A general anaesthetic (or anesthetic, see spelling differences) is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthesia provider in order to induce or maintain general anaesthesia to facilitate surgery. The biological mechanism(s) of the action of general anaesthetics are not well understood.
Mode of administration
Drugs given to induce or maintain general anaesthesia are either given as:
Most commonly these two forms are combined, with an injection given to induce anaesthesia and a gas used to maintain it, although it is possible to deliver anaesthesia solely by inhalation or injection.
Inhalational anaesthetic substances are either volatile liquids or gases and are usually delivered using an anaesthesia machine. An anaesthesia machine allows composing a mixture of oxygen, anaesthetics and ambient air, delivering it to the patient and monitoring patient and machine parameters. Liquid anaesthetics are vaporized in the machine.
Many compounds have been used for inhalation anaesthesia, but only a few are still in widespread use. Desflurane, isoflurane and sevoflurane are the most widely used volatile anaesthetics today. They are often combined with nitrous oxide. Older, less popular, volatile anaesthetics, include halothane, enflurane, and methoxyflurane. Researchers are also actively exploring the use of xenon as an anaesthetic.
Injection anaesthetics are used for induction and maintenance of a state of unconsciousness. Anaesthetists prefer to use intravenous injections as they are faster, generally less painful and more reliable than intramuscular or subcutaneous injections. Among the most widely used drugs are:
Full article ▸