First, what is the etiology of limb macrovascular injury The etiology of limb macrovascular injury: mostly due to trauma such as explosions, stab wounds, gunshot wounds, fractures, dislocations or soft tissue contusions, often occurring in bad limbs. Generally divided into two categories: open and closed. The severity of the local injury does not necessarily parallel the degree of vascular damage and can sometimes lead to serious consequences due to misdiagnosis. Vessels can spasm due to pressure, or they can be contusions with fracture of the intimal layer of the vessel, fracture of the subepithelium, or even partial or complete fracture of the vessel. Second, how to diagnose limb macrovascular injury Diagnosis of limb macrovascular injury: typical trauma style, can be combined with fracture and dislocation. Early limb pain, late due to nerve ischemia, pain disappears; injury distal artery pulsation is weakened or disappeared; local may have wound, pulsatile bleeding or hear blood murmur; injury artery distal limb pale, cyanosis, weakness or paralysis, decreased skin temperature, hypoesthesia or loss of sensation, may have edema; X-ray examination and angiography for reference. MRI helps to determine the site of vascular injury, Doppler also helps to blood flow interruption localization. Third, the large blood vessel injury of the limb includes the following first aid measures 1, hemostasis: cover the wound with sterile excipients, clean cloth and pressure bandage, also can be used fingers, palms compress the wound or its proximal arterial trunk for a few minutes and then bandage, if still can not stop bleeding, that is, the use of tourniquet on the proximal side of the limb and mark. 2. Combined fractures and dislocations should be fixed to relieve pain and prevent further injury. It is advisable to reset as soon as possible to reduce the compression of the artery. 3, closed arterial injury should be removed too tight dressings, plaster tube type, and flexion of the elbow (knee) to reduce the tension of the pulling blood vessels. 4, combined with fractures, before repairing the artery feasible internal fixation, or postoperative plaster, splint external fixation. 5.Significant swelling of the limb after fracture and severe soft tissue injury or deep subfascial hematoma formation, resulting in vascular compression is feasible when fasciotomy is performed to reduce compression. 6, surgical exploration of blood vessels, within 6-8 hours after the injury, blood completely interrupted need immediate surgical repair of blood vessels, such as partial collateral circulation and symptoms of inadequate blood supply, should be elective surgical repair of blood vessels, forearm or calf an arterial injury, may not require surgical repair. If it is vasospasm, give anesthesia or use poppy base solution gauze wet dressing to release the spasm, if necessary, after resection anastomosis, pay attention not to mistake the intima injury, tear, thrombus blockage, etc. as vasospasm. Fourth, what are the probing indications for large-vessel injury of the limb 1, the distal pulses of the limb are weakened or disappeared. 2, there is active arterial bleeding. 3.Large or continuously increasing hematoma. 4.Huge bleeding with shock. 5.Nerve injury adjacent to the vessel. 6.There are large arteries near the wound. 7.Some parts of fracture dislocation suspected to have vascular injury.