Chronic respiratory failure has the following etiologies: 1, respiratory pathology: such as bronchial inflammation, bronchospasm, foreign bodies and other obstruction of the airway, resulting in inadequate ventilation gas distribution unevenly resulting in a disproportionate ventilation blood flow, hypoxia and carbon dioxide retention; 2, lung tissue pathology: such as pneumonia, tuberculosis, emphysema, diffuse pulmonary fibrosis, adult respiratory distress syndrome, etc., can cause lung volume, ventilation effective diffusion reduction in area, and imbalance in the ratio of ventilation to blood flow causing hypoxia and/or carbon dioxide retention; 3, pulmonary vascular diseases: such as pulmonary embolism, reducing the effective circulating area of the lung in which hypoxia occurs; 4, thoracic lesions: such as thoracic trauma, surgical trauma, pneumothorax and pleural effusion, affecting thoracic activity and lung expansion leading to reduced ventilation; 5, nerve center and its conduction system and respiratory muscle diseases: such as cerebrovascular lesions, encephalitis Traumatic brain injury, drug poisoning, etc., directly or indirectly inhibit the respiratory center, poliomyelitis and blockage of muscle nerve joints due to polyneuritis, which affects conduction function, and severe muscle weakness impairs respiratory power causing hypoventilation.