Based on the clinical and X-ray findings, this patient has the following characteristics: First, the metal foreign body is 0.8 * 0.4 cm in the patient's thigh, and the foreign body travels to the pulmonary artery through the blood circulation. There are similar reports in the literature, most of which are shrapnel plugs, filter plugs, stents falling off, etc. [2, 3]. However, there has been no report of the case where the iron tablets in this case remained in the body for five years without any complications. Second, the position of the foreign body in the blood vessel changes rapidly. We believe that it may be related to the following factors: foreign bodies may cause the blood flow to change from laminar flow to turbulent or turbulent flow; pulmonary artery blood pressure decreases during diastole, and the blood flow pressure at the distal end of the vessel may be greater than that at the proximal end; body position changes and the effect of gravity.
Treatment experience: For any metal foreign body that is close to the blood vessels of the extremities or damaged blood vessels, before the foreign body is removed by debridement operation, the blood vessels of the affected limb should be checked with color Doppler ultrasound and CT imaging to clarify the relationship between the foreign body and the surrounding blood vessels; On the basis of the use of tourniquets, perform foreign body and blood vessel exploration, and reduce the rubbing of local tissues to prevent small foreign bodies from infiltrating the bloodstream; if foreign bodies are not found during the debridement during the operation, the patient should be less moved when the foreign body is suspected to be migrating and the operation should be terminated and ask the interventional department and cardiac surgery to consult, perform interventional surgery to remove the foreign body or install a filter or tennis sac to prevent the foreign body from further migrating; on the basis of installing the filter, it is transferred to the higher-level hospital, and the blood pressure should be actively controlled on the way to reduce the patient's movement. If the location of the foreign body is deep, but the patient is in good condition, he can be discharged after a few days of observation with anti-infection and anticoagulation treatment, and return to the hospital regularly for follow-up after discharge. If the patient is in poor condition and the blood draw index is abnormal, the foreign body should be removed by thoracotomy as soon as possible.