What is the fresh gas flow in Mapleson A circuit:-
Mapleson A or the Magill circuit is the circuit of choice for spontaneous ventilation. In all mapleson circuits, rebreathing of carbon dioxide is prevented by an adequate fresh gas flow and by the presence of adjustable pressure release valve. The exhaled carbon dioxide flows through the outer corrugated tube and out this valve from where it can be scavenged. Out of these, Mapleson A circuit is considered the best for spontaneous ventilation because it requires a fresh gas inflow rate of only 1 times minute ventilation to prevent rebreathing of carbon dioxide. In mapleson circuits D, E, and F, the amount of fresh gas flow required is 2.5 times a minute ventilation and in mapleson circuits B and C, it is much higher. But the disadvantage of mapleson circuit A is that it is not very useful in controlled ventilation because a minute ventilation as high as 20 L/minute (fresh gas flow rate should be greater than 3 times a minute ventilation) is needed to prevent rebreathing.
Equal to minute ventilation
Twice the minute ventilation
2.5 times the minute ventilation
Half the minute ventilation
Anesthesia Circuit