General anesthesia surgery after a drop in blood pressure, usually because of general anesthesia surgery, due to general anesthesia anesthetic has not been completely metabolized, respiratory muscle function has not been fully restored, resulting in breathing into the lungs inside the gas is reduced, the supply of oxygen is also relatively reduced, so this situation will lead to a drop in blood pressure. Generally, oxygen can be given, and when the anesthetic is completely metabolized and the function is restored, basically it can return to normal. In addition, there may also be due to their own disease caused by the drop in blood pressure, for example, is a serious trauma to the brain need to do general anesthesia surgery, or lung problems need general anesthesia surgery, there may be a primary disease of the brain and lungs, which leads to respiratory failure, or the lungs are not breathing smoothly, which leads to the drop in blood oxygen.