An infusion device (1) for administering a medical fluid to a patient (P) comprises a pump mechanism (11) for administering a medical fluid to a patient (P) through a line set (3), a sensor device (14) for measuring a measurement value indicative of a pressure in the line set (3), and a processor device (15) configured to automatically set, in an initial phase, a threshold value (15) to a value determined based on at least a mechanical characteristic of the line set (3) and/or the pump mechanism (11) and to determine, in an operational phase, whether an occlusion condition in the line set (3) is present based on the measurement value and the threshold value (Pthres)—；Herein, the processor device (15) is configured to adjust the threshold value (Pthres) if in the operational phase a pressure variation condition in the line set (3) different than an occlusion condition is detected by the processor device (15). In this way an infusion device is provided which may be able to reliably detect an occlusion condition even in case of multiple infusion devices acting on a line set in a multiline infusion.
