”Doctor, I feel a little out of breath, and my chest hurts a little.” On the evening of May 28, Zhou Laobao, a Sichuan earthquake casualty who had just been received by ambulance at Tongji Hospital for treatment, said softly to the doctor. Dr. Zhu, the orthopedic surgeon in charge of the bed, did not take his words lightly. Gently opened the plaster dressing on Zhou’s fractured left calf, and carefully examined, the yellow-brown left calf swollen very seriously, almost “elephant leg”, if from the diameter has been difficult to distinguish which is the calf and which is the thigh. Vascular surgery emergency consultation, lower extremity ultrasound, CT, a series of tests to confirm the left lower extremity deep vein thrombosis. The old man Zhou said he could not breathe and had chest pain, which was probably a small thrombus dislodged leading to focal pulmonary embolism. So, after careful discussion among several doctors of orthopedic vascular surgery, the treatment plan DD endovascular treatment was determined immediately! After corresponding preparation, the day after admission, old man Zhou underwent inferior vena cava filter implantation plus intubation thrombolysis on a bidirectional digital subtraction angiography machine in the catheterization laboratory. The intraoperative angiogram showed that the deep vein thrombus had crossed the iliac-aortic bifurcation, and the left iliac vein and vena cava had also developed thrombus. The vascular surgeon placed a special bird’s nest-shaped metal screen from the right femoral vein into the inferior vena cava and fixed it in the lumen to block the thrombus dislodged from the inferior vena cava and prevent the formation of pulmonary embolism. After 30 minutes, the operation was completed successfully. The doctors were glad that the surgery was done in time, otherwise the consequences would have been unimaginable once the thrombus developed to the level of renal vein. So, what is deep vein thrombosis and how dangerous it is? The veins of human body are divided into two systems: superficial veins and deep veins, usually we can see the “veins” that are superficial veins, while the deep veins are described as “deep” because they are located deeper, usually between the muscles, and cannot be seen by the naked eye. The role of the deep and superficial venous systems is to return the venous blood to the heart after it has been used by the tissues, figuratively speaking, they are like the sewers of the body, sending the “sewage” back to its designated place – the heart. The deep venous system plays a much larger role than the superficial venous system. Deep vein thrombosis is the abnormal clotting of blood in the deep vein lumen, blocking the vessel. Of all the veins, the deep veins of the human legs are the most prone to thrombosis because the veins of the legs are the farthest from the heart and because human uprightness also causes the venous blood in the legs to overcome gravity in order to return to the heart. The three main culprits of intravascular thrombosis are: blood hypercoagulation, slow blood flow, and damage to the intima. Blood is not a liquid with uniform density, there are many red blood cells, white blood cells, platelets and so on, which constantly transport various cells from the heart to the periphery and back to the heart. And in some special cases the cells that need to be transported increase, resulting in a higher concentration of blood, and if the blood flow is slow, the blood has a tendency to deposit red blood cells, white blood cells, etc. in the walls of the blood vessels. Just as the Yangtze River, which is laden with a lot of sediment, reaches a flat place at the mouth of the sea, when the water flow slows down and the sediment is deposited, an umbrella-shaped alluvial plain like the Yangtze Delta is formed. If there is damage to the inner wall of the blood vessels at this time, it will activate the platelets in the blood to release a variety of substances and activate the clotting system. While repairing the damage, tiny emboli are also formed in the blood vessels, which are likely to grow larger and larger, forming life-threatening blood clots. Now, looking back at Zhou’s problem, it can be deduced that the left calf was compressed by a heavy object for a long time during the earthquake, and the venous blood flow was not smooth, plus the fracture caused the fat in the bone marrow and other insoluble substances to run into the blood vessels, and as the buried sewer suddenly broke due to external damage, a large amount of sediment poured into the sewer and blocked it, forming a serious thrombosis. So what is the performance of deep vein thrombosis and what harm does it do to the patient? After the thrombosis, the blood can’t flow back effectively, just like a blocked sewer, the sewage can’t be discharged, resulting in blood stagnation and swelling of the limb far away from the blockage; if it doesn’t pass, it hurts, and the swollen limb often has different degrees of pain, which is more obvious when walking on the ground. As the old man Zhou mentioned above, the consequences of thrombus blocking blood vessels are serious, but what is more terrible is the thrombus falling off, which is a fatal bomb! Once the thrombus is dislodged, it will travel along the blood circulation pathway: inferior vena cava – right atrium – right ventricle, and finally into the pulmonary artery, resulting in pulmonary embolism. The embolism may cause ischemia in only a small part of the lung, but it is actually like igniting a bomb in the ammunition store, and a series of chain reaction leads to ischemia in a large part of the lung, losing the function of blood gas exchange, which often kills the patient. The most typical case is that many patients with a long history of bed-ridden, limb can not or only slightly active, just started to get out of bed to increase activity, stand up and then suddenly “ah” shouted, and then fell down, chest tightness, shortness of breath, accelerated heartbeat, and finally heartbeat, respiratory arrest. Is deep vein thrombosis only for patients with fractures like Mr. Zhou? –Of course not. Many diseases can lead to DVT. Risk factors include advanced age, mid- to late-term pregnancy, malignancy, obesity, varicose veins, paralysis, history of severe trauma, major surgery on the lower extremities (especially the hip joint), prolonged bed rest or heart failure. Without preventive measures, the chance of these patients suffering from deep vein thrombosis in the lower leg can be as high as 40% to 80%, and the chance of fatal pulmonary artery embolism is 1% to 5%. Even in normal people who