Deep vein thrombosis of lower extremity

Introduction to deep vein thrombosis of lower extremities Deep vein thrombosis refers to the abnormal condensation of blood in the deep veins, which occurs in the lower limbs. It is a relatively common disease in Europe and the United States. It is also increasing year by year in China. The disease cannot be diagnosed and treated in time in the acute stage. Some blood vessels may fall off, causing embolism of vital organs such as the lungs and brain of patients. Lead to death. Other patients are not immune to the occurrence of chronic thrombosis sequelae, causing long-term illness and affecting life and work ability. Deep vein thrombosis (DVT) can be seen in any age group, but statistics show that with the increase of age, the incidence rate is gradually increased, the incidence of 80-year-old population is more than 30 times that of 30-year-old population, the effect of age on the incidence of deep vein thrombosis There are many aspects, the age increases, and the risk factors of DVT also increase. Experiments show that the blood clotting factor activity is higher in the elderly, and the pumping effect of the calf muscle is weakened, so that the blood is in the soleus venous plexus and venous valve pocket. The stasis is heavier, so the incidence of DVT is higher than that of young people. basic knowledge The proportion of illness: 0.004%-0.008% (more common in the elderly over 50 years old) Susceptible people: no specific population Mode of infection: non-infectious Complications: pulmonary embolism dermatitis

Causes of deep venous thrombosis of lower extremities

Age factor (15%):

Deep vein thrombosis (DVT) can be seen in any age group, but statistics show that with the increase of age, the incidence rate is gradually increased, the incidence of 80-year-old population is more than 30 times that of 30-year-old population, the effect of age on the incidence of deep vein thrombosis There are many aspects, the age increases, and the risk factors of DVT also increase. Experiments show that the blood clotting factor activity is higher in the elderly, and the pumping effect of the calf muscle is weakened, so that the blood is in the soleus venous plexus and venous valve pocket. The stasis is heavier, so the incidence of DVT is higher than that of young people.

Limited activity (30%):

Clinically, patients with long-term bedridden are often prone to DVT. The autopsy found that the incidence of DVT in patients who were in bed for 0 to 7 days was 15%, while in bed for 2 to 12 weeks, the incidence of DVT was 79% to 94%. Among stroke patients, the incidence of DVT was 53% in patients with lower extremity paralysis, and the incidence of DVT was only 7% in those without lower extremity paralysis. In the long-distance car or by air travel, the incidence of DVT was also higher, and the calf muscles were higher. The pumping action plays an important role in the reflux of the lower extremity veins, and the venous return is significantly slowed after braking, thereby increasing the risk of DVT.

Venous thrombosis (25%):

23% to 26% of patients with acute DVT have a history of venous thrombosis, and these newly formed thrombosis often comes from the original diseased vein. The study found that patients with recurrent DVT often have hypercoagulable state.

Trauma factor (8%):

The autopsy of traumatic death found that 62% to 65% of the deceased had DVT. The trauma may lead to lower limb fracture, spinal cord injury, venous injury and surgical treatment, so that trauma patients are prone to DVT, and the blood is high after trauma. The clotting state also promotes thrombosis.

Surgical trauma (10%):

The high incidence of VT after surgery shows that surgery is an important risk factor for DVT. The age of the patient, the type of surgery, the size of the wound, the operation time and the bed rest time are all affecting the occurrence of DVT. The type of surgery is especially important. The incidence of post-DVT is about 19%, neurosurgery is about 24%, and femoral fractures, hip arthroplasty, and knee arthroplasty are as high as 48%, 51%, and 61%, respectively. It can be found that about half of the patients have 125I-labeled fibrinogen deposits in the lower extremities, and the rest can be found in fibrinogen deposition 3 to 5 days after surgery, but this does not indicate that DVT occurs immediately after surgery. Statistics show that the abdomen After surgery, 25% of patients developed DVT within 6 weeks after discharge. The causes of DVT caused by surgery include perioperative braking, postoperative intraoperative coagulation, anticoagulation and thrombolysis system abnormalities, and venous injury. Wait.

