Abstract: System for monitoring respiratory effort in a patient, comprising at least one pressure sensor, the pressure sensor being positioned in a catheter and being adapted for positioning in a chosen position in the oesophagus, the pressure sensor being adapted to monitor the pressure difference between the oesophagus and external pressure at a chosen rate. The system comprises flow measuring means for measuring the respiratory flow and analyzing means for calculating the respiratory admittance or the respiratory impedance as well as detecting the respiratory related arousals.