Professor Heimlich was an American surgeon for many years. In his clinical practice, he was shocked by the large number of cases of respiratory obstruction caused by food and foreign body asphyxiation. In emergency medicine, doctors often used the method of tapping the patient’s back or sticking their fingers into the mouth and throat to remove foreign bodies, but the result was not only ineffective but also made the foreign body deeper into the respiratory tract. After repeated research and many animal experiments, he finally invented the first aid method of using the residual gas in the lungs to form an airflow to flush out the foreign body. The principle of Heimlich first aid method: the use of impact on the abdomen – the soft tissue under the diaphragm, being a sudden impact, generating upward pressure, compressing the lower part of the two lungs, thus driving the residual air in the lungs to form a stream of air. This airflow with impact and directional long-drive in the trachea can drive away foreign bodies such as hard pieces of food blocking the trachea and larynx, so that people can be saved. What is the specific response to the “Heimlich maneuver” for children under 3 years old? The rescuer should immediately pick up the child, squeeze both sides of the child’s cheekbone with one hand, put the arm against the child’s front chest, and hold the back of the child’s neck with the other hand so that the child is face down on the rescuer’s knee. Pat the child on the back 1-5 times and observe whether the child spits out the foreign body. If the foreign body does not come out from the above operation, you can take another position, turn the child over and lie on the hard ground or bedpan, with the rescuer kneeling or standing on his or her foot side, or taking a sitting position, and make the child ride on the rescuer’s lap, facing forward. Rescuer with the middle finger or index finger of both hands, placed on the abdomen of the child under the thorax and umbilicus, and quickly pressed upward, but very gently. Repeat until the foreign body is expelled. For first aid adults, the rescuer stands behind the patient, wraps both arms around the patient’s waist, then makes a fist with one hand and places the thumb side of the fist on the patient’s abdomen under the thorax and above the umbilicus. Then use the other hand to grab the fist and quickly press upward on the patient’s abdomen. Repeat the above techniques until the foreign body is discharged. For self-rescue, use the last 3 steps of the above 4 steps for adults, or bend down slightly, lean on a fixed horizontal object, compress the upper abdomen with the edge of the object, and quickly impact upward. Repeat until the foreign body is expelled.