Fresh gas flow refers to the mixture of medical gases and

volatile anaesthetic 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 vapori ...

agents which is produced by an

anaesthetic machine An anaesthetic machine (British English) or anesthesia machine (American English) is a medical device used to generate and mix a fresh gas flow of medical gases and inhalational anaesthetic agents for the purpose of inducing and maintaining an ...

. The flow rate and composition of the fresh gas flow is determined by the

anaesthetist Anesthesiology, anaesthesiology, or anaesthesia is the medical specialty concerned with the total perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critical emergency medicine, ...

. Typically the fresh gas flow emerges from the common gas outlet, a specific outlet on the anaesthetic machine to which the breathing attachment is then connected. Some older forms of breathing attachment, such as the Magill attachment, require high fresh gas flows (e.g. 7 litres/min) to prevent the patient from

rebreathing A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is ...

their own expired carbon dioxide. More modern systems, e.g. the circle breathing attachment, use

soda lime Soda lime is a mixture of NaOH and CaO chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 ...

to absorb

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, so that expired gas becomes suitable to re-use. With a very efficient circle system, the fresh gas flow may be reduced to the patient's minimum

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

requirements (e.g. 250ml/min), plus a little volatile.

References

{{DEFAULTSORT:Fresh Gas Flow Anesthetic equipment

See also

References