Knock-back sputum discharge is to make the secretion attached to the lung and bronchus fall off by vibrating the airway through the chest wall, and make the secretion reach the fine bronchus through postural drainage and be discharged through the patient’s cough. Preparation before percussion and expectoration 1. Psychological care: explain the possible discomfort to the parents of the child before operation to reduce the tension and fear. 2. Nebulized inhalation: administer the medicine as prescribed by the doctor. 3. Ask the cooperating older children to take a deep breath and cough forcefully. Children who are unable to cough with sputum or who cannot cough can press the trachea of the upper sternal fossa to stimulate coughing up sputum. The operator fixes the hand into a dorsal rumbling palm hollow shape, i.e., the back of the hand is rumbling, the palm is hollow, the fingers are bent, the thumb is leaning against the index finger, rhythmically tapping from the bottom of the lung from bottom to top and from outside to inside, using the force of the wrist joint to tap rhythmically and evenly at the lesion site from the periphery toward the lung door. From a physical point of view, the faster the frequency, the easier it is to drop objects placed on elastic surfaces; if the frequency is slow, it is ineffective for sputum removal, avoiding the scapular spine, and preferably after nebulization. Note: Do not knock on the upper and lower ribs, spine, breast and other parts. Fourth, the best posture of children’s back tapping Choose the sitting or lying position of the patient according to the condition, when tapping the back, one hand should hold the child’s chest (or lie on the bed sideways) head down on the bed or pick up and place it between the operator’s knees, according to the principle of postural drainage, after the sputum bolus is dislodged, it is easier to enter the atmospheric tract and cough out smoothly, and should focus on the parts of the chest and the lower back area that are more likely to deposit liquid, and if one has pneumonia If you have pneumonia, you should also focus on patting the diseased area. The best time to tap on the back to expel sputum should be early in the morning after waking up, as a large amount of sputum will be deposited in the respiratory tract during the night due to the body position; the usual pat on the back should be done before the child eats milk or food to prevent vomiting. Sixth, the key to percussion and sputum excretion 1, auscultation: understand the sputum sound through doctor’s auscultation. 2.Frequency: from the physical point of view, the faster the frequency, the easier the object placed on the elastic table while falling, if the frequency is too slow, it is not effective for sputum discharge. 3.Position: according to the presence of sputum sound site, different positions can be taken, such as sitting position for inflammation in the apical part of the lung, lateral position for inflammation in the base of the lung and middle part of the lobe, decubitus lateral position, head down position.