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).The primary beat morphology analysis unit (120) discriminates heart beats in areceived basic electrocardiogram signal (HECG), classifies each beat into oneout of at least two different beat categories, and associates each segment ofthe signal (HECG) with relevant event-type data. The event-type data and thebasic electrocardiogram signal (HECG) together form an enhancedelectrocardiogram signal (ECGCL), based upon which the primary beat morphologyanalysis unit (120) determines whether one or more secondary signal analysesshould be performed. Depending on the enhanced electrocardiogram signal's(ECGCL) properties, the bank of secondary analysis units (B2) performs none,one or more of up to at least two different types of secondary analyses, andfor each analysis performed produces a respective test signal (PHRV, PEBC,PHRT) - The alarm generating unit (158) receives the test signals (PHRV, PEBC,PHRT) , and triggers an alarm signal (.alpha.) indicative of an estimatedrapid blood pressure decrease, if at least one alarm criterion is fulfilled.
