis. We estimate that two judges should provide a reliable assessment. High fidelity simulation should be studied further for assessing clinical performance.

Anesthesia↗
PubMed2000

Dynamic susceptibility contrast enhanced MRI in reversible posterior leukoencephalopathy syndrome associated with haemolytic uraemic syndrome.

We describe a case of reversible posterior leukoencephalopathy associated with haemolytic uraemic syndrome. Following remission confirmed on MRI, the patient relapsed several months later. Neuroimaging findings on conventional MRI and FLAIR sequences and dynamic susceptibility contrast enhanced MRI are described. White matter abnormalities may be shown on CT or MRI in this syndrome. However, dynamic susceptibility contrast enhanced MRI showed far more extensive abnormality within the brain. In addition, phase contrast angiographic measurement of flow in the carotid and basilar arteries indicated a significant elevation of cerebral blood flow, suggesting a decrease in global cerebrovascular resistance. These observations support existing theories that the disorder is manifested by autoregulatory disturbance in small cerebral vessels. Our findings suggest that this abnormality is far more extensive than is demonstrated on T2 weighted MR images and that it is associated with global abnormality of cerebrovascular autoregulation.

Adult↗
PubMed1987

Influence of race of cadaveric kidney donor and recipient on graft survival: a multifactorial analysis.

Actuarial survival analysis of 889 cadaver transplant patients between 1972 and 1981 in Michigan reveals functional graft (P = .0003) and patient (P = .004) survivals are improved when donors and recipients are of the same race (black or white). The Cox regression model for multifactorial analysis confirms the significantly lower graft survival for the mixed racial combination group with a relative risk of 1.27 (P less than .05). By this analysis, other significant factors adversely affecting the graft survival rates include diabetes as a cause of end-stage renal disease, earlier date of transplantation, shorter duration of prior dialysis, and a significant center effect. Patient survival has a significantly greater relative risk for the black to white racial combination, diabetes, earlier calendar year of transplantation, and age of patient. While the mixed racial group was slightly older (delta = 2 years), had more hypertension, less glomerulonephritis, and more HLA mismatches, our analysis by the Cox regression model suggests that these factors played only minor roles (P greater than .05) regarding graft survival rates. Therefore, our data suggest that independent of several other factors, cadaver kidneys have a better functional outcome when they are transplanted into recipients of the same race.

Actuarial Analysis↗
PubMed1985

End-stage renal disease in Michigan. Incidence, underlying causes, prevalence, and modalities of treatment.

In Michigan from 1974 through 1981 the average annual end-stage renal disease (ESRD) incidence was 7.76 for males and 5.55 for females per 100,000 population. Those over 35 years of age had higher incidence rates. The average incidence for black ESRD patients was 20.75, compared with 4.78 for white ESRD patients. Thus, the risk of ESRD was 4.34 times higher in the black population. In 1981, the stated causes of ESRD in the ESRD population were diabetes mellitus (24.5%), hypertension (24.2%), and glomerulonephritis (20.9%). Black ESRD patients, compared to white, had relative risks of 3.8 for diabetes mellitus, 10.9 for hypertension, and 1.7 for glomerulonephritis. The ESRD point prevalence increased from 11.58 in 1974 to 31.68 in 1981. Males predominated over females; the sex-specific ESRD prevalence in 1981 being 36.74 and 26.83, respectively. Blacks predominated over whites; the black and white ESRD prevalences in 1981 were 80.27 and 24.81, respectively. Prevalence over these years increased faster for older age groups. Hemodialysis at a center has been the major ESRD treatment modality. The percentage of all ESRD patients on home hemodialysis steadily decreased from 1974 through 1981. Similarly, on a percentage basis, fewer patients were transplanted in 1981 than in 1974. The number of ESRD patients treated by chronic ambulatory peritoneal dialysis increased more than sevenfold from 1979 through 1981.

Adolescent↗
PubMed1984

Case mix in end-stage renal disease. Differences between patients in hospital-based and free-standing treatment facilities.

This study examines the mix of cases in facilities for the treatment of end-stage renal disease in Michigan during the period January 1973 through September 1981. We compared 3135 patients treated in 29 hospital-based facilities with 307 patients treated in five proprietary, free-standing facilities. Patients were assigned to one of five severity groups on the basis of age, race, primary renal diagnosis, and accompanying conditions. The five severity groups were differentiated by the probability of death in the first year of treatment and the risk of death over the course of treatment. We then compared the distribution of patients in the five severity groups in hospital-based facilities with that in free-standing facilities. Hospital-based facilities had a higher percentage of patients in the higher-severity groups. When severity was measured by one-year survival, the difference was statistically significant. Sixty per cent of hospital-based patients were in the three highest severity groups, as compared with 50 per cent of patients in free-standing facilities. Within each severity group, hospital-based patients had a lower five-year survival rate than patients in free-standing facilities. Our findings suggest that the case mix in hospital-based facilities may include more severe cases than that in proprietary, free-standing facilities, but more data from more facilities will be needed before firm conclusions can be drawn. If the cost of providing services is related to case-mix severity, such data could have implications for federal reimbursement policies.

Adolescent↗
PubMed1982

Analysis of survival of end-stage renal disease patients.

