Abstract: A ventilator to be connected to the airways of a human or an animal includes several functional units, each functional unit being controlled and/or supervised by a separate microprocessor. At least one of the functional units has an analog control unit whereby the microprocessor only compensates for the coarseness in the regulating function of the analog control unit to increase the accuracy. This makes the ventilator efficient, accurate and safe.

Abstract: A ventilator for supplying and emitting respiratory gas to and from the airways of a human or an animal patient has a multiple-function safety valve located between a 10 control valve and the airways. The safety valve is biased in its closing direction by two springs, which apply force that corresponds to a predetermined overpressure, and is biased in its opening direction by a spring loaded piston, which applies force that exceeds the force of the springs. When electrical power is supplied to the ventilator, an electromagnet is energized. The electromagnet pulls the piston against the force of its spring load, and the safety valve closes. By means of a control device, the pressure in an inspiration section of the ventilator can be monitored and the electromagnet is disconnected at a programmed overpressure. In the event of a power failure, the safety valve will open and air can pass through the open safety valve to the airways.