Blood leaving the veins is the clinical manifestation of crush syndrome. Crush syndrome is a series of pathological changes in the body caused after a person is crushed by a stone and earth, especially a muscular limb is crushed for more than one hour (e.g. thigh). Due to damage to the skin and flesh, blood leaving the veins, stasis of blood, stagnation of qi and blood, and meridian occlusion, localized pain, swelling of the limb, indentation and hardening of the skin, subcutaneous stasis of blood, and increased skin tension. How to check for extrusion syndrome? 1.Local manifestations Due to the damage of the skin and flesh, blood leaving the veins and blood accumulation, stagnation of qi and blood, meridian occlusion, local pain, swelling of the limb, indentation of the skin, hardening, subcutaneous bruising, increased skin tension, blister formation around the compressed skin, when checking the blood circulation status of the limb, it is worth noting that if the pulse at the distal end of the limb does not weaken, there is still a risk of ischemic necrosis of the muscle tissue, pay attention to check The muscle and nerve function of the limb, active activity and passive pulling can cause pain, which is helpful to determine the muscle groups in the fascial interval area involved. 2, systemic manifestations Due to internal injury to qi and blood, meridians and internal organs, patients appear dizzy, loss of appetite, lack of color, chest tightness and abdominal distension, constipation and other symptoms, accumulation of silt and heat can manifest fever, red face, yellow urine, red tongue, yellow greasy coating, frequent pulse, etc. In severe cases, palpitation, shortness of breath, and even pale face, cold extremities, sweating like oil and other desiccation (shock). The main features of the extrusion syndrome are as follows: (1) shock: some casualties may not appear in early shock, or shock period is short and not detected, some casualties due to the strong nerve stimulation of extrusion injuries, extensive tissue destruction, a large amount of blood volume loss, can quickly produce shock, and constantly aggravated; (2) myoglobinuria: this is an important condition for the diagnosis of extrusion syndrome, the casualty in the injured limb after the relief of pressure Brown urine or self-reported hematuria within 24 hours after decompression of the injured limb should be considered myoglobinuria, the concentration of myoglobinuria in blood and urine, peaks 3 to 12 hours after decompression of the injured limb, then gradually decreases and can turn clear on its own after 1 to 2 days; (3) hyperkalemia: because of muscle necrosis, a large amount of intracellular potassium enters the circulation, coupled with the difficulty of potassium excretion in renal failure, the blood potassium can rise daily during the oliguric phase (4) acidosis and azotemia: after muscle ischemic necrosis, a large amount of phosphate, sulfate and other acidic substances will be released, which will lower the pH of body fluid and lead to metabolic acidosis, and after severe trauma, tissue catabolism and metabolism will be exuberant. A large amount of intermediate metabolites will accumulate in the body after severe trauma, and the non-protein nitrogen will rise rapidly. Clinically, a series of manifestations such as confusion, deep breathing, irritability and thirst, nausea and other acidosis and uremia should be seen, and the specific gravity of urine should be measured frequently.