circuit (redirected from reentrant circuit)

circuit /cir·cuit/ (ser´kit) [L.] the round or course traversed by an electric current.

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reverberating circuit  a neuronal pathway arranged in a circle so that impulses are recycled to cause positive feedback or reverberation.

reentrant circuit  the circuit formed by the circulating impulse in reentry.

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circuit

a round course, or course followed by, for example, electrical current, anesthetic gas, a traveling judge.

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Bain coaxial circuit

a variant of the T-piece circuit of delivery of anesthetic gas in which the fresh gas passes up a central tube and the expired gas passes out through the outer sleeve.

breathing circuit

of an anesthetic machine is the pathway by which the volatile anesthetic agent and oxygen are conveyed to the patient and carbon dioxide is removed. The two methods for removal of carbon dioxide are that of venting all expired gases to the exterior, and the method of absorbing the CO₂ chemically and rebreathing the expired gas. The two basic circuits are the open circuit in which the patient has access to environmental air as well as the anesthetic-oxygen mixture and exhales into the environment, and the closed system in which all gases are rebreathed. The latter may be a to-and-fro system or a circle system, the latter based on the use of unidirectional valves to ensure that the gases always pass in the correct direction. See also Bain coaxial circuit (above), circle breathing circuit (below), coaxial circuit (below), Lack circuit (below), Magill circuit (below), schimmelbusch mask, T-piece circuit (below).

circle breathing circuit

in an anesthetic machine; the flow of gases is directed by an inclusion in the system of two unidirectional valves, one in an expiratory and one in an inspiratory tube. The rebreathing bag and the canister of sodalime for CO₂ absorption are located between the two tubes.

coaxial circuit

a system for the delivery of gaseous anesthetic which has separate conduits for fresh gas and expired air and is essentially the same as the T-piece system except that one conduit is inside the other. An attractive system because the exhaust gases can be ducted to the exterior.

Lack circuit

a coaxial breathing circuit used in anesthesia. Fresh gas flows up the outer sleeve, expired air and gas pass down the inner tube.

Magill circuit

a breathing circuit used in anesthesia. It includes a reservoir bag, wide-bore corrugated tubing and a spring-loaded expiratory valve. It is a semiclosed system in which rebreathing is prevented by having the gas flow rate from the cylinders slightly in excess of the patient's minute respiratory volume.

Mapleson circuit

an anesthetic breathing circuit in which the fresh gas flow is used to remove exhaled carbon dioxide. The Mapleson A circuit is called also the Magill circuit (above), Mapleson D circuit is called also the Bain circuit (above), and the jackson-rees t-piece is the Mapleson F circuit.

non-rebreathing circuit

anesthetic breathing circuits in which exhaled gases are discharged to the environment and do not pass back to the patient. See Magill circuit (above).

parallel circuit

a variation on the Bain and Lack circuits (above) in which there are two tubes running side by side instead of one inside the other.

rebreathing circuit

anesthetic breathing circuits in which the exhaled gas is recirculated to the patient with CO₂ removed.

T-piece circuit

a breathing circuit used in anesthesia. Shaped like a T. The exhaled gases are passed into a reservoir tube from which they are pushed by fresh gas from the anesthetic machine as it passes from the stem to the other arm of the T during expiration. There are no valves.

x-ray circuit

a complete path along which an electrical current flows. In its simplest form it includes a source of electrons (power source), a load or resistance, and a conductor.