Effects of High-intensity Noninvasive Positive Pressure Ventilation in AECOPD

In the high-intensity NPPV group, patients will undergo pressure-limited NPPV (eg, NPPV in spontaneous/timed mode) at a higher IPAP level. IPAP is initially set at 10 cmH2O and continuously adjusted by increments and decrements of 1-2 cmH2O (typically ranging between 20 and 30 cmH2O), according to patients' tolerance, to obtain a tidal volume (VT) of 10-15 mL/kg. IPAP should be increased as much as possible to decrease PaCO2 to a normal level. However, if PaCO2 decreases to less than 35 mmHg, IPAP should be decreased to achieve normocapnia.

In the low-intensity NPPV group, patients will undergo pressure-limited NPPV (eg, NPPV in spontaneous/timed mode) with a conventional IPAP level. IPAP is initially set to 10 cmH2O and is continuously adjusted by increments and decrements of 1-2 cmH2O (up to 20 cmH2O), according to patients' tolerance, to obtain a VT of 6-10 mL/kg.