Pharmacological Profile of Currently Used Inhaled Anesthetics
This volatile anesthetic is a nonflammable fluorinated isopropyl ether. It has a vapor pressure of 162 mm Mercury at 20 degree Celsius and boils at 58.5 degree Celsius. The blood/gas coefficient is 0.59 and the MAC in 100 percent oxygen is 1.71 and in 63.5 percent nitrous oxide 0.66.
Sevoflurane undergoes temperature dependent degradation by baralyme and soda lime. Therefore, it cannot be used in low flow or closed systems anesthesia. Sevoflurane reacts with CO2 absorbents to form a special haloalkene, the so-called Compound A. Compound A is metabolized to nephrotoxins and can lead to kidney damage. The minimum fresh gas flow has been recommended to be at least two liters per minute. Sevoflurane produces a dose-dependent decrease in arterial blood pressure due to peripheral vasodilatation. It should therefore not be used in patients with aortic valve stenosis. It does not sensitize the heart to arrhythmias or cause coronary artery steal syndrome. Unlike desflurane, sevoflurane does not irritate the airway. Due to its low solubility in blood it can be used for rapid induction of anesthesia without intravenous anesthetics. This is one of the reasons why it is currently replacing halothane for mask induction in pediatric patients. Like all other inhalation anesthetics, sevoflurane can trigger malignant hyperthermia in susceptible patients.
Induction of anesthesia can be achieved by using 1.5 to 3 percent sevoflurane in air or in oxygen, or by using 0.7 to 2 percent sevoflurane in 65 percent nitrous oxide. Sevoflurane does not cause coughing and excitation during induction and can be used without intravenous anesthetics. Maintenance of anesthesia can be achieved with 0.4 to 2 percent sevoflurane. The low tissue solubility of sevoflurane results in rapid elimination and awakening.