Abstract: Cannula (1) for direct drainage of venous blood from both venae cavae, comprising an insertion piece (3) for insertion into the venae cavae through the right atrium and a connecting piece (2) secured to the insertion piece (3) for connecting with a suction device. The insertion piece comprises two openings (5, 8) at opposite ends of the insertion piece for draining the superior vena cava and the inferior vena cava respectively. The insertion piece is substantially longer than the distance between the entrances of both venae cavae in the right atrium, and has a diameter allowing insertion through the entrance of one vena cava in the right atrium and to the opposite vena cava. The insertion piece has an opening (8) near a free end, and a side opening (5) near a junction of the insertion piece with the connection piece.