Will air be infused when the IV fluid runs out and blood flows back?

　　Under normal circumstances, when an intravenous (IV) infusion runs out and blood reflux occurs, air may enter the IV line. A detailed explanation is as follows:

　　The air in an IV bottle or bag serves to maintain pressure equilibrium. As the liquid flows out of the container, air automatically enters to replace it and maintain this balance. Once the IV fluid is fully administered, a certain amount of air typically enters the bottle or bag. This is a normal phenomenon and generally does not pose harm to the body. However, if excessive air enters, it may lead to an air embolism—blocking blood vessels—and in severe cases, could be life-threatening. Therefore, during IV infusion, it's important to control the infusion rate, adjust the height of the IV bag, and take other measures to minimize the amount of air entering. Additionally, once the IV bag is empty, the tubing should be promptly clamped to prevent air from entering the patient’s body.

　　In summary, while some air naturally enters the IV container after the fluid is depleted, precautions should be taken to minimize air volume and avoid potential risks. If you have any concerns or experience discomfort, consult healthcare professionals immediately.