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Biomedical subjects

J Lindsay

Publications and source records attributed to J Lindsay.

At least 73 records · Page 4Linked to original sources
PubMed1996

Optimal cut-points when screening for more than one disease state: an example from the Canadian Study of Health and Aging.

A method is described for choosing optimal cut-points in screening test with a continuous score in order to divide people into any number of disease categories. The cut-points are chosen to minimize the overall expected loss, given a matrix of losses incurred by misclassifications. It is shown that the optimal cut-points depend on the column differences of the loss matrix. The effect of changing the loss matrix is examined. For the error counting matrix, where misclassifications are given equal weight, it is shown that the relationship between the minimal loss cut-point and the receiver operating characteristic (ROC) curve for two disease categories extends to the general case. The results of a study in which elderly people were screened for cognitive impairment and dementia are used to illustrate the method.

Aged↗
PubMed1996

Load dependence of left atrial and left ventricular filling dynamics by transthoracic and transesophageal Doppler echocardiography.

This article evaluates the pattern and effect of varying loading conditions on pulmonary venous flow and transmitral flow obtained by transthoracic and transesophageal echocardiography. We have conducted a two-stage study. A transthoracic echocardiographic study was performed in 15 patients with coronary artery disease and preserved left ventricular function. The transesophageal approach was used before open heart surgery where hemodynamic conditions were invasively monitored. Sublingual nitroglycerin (NTG) was administered to lower systolic blood pressure (mean 18 mm Hg) and resulted in a significant decrease in the peak passive left ventricular diastolic filling velocity (E wave) from 72 +/- 23 to 49 +/- 16 cm/s without marked changes in pulmonary venous flow pattern. In the transesophageal part of the study, Doppler-derived systolic (J), diastolic (K), and retrograde (R) phases of pulmonary venous flow, and passive (E) and active (A) phases of mitral flow were measured. Hemodynamic data were obtained invasively. Loading conditions were increased by infusion of saline and phenylephrine and reduced by NTG. Increased preload resulted in an augmented mitral E wave, an increased J wave, and an increased retrograde flow wave from the pulmonary veins. These changes were reversed by reduction of preload with NTG. Monitoring mitral and pulmonary venous flow may provide a relatively noninvasive means to assess directional changes in left ventricular preload.

Aged↗
PubMed1996

Major causes of death and hospitalization in Canadian seniors.

Since Canadian seniors are living longer, their proportion of the general population is getting increasingly larger. This paper focuses on presenting the leading causes of death and hospitalization in seniors (aged 65 and over), examining interprovincial differences and comparing trends from one decade to another. Although both mortality and hospitalization rates for coronary heart disease were found to be stable or falling during the past couple of decades, it remains the leading cause of death and hospitalization for both sexes. Lung cancer; stroke; chronic bronchitis, emphysema and asthma; pneumonia; and accidental falls are some of the other major causes of death and/or hospitalization in seniors.

Aged↗
PubMed1996

Dementia among seniors.

The prevalence of dementia increases sharply in old age and is higher among women than men. Alzheimer's disease, the most common form of dementia, affects a greater proportion of women. On average, the number of years lived with dementia is longer for women, and women with dementia are more likely to be living in institutions than men with the condition.

Age Distribution↗
PubMed1995

Polyacrylamide-based redox polymer for connecting redox centers of enzymes to electrodes.

Enzyme electrodes based on complexing a water-soluble copolymer of acrylamide and vinylimidazole with [Os(dmebpy)2C1]+/2+ (dmebpy = 4,4'-dimethyl-2,2'-bipyridine) and cross-linking with oxidases by water-soluble cross-linkers are described. The potential of the polyacrylamide-based redox polymer is +55 mV (SCE), a typical electron diffusion coefficient (De) in the redox hydrogel that results from its cross-linking is (1.3 +/- 0.1) x 10(-9) cm2/s. The properties of the enzyme electrodes formed when this redox hydrogel "wired" horseradish peroxidase (HRP), lactate oxidase (LOx) or glucose oxidase (GOx) depended on the thickness of the hydrogel film, the chemistry of their cross-linking, and their enzyme content. At the wired HRP electrodes, H2O2 was electrocatalytically reduced to water at 0.0 V (SCE). Lactate and glucose were electrocatalytically oxidized at 0.16 V (SCE). The GOx electrodes, when made with 140 micrograms/cm2 thick polymer films, were selective for glucose in the presence of physiological concentrations of urate and ascorbate.

