Mechanical ventilation is used to augment or take over an individual's spontaneous respiration. This intervention may be required to address acute oxygenation difficulties or compensate for ventilatory pump failure. Mechanical ventilation is usually continued until the acute lung injury and/or pump failure recovers. Less commonly mechanical ventilation is used as a treatment in its own right to control chronic hypoventilation in patients with chest wall, neuromuscular or obstructive lung disease