In some critically ill, elderly and frail patients, when coughing, sputum is not easy to cough out, sputum is easy to be retained in the bronchial tube and the aggravation of respiratory failure, lung infection is difficult to improve. At this time, it is necessary to perform bronchoscopy to suck out the secretions in the trachea, but the following side effects can occur during bronchoscopic suctioning. The first and most common is coughing up blood, which is caused by traumatic bleeding of the tracheal wall due to improper insertion or rough operation of the bronchoscope and violent coughing of the patient. The second is hypoxemia, which occurs during the operation of tracheoscopy when the larynx and trachea are stimulated and spasm induces dyspnea, which is manifested as hypoxia. Furthermore, there are cardiac complications. Patients are more likely to have an increased heart rate, and are prone to cardiac arrhythmia, but rarely cardiac arrest. In addition, a small number of patients, especially those with chronic obstructive pulmonary disease and elderly patients, are susceptible to the spread of infection and fever during tracheoscopic irrigation and sputum aspiration.