Pathogenesis

The classic Virchow theory believes that: vascular wall damage, abnormal blood flow and changes in blood components are the three main factors causing venous thrombosis. At present, molecular level research results have a new understanding of this theory, normal venous endothelial cells can Secretion of a range of anticoagulants such as prostaglandin I2 (PGI2, prostacyclin), antithrombin cofactor, thrombomodulin and tissue plasminogen activator (t-PA), but in some cases The venous endothelium can be transformed from an anticoagulant state to a procoagulant state, endothelial cells produce tissue factor, von Willebrand factor and fibronectin, etc., permeability of the endothelial layer increases, and leukocytes adhere to the surface of endothelial cells, while the endothelium is visible. The original anticoagulant function of the cells is inhibited, and inflammatory cells trigger and enhance thrombus formation. The secretion of interleukin-1 (IL-1) and tumor necrosis factor (TNF) can promote fibrinogen deposition and inhibit Fibrinolysis; TNF inhibits the expression of thrombomodulin in endothelial cells, transforming endothelial cells from an anticoagulant state to a procoagulable state.

Many venous thrombosis originate from the slow blood flow, such as the calf gastrocnemius venous plexus, venous valve pocket, etc. It is clinically found that limb brakes or long-term bed rest patients are prone to venous thrombosis, which suggests that slow blood flow is a factor of thrombosis. First, compared with pulsed blood flow, static streamlined blood flow easily causes severe hypoxic state at the bottom of the venous valve. Hypoxia causes endothelial cells to attract white blood cells to adhere and release cytokines, which in turn damages the venous endothelial layer and stagnates blood flow. The accumulation of activated coagulation factors and the continuous consumption of anticoagulant substances, the coagulation-anticoagulation balance is broken, resulting in venous thrombosis, so blood stasis is another factor of thrombosis.

Activated coagulation factors in the blood play an important role in the process of thrombosis. Activated coagulation factors activate prothrombin along endogenous and exogenous coagulation pathways, converting fibrinogen to fibrin and eventually forming thrombus. If there is no activated blood coagulation factor, even if there is blood stasis and vascular damage, the thrombus will not form. Similarly, there is an activated blood coagulation factor, and no thrombus can form. The activated blood coagulation factor will be cleared by the body soon. Therefore, the venous thrombosis is It is formed under the action of multiple factors, and the change of blood composition is the most important factor of thrombosis. The three systems of coagulation-anticoagulation-fibrinolysis in the body are in equilibrium under normal conditions, and any coagulation function is enhanced, anticoagulation-fiber Factors that inhibit the action of the action will all contribute to thrombosis.

Malignant tumor

Statistics show that 19% to 30% of patients with DVT have malignant tumors. Lung cancer is the most common malignant tumor that causes DVT. Others such as genitourinary system and gastrointestinal system malignant tumors are also prone to DVT. Sometimes DVT can be used as Messengers of malignant tumors, when DVT occurs without obvious incentives, should be alert to possible malignant tumors. The causes of DVT caused by malignant tumors are various. The most important reason is that malignant tumors release procoagulant substances and improve blood coagulation factors. The activity of fibrinogen and platelet count in the blood of tumor patients is often higher than normal, while the concentration of anticoagulant substances such as antithrombin, protein C and S protein is lower than normal. In addition, surgical treatment and chemotherapy of tumors are also The main factors leading to DVT, breast cancer, lymphoma, plasma cell disease and other chemotherapy patients, the incidence of DVT is significantly increased, which may be related to the toxic effects of chemotherapy drugs on vascular endothelial cells, induce hypercoagulable state, inhibit fibrinolytic activity, tumor cells Necrosis and venous intubation are related to factors.

2. Primary hypercoagulable state

Common in patients with genetic mutations or hereditary anticoagulant defects, 5% to 10% of all DVT patients are caused by primary blood hypercoagulation, and normal human anticoagulant systems include antithrombin, protein C. System, tissue factor pathway (exogenous coagulation pathway) inhibitor, etc., antithrombin can inhibit Xa, IXa, XIa and XIIa factors, heparin and heparin-like mucopolysaccharide on the surface of vascular endothelial cells can promote its anticoagulant effect, C Protein, S protein system can bind thrombin and thrombomodulin on the surface of endothelial cells, inhibit the activity of factor V and factor VIII, gene defects lead to the lack of anticoagulant substances, blood in a hypercoagulable state, lack of primary anticoagulant substances The proportion in the population is about 0.5%, including homozygous gene defects and heterozygous gene defects. The proportion of thrombosis in homozygous gene defects is much higher than that of heterozygotes. The primary blood coagulation DVT occurs for the first time. Time is often before the age of 45, often induced in some cases (such as surgery, trauma, etc.), and the thrombus is easy to recur, the site of the thrombus is often atypical, the mesenteric venous blood is often seen clinically. Suppository, intracranial venous sinus thrombosis.

