Lung ventilator (14) and/or anaesthesia machine with a blender for mixing a pressurised medical gas, e.g. oxygen, with air drawn in by a blower (1), comprising a gas line (10) for the medical gas, and an air line (11), which open into a common breathing gas line (12), whereby the opening of the gas line (10) into the common gas line (12) is downstream of the blower (1) and in the gas line (10) a regulating valve (8) is provided for variable adjustment of the gas flow and in the common breathing gas line (12) a regulating valve (4) is provided for dosing the breathing gas, and whereby in the breathing gas line (12) a flow sensor (3) is provided for measuring the breathing gas flow and in the gas line (10) a flow sensor (9) is provided for measuring the gas flow.
