This is a multicentre, double-blind, placebo-controlled Phase III randomized clinical trial designed to evaluate the efficacy and safety of inhaled aprotinin in adult patients with moderate or severe acute respiratory distress syndrome (ARDS). A total of 156 critically ill patients admitted to intensive care units will be randomized to receive either inhaled aprotinin or placebo in addition to standard supportive care. The primary objective is to determine whether aprotinin improves clinical outcomes based on a composite endpoint of ventilator-free days at 28 days.
Acute onset of respiratory failure within 1 week of a known clinical insult or new/worsening respiratory symptoms.
Respiratory failure not fully explained by cardiac failure or fluid overload; objective evaluation of cardiac failure or fluid overload is required if ARDS risk factors are absent.
Radiographic abnormalities on chest X-ray or CT scan: bilateral opacities not fully explained by effusions, nodules, masses, or lobar/segmental collapse.
Moderate ARDS: PaO₂/FiO₂ >100 mmHg and ≤200 mmHg with Positive End-Expiratory Pressure (PEEP) ≥5 cmH₂O.
Pregnant or lactating women, or positive/indeterminate pregnancy test (serum or urine).
Simultaneous participation in another pharmacotherapy protocol.
Life expectancy <24 hours.
Clinical condition in which, in the investigator's opinion, ventilator withdrawal is extremely unlikely (e.g., motor neuron disease, Duchenne muscular dystrophy, rapidly progressive interstitial lung disease).