During the infusion process, if the pressure of the venous vessels is high, small air bubbles do not easily enter the vessels, and nowadays there is a filtering device in the infusion set. The gas that enters the blood vessels is usually relatively small and will soon dissolve in the blood and will not affect the health of the body. However, if more air enters, symptoms usually appear in a few minutes, so its danger period is usually no more than 30 minutes. If a large amount of gas enters the blood vessel in a short period of time, more than 100ml, it may produce air embolism, and the gas will enter the heart with blood circulation, and when the heart carries out contraction and diastole, the gas mixes with the blood to produce bubbles, resulting in the reduction of effective ejection fraction, the whole body tissues and organs appearing ischemia and hypoxia, and finally respiratory difficulty and multi-organ failure, which can be life-threatening in serious cases. However, this situation can only occur under large negative pressure, and generally does not occur during infusion. When air enters the blood vessels during the infusion process, it is necessary to observe whether the patient has any abnormal performance such as panic, chest tightness, nausea, vomiting, irritability, chest pain, coughing, difficulty in breathing, etc. Generally, it is enough to observe for a few minutes or ten minutes.