[Mask induction and one-lung ventilation with sevoflurane]. / Maskeneinleitung und Ein-Lungenventilation mit Sevofluran.

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%. Some 88 to 100% of the volunteers or patients would accept a mask induction again. Clinical experience shows that sevoflurane is well indicated for mask induction in adults. Acute severe bronchospasm is a feared complication of anesthesia with an incidence of 1.7%. Although halothane is often recommended as the agent of choice in patients with reactive airways, there is little evidence in humans that it is more effective than other volatile agents. The bronchodilating effects of sevoflurane are comparable to those of other volatile anesthetics, it produces minimal airway irritation and allows rapid adjustment of anesthetic depth. These properties and our clinical experience suggest that sevoflurane is a useful choice for patients with reactive airways. Hypoxemia during one-lung ventilation (OLV) occurs in 9-27% of patients and remains a clinical problem. 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.

[Interactions of dry soda lime with enflurane and sevoflurane. Clinical report on two unusual anesthesias]. / Interaktion von trockenem Atemkalk mit Enfluran und Sevofluran. Klinischer Bericht über zwei ungewöhnliche Anästhesieverläufe.

UNLABELLED: We report two cases of unexpected courses of inhalation anaesthesia with sevoflurane and enflurane which were caused by the presence dry soda lime. Case 1: During mask induction of a healthy 46-year-old female patient for elective hysterectomy it was noted that the vaporizer setting of 5% sevoflurane (in 50% O2, 50% N2O) did not result in the expected increase of inspiratory sevoflurane concentration. At the same time, the anaesthesiologist observed that the patient did not lose consciousness while the temperature of the soda lime canister increased sharply and the colour of the soda lime turned to blue with condensing water visible in the tubing. It was later determined that this anaesthesia machine had not been used for more than 2 weeks. Analysis of the soda lime showed a water content of <1%. Case 2: Following intravenous induction of a non-smoking 64-year-old male patient for elective gastrectomy, it was noted that the concomitant inhalation of enflurane was associated with a sharp rise in the temperature of the soda lime canister, a colour change of the soda lime to blue and a decrease in the measured inspiratory enflurane concentration despite an unchanged or even increased vaporizer setting. Arterial blood gas analysis revealed a CO-Hb concentration of 8.8% with otherwise normal acidity and partial gas pressures. Immediate change of the absorbant resulted in a decline in the CO-Hb concentration to 6.9% within 3 h. It was later determined that the anaesthesia machine had not been used for 34 h. Analysis of the soda lime showed a water content of 5.4%. DISCUSSION: Both case reports were associated with a rise in temperature and a colour change to blue of the soda lime. Reactions of desflurane, enflurane or isoflurane with dry soda lime resulting in significant CO-Hb formation have been previously reported. Reactions of sevoflurane with dry soda lime have been observed but have so far not been published. Until further analysis of these phenomena is completed, it is mandatory for the patient's safety to guarantee that only soda lime with a sufficient water content be used for clinical anaesthesia.