The invention is directed towards an ambulatory infusion device for the infusion of a liquid drug into a patients body over an extended time period, comprising:a) an infusion cannula (25, 125, 225) designed to be placed in the patients subcutaneous tissue (65),b) at least two electrodes (28, 29, 128, 129, 228a - 228g), at least one of the electrodes being a subcutaneous electrode (28, 29, 128, 228a - 228g), the at least one subcutaneous electrode (28, 29, 128, 228a - 228g) being comprised by the infusion cannula (25, 125, 225),c) an impedance measuring unit (30, 230), the impedance measuring unit (30, 230) being operatively coupled to the at least two electrodes (28, 29, 128, 129, 228a - 228g) and being further designed to measure at least one impedance value between the at least two electrodes (28, 29, 128, 129, 228a - 228g),d) an event trigger unit (35, 135, 235) operatively coupled to the impedance measuring unit (30, 230) and being designed evaluate the at least one impedance value and to generate an event trigger if evaluation of the at least one impedance value indicates the occurrence of an administration anomaly.
