The wound therapy device (20,40) has pressure sensor (2) to generate the pressure measurement values by sensing pressure in wound space. A pump unit (4) aspirates fluid from wound space to drainage container (1) via drainage line (3). An instillation line (8) delivers instillation fluid from instillation container (7) into wound space. A control unit (5) switches off the pump unit when a predefined upper low-pressure threshold value is reached in wound space, and interrupts the delivery of instillation fluid when a predefined lower low-pressure threshold value is reached. An independent claim is included for method for determining instillation fluid volume for instillation therapy of wound.
