Der Anaesthesist
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Review Comparative Study
[Sevoflurane in pediatric anesthesia. Malignant hyperthermia].
Inhalational anaesthesia is the most common anaesthesia technique in paediatric anaesthesia worldwide. Up to now the standard anaesthetic used is halothane. Because halothane is tolerated in the upper airways without side effects it is well suited for the inhalational induction of anaesthesia. ⋯ However, shorter recovery times lead to earlier perception of postoperative pain, requiring adequate pain management. (4) The hemodynamic stability after administration of sevoflurane is favourable to that after halothane in paediatric patients, leading to significantly less bradycardia. (5) In paediatric patients no negative effects on kidney function have been observed after administration of sevoflurane. There is no scientific basis for organotoxic effects, thus sevoflurane is suitable for low-flow and minimal-flow anaesthesia. (6) The duration of the action of muscle relaxants is increased to a greater extent in presence of sevoflurane compared to halothane. Consequently, the total dose of muscle relaxants can be reduced using sevoflurane. (7) Similar to the established inhalational anaesthetics sevoflurane triggers malignant hyperthermia (MH) and must not be used in patients in which MH is suspected or in which a predisposition for MH is known.
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An ideal anaesthetic should allow rapid, pleasant, and predictable induction, maintenance and emergence from anaesthesia. Little information is available about sevoflurane use in elderly patients. The pharmacological profile of sevoflurane may be advantageous in geriatric patients because low solubility in the blood is a prerequisite for rapid changes in anaesthetic depth. ⋯ However, there is still controversy if the occurrence of postoperative cognitive and mental impairment is reduced in elderly patients if drugs with fast elimination characteristics are use. Few data are available on the use of sevoflurane in geriatric patients with renal impairment. Further studies are needed to clarify if the administration of sevoflurane is safe in this population of patients.
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During sevoflurane anaesthesia cerebral blood flow is preserved or slightly decreased. Cerebral oxygen consumption is reduced to 50% under 1 MAC sevoflurane. Autoregulation of cerebral blood flow and responsiveness of cerebral blood flow to changes in Pa CO2 are widely preserved. ⋯ Recovery of cognitive and psychomotor functions seems to be faster and more complete after sevoflurane than after isoflurane anaesthesia. In inducing seizure like EEG or muscle activity, sevoflurane seems to be comparable with isoflurane. There is no limitation of sevoflurane use in patients with concomitant psychiatric or neurological diseases, and sevoflurane may be valuable addition in neurosurgery or carotid surgery.
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Due to its low solubility and the high maximum concentration delivered by the vaporizer sevoflurane is especially suitable for the performance of low flow anaesthetic techniques. High flow phases for wash-in or wash-out of anaesthetic gases can be kept short, the difference between the volatile's concentration in the fresh gas and within the breathing system is comparatively small, and the time constants are short even during low flow anaesthesia. The monitoring, required to sufficiently ensure the safety of the patients, corresponds to the current obliging technical safety standards. ⋯ Thoroughly the use of sevoflurane with dry soda lime must be avoided, as this volatile in an extreme exothermic reaction is absorbed nearly totally and degraded to a considerable degree by dry carbon dioxide absorbent. The gaseous degradation products are pungent and possibly may be harmful to the patients. Only by low flow anaesthesia the use of sevoflurane will gain an economically and ecologically acceptable range of efficiency.