The invention relates a venous cannula for use in a cardiopulmonary bypass system or during extra-corporeal life support (ECLS)/membrane oxygenation (ECMO), the venous cannula being composed of an elongated, flexible tubular body having a proximal tip end for insertion in a vein towards the heart of a human or animal subject, and a distal end for connection to the cardiopulmonary bypass/ECLS/ECMO system, the elongated, flexible tubular body being equipped with a drainage capacity by volume for draining blood from the vein, which drainage capacity varies between the proximal tip end and the distal end.
