1. I NDICATIONS FOR MECHANICAL VENTILATION 1.Hypoxemic respiratory failure 2. Hypercarbic respiratory failure

2. Hypoxemic respiratory failure is present when arterial O2 saturation (SaO2) 0.6. The goal of ventilator treatment in this setting is to provide adequate SaO2 through a combination of supplemental O2 and specific patterns of ventilation that improve V˙ /Q˙ matching and reduce intrapulmonary shunt.

3. Hypoxemic respiratory failure Most commonly results from conditions such as Pneumonia pulmonary edema pulmonary hemorrhage respiratory distress syndrome

4. Hypercarbic respiratory failure results from conditions that decrease minute ventilation or increase physiologic dead space such that alveolar ventilation is inadequate to meet metabolic demands. Acute hypercarbic respiratory failure is characterized by arterial PCO2 values > 50 mmHg and an arterial pH < 7.30.

5. Clinical conditions associated with hypercarbic respiratory failure include Neuromuscular diseases, such as myasthenia gravis, Ascending polyradiculopathy, Myopathies Diseases that cause respiratory muscle fatigue due to increased workload, such as asthma, chronic obstructive pulmonary disease, and restrictive lung disease.