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 anaesthesiamachine.
An anaesthesiamachine allows composing a mixture of oxygen, anaesthetics and ambient air, delivering it to the patient and monitoring patient and machine parameters.
The anaesthetic machine (or anesthesia machine in America) is used by anaesthetists to support the administration of anaesthesia.
Older machines may have cylinder yokes and flowmeters for carbon dioxide and cyclopropane.
A pre-use check of the anesthesia machine is recommended before every single case and has been shown to decrease the risk of 24-h severe postoperative morbidity and mortality (Arbous et al Anesthesiology 2005).