3. Postpartum

The incidence of postpartum deep venous thrombosis is higher, and DVT patients in domestic pregnancy are relatively rare. The occurrence of postpartum DVT is closely related to the hypercoagulability of blood. Postpartum placental exfoliation can quickly stop bleeding in a short period of time, without causing major bleeding after production. It is directly related to the hypercoagulable state of the blood. During pregnancy, the placenta produces a large amount of estrogen, which reaches the highest peak at full term. The amount of estriol in the body can be increased to 1000 times that of non-pregnancy. Estrogen promotes various liver production. Coagulation factors, as well as a large increase in fibrinogen in the end of pregnancy, aggravation of hypercoagulable state, may lead to DVT.

4. Oral contraceptives

As early as the 1960s, oral contraceptives were reported to cause DVT. It has been found that one in four women of childbearing age with DVT is related to the use of contraceptives. The survey also found that DVT caused by DVT in women of childbearing age. The embolization is significantly reduced. The reason that the contraceptive is easy to cause DVT may be related to the mutation of coagulation factor V, which makes the coagulation factor V reduce the anticoagulant effect of protein C. The larger the dose of estrogen in the contraceptive, the more likely it is to cause DVT, the dose is >50g. The contraceptive pill has a greater risk of thrombosis than the contraceptive <50g. The third-generation contraceptive is easier to trigger DVT than the second-generation contraceptive because the progesterone in the third-generation contraceptive is mainly desogestrel. , norgestrel or gestodene, these progestogens are also prone to thrombosis, the survey shows that women of childbearing age who take third-generation contraceptives with DVT are 8 times less than contraceptives.

Estrogen is also used to treat male prostate hypertrophy and female climacteric syndrome, as well as lactation in lactating women. The incidence of DVT is also higher in these people. Estrogen has elevated blood viscosity, increased blood fibrinogen, plasma. Concentrations of Factor VII and X increase the adhesion and aggregation of platelets and are therefore prone to thrombosis.

5. Blood type

It has been found that there is a certain relationship between blood type and DVT. People with type A blood are most likely to suffer from DVT. Relatively speaking, the risk of DVT in type O blood is the least. The reason is not completely clear. The surface of human vascular endothelial cells with different blood types is found. Some of the structures are different, and the von Willebrand factor on the surface of type O blood endothelial cells is significantly reduced.

6. Ethnicity

The incidence of DVT in Europe is much higher than in Asia. Although racial differences may lead to blood clotting and different anticoagulant systems, differences in lifestyle and diet may also affect the incidence of DVT. The rate is higher than that of black Africans of the same race.

7. Central venous cannula

Clinically, more and more central venous intubation, resulting in a corresponding increase in the incidence of DVT, especially in patients with upper extremity DVT, 65% of patients with central venous cannulation, venous cannulation not only damage the vessel wall, but also in the vein cannula The surface is also prone to thrombosis. The type of catheter has a great influence on the occurrence of DVT. Polytetrafluoroethylene (PTFE) catheter or heparin-coated catheter has a lower chance of DVT than other catheters. Catheter diameter, venipuncture The number of times, the time of placement, and the medication being infused will affect the occurrence of DVT.

8. Enteritis

Clinically, it is often reported that patients with enteritis have pulmonary embolism. The cause of DVT caused by enteritis is unclear. It is only found that the blood platelet count, blood coagulation factor V, VIII and fibrinogen concentration are significantly increased in these patients, and the DVT site caused by enteritis is often not Typical, such as intracranial venous sinus thrombosis.

9. Systemic lupus erythematosus

Patients with systemic lupus erythematosus often have arteriovenous thrombosis, repeated abortion, thrombocytopenia and neurological diseases, which may be related to the high level of lupus antithrombin antibody and anti-cardiolipin antibodies in active phase. Other autoimmunity The patient also had a similar situation. The study found that patients with systemic lupus erythematosus had a 6-fold higher chance of developing venous pulmonary embolism with anti-thrombin antibody, while the anti-cardiolipin antibody was higher in the control group. 2 times.

