Monitoring MI- E protocol: signals and instrumentation As a signal acquisition system, an external polygraph (16Sp Powerlab, ADInstruments, Sydney, Australia), equipped with a pressure transducer (1050 model) and a pneumotachograph (S300, instrumental dead space _ 70 mL, resistance _ 0.0018 cm H2O/L/s) was connected to MI-E device. Sampling frequency was set to 200 Hz, and the polygraph was connected to a personal computer equipped with Chart 7.0 software for Windows.