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Biomedical subjects

M M Ravitch

Publications and source records attributed to M M Ravitch.

At least 19 recordsLinked to original sources
PubMed2000

Medical and veterinary students' structural knowledge of pulmonary physiology concepts.

PURPOSE: The goal of this study was to assess quantitatively medical and veterinary students' knowledge structures of 12 pulmonary physiology concepts before and after receiving a focused instructional block. The "goodness of fit" and internal consistency reliability of the students' knowledge structures were evaluated. Indexes of the students' structural knowledge were correlated with customary measures of student learning of the same concepts. METHOD: Knowledge structures were assessed using a questionnaire that requested similarity judgments about all possible pairs of the concepts: n(n - 1)/2 = 66 pairs. The similarity judgment data were analyzed using the individual differences (INDSCAL) model of multidimensional scaling (MDS). Dimension weights for individual students were then correlated with their final examination scores. RESULTS: A four-dimensional MDS solution provided the best structural fit to the pairwise concept-similarity data. Dimension 1 ranges from control of breathing to lung gas exchange. Dimension 2 ranges from control of breathing to respiratory mechanics. Dimension 3 separates perfusion from diffusion. Dimension 4 addresses ventilatory control. Hierarchical concept clusters are located within this framework. However, indexes of structural learning did not correlate with other measures of knowledge about the same concepts. CONCLUSION: The study outcomes, in contrast to research in other fields, suggest that structural knowledge in this domain differs from knowledge assessed by standard examinations. Further research involving other basic science or clinical concept sets is needed to verify or refute this finding.

Education, Medical↗
PubMed2000

Quantitative concept mapping in pulmonary physiology: comparison of student and faculty knowledge structures.

Quantitative concept mapping, in contrast with qualitative approaches, is rigorous scientifically and permits statistical analyses of data about concept learning. This study extends past quantitative research on the structure of student concept learning in pulmonary physiology. Pathfinder scaling is used to derive concept maps for medical and veterinary students and their physiology instructors at Northwestern University and the University of Wisconsin, respectively. The concept maps are evaluated for coherence (internal consistency), student-instructor similarity, and correlation of similarity with final examination scores. Results show that student and instructor concept maps are coherent and that student concept maps become increasingly similar to instructors' concept maps from pre- to postinstruction, but that student-instructor concept map similarity does not correlate with examination performance. Research outcomes are discussed concerning possible sources of variation in student and faculty knowledge structures.

Data Collection↗
PubMed1986

Comparison of physicians' decisions regarding estrogen replacement therapy for menopausal women and decisions derived from a decision analytic model.

Decisions regarding estrogen replacement therapy were obtained from 50 physicians for 12 cases representing menopausal women with systematically varying levels of cancer risk, fracture risk, and symptom severity. Their decisions were compared with a decision analytic model for which each physician provided needed quantities--subjective probabilities, utilities of various outcomes, and weightings of the importance of the outcome categories. The majority of observed decisions were not to treat. By contrast, the decision analysis based on physician-provided estimates indicated that the optimal strategy was either to treat or a toss-up. Sensitivity analysis showed that these conclusions would hold over all possible utilities, over all plausible probabilities of cancer, and so long as symptom relief and fracture prevention were also considered as treatment objectives. The increased probability of early detection of cancer by regular follow-up was systematically incorporated into the decision analysis but apparently neglected in unaided clinical judgment, which follows the principle of minimizing the most important risk, regardless of its probability.

Decision Theory↗
PubMed1986

Closure of the urinary bladder with stainless steel and absorbable staples.

Stapling is widely accepted in the field of pulmonary and gastrointestinal surgery. However, this has not been the case in urinary tract surgery, presumably because of the possibility of stone formation on the staples. In addressing the issue, both stainless steel staples and absorbable staples (PolysorbTM) were evaluated in 104 linear stapled closures of dog bladders. The mucosa to mucosa closures were performed in bladders with sterile, acutely infected, and chronically infected urine. Staple lines were resected and examined both grossly and microscopically at periods from 1 week to 4 months after the closures. No animal suffered a clinical leak or abscess formation. Four steel closures developed exposed staples, one of which developed a small amount of crystal formation. Twenty-nine absorbable closures contained exposed staples in which two closures developed crystal formation. All closures were secure and healed without difficulty. It appears that closure of the bladder with stainless or absorbable staples is safe and effective.

Absorption↗
PubMed1985

Rationale for physicians' decisions to refer obese patients.

Health care costs are an increasing burden upon American society. Referral of patients to a specialist generates additional cost. We studied the reasons behind decisions to refer patients with uncomplicated obesity to endocrinologists. Obesity may be viewed as a paradigm of diseases with relatively well-known etiology, low morbidity and mortality, chronicity, and poor outcome from standard therapy. In addition, it is a disease that is rarely curable by medical intervention, requiring behavioral change. Physicians have little direct experience in the differential diagnosis of endocrine disease, because of its low prevalence. We studied the referral decisions of 45 physicians in three medical specialties. Clinical decision making was studied using a standard set of 24 carefully structured case reports of obese women, all without obvious endocrine disease cues on history or physical. In these cases the patients' desire to be seen by endocrinologists was the major factor in the decision to refer. Referrals were not made primarily to rule out suspected endocrine disorder or because of concern for increased risk of morbidity.

Body Weight↗
PubMed1985

Intersecting staple lines in intestinal anastomoses.

With the wide application of the stapling instruments in thoracic and general surgery, a number of techniques have been introduced that involve intersecting staple lines. If these simply involve two applications of the liner staplers (TA series), the problem is only one of the effect of the intersection on the circulation, particularly at the corner. With the GIA linear anastomotic instruments or the EEA circular anastomotic instrument, the question arises as to the integrity of the staple line that is cut through by the knives in these instruments. A large experience here and abroad attests to the safety of the TA intersecting lines in intestine and lung, presumably because the circulation continues through the staple line. The use of the circular anastomosing instrument, EEA, across linear staple lines has been spreading clinically with good reports. Studies were undertaken in dogs of the fate of the TA staple lines when the EEA stapler was used for rectal resection or for a Billroth I gastroduodenal reconstruction. In 20 rectal anastomoses and 10 Billroth I reconstructions, there were no leaks, dehiscences, or evidences of failure, whether the EEA transsected the linear staple line once or twice. Most frequently the knife bent the intersected staple and transferred it to the doughnut that was removed. Much less frequently a staple was cleanly transsected by the knife, and only twice did we see no evidence of damage to the staples in the TA line.

Abscess↗
PubMed1984

Contemporary stapling instruments and basic mechanical suture techniques.

This article provides a description and demonstration of the basic linear staple closures and anastomoses, as well as of circular anastomoses. Depending on the technique used, bowel may be closed in a mucosa-to-mucosa or serosa-to-serosa fashion, and comparable results with either modality are demonstrated.

Equipment Design↗
PubMed1984

Varieties of stapled anastomoses in rectal resection.

This article presents numerous illustrations that show a variety of techniques for the restoration of intestinal continuity after low anterior resection. The conclusion is that, at extremely low levels, the EEA stapler anastomosis can be securely performed at levels at which manual anastomosis would not be possible.

Humans↗