Enhancement technology, ethics, and public policy.
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Biomedical subjects
Publications and source records attributed to R M Sade.
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BACKGROUND: Clotting complications in patients with mechanical valve prostheses can be prevented with either warfarin sodium (Coumadin; DuPont, Wilmington, DE) or antiplatelet agents. In children, it is not known whether one treatment regimen is more effective or safe than the other. METHODS: We prospectively followed up 64 children and young adults (aged 18 years or younger at implantation) with a mechanical valve on the left side of the heart, from October 1986 through October 1996. Forty-eight patients were treated with Coumadin and 16 with aspirin and dipyridamole. The two groups were similar in age, sex, valve location and size, mean length of follow-up, and operative indication. There has been a total follow-up of 272 patient-years on Coumadin and 116 patient-years on aspirin and dipyridamole. RESULTS: There was no difference between the two groups in survival or freedom from thromboembolism. Bleeding occurred more often in the patients taking Coumadin, but this difference was not statistically significant. Analysis of the literature showed thromboembolism and bleeding rates to be similar in the patients receiving Coumadin and those receiving antiplatelet agents. CONCLUSIONS: Coumadin and the combination of aspirin plus dipyridamole provided similar protection against complications in this group of children and young adults with left-sided St. Jude (St. Paul, MN) mechanical valves. The choice between the two regimens may depend on other factors, such as patient preference and convenience.
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OBJECTIVES: This study attempted to provide a formula for calculation of the pulmonary/systemic flow ratio in children after bidirectional cavopulmonary anastomosis. BACKGROUND: With the bidirectional cavopulmonary anastomosis, only the superior vena cava blood is oxygenated by the lungs. The inferior vena cava flow recirculates into the systemic circulation. The ratio of these flows will determine systemic arterial saturation. METHODS: According to the Fick principle, 1) Systemic cardiac output (liters/min) = Pulmonary venous flow + Inferior vena cava flow; 2) Systemic blood oxygen transport (ml/min) = Pulmonary venous blood oxygen transport + Inferior vena cava blood oxygen transport. By substituting the first equation into the second, Pulmonary/systemic flow ratio = (Systemic saturation - Inferior vena cava saturation)/(Pulmonary venous saturation - Inferior vena cava saturation). RESULTS: We applied the third formula to data obtained from 34 catheterizations in 29 patients after bidirectional cavopulmonary anastomosis. Mean [+/- SD] age at operation was 1.70 +/- 1.43 years, and mean age at catheterization was 2.95 +/- 1.65 years. The pulmonary/systemic flow ratio calculated for all 29 patients was 0.58 +/- 0.09. Of 17 patients with aortography, 10 had systemic to pulmonary collateral vessels. Patients with collateral vessels had a significantly higher pulmonary/systemic flow ratio (0.61 +/- 0.07 vs. 0.53 +/- 0.07, respectively, p < 0.02) and systemic saturation (88 +/- 4% vs. 82 +/- 4%, respectively, p < 0.002) than those without collateral vessels. The pulmonary/systemic flow ratio in those patients with no collateral vessels was similar to the previously reported echocardiographically derived superior vena cava/systemic flow ratio in normal children. CONCLUSIONS: The pulmonary/systemic flow ratio after bidirectional cavopulmonary anastomosis can be calculated. Pulmonary blood flow in these patients determines systemic saturation and accounts for the majority of venous return in young children.
BACKGROUND: Arrhythmias occur frequently after Fontan operations, and are related in part to high atrial pressure, wall distention, and scarring caused by extensive suture lines. These arrhythmic factors may be avoided by an extracardiac total cavopulmonary anastomosis. We have embarked on a program of conversion of the hemi-Fontan operation to a fenestrated extracardiac Fontan procedure with a relatively simple operation. METHODS: In a 4-month period ending in December 1994, 4 consecutive patients underwent this procedure. The inferior vena cava was divided and the cardiac end was oversewn. A large (20 to 25 mm) ascending aortic homograft, from which the inlet portion and valve had previously been excised, was interposed between the divided distal end of the inferior vena cava and the hood of the superior cavopulmonary anastomosis. A 4-mm fenestration with a pursestring snare mechanism was placed within the cavoatrial patch that had been implanted at the time of the hemi-Fontan procedure. RESULTS: There were no deaths, and the average length of stay was 12 +/- 4 days (range, 8 to 18 days). In early follow-up, there have been no atrial arrhythmias, and three of the four fenestrations have been documented to be patent. CONCLUSIONS: An extracardiac fenestrated Fontan procedure can safely and successfully be performed after a hemi-Fontan operation, and may have both hemodynamic and arrhythmic benefits.
Competing contemporary theories of health, the reductionist (purportedly value-free) and the relativist (purportedly value-based) theories, both rest upon an understanding of value as grounded in desiring, a subjective state. Both can be classified as subjectivist theories. An alternative set of theories, those resting on an understanding of value as grounded in desirability (or goodness) of an objective goal, can be classified as objectivist theories. The ultimate goal of all living things is life, the standard by which states or functions can be measured, and thereby defined as healthy or disease states. While disease can be classified in a taxonomy of biological dysfunctions without remainder, health is a richer concept that includes not only biological values, but also moral values, both leading to the ultimate goal of human flourishing.
BACKGROUND: Interviews are commonly used to measure noncognitive traits of medical school applicants. The present study investigated the influence of knowledge of applicants' cognitive abilities on interviewers' ratings of noncognitive traits. METHOD: Academic and demographic predictors of interview ratings of applicants' noncognitive traits were examined at the Medical University of South Carolina College of Medicine during two years: 1992, when applicants' Medical College Admission Test (MCAT) total scores and undergraduate grade-point averages (GPAs) were available to interviewers; and 1993, when MCAT and GPA data were not available. In 1992, 226 applicants met study criteria (i.e., they received ratings from three interviewers in addition to having MCAT and GPA data on file); in 1993, 245 applicants met the criteria. Step-wise regression analyses were conducted to measure the influences of seven independent variables on applicants' interview ratings. Two-way analyses of variances and t-tests were used to determine the effects of gender of applicants and interviewers. Cronbach's alpha coefficients were used as measures of interviewers' reliability. RESULTS: GPA was the best predictor for both years but accounted for double the amount of variance in interview ratings in 1992 (15.7%) compared with 1993 (7.4%). The reliability coefficients for the interviewers were .496 for 1992 and .473 for 1993. CONCLUSION: If the goal of the medical school admission interview is to assess noncognitive traits independently from academic skills, the authors recommend that MCAT and GPA data not be available to interviewers during interviews. The authors also found that gender and race influenced interview ratings in accordance with affirmative-action goals. Finally, the authors found that interview scores were only moderately reliable across different interviewers. They discuss ways to increase their reliability.
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We reviewed our 12-year experience with 254 adult patients who had St. Jude valves in the aortic position and used multivariate analysis to examine risk factors possibly affecting long-term morbidity and mortality. Nineteen-millimeter or 21-mm valves were implanted in 115 patients. Poor preoperative congestive heart failure status was associated with persistent congestive heart failure on late follow-up. Preoperative congestive heart failure and coronary artery disease were the only predictors of overall late death. Late deaths associated with heart failure and late sudden deaths were examined separately. Preoperative degree of heart failure was the only predictor of late death with associated heart failure. The implantation of a 19- or 21-mm valve in patients with a body surface area greater than 1.9 m2 somewhat increased the risk of late sudden death. In patients with a body surface area greater than 1.9 m2 and with a 19-mm or 21-mm annulus, consideration should be given to using a high-performance St. Jude valve or performing an annulus-enlarging procedure if this can be done with negligible morbidity.