10. Other

Whether obesity, varicose veins of lower extremities and cardiac insufficiency are the predisposing factors of DVT is still controversial. Multivariate statistical analysis considers obesity, varicose veins of lower extremities and cardiac insufficiency are not independent predisposing factors. These patients may be susceptible to DVT. Associated with other risk factors.

Most of the above 15 susceptibility factors are hypercoagulable in blood components, resulting in deep vein thrombosis of the lower extremities. Therefore, the change of blood components into hypercoagulable state in Virchow's theory is the determinant of DVT formation.

Pathological changes

1. Pathology: Venous thrombosis is divided into 3 types: white thrombus, red thrombus and mixed thrombus. White thrombus is mainly composed of fibrin, platelets and white blood cells. It contains only a small amount of red blood cells. Red blood clots are mainly composed of a large number of red blood cells and fibrin. Containing a small amount of platelets and white blood cells, white blood clots and red blood clots often mix together to form a mixed blood clot. When the venous thrombus is formed, it is a white blood clot, which constitutes a thrombus head. The secondary body and tail of the secondary derivation are mainly red blood clots.

Once the venous thrombosis is formed, it is in the process of continuous evolution. On the one hand, due to venous thrombosis, the venous lumen is narrowed or occluded, and new thrombus is formed on the surface of the venous thrombus, which is derived from the proximal and distal end, respectively. There is no adhesion between the early and the venous wall, the thrombus floats in the lumen, easily falls off, causing pulmonary embolism, late fibroblasts, bud-like capillaries invade the thrombus, and the thrombus becomes tightly adhered to the wall after the machine is formed. In the early stage of venous thrombosis, endothelial cells on the surface of the affected vein secrete thrombolytic substances, dissolve thrombus, while white blood cells, especially monocytes, invade the thrombus, activate urokinase-type plasminogen activator (u-PA) and tissue type. Plasminogen activator (t-PA) enhances thrombolytic activity, causing many fissures in venous thrombosis, thrombolysis and contraction and fragmentation of intravascular thrombus, resulting in the expansion of fissures and the gradual migration of new endothelial cells. The fissure surface can eventually re-open most of the blocked veins. The valve of this recanal vein is often destroyed, and some of the residual fiber adhesions in the lumen Venous recanalization procedure varies, it normally takes six months to 10 years.

Lower extremity iliofemoral venous thrombosis is more common on the left side, which is 2 to 3 times of the right side. It may be longer with the left iliac vein and the right iliac artery crosses it, which is related to different degrees of compression of the left iliac vein.

Lower extremity venous thrombosis, especially after main vein thrombosis, the blood flow back of the affected limb is blocked. In the acute phase, the blood cannot flow back through the main vein, so that the intravenous pressure is rapidly increased, and the water in the blood penetrates into the tissue through the capillaries, causing the tissue. Swelling, at the same time, increased venous pressure, forcing the collateral vein to dilate, open, and the stagnant blood flows back through the collateral vein, causing the swelling to gradually subside.

2. Pathological classification

(1) According to the embolization of blood vessel parts: There are three types of lower extremity DVT, namely, peripheral type, central type and mixed type.

1 Peripheral type: also known as calf muscle venous plexus thrombosis, after thrombosis, due to thrombus limitations, most of the symptoms are mild, most of the treatment can be ablated or mechanized, but also autolytic, a small number of untreated or improper treatment, can be to the thigh Expanded into a mixed type, small embolism can cause mild pulmonary embolism, which is often overlooked clinically. Clinically, the main manifestations are calf pain and mild swelling, limited activity, and the symptoms are consistent with the time of thrombosis. The main signs are pain caused by pulling the gastrocnemius muscle when the foot is dorsiflexion (Homan sign positive) and gastrocnemius pressure pain (Neuhof sign positive).

2 Central type: also known as iliac vein thrombosis, more common on the left side, manifested as swelling below the buttocks, lower limbs, groin and affected side of the superficial venous engorgement, skin temperature rises, deep veins tend to tender, thrombus can extend up to The inferior vena cava can affect the entire deep vein of the lower extremity and become a mixed type. Thrombosis can lead to pulmonary embolism and threaten the life of the patient.

3 mixed type: that is, all the deep veins of the lower extremities and muscle venous plexus have thrombosis, which can be extended by the surrounding type. The initial symptoms are mild and no attention is paid. Later, the swelling plane gradually rises until the edema of the whole lower extremity is discovered. The clinical manifestations are inconsistent with the time of thrombosis, and can also be caused by the central type of downward expansion, and its clinical manifestations are not easily distinguished from the central type.

