Chronic respiratory failure occurs on the basis of pre-existing lung diseases, such as chronic obstructive pulmonary disease, severe tuberculosis, interstitial pulmonary fibrosis, pneumoconiosis, thoracic lesions and chest surgery, trauma, extensive pleural thickening, thoracic deformity, etc. The most common cause is COPD, which can be manifested as type I respiratory failure in the early stage and type II respiratory failure as the condition gradually worsens and pulmonary function becomes worse. In the stable stage of chronic respiratory failure, although PaO2 is reduced and PaCO2 is increased, the patient can be stabilized within a certain range through compensation and treatment, and the patient can still engage in general work or daily life activities. Once aggravated by respiratory tract infection or other causative factors, it can be manifested as a significant decrease in PaO2 and a significant increase in PaCO2, at which time it can be called an acute attack of chronic respiratory failure, which is the most common type of chronic respiratory failure in our clinic. Cold prevention: In the cold winter or when the temperature suddenly drops, pay attention to keep warm and prevent cold, which is of great significance to prevent the occurrence of respiratory failure in chronic obstructive pulmonary disease. The mechanisms are: avoid cold-induced bronchospasm and increased secretion, prevent alveolar ventilation from decreasing; avoid cold-mediated diuresis, prevent blood viscosity from increasing, blood flow from slow stagnation, lung tissue blood circulation, especially microcirculation obstruction; avoid cold, reduce the occurrence of bronchopulmonary infection.