Figure 2 Clinical course of respiratory managementThe timeline shows major interventions, ventilator modes, corticosteroid therapy, and respiratory parameters during hospitalization. The solid line represents the PaO2/FiO2 (P/F) ratio, and the dotted line indicates positive end-expiratory pressure (PEEP). Ventilator modes used during the course are shown at the bottom (airway pressure release ventilation [APRV] and pressure support ventilation [PSV]). Gray bars indicate the dose of methylprednisolone (mPSL). Arrows denote the timing of tracheostomy and chest tube insertion, and the horizontal bar represents the period of inhaled nitric oxide (NO) therapy. Severe hypoxemia initially required high PEEP and APRV support; oxygenation gradually improved over time, allowing reduction of ventilatory support.