A Pilot Trial of Pressure Muscle Index-Targeted PSV Trial

The pressure support is adjusted according to PMI between 0 and 2 cmH2O. After application of PSV mode in mechanically ventilated patients, the initial PS level was first set based on respiratory rate (RR) \<35 beats/min and 6-8 ml/Kg tidal volume (Vt) per predict body weight (PBW), and then modified according to PMI at a frequency of twice a day (morning and afternoon bedside rounds)# 1) Perform three end- inspiratory occlusions, with at least 1 minute between each measurement, and calculate the mean PMI. 2) Determine whether the PMI is within the target range (0≤PMI≤2cmH2O). 3) If the PMI is not within the target range, adjust the PS level up or down by 1-3 cmH2O and balance for 3-5 minutes. 4) Repeat the above steps until PMI reaches the target. 5) Additional: During PS adjustment, if Vt≤4ml/Kg, respiratory acidosis, respiratory distress, Vt≥8ml/Kg, respiratory alkalosis occurs, return to the safe PS level before adjustment and optimize other treatments.

Standard of care: the pressure support is adjusted to obtain a VT between 6 and 8 ml/kg PBW and RR between 20 and 35 breaths/min.