(2) According to the range of involvement: According to the range of blood vessels involved in embolization, the deep vein thrombosis of the lower extremity is divided into full-limb and segmental.

1 total limb type: the lesion involves the entire lower extremity deep vein trunk, according to the degree of recanalization is divided into 3 types: type I, deep vein trunk is completely occluded; type II, deep vein trunk part recanal, which is divided into 2 subtypes , IIA, part of the recanalization is mainly occlusion, only the segmental recanalization; IIB, part of the recanalization is mainly recanalization, the deep vein has been a continuous channel, but the diameter of the tube is uneven, and the recanalization is not complete. The hemodynamics of type I and type II are mainly caused by deep venous blood reflux disorder. Type III, the deep vein trunk is completely recanalized, but the valve is completely destroyed, the shape of the wall is stiff, or the expansion is distorted, and its hemodynamics has been reflowed. The obstacle turned to blood backflow.

2 segment type: the lesion is limited to some vein trunks, such as iliac vein, iliac-femoral vein, superficial femoral vein, femoral-iliac vein, iliac vein, iliac vein, genital venous plexus or calf deep vein thrombosis sequelae.

Prevention of deep venous thrombosis of lower extremities

Deep vein thrombosis of the lower extremities can not only cause fatal pulmonary embolism, but also its sequelae have a great impact on the patient's labor ability and quality of life. A series of preventive measures are taken for patients with risk factors, which can significantly reduce deep vein thrombosis. Incidence, there are currently two main methods for preventing deep venous thrombosis of the lower extremities: drug prevention and mechanical physics.

Drug prevention

(1) Low-dose heparin: Heparin has a clear anticoagulant effect, which can prevent thrombosis in vivo and in vitro, but heparin has side effects that cause hemorrhage. Heparin may be used before or after surgery, which may cause bleeding on the wound surface and blood loss during operation. Increase, in view of this, currently advocates a small dose method to reduce the risk of bleeding, the specific method is 2h before surgery, heparin 5000U subcutaneous injection; every 8 ~ 12h after surgery, heparin 5000U subcutaneous injection, due to different races, China's heparin The dosage should be appropriately reduced, generally 3000U subcutaneous injection. Statistics show that the low-dose heparin method can significantly reduce the incidence of postoperative deep venous thrombosis and the incidence of pulmonary embolism, without increasing intraoperative and postoperative hemorrhage, but the wound Local hematoma is more common. During the medication, it is generally unnecessary to detect coagulation, but platelets should be monitored to prevent heparin-induced thrombocytopenia.

(2) Low molecular weight heparin: Heparin is a mixture with a molecular weight composition ranging from 4,000 to 20,000, with an average of 15,000. Low molecular weight heparin is extracted from heparin and has a molecular weight of 4000 to 6000. Anticoagulant effect is countered. The factors of Xa and IIa, compared with heparin, have stronger anti-Xa factor than anti-IIa factor (the ratio of the two is 2:1 to 4:1, and heparin is 1:1), so its bleeding tendency is smaller than heparin. The half-life is longer than that of heparin. The bioavailability is lower than that of heparin after subcutaneous injection. At present, low molecular weight heparin has been widely used in clinical practice abroad, and heparin has become the first choice for preventing thrombosis. The low molecular weight heparin produced by each manufacturer has its own composition. Different, the specific dose should refer to the instructions of each product, low molecular weight heparin due to long half-life, only need subcutaneous injection 1 or 2 times a day, low molecular weight heparin can also cause thrombocytopenia, but the incidence of heparin is lower, due to two There is a crossover between the patients, so patients with heparin-induced thrombocytopenia cannot be replaced with low molecular weight heparin, using low molecular weight heparin. There is no need to monitor coagulation, low molecular weight heparin such as excess, like heparin, can be used with protamine.

(3) Oral anticoagulant: mainly coumarins, the most commonly used is warfarin, in order to prevent deep venous thrombosis of lower limbs after surgery, it can be used before and after surgery, it is necessary to pay attention to warfarin The onset time is usually 3 to 4 days after taking the drug. Because warfarin has large differences and the treatment window is narrow, the prothrombin time (PT) should be monitored during the treatment, and the international normalized ratio (INR) should be controlled at 2.0. ~ 3.0, some scholars suggest that the amount of warfarin should be different for different operations. For hip joints, knee arthroplasty, warfarin dose is slightly larger, and for general abdominal surgery, lower limb fracture reduction surgery, the dose can be If the warfarin is excessive, the risk of bleeding increases. At this time, vitamin K1 can be used to fight.