Traditional life-table analysis of differences in patient survival for various end-stage renal disease (ESRD) treatment modalities ignore the fact the ESRD patients face sequential risks because they frequently experience more than one mode of therapy. A modification of the usual life-table analysis is suggested as being more appropriate. This modified method takes into account the "time-to-treatment" bias, which, in this instance, is the time spent on the first modality of treatment (that is, center dialysis). The survival data of more than 2,000 ESRD patients in the State of Michigan during the 5-year period, 1974 to 1978, are used to illustrate this method.

Adolescent↗
PubMed1982

Starch peritonitis following peritoneal dialysis.

Peritoneal dialysis is used frequently in the treatment of patients having renal failure. A 43-year-old patient developed acute abdominal symptoms 7 days after completion of peritoneal dialysis. Celiotomy demonstrated peritonitis with presence of starch powder. Resolution occurred rapidly after removal of the powder. Starch peritonitis after peritoneal dialysis can be obviated by careful washing of gloves. It can be managed without operative intervention. Peritonitis due to starch dusting powder can occur as a complication of peritoneal dialysis.

Adult↗
PubMed1980

Familial hyperuricemia and renal disease.

Information on a familial syndrome of hyperuricemia and renal disease with or without gout was obtained on 33 of 41 blood relatives: Nine had renal disease; abnormalities of the urinary sediments were minimal; serum uric acid levels were elevated in seven and were not measured in two. Hyperuricemia was noted in three additional family members without evidence of renal disease. Goulty arthritis (three patients) did not precede renal disease. One individual had hyperuricosuria. The following erythrocyte purine enzyme levels were normal: adenine phosphoribosyltransferase, hypoxanthine-guanine phosphoribosyltransferase, phosphoribosylpyrophosphate, synthetase, adenosine deaminiase, and purine nucleoside phosphorylase. Renal biopsy specimens showed focal global and segmental sclerosis of glomeruli, occasional hypercellularity, foci of atrophic tubules, chronic interstitial inflammation, and folding and wrinkling of glomerular basement membrane without electron-dense deposits. There were no immunofluorescent abnormalities.

Arthritis↗
PubMed1978

Intrarenal hemodynamics and renal function in postobstructive uropathy.

Impairment of renal function was noted after release of 24 hr of unilateral (UUO) and bilateral (BUO) ureteral obstruction. After release of obstruction fractional sodium excretion was identical in both obstructed and intact kidney of UUO rats, whereas massive natriuresis occurred in BUO rats. Renal blood flow in BUO rats, determined by the microsphere method after released of 24 h of obstruction, was approximately 60 per cent of control values. Mean renal blood flow of the obstructed kidney of UUO rats after release of obstruction was 78 per cent of the mean renal blood flow of the contralateral unobstructed kidney. No redistribution of intrarenal blood flow was noted in UUO and BUO rats. Filtration fractions of obstructed kidneys from BUO and UUO rats after release of obstruction were lower than those of controls, suggesting that preglomerular vasoconstriction is primarily involved in the reduction of glomerular filtration rate.

Animals↗
PubMed1977

Effect of minoxidil on blood pressure and hemodynamics in severe hypertension.

Eighteen patients with diastolic hypertension (100 to 120 mm Hg), in addition to propranolol, 160 mg daily, and hydrochlorothiazide, 100 mg daily, received progressively increased doses of either minoxidil or placebo in a double-blind crossover study. With minoxidil (average dose 19.7 mg) blood pressure decreased from 165/109 to 138/89 mm Hg without the appearance of orthostatic hypotension. Hypertrichosis and fluid retention did occur, with an average weight gain of 1.8 kg, concomitant with an increased plasma volume. Pulse rate and cardiac output increased; no significant changes were observed in plasma renin activity, renal plasma flow, glomerular filtration rate or excretion of catecholamines or aldosterone. Minoxidil appears to be a useful antihypertensive drug for treating patients who do not respond adequately to therapy with diuretic and beta adrenergic blocking agents.

Adult↗
PubMed1977

In vitro uptake of gentamicin by rat renal cortical tissue.

The mechanism of gentamicin uptake in vitro by renal cortical slices of rat kidney was investigated. The cortical-slice-uptake ratio of gentamicin concentration in 1.0 g of tissue water to that of 1.0 ml of incubation medium (SW/M) was 1.44 +/- 0.04. The uptake of gentamicin was inhibited by 2 x 10(-5) M dinitrophenol (SW/M = 1.03 +/- 0.04) and by anoxia (SW/M = 1.01 +/- 0.04). The results indicate that aerobic phosphorylation is required to transport gentamicin into the cells. The uptake of p-aminohippurate and tetraethylammonium chloride by renal cortical slices was not affected by gentamicin.

Animals↗
PubMed1977

Renal hemodynamics in HgCl2-induced acute renal failure.

Renal blood flow (RBF), outer cortical blood flow (OC-rbf) and inner cortical blood flow were determined by the microsphere method in water-drinking rats and chronic saline-drinking rats at 3, 12 and 24 h after injection of HgCl2, 4.7 mg/kh body weight. RFB and OC-rbf were decreased in both groups at 3 h post HgCl2 injection. Persistent reduction of OC-rbf was noted in water-drinking rats at 12 and 24 h post HgCl2 even though the total RBF returned to normal by 24 h. These parameters were normal in chronic saline-drinking rats. Despite normal RBF in water-drinking and saline-drinking rats, serum creatinines were still signigicantly elevated 24 h post HgCl2. Therefore, alterations in total renal perfusion do not entirely account for the decreased renal function that occurs under these circumstances.

Acute Kidney Injury↗