Adults with MI-E criteria (PCFbaseline <160 l /min). A pneumotachograph, PeakAnalysis software and nasobucal mask were used to monitor and analyze flow/time curves. Protocol included 9 PCF values in each patient: 1 baseline, 4 related with inspiratory pressure in sequential increase of 10 cmH2O (10 to 40 cmH2O) and 4 adding expiratory pressures (±10 to ±40cmH2O)