Apparatus for a ventilator, comprises a control means (108) configured to: receive state information indicative of pressure being above or below at least one predetermined threshold pressure at at least one pressure switch (208), and control an air movement device to repeatedly cause inflation of lungs of the patient and allow deflation, dependent at least on the received state information. In use, the at least one pressure switch is located at a pressure representative of air pressure in lungs (202) of a patient. The state information does not comprise an absolute numerical pressure value at the at least one pressure switch.
