2. Classification (1) According to Paco 2 a(Type 1) respiratory failure Hypoxemic respiratory failure a Pao2 of less than 60 mm Hg with a normal or low Paco2 Cause of: Edema. vascular disease. Chest Wall& Pleural disease a(Type ll)respiratory failure( Hypercapnic respiratory failure - a Pao2 low 60 mm Hg and PaCcO, of more than 50 mm Hg Cause of: Airway obstruction, Neuromuscular diseaseType Hypercapnic respiratory failure） a PaO2 low 60 mm Hg and PaCO2 of more than 50 mm Hg. Cause of：Airway obstruction, Neuromuscular disease. Type I Hypoxemic respiratory failure） a PaO2 of less than 60 mm Hg with a normal or low PaCO2 . Cause of：Edema, Vascular disease, Chest Wall & Pleural disease