A drainage device useable for treating patients with a pulmonary air leak, the device comprising suction mode control means, where a pressure sensor is connected to the suction mode control means for supplying a pressure signal representative of the pressure in a collection chamber, and an air flow sensor is connected to the suction mode control means to supply a flow signal representative of the flow of air evacuated from the collection chamber, and in that the suction mode control means is arranged to switch between a first suction mode and a second suction mode based on an algorithm involving the flow signal and the pressure signal.
