Pericardiocentesis is a diagnostic and therapeutic procedure that involves direct puncture into the pericardial cavity with the aid of a puncture needle. For patients undergoing first-time pericardiocentesis aspiration, the first dose of fluid should not be greater than 200 ml, and the extraction of fluid must be performed slowly. It is mainly used to determine the nature of the pericardial effusion and to relieve the symptoms of cardiac tamponade, and can also be used for the treatment of pericardial pus. During the process of giving a puncture, the patient must avoid coughing and deep breathing, and if necessary, the patient is advised to take relevant sedative medication before the puncture. After the puncture procedure, the patient needs to rest in bed for at least four hours and have his heart rate, blood pressure, pulse rate, and respiratory rate measured every half hour. If the patient has only a small amount of pericardial fluid, pericardiocentesis is generally not recommended. When performing a pericardiocentesis, it is important to choose the appropriate position. If the needle is inserted in the apical region, choose the seated position; if the needle is inserted under the glabella, choose the sloped recumbent position.