Respiratory failure is a severe breathing difficulty that can lead to hypoxia and carbon dioxide retention. The causes of respiratory failure can be broadly classified into the following categories: First, there are diseases of the lung parenchyma, such as various lung infections, pneumonia, pulmonary edema, lung abscess, and diseases of the lung interstitium. Another type involves obstruction of the airway, including obstruction in the upper respiratory tract, which covers the nose, pharynx, and larynx, as well as obstructions in the lower respiratory tract, which can also lead to respiratory failure. Third, there are diseases involving the peripheral nervous transmission system and the respiratory machinery, such as acute infectious polyradiculoneuritis, poliomyelitis, and some cervical spine injuries. These can severely affect the respiratory center and respiratory nerves, leading to respiratory failure.