Acrylic Resins↗
PubMed1994

Discordance in the predictors of mortality vs. those of ischemic complications following transcatheter coronary intervention.

Outcomes of percutaneous transluminal coronary angioplasty (PTCA) depend upon the skill of the angioplasty team and on the characteristics of the patient population. Comparisons of outcomes from different laboratories must take into account the latter. A discordance may exist between the baseline predictors of death in hospital following PTCA and those for periprocedural ischemia. Baseline clinical and procedural characteristics of 3,725 patients who underwent PTCA during 1991 and 1992 were compared with complications by multivariate analysis. The age of the patient and the occurrence of an MI within the previous 30 days were the most powerful independent predictors of death. Ischemic complications were not independently associated with these factors. Emergency CABG was associated independently with target lesion complexity and abrupt reclosure, with unstable angina or attempted saphenous vein graft dilatation. Thus, mortality may more directly reflect baseline clinical characteristics than the skill of operators in avoiding ischemic complications.

Age Factors↗
PubMed1994

Morbidity and mortality rates in elderly patients undergoing percutaneous coronary transluminal angioplasty.

Although successful dilatation of a target lesion by means of percutaneous transluminal coronary angioplasty (PTCA) can be attained as frequently in elderly as in younger patients, elderly patients have a higher risk of complications. Furthermore, cohorts of patients older than 75 years and undergoing PTCA include more women and more cases of unstable angina, factors that increase the risk of complications. Included in this analysis of 3199 PTCAs performed between January 1991 and September 1992 were 474 (14.8%) patients who were > or = 75 years old. Age was an independent risk factor for death, acute myocardial infarction, need for transfusion, and need for arterial repair after PTCA. The frequency of successful dilatation of individual lesions, emergency coronary bypass surgery, or repeated PTCA of the same lesion was not related to age. In previous studies no association has been demonstrated between age and increased risk of in-hospital reclosure. The presence of more severe coronary disease and of the greater frequency of coexisting morbid conditions makes elderly patients less able to tolerate unsuccessful or complicated PTCA.

Age Factors↗
PubMed1994

[An evaluation of multi-faceted program: intervention with violent spouses].

This article presents the results obtained from a study on the efficiency of a treatment program aimed at violent spouses. More particularly, three dimensions are evaluated, namely the program's effect on the incidence of violent behaviour (physical, verbal, psychological and sexual), on the participant's attitude toward the roles of men and women, as well as on the self-esteem of participants. Data on the violent behaviour of men was collected from them and from their spouses. The study reveals that the program tends to reduce all forms of violence and that its maximum efficiency is mostly noticed in the period following the program. On a different note, the program is less efficient when basing results on women's declarations than on men's. Finally, the program's efficiency varies according to the form of violence observed.

Adult↗
PubMed1994

Feasibility of on-line transesophageal echocardiography during balloon mitral valvulotomy: experience with 93 patients.

Percutaneous balloon mitral valvulotomy (PBMV) has become an established method of treating symptomatic patients with rheumatic mitral stenosis. PBMV is performed with fluoroscopic guidance alone in most centres. However, even experienced operators can be misled by radiographic anatomic landmarks. Transesophageal echocardiography (TEE) provides high-quality images of the atrial septum, left atrium, mitral valve, and surrounding structures and has a number of unique advantages that make it a useful adjunct to fluoroscopy for guidance and monitoring of patients during PBMV. The aim of this study was to demonstrate the feasibility, safety, and utility of on-line TEE during PBMV on awake patients. TEE was performed on 93 consciously sedated, awake patients in the cardiac catheterisation laboratory during PBMV. Ninety five patients were successfully intubated in the supine position. Two patients were excluded from PBMV based on mobile thrombi near the mouth of the left atrial appendage. The TEE was well-tolerated in the 93 patients who underwent PBMV, and no complications of TEE were detected. Major complications of PBMV were detected in 7 patients (severe MR, n = 3; tamponade, n = 1; large ASD, n = 3). We conclude that on-line TEE during PBMV is feasible, safe, and well tolerated. TEE-guidance facilitates transseptal catheterization and proper positioning of balloon catheters across the mitral orifice. TEE can help monitor the adequacy of PBMV and help decide whether or not subsequent dilatations are necessary. TEE can rapidly detect complications and thereby guide appropriate management of these complications.

Adolescent↗