A monitoring mechanism (100) to predict the rapid symptomatic decrease in blood pressure in a subject (P), the mechanism (100) comprises: an extracorporeal blood flow circuit (20) configured to connect to a subject's cardiovascular system ( P), said extracorporeal blood flow circuit (20) comprises at least one pressure sensor (4a, 4b, 4c) for generating measurement data comprising a temporal sequence of pulse shape parameters (pPS) representing variations of the pressure in at least one blood vessel of the subject (P)； and a monitoring device (120) comprising: an input (28) for receiving measurement data of said at least one pressure sensor (4a, 4b, 4c) in the extracorporeal blood flow circuit (20), the data of Measurement comprises the temporal sequence of pulse shape parameters (pPS), and a data analysis part (29) adapted to repeatedly receive the pulse shape parameters (pPS), investigate whether a measurement (PM, SM) of one or more than the pulse shape parameters (pPS) meet a decision criterion, and if so, cause an output signal (α) to be generated, where the output signal (α) indicates a rapid symptomatic decrease in the expected blood pressure in the subject (P).Un mecanismo de monitorización (100) para predecir la disminución sintomática rápida de la tensión arterial en un sujeto (P), el mecanismo (100) comprende: un circuito de flujo sanguíneo extracorporal (20) configurado para conectarse a un sistema cardiovascular del sujeto (P), dicho circuito de flujo sanguíneo extracorporal (20) comprende al menos un sensor de presión (4a, 4b, 4c) para generar datos de medición que comprenden una secuencia temporal de parámetros de forma de pulso (pPS) que representan variaciones de la presión en al menos un vaso sanguíneo del sujeto (P)； y un dispositivo de monitorización (120) que comprende: una entrada (28) para recibir datos de medición de dicho al menos un sensor de presión (4a, 4b, 4c) en el circuito de flujo sanguíneo extracorporal (20), los datos de medición co
