An Infusion pump device comprises a pumping means (2) having a fluid inlet (4) which is adapted to be connected to a vial (8) for taking fluid out of the vial (8) and a fluid outlet (6) which is adapted to be connected to an infusion catheter (20, 22), and a controlling means which is adapted to be connected to the vial (8) and to control pressure inside the vial so as to avoid occurrence of underpressure at the fluid inlet (4).
