Der Anaesthesist
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In obstetrics, general anaesthesia is increasingly being replaced by peridural anaesthesia. The cases where general anaesthesia is still used are those involving increased risk. It is therefore not surprising that, for example, maternal mortality in cases of caesarian section under general anaesthesia has not decreased. ⋯ In a comparison of sevoflurane and peridural anaesthesia, there was no difference in outcome for the child and the maternal results showed only the expected procedure-specific differences in circulatory parameters and early postoperative analgesia requirement. A second study involving continuous pEEG monitoring (SEF90) showed advantages of sevoflurane over isoflurane in the initial phase of surgery and in the recovery phase. However, the value of sevoflurane in obstetric anaesthesia will have to be confirmed in more extensive studies.
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The low blood/gas solubility, the rapid uptake and nonpungent odor permits mask induction with sevoflurane in adults. Depending on the induction techniques (tidal breathing, deep breaths or single-breath induction), the use of nitrous oxide and the concentration of inspired sevoflurane anesthesia can rapidly be induced within 41-178 s. Adverse effects like coughing, breath-holding or increased secretions occur with a low incidence of 2%-20%. ⋯ Although hypoxic pulmonary vasoconstriction is directly inhibited by volatile anesthetics in in vitro studies, this effect is usually of minor clinical consequence. The use of volatile anesthetics may be advocated because of their salutory effects on bronchomotor tone, high potency (allowing high inspired concentration of oxygen while avoiding awareness) and rapid adjustment of anesthetic depth. Sevoflurane possesses these attributes and may be useful for OLV.
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Propofol is known to possess direct antiemetic effects. Its use for induction and maintenance of anaesthesia has been shown to be associated with a lower incidence of postoperative nausea and vomiting (PONV) when compared to any other anaesthetic drug or technique. ⋯ The possible effects of propofol on the cerebral cortex, its interactions with the dopaminergic and the serotoninergic systems are evaluated by the known clinical and basic science results. Finally, the advantages and disadvantages of using propofol to decrease the incidence of PONV in clinical practice are discussed.
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Sevoflurane, like all currently used volatile anaesthetics, is degraded by carbon dioxide absorbents. The most significant degradant is a haloalkene known trivially as "compound A". Compound A is nephrotoxic in rats and, at higher doses, in nonhuman primates, causing proximal tubular necrosis. ⋯ There have been no case reports of compound A-associated renal injuryin humans. In volunteers, one study found changes in experimental but not conventional renal markers, while other investigations show no significant changes in either standard or experimental markers. The mechanism of compound A nephrotoxicity in rats appears to involve metabolism to glutathione and cysteine conjugates, and their subsequent renal uptake and metabolism by pathways that are different in rats and humans.
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The cardiovascular effects of sevoflurane are similar to those of isoflurane with some minor exceptions. In contrast to isoflurane and particularly to desflurane, sevoflurane has not been associated with increases in heart rate in healthy volunteers and in patients. ⋯ In several multi-center studies of patients with coronary artery disease or at high risk for coronary artery disease receiving either sevoflurane or isoflurane for either cardiac or non-cardiac surgery, the incidence of myocardial ischemia and infarction did not differ between treatment groups. In both human and animal models, sevoflurane preserves cerebral blood flow and reduces cerebral metabolic rate, much like isoflurane.