System and method for the measurement of cardiac output

The invention concerns a system for the measurement of cardiac (1) output. The system comprises a heating resistor (2) placed in the vena cava (6), a temperature sensor (5) placed in the pulmonary trunk (4), an isolation interface (12) for separating an isolated side (14) and a non-isolated side according to patient potential, a power source (11) which is placed on the non-isolated side and produces the energy to be supplied to the heating resistor (2), and measuring elements (18, 19, 20) for the measurement of the power supplied to the heating resistor 92). According to the invention, the power measuring (18, 19, 20) elements are disposed on the isolated side (14), allowing the effective power supplied to the heating resistor (2) to be computed as accurately as possible.