Desflurane

Desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether; CAS 57041-67-5; molecular formula C3H2F6O; molecular weight 168.04) is a fully fluorinated methyl ethyl ether developed by Ross Terrell at Anaquest in the 1980s and approved by the FDA in 1992 (Suprane). The minimum alveolar concentration (MAC) at age 40 is 6.0 percent in oxygen, the highest of the clinical volatile anesthetics; the blood-gas partition coefficient is 0.42, the lowest in the class, producing the fastest induction and emergence kinetics among approved inhalational agents. The high vapor pressure (664 mmHg at 20 degrees Celsius, near the boiling point of 23 degrees Celsius) requires a heated, pressurized vaporizer (Tec 6 or equivalent) rather than the variable-bypass design used for isoflurane and sevoflurane. Mechanism is the standard halogenated ether profile: GABA-A positive allosteric modulation, K2P channel activation, glycine and NMDA modulation. Hepatic metabolism is minimal (less than 0.02 percent of an absorbed dose), the lowest among inhalational anesthetics, virtually eliminating fluoride-related nephrotoxicity and trifluoroacetylated hepatotoxicity. The principal clinical limitations are airway irritation that precludes inhalational induction (coughing, breath-holding, laryngospasm at concentrations above 6 percent in non-anesthetized patients) and sympathetic stimulation with rapid concentration increases producing transient tachycardia and hypertension. The high MAC and high vapor pressure make desflurane the most expensive volatile per case at typical fresh gas flows, though low-flow techniques mitigate cost. Environmental concerns about high global warming potential (GWP100 approximately 2540 versus 130 for sevoflurane and 510 for isoflurane) have driven institutional restrictions on desflurane use in several health systems.