RESPIRATORY DISORDERS. Acute Respiratory Distress Syndrome (ARDS) Definition: Acute Respiratory Distress Syndrome (ARDS) is a life-threatening lung condition characterized by severe inflammation and fluid accumulation in the alveoli, leading to hypoxia and respiratory failure. Causes: Signs & Symptoms: Complications: Diagnosis: Management: Bronchiolitis Definition: Bronchiolitis is a viral lower respiratory tract infection, causing inflammation and obstruction of small airways (bronchioles), primarily in infants <2 years. Causes: Signs & Symptoms: Complications: Diagnosis: