In appropriately selected patients, NPPV decreases intubation rate, improves survival, and is cost-effective. Pressure support ventilation is commonly used successfully for NPPV. An issue with the use of pressure support is the ability of the ventilator to detect the end of inhalation in the presence of leaks or in patients with severe airflow obstruction. A concern with portable pressure ventilators is the potential for rebreathing of carbon dioxide. Despite these issues, pressure support ventilation has been used successfully for noninvasive ventilation in thousands of patients with acute respiratory failure.