A self-contained jet pump type breathing apparatus is provided for introducing gases into the lungs of a patient having an inspiratory jet pump for sweeping gases toward the patient, an expiratory jet pump for sweeping exhaled gases away from the patient and an absorber for absorbing carbon dioxide from the exhaled gases which are again supplied to the respiratory jet pump. An anesthetic introduction conduit permits the flow of anesthetic gases into the breathing apparatus. In addition, a jet producer device, is also provided, which obtains fresh compressed gases from the absorber and compressor and supplies pulsating pressurized gases to the respiratory jet pumps.