An anaesthetic machine

The anaesthetic machine (or anesthesia machine in America) is used by anaesthetists to support the administration of anaesthesia. The commonest 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. Image File history File links Download high resolution version (480x640, 72 KB)AN Anaesthetic Machine A Datex Ohmeda British machine, in use in Buckinghamshire England Copyright CjW, author and photographer, free to use with my byline. ... Image File history File links Download high resolution version (480x640, 72 KB)AN Anaesthetic Machine A Datex Ohmeda British machine, in use in Buckinghamshire England Copyright CjW, author and photographer, free to use with my byline. ... An anesthesiologist (American English), or anaesthetist (British English), is a medical doctor trained to administer Australia, for example, training is overseen by the United States, anesthesiologists are medical doctors (MD). ... Anesthesia (AE), also anaesthesia (BE), is the process of blocking the perception of pain and other sensations. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odor. ... Isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether) is a halogenated ether used for inhalation anesthesia. ... Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ...

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. The armed forces of a state are its government sponsored defense and fighting forces and organizations. ...

The machine normally includes the following components:

• connections to piped hospital oxygen, medical air, and nitrous oxide. Pipeline pressure from the hospital medical gas system (wall outlet) should be around 50 PSI (400kPa; 4 atmospheres).
• back-up gas cylinders of oxygen, air, and nitrous oxide attached via a specific yoke with a Bodok seal. Older machines may have cylinder yokes and flowmeters for carbon dioxide and cyclopropane. Many new machines only have oxygen reserve cylinders. The regulators for the cylinders are set at 45 PSI (360kPa; 3.6 atmospheres). If the cylinders are left on and the machine is plugged into the wall outlet, gas from the wall supply will be used preferentially, since it is at a higher pressure. In situations where pipeline gases are not available, machines may safely be used from cylinders alone, provided fresh cylinders are available.
• a high-flow oxygen flush which provides pure oxygen at 30 litres/minute
• pressure gauges and regulators to protect the machine components and patient from high-pressure gases
• flow meters (rotameters) for oxygen, air, and nitrous oxide, which are used by the anaesthetist to provide accurate mixtures of medical gases to the patient
• one or more anaesthetic vaporisers to accurately add volatile anaesthetics to the fresh gas flow
• a ventilator
• physiological monitors to monitor the patient's heart rate, ECG, blood pressure and oxygen saturation (additional monitors are generally available to monitor temperature, arterial blood pressure central venous pressure,etc). In addition, the composition of the gases delivered to the patient (and breathed out) is monitored continuously.
• breathing circuits, most commonly a circle attachment
• a heat and moisture exchanger (HME)
• scavenging system to remove expired anaesthetic gases from the operating room. Scavenged gases are usually vented to the atmosphere.
• suction apparatus

Based on experience gained from analysis of mishaps, the modern anaesthetic machine includes several safety devices, including: General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Look up air in Wiktionary, the free dictionary. ... Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odor. ... Industrial compressed gas cylinders used for oxy-fuel welding and cutting of steel. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Look up air in Wiktionary, the free dictionary. ... Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odor. ... The modern day Bodok seal is a specialised washer that has the crucial role of ensuring an air-tight seal between the regulator of an anaesthetic machine and a gas cylinder. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Molecule structure formula of cyclopropane Cyclopropane is a cycloalkane molecule with the molecular formula C3H6 consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms. ... A Rotameter is a device that measures the flow rate of liquid or gas in a closed tube. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Look up air in Wiktionary, the free dictionary. ... Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O. Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odor. ... An anaesthetic vaporiser is a device generally attached to an anaesthetic machine which delivers a given concentration of a volatile anaesthetic agent. ... The volatile anaesthetics are a class of general anaesthetic drugs. ... Ambulance ventilation equipment A medical ventilator is a device designed to provide mechanical ventilation to a patient. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Heart rate is a term used to describe the frequency of the cardiac cycle. ... ECG may also refer to the East Coast Greenway Lead II An Electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph. ... Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... Oxygen saturation is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. ... Temperature is also the name of a song by Sean Paul. ... Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... Central venous pressure (CVP) describes the pressure in the thorax near the right atrium of the heart (i. ... Saturns atmosphere is made up of hydorgen, helium and methane ...

• hypoxic mixture alarms to prevent gas mixtures which contain less than 21% oxygen being delivered to the patient. In modern machines it is impossible to deliver 100% nitrous oxide to the patient to breathe. Oxygen is automatically added to the fresh gas flow even if the anaesthetist should attempt to deliver 100% nitrous oxide.
• ventilator disconnection alarms
• interlocks between the vaporisers preventing inadvertent administration of more than one volatile agent concurrently
• alarms on all the above physiological monitors.
• the Pin-Index system, which prevents cylinders being accidentally connected to the wrong yoke
• the NIST (Non-Interchangeable Screw Thread) system for pipeline gases, which prevents piped gases from the wall being accidentally connected to the wrong inlet on the machine
• pipeline gase hoses have non-interchangeable Schrader valve connectors, which prevents hoses being accidentally plugged into the wrong wall socket

There is generally a small work bench built into the machine where airway management equipment is kept within ready reach of the anaesthetist. It has been suggested that hypoxemia be merged into this article or section. ... A schrader valve on a bicycle tire. ...

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. Type F Mains power plug & socket The term mains usually refers to the general purpose AC electrical power supply (as in Ive connected the appliance to the mains). The term is not usually used in the United States and Canada. ... The word battery has a number of senses, most of which are discussed in articles cited below. ...

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). The BOC Group is the official name of the multi-national industrial gas company more commonly known as BOC. As of 2003, BOC has over 44,000 employees on six continents, with sales of over £4. ... 1875 was a common year starting on Friday (see link for calendar). ... For the movie, see 1941 (film) 1941 (MCMXLI) was a common year starting on Wednesday (the link is to a full 1941 calendar). ...

External links

• Virtual Anesthesia Machine (VAM), a free transparent reality simulation of a generic anesthesia machine from University of Florida
• Various anesthesia-related simulations
• A free workbook with structured exercises for use with the VAM simulation
• Virtual Anaesthesia Textbook
• FRCA UK - Resources for UK anaesthetist in training
• Medical Equipment Update - Written by industry insiders, this blog offers advice on purchasing anesthesia machines.