An inhalational anesthetic is a chemical compound possessing general anesthetic properties that can be delivered via inhalation. They are administered through a face mask, laryngeal mask airway or tracheal tube connected to an anesthetic vaporiser and an anesthetic delivery system. Agents of significant contemporary clinical interest include volatile anesthetic agents such as isoflurane, sevoflurane and desflurane, as well as certain anesthetic gases such as nitrous oxide and xenon. List of inhalational anaesthetic agents Currently-used agents Desflurane Isoflurane Nitrous oxide Sevoflurane Xenon Previously-used agents Although some of these are still used in clinical practice and in research, the following anaesthetic agents are primarily of historical interest in developed countries: Acetylene Chloroethane (ethyl chloride) Chloroform Cryofluorane Cyclopropane Diethyl ether Divinyl ether Enflurane Ethylene Fluroxene Halothane (still widely used in the developing world and is on the WHO Model List of Essential Medicines) Methoxyflurane (still used currently as an analgesic) Methoxypropane Trichloroethylene Vinyl chloride Never-marketed agents Aliflurane Halopropane Norflurane Roflurane Synthane Teflurane Volatile anaesthetics Volatile anaesthetic agents share the property of being liquid at room temperature, but evaporating easily for administration by inhalation. The volatile anesthetics used in the developed world today include: Desflurane, isoflurane and sevoflurane. Other agents widely used in the past include ether, chloroform, enflurane, halothane, methoxyflurane. All of these agents share the property of being quite hydrophobic (i.e., as liquids, they are not freely miscible with water, and as gases they dissolve in oils better than in water). The ideal volatile anaesthetic agent offers smooth and reliable induction and maintenance of general anaesthesia with minimal effects on other organ systems. In addition it is odorless or pleasant to inhale; safe for all ages and in pregnancy; not metabolised; rapid in onset and offset; potent; and safe for exposure to operating room staff. It is also cheap to manufacture; easy to transport and store, with a long shelf life; easy to administer and monitor with existing equipment; stable to light, plastics, metals, rubber and soda lime; non-flammable and environmentally safe. None of the agents currently in use are ideal, although many have some of the desirable characteristics. For example, sevoflurane is pleasant to inhale and is rapid in onset and offset. It is also safe for all ages. However, it is expensive (approximately 3 to 5 times more expensive than isoflurane), and approximately half as potent as isoflurane. Gases Other gases or vapors which produce general anaesthesia by inhalation include