Masui. The Japanese journal of anesthesiology
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It is widely known that electroencephalogram (EEG) shows dramatic changes with increase of the concentration of anesthetic. It is considered that volatile anesthetics (i. e. isoflurane, sevoflurane), barbiturates, propofol show anesthetic effect by potentiating GABAA receptor. Changing patterns of EEG by these anesthetics are quite similar. ⋯ However this is not always the required condition for adequate anesthesia, because alpha power never becomes larger in some patients even when the anesthetic level was judged as adequate by concentration dependent changing patterns of EEG. As EEG changes in relation to the concentration of anesthetic, it seems to be correlated with the level of consciousness. But EEG patterns during anesthesia are mainly determined by the condition of thalamic neurons, and it would merely indicate the level of hypnosis indirectly.
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We showed the effect sites of anesthetics in the central nervous system (CNS) network. The thalamus is a key factor for loss of consciousness during natural sleep and anesthesia. Although the linkages among neurons within the CNS network in natural sleep are complicated, but sophisticated, the sleep mechanism has been gradually unraveled. ⋯ Recent literatures have shown that the effects of anesthetics are specific rather than global in the brain. It is interesting to note that thalamic injection of anti-potassium channel materials restored consciousness during inhalation anesthesia, and that the sedative components of certain intravenous anesthesia may share the same pathway as natural sleep. To explore the sensitivity and susceptibility loci for anesthetics in the thalamocortical neurons as well as arousal and sleep nuclei within CNS network may be an important task for future study.
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We report 3 cases of anterior mediastinal masses in which we avoided providing general anesthesia for a biopsy and a central venous catheter placement. In all cases, chest X-rays on admission showed mediastinal mass ratio (MMR) greater than 44% and thoracic computed tomographic scans demonstrated cross sectional area (CSA) of the trachea 60% less than expected and the main stem bronchi narrowing. We made a decision not to provide general anesthesia, considering the risk of airway obstruction after induction of general anesthesia. ⋯ In case 3, a 3-year-old boy, preoperative corticosteroids and chemotherapy improved MMR 67% to 34% and %CSA 60% to 95%. On day 8 of admission a biopsy was performed under general anesthesia uneventfully. We emphasize not only clinical signs but also radiological signs are important to evaluate the safety in induction of general anesthesia for the management of the cases of anterior mediastinal masses.
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OS-1 is an oral rehydration solution that conforms with the principles of oral rehydration therapy. It may be useful for preoperative fluid management of surgical patients. While intake of clear fluids 2 hours before surgery is considered safe, it is not known if the same applies to OS-1. We therefore investigated the safety of OS-1 for preoperative patients as compared with clear fluids. ⋯ We concluded that allowing elective surgical patients to drink OS-1 until two hours before anesthesia did not affect the volume of gastric contents.