A ventilation system (1, 10) is combined with a measuring method (2, 22, 222) for electric impedance tomography (EIT). Bidirectional data exchange between the two systems is provided. Both the ventilation system (1, 10) and the measuring system (2, 22, 222) have a first and second communications electronic unit (11, 12) each with associated transmitting and receiving means for the bidirectional data exchange.