Anesthesiology
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One possible mechanism of impaired oxygenation in cardiac surgery with extracorporeal circulation (ECC) is the accumulation of extravascular lung water (EVLW). Intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) also may increase after separation from ECC, which can influence both cardiac performance and pulmonary capillary fluid filtration. This study tested whether there were any relationships between lung fluid accumulation and pulmonary gas exchange during the perioperative period of cardiac surgery and ECC. ⋯ Cardiac surgery with the use of ECC induces alterations of thoracic intravascular and extravascular fluid volumes. Postoperatively, increased ITBV and PBV need not be associated with higher EVLW. Thus, sufficient mechanisms protecting against lung edema formation or providing resolution of EVLW probably are maintained after ECC. Since oxygenation is impaired during and after cardiac surgery, it is concluded that mechanisms other than or in addition to changes of ITBV, PBV, and EVLW predominantly influence gas exchange.
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Remifentanil (GI87084B) is a new short-acting opioid with a unique ester structure. Metabolism of remifentanil by ester hydrolysis results in very rapid elimination. The aim of this study was to characterize in detail the pharmacokinetic profile of remifentanil in healthy male volunteers. ⋯ Remifentanil is a new, short-acting opioid with promising clinical potential in anesthesiology.
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The newly developed neuromuscular blocking agent, mivacurium, has been evaluated in adults and children, but there are no data on its effects in infants. This study was designed to evaluate the neuromuscular effects of mivacurium by dose-response analysis, and its cardiovascular effects in 90 infants 2-11 months of age anesthetized with 1% halothane and nitrous oxide:oxygen. ⋯ The ED50 duration of action and infusion requirements of mivacurium in infants 2-6 months of age are comparable with those of infants 7-11 months of age.
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There has been little systematic examination concerning the comparative effects of the anesthetized versus the awake state on outcome from cerebral ischemia. This experiment evaluated infarct volume and neurologic function in rats subjected to temporary focal ischemia while anesthetized with either sevoflurane or halothane. Outcome in these animals was compared to that observed in rats maintained unanesthetized during a similar ischemic insult. ⋯ Both halothane and sevoflurane substantially reduced damage in this focal ischemia model when compared to outcome resulting from the same insult induced in awake rats. The reduction in intraischemic mean arterial pressure caused by the anesthetics did not seem contributory to outcome. Brain temperature differences among the groups were not defined. Because small differences in pericranial temperature were shown to have major effects on outcome, further work is required to determine if differences in brain temperature explain the observed protective effects of these anesthetics.
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It generally is assumed that the potency of inhalational anesthetics remains unchanged during the course of the administration of an anesthetic. Only one study has indicated a decrease of minimum alveolar concentration with time. In this study, an effect of the duration of anesthesia administration and surgery on the potency of isoflurane was investigated by determining MACtetanus (the minimum alveolar concentration that prevents movement in response to electrical tetanic stimulation in 50% of patients) before and after surgery. ⋯ The authors conclude that MACtetanus decreases during the administration of anesthesia and the performance of surgery.