Disclosed is a respirator which comprises an electronic control device and a pneumatic main line in which the following are connected pneumatically: a respiratory gas source, a valve, a mixing chamber, a gas-dosing unit, and a supply line. The gas-dosing unit is configured to convey external air and/or oxygen and/or anesthetic gas into the mixing chamber, the respiratory gas source is configured to deliver respiratory gas to the supply line, the mixing chamber is configured to make available respiratory gas, the supply line is configured to supply the patient with respiratory gas, and the valve is configured to at least temporarily reduce a stream of respiratory gas to a patient.
