Postoperative back patting and coughing will inevitably cause pain at the incision, but this is usually acceptable. Some patients do not feel particularly uncomfortable when their back is patted by the medical staff, while their family members are very emotional and reluctant to cooperate with back patting and coughing when their back is patted. Some patients also ask: I have no sputum, why do I have to cough? Cardiac surgery is usually performed under general anesthesia, the entire surgical process and postoperative recovery process requires tracheal intubation and ventilator, this process will lead to an increase in secretions in the trachea; in addition to the extracorporeal circulation, medications, cardiac function and other impact on the lungs, will lead to varying degrees of lungs, tracheal secretions increase, especially preoperative smoking patients, the amount of sputum will increase significantly. If this sputum cannot be discharged in time, some of the small airways and even the thick bronchial tubes will be blocked, which we call “atelectasis”. Atelectasis affects the oxygenation of the body (i.e. leads to hypoxia) and greatly increases the chance of lung infections, and severe sputum thrombus obstruction may even lead to the death of the patient. Therefore, postoperative back patting and coughing up sputum play a very important role in preventing pulmonary atelectasis and lung infection. Even if there is no sputum, back patting and coughing will help prevent the occurrence of pulmonary atelectasis and favor the recovery of lung function, patients or family members, must cooperate well.