Noninvasive ventilation is commonly employed in patients with pneumonia or acute respiratory distress syndrome (ARDS) and has been shown to reduce the need for intubation and invasive mechanical ventilation. However, the rate of noninvasive ventilation failure remains substantial, at approximately 40%. Compared with patients in whom noninvasive ventilation succeeds, those who experience noninvasive ventilation failure have a higher likelihood of mortality during their intensive care unit or hospital stay. Therefore, improving the success rate of noninvasive ventilation is clinically important. In patients with lung consolidation receiving invasive mechanical ventilation, high positive end-expiratory pressure (PEEP) can improve oxygenation. Noninvasive ventilation operates on similar physiological principles and can also deliver high PEEP via a mask interface. Nevertheless, there is limited evidence regarding the use of high PEEP during mask-delivered noninvasive ventilation. This study aimed to evaluate whether high PEEP can increase intubation-free survival in patients with pneumonia or ARDS who are treated with noninvasive ventilation.