A portable, stand-alone, mechanical device designed to continuously or intermittently administer a mixture of gases [e.g., oxygen (O2), ambient air, nitrous oxide (N2O), anaesthetic agents] to provide a patient with an appropriate level of anaesthesia. It delivers gases to the patient from medical gas cylinders and typically includes mechanical gas-delivery devices (e.g., flowmeters and vaporizers), a manual anaesthesia ventilator, and a patient breathing circuit. It will typically be used by the military or in unconventional surgical settings.