Abstract: A medical signal analyzer comprises a sensing device (1) including at least one sensor for monitoring at least one parameter derived from a physiological measurement taken from a patient under observation, a data collection device (2), coupled to the sensing device for receiving and sampling an output signal of the sensing device and generating digital signals representative of the parameter over a predetermined time interval, a data analysis means (4) comprising means operable to recognize in the digital signals received over a signal link from the data collection device a plurality of predetermined information features, and means for classifying at least one of the said features, to produce first output signals representative of the existence of such features and representative of feature classifications, signal storage means (6) arranged to receive and store the said first output signal as a short term knowledge base, database storage means for storing reference data as a long term knowledge base (10), an