The invention relates to cardiac-activity based prediction of a rapid drop ina patient's blood pressure during extracorporeal blood treatment. A proposedalarm apparatus (100) includes a primary beat morphology analysis unit (120),a bank of secondary analysis units (B2) and an alarm generating unit (158). Theprimary beat morphology analysis unit (120) discriminates heart beats in a receivedbasic electrocardiogram signal (H), classifies each beat intoone out of at least two different beat categories, and associates each segmentof the signal (H) with relevant event-type data. The event-typedata and the basic electrocardiogram signal (H) together forman enhanced electrocardiogram signal (ECG), based upon which theprimary beat morphology analysis unit (120) determines whether one or more secondarysignal analyses should be performed. Depending on the enhanced electrocardiogramsignal's (ECG) properties, the bank of secondary analysisunits (B2) performs none, one or more of up to at least two different types of secondaryanalyses, and for each analysis performed produces a respective test signal(P, P, P) - The alarm generating unit(158) receives the test signals (P, P, P), and triggers an alarm signal (α) indicative of an estimated rapid bloodpressure decrease, if at least one alarm criterion is fulfilled.
