Evidence of widespread alveolar injury:

• Multilobar infiltrates on chest imaging

• Symptoms and signs of pneumonia

• Increased A–a gradient, restrictive pattern on pulmonary function test

Absence of LRT infection after appropriate evaluation:

• Bronchoalveolar lavage negative for bacterial and nonbacterial pathogens

• Serological studies negative for viral and fungal infections

• Lung biopsy if patient's condition permits and above work-up is inconclusive

Absence of cardiac dysfunction, acute renal failure or iatrogenic fluid overload as aetiology for pulmonary dysfunction