inflating bag 12 2 a source of fresh gas i e not containing vapour e g oxygen or oxygen plus nitrous oxide 13 with a flow meter 22 a a port 15 for input of fresh gas 13 b a port 16 for a fresh gas reservoir bag 17 c a port to which is attached a one way inflow valve that opens when the pressure inside the manifold is 5 cm h 2 o less than atmospheric pressure such as livingston health care services catalog part 9005 18 assuring that all of the fresh gas is utilized before opening d a bag of gas 19 whose pco 2 is equal approximately to that of the mixed venous pco 2 connected to inflow valve 18 alternatively the valve and gas reservoir bag can be replaced by a demand regulator such as lifetronix mx91120012 similar to that used in scuba diving and a cylinder of compressed gas e a port to which is attached a one way outflow valve 20 such as livingston health care services catalog part 9005 that allows release of gas from the manifold to atmosphere when the pressure in the manifold is greater than 5 cm h 2 o the distal end of the nonrebreathing valve laerdal type 9 is attached to the patient the proximal port of the nonrebreathing valve is attached to a 3 way respiratory valve 21 which can direct inspiratory gas either from the circle anaesthetic circuit fig4 b or from the new circuit fig4 c the expiratory manifold 10 of the self inflating bag 39 s non rebreathing valve is attached to the expiratory limb of the anaesthetic circuit 3 regardless of the source of inspired gas exhalation is directed into the expiratory.