Aspiration can be performed when there is sputum in the respiratory tract that cannot be expelled by itself to avoid serious consequences such as infection, hypoxia and asphyxia in patients. There are mainly the following contraindications for aspiration: 1. skull base fracture: patients with skull base fracture should not be aspirated through the nasal cavity to reduce intracranial retrograde infection; 2. nasopharyngeal bleeding: when there are bleeding symptoms in the nasopharynx or more serious acute inflammation or tumor, aspiration through the nasal cavity should not be avoided to avoid aggravating bleeding by damaging the nasal mucosa; 3. gastrointestinal bleeding: patients with upper gastrointestinal bleeding, aspiration at this time may aggravate It is generally recommended to dissolve sputum by nebulized inhalation and other means; 4. heart dysfunction: patients with serious heart dysfunction, avoid arrhythmia and cardiac arrest induced by hypoxia; 5. taking corrosive drugs: patients taking corrosive drugs are prone to damage the tracheal mucosa when aspirating sputum. Pay attention to the patient’s vital signs during aspiration, pay attention to aseptic operation, do not spend more than 15 seconds at a time, and the order of aspiration is usually in the airway first, followed by the oral cavity and nasal cavity.