The tidal volume for adult CPR is 6-7 ml/kg. During CPR and artificial respiration, a relatively low tidal volume will be more conducive to CPR, and excessive tidal volume and blowing too fast should be avoided to cause hyperventilation of the patient. Too large a tidal volume and too fast blowing will cause the esophagus to open, blowing gas into the stomach and causing gastric distension. On the one hand, gastric distension will lead to vomiting, reflux of stomach contents and aspiration into the airway; on the other hand, it will also elevate the diaphragm, affecting the expansion of the lungs during blowing, all of which are not conducive to cardiopulmonary resuscitation (CPR). In order to avoid excessive tidal volume during artificial respiration, it is not necessary to take a deep breath before blowing, normal inhalation is sufficient, the speed of blowing should be slow, and the time of blowing should be more than 1 second, and it is sufficient to be able to see the patient’s chest rise and fall.