Anesthesiology
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Comparative Study Clinical Trial Controlled Clinical Trial
What is the best way to determine oropharyngeal classification and mandibular space length to predict difficult laryngoscopy?
Previous studies have suggested that the degree of visibility of oropharyngeal structures (OP class) and mandibular space (MS) length can predict difficult laryngoscopy. However, those studies were either inconsistent or omit description of how to perform these tests with regard to body, head and tongue position, and the use of phonation, hyoid versus thyroid cartilage and inside versus outside of the mentum. The purpose of this investigation was to determine which method of testing best predicts difficult laryngoscopy. ⋯ Based on the above ROC areas and ease of performing the test for the patient, we recommend that these tests be performed with patients in the sitting position, with the head in full extension, the tongue out, and with phonation, and with distance measured from the thyroid cartilage to inside of the mentum. Nevertheless, it is clear that these two tests, either used alone or in combination, will fail to predict a few difficult laryngoscopies and that they will predict difficult laryngoscopy in a significant number of patients in whom the trachea is easy to intubate.
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Comparative Study Clinical Trial
Bedside assessment of intravascular volume status in patients undergoing coronary bypass surgery.
Management of intravascular volume is crucial in patients after cardiopulmonary bypass as myocardial dysfunction is common. The purpose of this study was to validate a novel bedside technique for real-time assessment of intravascular volumes. ⋯ This study shows that bedside determinations of intravascular blood volumes are feasible and that these measurements are more indicative of intravascular volume status than are either pulmonary capillary wedge or central venous pressures in the post-cardiopulmonary bypass period. Our data also demonstrate that despite a normal central blood volume both circulating and total blood volume are significantly increased in the immediate post-cardiopulmonary bypass period.
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Left ventricular diastolic function is known to be impaired in patients with coronary artery disease and patients with valvular aortic stenosis. Phenylephrine is frequently administered as an intravenous bolus in these patients perioperatively to increase coronary perfusion pressure. Although this is common practice, there is no information about the effect of phenylephrine bolus administration on left ventricular filling dynamics. ⋯ Phenylephrine bolus administration causes an alteration of left ventricular filling in coronary artery disease patients that seems to be more marked than that seen in normal subjects. In patients with aortic stenosis no deleterious effects were observed in response to phenylephrine.
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Comparative Study
Inhibition of volatile sevoflurane degradation product formation in an anesthesia circuit by a reduction in soda lime temperature.
Sevoflurane reacts with carbon dioxide absorbents, such as soda lime, to release the volatile products compounds A and B. These two products, which have been detected in anesthesia circuits, are among five formed when sevoflurane is degraded by soda lime at increased temperature; the others, compounds C, D, and E, have been detected only in heated sealed systems. The current study attempted to determine the influence of soda lime temperature on compounds A and B generation in an anesthesia circuit and whether a decrease in soda lime temperature could eliminate product formation in the circulating gases. ⋯ This study demonstrates that the release of volatile sevoflurane degradation products in an anesthesia circuit is highly dependent on soda lime temperatures. A reduction of the temperature of soda lime may be a feasible method of preventing the release of significant levels of sevoflurane degradation products without interfering with carbon dioxide absorption or altering the sevoflurane concentration.
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Volatile anesthetics depress left ventricular mechanical performance during multiple phases of the cardiac cycle. The effects of sevoflurane on systolic and diastolic function have yet to be fully evaluated. This investigation characterized the systemic and coronary hemodynamic, inotropic, and lusitropic actions of sevoflurane in chronically instrumented dogs in the presence and absence of autonomic nervous system (ANS) reflexes. ⋯ Sevoflurane caused direct negative inotropic and lusitropic effects in chronically instrumented dogs with and without ANS blockade.