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The anaesthetic machine (or anesthesia machine in America) is used by anaesthetists to support the administration of anaesthesia. The most common type of anaesthetic machine in use in the developed world is the continuous-flow anaesthetic machine, which is designed to provide an accurate and continuous supply of medical gases (such as oxygen and nitrous oxide), mixed with an accurate concentration of anaesthetic vapour (such as isoflurane), and deliver this to the patient at a safe pressure and flow. Modern machines incorporate a ventilator, suction unit, and patient-monitoring devices. The original concept was invented by the British anaesthetist H.E.G. Boyle in 1917. Prior to this time, anaesthetists often carried all their equipment with them, but the development of heavy, bulky cylinder storage and increasingly elaborate airway equipment meant that this was no longer practical for most circumstances. The anaesthetic machine is usually mounted on wheels for convenient transportation.
Additional recommended knowledge
Simpler anaesthetic apparatus may be used in special circumstances, such as the TriService Apparatus, a simplified anaesthesia delivery system invented for the British armed forces, which is light, portable and may be used effectively even when no medical gases are available.
Many of the early innovations in U.S. anaesthetic equipment, including the closed circuit carbon-dioxide absorber (aka: the Guedel-Foregger Midget) and diffusion of such equipment to anaesthetists within the United States can be attributed to Dr. Richard von Foregger and The Foregger Company.
Components of a typical machine
A modern machine typically includes the following components:
There is generally a small work bench built into the machine where airway management equipment is kept within ready reach of the anaesthetist.
Safety features of modern machines
Based on experience gained from analysis of mishaps, the modern anaesthetic machine incorporates several safety devices, including:
The functions of the machine should be checked at the beginning of every operating list in a "cockpit-drill". Machines and associated equipment must be maintained and serviced regularly.
Older machines may lack some of the safety features and refinements present on newer machines. However, they were designed to be operated without mains electricity, using compressed gas power for the ventilator and suction apparatus. Modern machines often have battery backup, but may fail when this becomes depleted.
The modern anaesthetic machine still retains all the key working principles of the Boyle's machine (a British Oxygen Company trade name in honour of the British anaesthetist H.E.G. Boyle (1875-1941).
A two-person (Operating Theatre Practitioner and anaesthetist) pre-use check of the anaesthetic machine is recommended before every single case and has been shown to decrease the risk of 24-hour severe postoperative morbidity and mortality (Arbous et al Anesthesiology 2005). Various regulatory and professional bodies have formulated checklists for different countries - see http://vam.anest.ufl.edu/guidelines.html. A free transparent reality simulation of the checklist recommended by the United States Food & Drug Administration is available from the Virtual Anesthesia Machine web site ( see below) after registration which is also free.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Anaesthetic_machine". A list of authors is available in Wikipedia.|