Fractal dimensions of chaotic saddles of dynamical systems.
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Biomedical subjects
Publications and source records attributed to E Ott.
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Considering the heart as a physical pump cardiac efficiency is calculated from the ratio of cardiac work performed to the maximum level of energy of the heart. The aim of the study was to compare cardiac efficiency with cardiac output and right ventricular ejection fraction. Nine patients scheduled for coronary artery bypass grafting were investigated. A femoral arterial and a right ventricular ejection fraction pulmonary artery catheter were placed in the awake state. Anaesthesia was induced with eltanolone and fentanyl. Cardiac output, pulmonary artery and central venous pressures, and right ventricular ejection fraction were measured in the awake state (baseline), 2 min after induction of anaesthesia and 1 and 5 min after intubation. Cardiac efficiency was calculated by dividing the stroke work by the maximum energy of the heart as calculated from the pressure volume diagram. An analysis of variance was carried out for cardiac efficiency, cardiac output and right ventricular ejection fraction. Cardiac efficiency was significantly (p < 0.05) reduced 1 min after intubation from 28 +/- 11 to 14 +/- 5%. In contrast the right ventricular ejection fraction (from 48 +/- 10 to 35 +/- 13%) and cardiac output (from 6.5 +/- 1.5 to 5.3 +/- 1.2 L/min) did not change significantly during the induction of anaesthesia. Cardiac efficiency was found to be a more sensitive parameter to describe changes in the right ventricular function than the ejection fraction and cardiac output during induction of anaesthesia with eltanolone and fentanyl which was used as a model to vary cardiac performance and afterload.
We evaluated the hemodynamic profile of eltanolone and fentanyl versus thiopental and fentanyl anesthetic induction in patients with documented coronary artery disease. Fifty patients scheduled for coronary artery bypass grafting were randomly assigned to two treatment groups (25 patients each). Anesthesia was induced by eltanolone (0.5 mg/kg) or by thiopental (3 mg/kg). Each patient also received 3 micrograms/kg fentanyl and 0.1 mg/kg vecuronium. Heart rate, arterial, pulmonary arterial, central venous, and pulmonary capillary wedge pressures, and cardiac output were determined in the awake state, 2 min after induction of anesthesia, and at 1 and 5 min after intubation, which was performed 3 min after induction. Between-group statistics showed significantly (P < 0.05) lower mean arterial pressure and systemic vascular resistance for eltanolone-treated patients at all measuring points. Pulmonary capillary wedge pressure was lower at 1 min after intubation; left ventricular stroke work index was lower at 1 and 5 min after intubation in the eltanolone group. We conclude that the lower mean arterial pressure with eltanolone as compared to thiopental is a result of greater peripheral vasodilation.
Serotyping of 50 streptococcal strains of serological group B isolated from human clinical specimens in Chile revealed mainly the serotypes Ia, II and III, either alone or in combination with protein antigens c or R. No significant difference in serotype distribution was detected between group B streptococci isolated from cervical swabs from clinically healthy women and those isolated from various pathological processes. Determination of antibiotic susceptibility of the bacteria demonstrated resistance to tetracycline and minocycline in 29 isolates. All 29 tetracycline-resistant cultures hybridised with a gene probe for tet(M). Again, no differences were detected between the group B streptococcal isolates of various origins.
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Radiosurgery with the Gamma Knife was performed in 12 patients with parkinsonism. In 9 patients small lesions were created in the head of the caudate nucleus bilaterally. Two patients underwent radiosurgical thalamotomy, and 1 patient was treated with caudatotomy and thalamotomy. After a follow-up period of 1-12 months, 9 patients of the caudatotomy group and all patients with thalamotomies showed clear benefit. There was no complication or side effect that could be related to the treatment. Pre- and postoperative testing was performed with the Unified Parkinson Rating Scale and with objective motor tasks. Caudatotomy proved to be an effective treatment for bradykinesia and rigidity, while tremor was ameliorated by thalamotomy. Functional neurosurgery with the Gamma Knife would seem to be a good alternative to open procedures with low morbidity and no mortality. Advantages and drawbacks of radiosurgical techniques for the treatment of parkinsonism are discussed.
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