Although the respiratory rhythm is generated in the brain, its activity can be reflexively regulated by afferent impulses from the respiratory organs themselves as well as from skeletal muscles and sensory apparatus of other organ systems, some of the important reflexes are described below. 1. pulmonary tensor reflex 2. respiratory muscle proprioceptive reflex 3. defensive respiratory reflex There are receptors throughout the respiratory tract, which are vagal afferent nerve endings distributed in the mucosal epithelium, and when stimulated mechanically or chemically, they cause a defensive respiratory reflex to remove the irritant and avoid its entry into the alveoli. 1. Cough reflex: It is a common and important defensive reflex. Its receptors are located in the mucosa of the larynx, trachea and bronchi. The receptors above the large bronchi are sensitive to mechanical stimuli, while those below the secondary bronchi are sensitive to chemical stimuli. Afferent impulses are transmitted via the vagus nerve to the medulla oblongata, triggering a series of coordinated reflex responses that cause the cough reflex. When coughing, there is first a short or deep inspiration, followed by a tight closure of the vocal hilum and a strong contraction of the expiratory muscles, resulting in a rapid rise in intrapulmonary and pleural cavity pressure, followed by a sudden opening of the vocal hilum, and due to the great difference in air pressure, the gas rushes out of the lungs at a very high rate, expelling foreign bodies or secretions from the airways. When coughing violently, the intrapleural cavity pressure rises significantly, which can obstruct the venous flow and increase the venous pressure and cerebrospinal fluid pressure. 2. Sneeze reflex: It is a reflex similar to coughing, with the difference that: the stimulus acts on the nasal mucosal receptors, the afferent nerve is the trigeminal nerve, the reflex effect is the palatal lobe drops and the tongue presses toward the soft palate instead of the vocal cords closing, and the exhaled air is mainly ejected from the nasal cavity to clear the irritants in the nasal cavity. 4, the respiratory reflex caused by the pulmonary paracapillary (J-) receptors 5, the respiratory effect of certain acupuncture points stimulation respiratory distress syndrome of newborn (RDSN): also known as pulmonary hyaline membrane disease (HMD), refers to RDSN (respiratory distress syndrome of newborn): also known as hyaline membrane disease (HMD), is a condition characterized by progressive dyspnea, cyanosis, expiratory moaning, inspiratory trismus and respiratory failure shortly after birth. It is mainly seen in preterm infants, especially at gestational age less than 32-33 weeks. The basic features are progressive alveolar opacification, impaired fluid transport, and hyperpermeable alveolar-pulmonary capillary-alveolar exudative lesions due to immature lung development and lack of lung surface active substances. The pathology is characterized by an eosinophilic hyaline membrane attached to the alveolar wall to the terminal fine bronchial wall. Respiratory therapy and critical care techniques, mainly mechanical ventilation and ventilator therapy, have been able to survive more than 90% of children with RDSN. Chronic respiratory failure: It occurs on the basis of pre-existing lung diseases, such as chronic obstructive pulmonary disease, severe tuberculosis, interstitial fibrosis, pneumoconiosis, thoracic lesions and chest surgery, trauma, extensive pleural thickening, thoracic deformity, etc. The most common cause is COPD, which can manifest as type I respiratory failure in the early stage and type II respiratory failure as the disease 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. Chronic respiratory failure mostly has certain underlying diseases, but acute attacks of decompensated respiratory failure can be directly life-threatening and must be rescued in a timely and effective manner.