fly long distances by airplane, there is a very high prevalence of thrombosis. As mentioned above, blood hypercoagulation, slow blood flow and intimal damage are the three main culprits of thrombosis. During long-distance flights, lack of oxygen in the cabin, repeated circulation of air, and forgetting to drink water when fatigued …… all these factors make the blood in a hypercoagulable state. Many passengers on the plane, they are used to sitting in the seat to rest or simply sleep, the lack of exercise makes the blood flow slows down, all factors interact, the blood is very easy to form blood clots. In order to arrange the most seats, the distance between the front and back of the economy class seats is very small, which objectively restricts the movement of passengers, making passengers in economy class most likely to get deep vein thrombosis, which is historically known as this thrombosis disease in long-distance flights as economy class syndrome. But this in no way means that passengers in first class can rest easy, if not pay attention to prevention, also easy to get blood clots. A survey found that for ordinary passengers, pulmonary embolism may occur after 3 to 4 hours of flight time; the longer the flight time, the higher the risk of deep vein thrombosis and pulmonary embolism. Pregnant women, people on oral contraceptives, people with high blood viscosity and other passengers whose blood is in a state of hypercoagulability are more vulnerable to the disease. Finally, how to prevent and treat deep vein thrombosis? First of all, we should strengthen the awareness, especially the high-risk group of the disease, and raise the vigilance at all times; secondly, we should drink more water to reduce the viscosity of blood; in addition, we should pay attention to not keep a posture for a long time, and stand up regularly for activities; also, we should avoid smoking and drinking, which are bad habits that can make the blood in a hypercoagulable state. In addition, for those who often make long-distance travel (please note that it is not limited to air travel), there are some additional suggestions: 1, travel clothing and footwear should be loose, which will help blood circulation. 2, do not stuff luggage under the seat, so that the legs have enough space to move. 3, sleep to maintain a comfortable state, do not cross the legs, do not tighten the body, because this will form a squeeze on the blood system. 4. It will form a squeeze on the blood system.4. Travelers who are in a hypercoagulable state themselves should consult a doctor before traveling to see if they are fit to travel or what special precautions should be taken, such as wearing long elastic stockings and taking oral anticoagulants. If you find or suspect that you have deep vein thrombosis, you should consult a doctor in time to have the diagnosis confirmed and standardized treatment by a professional. It is not difficult to diagnose deep vein thrombosis by ultrasound, CT, MRI and some related tests of lower limb blood vessels. Treatment methods can be divided into two categories: medication and surgical thrombosis. Drug treatment includes anticoagulants (heparin, coumarin derivatives, etc.), thrombolytic drugs (streptokinase, urokinase) and blood volume expanding drugs (dextran), etc. In turn, surgical methods can be divided into traditional incisional thrombectomy and endovascular treatment. Among them, endovascular treatment is gaining more and more attention due to its less invasive, higher safety and shorter recovery period. Through the peripheral vein route, a metal stent with a filter is placed into the inferior vena cava using a specially designed delivery device, which can prevent the dislodged thrombus in the deep veins of the lower limbs from entering the inferior vena cava and prevent the occurrence of pulmonary embolism. It provides the most reliable guarantee for the patient’s life safety. Among them, intermittent balloon compression and graded compression elastic stockings have both preventive and therapeutic effects. The former requires a fixed power supply and compresses the legs with regular inflation and deflation sequence of the airbags wrapped around the legs to promote the return of blood to the heart; the latter has a pressure that does not make sense in different parts, gradually decreasing from the soles of the feet to the thighs, which can play a role in driving back the blood when the wearer’s legs are moving. Because of its health care role even many people who are not at risk also like to wear. And China’s traditional medicine as early as in the “Yellow Emperor’s Classic of Internal Medicine” on the circulation of blood in the early in the “Yellow Emperor’s Classic of Internal Medicine” on the circulation of blood in the initial elaboration, and “pulse to pass, blood is moving”, “pulse paralysis, “Drain the blood qi and make it flow” and other discussions. Sun Simiao’s “Prepared Emergency Thousand Jin Medicine Formula” has the record that “pain is caused by stagnation of qi and blood, swelling is caused by obstruction of veins, and heat is generated by prolonged stasis”, which indicates that there is a certain understanding of deep vein thrombosis. It is also recorded in the “Treatise on Blood Evidence” that “it is advisable to remove stagnant blood and eliminate swelling”, “for those who have stagnant blood and swelling pain, it is advisable to eliminate stagnant blood”, and “when stagnant blood is dispersed, the pain and swelling will be removed”. Looking at the discussions of medical doctors in past generations, it is found that factors such as prolonged bed rest after surgery and trauma are prone to damage the Ying Qi, resulting in poor Qi flow. “Qi is the marshal of blood”, and poor Qi flow slows down blood flow, which, together with external injury, leads to stasis of blood in the ligaments, or to deficiency of the body and stasis of blood. Poor blood flow, stasis blocking the vasculature, vasculature stagnation and blockage, not pass is pain, the return flow of blood is blocked, water and fluid overflow, gathering damp heat. In conclusion, dampness, heat, stasis and deficiency are the main pathological basis of this disease, and dampness-heat and blood stasis are the main causative factors. The treatment of this disease should follow the principle of prevention before illness and prevention after illness. In the treatment, a holistic and dialectical view should be established, depending on the patient’s general condition, and according to the patient’s cold, heat, deficiency and actuality, the diagnosis and treatment should be carried out to achieve the target.