Sevoflurane

Quick Answer

Sevoflurane is a fluorinated ether inhalational anaesthetic with blood:gas partition coefficient 0.65 (low solubility), enabling rapid induction and emergence compared to isoflurane (1.4) and halothane (2.4). MAC (Minimum Alveolar Concentration): 2.0-2.5% in adults, 2.5-3.3% in children, reduced 6-8% per decade after age 40. Induction: Pleasant, non-irritant odour makes it suitable for inhalational induction in children (8% via mask with N₂O 60% or O₂). Metabolism: 2-5% hepatic metabolism by CYP2E1 to hexafluoroisopropanol (HFIP) and inorganic fluoride; fluoride levels usually <50 μmol/L but can reach 100 μmol/L after prolonged high-dose exposure. Compound A: Degradation product formed by reaction with CO₂ absorbents (soda lime, baralyme), nephrotoxic in rats but not clinically significant in humans at typical concentrations. Low-flow anaesthesia: Use FGF 1-2 L/min with sevoflurane safe; avoid FGF <1 L/min for >4 hours to minimize Compound A. Cardiovascular effects: Dose-dependent myocardial depression and vasodilation (reduced SVR), preserved baroreceptor reflex (heart rate increases with hypotension unlike halothane). Respiratory: Bronchodilation, dose-dependent respiratory depression, reduced tidal volume with increased respiratory rate, irritant to airways (less than desflurane). Contraindications: MH-susceptible patients (triggers MH), severe hepatic impairment (reduced metabolism). Indigenous considerations: No specific alterations in pharmacokinetics, but higher obesity rates may require dose adjustments and careful MAC monitoring. [1-10]