An apparatus for removing body fluids from a body cavity by suction, such as a thorax, gastric or any other human body cavity or a wound, comprises means (9) to increase the pressure difference between a pressure in a drainage lumen (3) and a pressure in the atmosphere when an auxiliary lumen (5) is open. The apparatus enables removal of clots or other plugs of the catheter and drainage tube in an efficient and not patient disturbing way.
