The MERA-F breathing circuit is a light in weight, disposable, multi-purpose breathing system corsisting of double coaxial tubes ; inner tube for inspiration and outer corrugate tube for expiration. This circuit is especially effective on head and neck operations that may lead to :Iccidental disconnection or extubation. And the circuit provides effective carbon dioxide elimination with only conventional total fresh gas flow(70 ml/kg/minute) and appropriate maintenance of heat and humidity of the airway mucosa.