Air embolism in dialysis is a rare but serious complication that can lead to death if not handled properly, mostly caused by improper operation, mainly due to the following reasons: 1. It may be due to poor or broken connection of the line or venipuncture needle. 2. The bevel of the arterial puncture needle does not enter the endovascular vessel completely, or the central venous catheter is broken or dislodged. 3. The air in the dialysis tubing is not completely drained. 4. The air is sucked into the tubing when the fluid is not closed in time when the dialysis tubing is replenished. 5. The air enters the body with the blood when the dialysis blood is returned improperly. These are the most common causes, and must be avoided in operation.