A new universal anaesthetic circuit using a preferential-flow T-piece.

A new co-axial anaesthetic circuit, employing a preferential-flow T-piece which eliminates the need for valves in the circuit, has been designed. Its efficiency has been shown to compare favourably with that of conventional circuits for use in spontaneous respiration and under conditions of controlled ventilation. The proposed system has the advantage of convenience, in that there is no need to disconnect the system from the patient nor from the anaesthetic machine when it is necessary to change from spontaneous to controlled ventilation or should a circle absorber be incorporated within the circuit. The system has been shown to offer lower resistance than the Mapleson A circuit.