Isoflurane (Forane) is a structural isomer of enflurane and produces similar pharmacological properties: some analgesia, some neuromuscular blockade, and depressed respiration. In contrast, however, isoflurane is considered a particularly safe anesthetic in patients with isch-emic heart disease, since cardiac output is maintained, the coronary arteries are dilated, and the myocardium does not appear to be sensitized to the effects of cate-cholamines. Also, blood pressure falls as a result of va-sodilation, which preserves tissue blood flow. Isoflurane causes transient and mild tachycardia by direct sympathetic stimulation; this is particularly important in the management of patients with myocardial ischemia.
Unlike enflurane, isoflurane does not produce a seizurelike EEG pattern. Furthermore, the metabolic transformation of isoflurane is only one-tenth that of enflurane, so fluoride production is quite low. Among the halogenated hydrocarbons, isoflurane is one of the most popular, since it preserves cardiovascular stability and causes a low incidence of untoward effects.
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