Device for the continuous monitoring of blood characteristic quantities comprising an external cardiovascular supporting circuit, said circuit comprising a venous line which conveys blood from the patient to an oxygenator, and along which at least one pump is arranged, and an arterial line which returns blood from the oxygenator to the patient, where said oxygenator comprises at least one blood inlet port connected to said venous line and at least one blood outlet port connected to said arterial line, at least one inlet channel and at least one outlet channel of a work gas intended to supply oxygen to the blood and/or to remove carbon dioxide from the same, comprising: - a venous saturation sensor connected to the venous line and one arterial saturation sensor connected to the arterial line suitable for the continuous measurement of the quantities consisting of venous saturation (SAT V) of oxygen and of arterial saturation (SAT A) of oxygen, respectively; - at least one blood flow sensor inserted along said venous line and suitable for the continuous measurement of the quantity constituted by the flow of blood (Qb) sent by said pump to the oxygenator; - at least one hemoglobin sensor inserted in a point of the external cardiovascular supporting circuit and suitable for the measurement of the quantity constituted by the hemoglobin (Hb); - data entering means by the operator; - an electronic control unit provided with a microprocessor and operationally connected to a display, said microprocessor being adapted to receive the data measured by said sensors (7, 8, 11, 12) and the data entered by the operator to make them appear at least partially on said display; - at least one sensor of the flow of work gas inserted in a point of the external cardiovascular supporting circuit and suitable for the continuous measurement of the flow of work gas (Gf); - at least one capnometer inserted in a point of the external cardiovascular supporting circuit and adapted to measure the concentration of carbon dioxide in the blood; wherein said microprocessor is provided with means adapted to calculate the quantity relating to the amount of carbon dioxide removed by the oxygenator (V'CO 2 ML) and the quantity relating to the amount of oxygen transferred by the oxygenator (V'O 2 ML), and wherein said microprocessor is programmed to display in numerical form on the display the values of all the quantities measured and calculated and in graphic form at least some of said values characterized by the fact that it comprises: acquisition means configured to acquire the amount of carbon dioxide removed from the patient's lung (V'CO 2 NL) and by the fact that said microprocessor is provided with means adapted to calculate the quantity relating to the amount of total removed carbon dioxide (V'CO 2total). - a venous saturation sensor connected to the venous line and one arterial saturation sensor connected to the arterial line suitable for the continuous measurement of the quantities consisting of venous saturation (SAT V) of oxygen and of arterial saturation (SAT A) of oxygen, respectively; - at least one blood flow sensor inserted along said venous line and suitable for the continuous measurement of the quantity constituted by the flow of blood (Qb) sent by said pump to the oxygenator; - at least one hemoglobin sensor inserted in a point of the external cardiovascular supporting circuit and suitable for the measurement of the quantity constituted by the hemoglobin (Hb); - data entering means by the operator; - an electronic control unit provided with a microprocessor and operationally connected to a display, said microprocessor being adapted to receive the data measured by said sensors (7, 8, 11, 12) and the data entered by the operator to make them appear at least partially on said display; - at least one sensor of the flow of work gas inserted in a point of the external cardiovascular supporting circuit and suitable for the continuous measurement of the flow of work gas (Gf); - at least one capnometer inserted in a point of the external cardiovascular supporting circuit and adapted to measure the concentration of carbon dioxide in the blood; wherein said microprocessor is provided with means adapted to calculate the quantity relating to the amount of carbon dioxide removed by the oxygenator (V'CO 2 ML) and the quantity relating to the amount of oxygen transferred by the oxygenator (V'O 2 ML), and wherein said microprocessor is programmed to display in numerical form on the display the values of all the quantities measured and calculated and in graphic form at least some of said values characterized by the fact that it comprises: acquisition means configured to acquire the amount of carbon dioxide removed from the patient's lung (V'CO 2 NL) and by the fact that said microprocessor is provided with means adapted to calculate the quantity relating to the amount of total removed carbon dioxide (V'CO 2total).