Anesthesia and analgesia
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Several characteristics of sevoflurane biotransformation are apparent from the preceding investigations. Metabolism is rapid, with fluoride and HFIP appearing in plasma within minutes after the start of sevoflurane administration (38-40,51). Peak plasma fluoride concentrations generally occur within approximately 1 h after the termination of sevoflurane administration in most patients, regardless of the dose or duration of exposure (ranging from 0.35-9.5 MAC-h) (39,48). ⋯ Although both sevoflurane and methoxyflurane may produce plasma fluoride concentrations in excess of 50 microM, they have not produced the same nephrotoxic effects. Clearly, anesthetic metabolism and anesthetic toxicity can no longer be considered synonymous. The introduction of sevoflurane into clinical practice will hopefully stimulate new investigations into biochemical mechanisms of anesthetic toxicity and continued clinical investigations regarding the relationship between anesthetic metabolism and organ toxicity.
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Sevoflurane appears to have several properties that make it an attractive alternative to the currently available anesthetics for outpatient anesthesia. The relative low solubility of sevoflurane, as well as an impressive lack of airway irritation, makes it a very useful anesthetic for inhalation induction of anesthesia. This feature is likely to make sevoflurane a population choice for pediatric outpatient anesthesia. ⋯ The relatively low solubility of sevoflurane will facilitate its use with total gas flow rates of 2-3 L/min. In the final analysis, clinicians will have to balance the cost of sevoflurane (versus halothane, enflurane, isoflurane, and desflurane) against its potential advantages in the ambulatory surgery population. Although the search for anesthetics that are more ideally suited for use in the outpatient setting will continue, sevoflurane clearly represents a step in the right direction (3).
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In conclusion, sevoflurane appears to be similar to isoflurane and desflurane with a few exceptions. Sevoflurane was not associated with increases in heart rate in adult patients and volunteers, whereas higher MACs of isoflurane and desflurane and rapid increases in the inspired concentrations of these two anesthetics have been associated with tachycardia. Increasing concentrations of sevoflurane progressively decrease blood pressure in a manner similar to the other volatile anesthetics, and in unstimulated volunteers this decrease may be slightly less than with isoflurane at a higher MAC. ⋯ Sevoflurane reduces baroreflex function in a manner similar to other volatile anesthetics. In several multicenter studies where patients with CAD or patients at high risk for CAD were randomized to receive either sevoflurane or isoflurane for cardiac or noncardiac surgery, the incidence of myocardial ischemia, infarction, and cardiac outcomes did not differ between treatment groups. Thus, sevoflurane has not been associated with untoward cardiovascular changes in volunteers and patients undergoing elective surgery compared with other volatile anesthetics, and it appears to offer a more stable heart rate profile than either isoflurane or desflurane.