The S9 VPAP ST-A portable ventilator with iVAPS automatically adjusts the level of pressure support to achieve and maintain target alveolar ventilation for stable gas exchange in a variety of breathing conditions. It offers pressures to 30 cm H2O, which allows the treatment of the full range of NIV patients, and is suitable for non-dependent patients weighing 13kg and over or 30kg and over when using iVAPS.