(4) Oral anti-platelet drugs: the most commonly used are aspirin and ticlopidine. By inhibiting platelet aggregation and release response, oral antiplatelet drugs can reduce the risk of thrombosis, but after clinical use, aspirin is mainly targeted Platelet action has almost no effect on coagulation factors, so there is more bleeding on the wound surface during surgery, but its effect on preventing deep venous thrombosis of lower extremities is not as good as low molecular weight heparin and warfarin.

(5) Others: The anticoagulant effect of low molecular weight dextran (average molecular weight is 40,000) mainly includes: 1 hemodilution; 2 reduction of platelet adhesion; 3 improvement of thrombus solubility, intravenous infusion during and after surgery 500ml dextran 40 has a certain effect on the prevention of deep venous thrombosis of the lower extremities. The side effects mainly include bleeding tendency, excessive expansion and allergic reaction.

Lower extremity deep venous thrombosis complications Complications pulmonary embolism dermatitis

The main complications of this disease are as follows:

1, pulmonary embolism

Pulmonary embolism refers to a pathological process caused by obstruction of the pulmonary artery or its branches by embolism. The diagnosis rate is low, the rate of misdiagnosis and mortality is high. According to the literature, 650,000 people have pulmonary embolism every year in the United States, and 24 people died of pulmonary embolism. 10,000 people in the UK, there are 40,000 non-fatal pulmonary embolisms per year, and about 20,000 hospitalized patients with pulmonary embolism. Some scholars believe that 80% to 90% of pulmonary embolism emboli are derived from deep venous thrombosis of the lower extremities, especially in The incidence of emboli is higher during thrombolytic therapy. Large emboli can cause patients to die within a few minutes. It is reported that the mortality of pulmonary embolism caused by iliac vein thrombosis is as high as 20% to 30%, typical symptoms of pulmonary embolism. For breathing difficulties, chest pain, cough, hemoptysis, the three major signs are pulmonary snoring, the second sound of the pulmonary valve area is hyperthyroidism, galloping, therefore, the prevention of clinical pulmonary embolism is more important than the treatment, the current clinical prevention of pulmonary embolism The vena cava filter is placed by a vena cava filter. The inferior vena cava filter is a device made of wire. It is placed in the inferior vena cava through a special delivery device to intercept the larger blood clot in the blood flow and avoid entering the pulmonary artery with blood flow, resulting in death. Sex Embolization, but the placement of the filter can occur such as filter displacement, obstruction, bleeding and other complications, and the cost is high, so the clinical indications should be strictly controlled. The following conditions may consider the placement of filters: 1DVT contraindications anticoagulant therapy or anticoagulant therapy Severe bleeding complications, 2 anticoagulant therapy still have pulmonary embolism, 3 arterial thrombectomy or pulmonary thromboendothelial debridement, 4 residual DVT after first pulmonary embolism, 5 extensive extensive iliac vein thrombosis, inferior vena cava filter The placement should be performed on the healthy side. If the bilateral iliac vein thrombosis is present, the right internal jugular vein should be placed.

2, bleeding

The main complication of thrombolytic therapy is hemorrhage, especially the gastrointestinal tract and intracranial hemorrhage. Therefore, the blood type, hemoglobin, platelet and coagulation function should be checked before thrombolytic therapy; the dose is usually adjusted by prothrombin time (PT). ) and partial prothrombin time (APTT) is maintained at 2 to 2.5 times the normal value. After thrombolysis and thrombolysis, patients should be closely observed for bleeding tendency, such as vascular puncture points, skin, gums, etc. Have or without gross hematuria and microscopic hematuria, with or without abdominal pain, melena, etc.; if there is bleeding at the puncture site, it can be used to stop bleeding, severe hemorrhage should stop thrombolysis, and blood transfusion or plasma symptomatic treatment, should guide the hemorrhagic complications Self-observation and prevention of patients, such as bleeding gums, nasal bleeding, bleeding of skin and mucous membranes, black stools, etc. Patients do not need to be hard, sharp teeth, digging nostrils, ear canal, do not force cough to avoid hemoptysis; use soft hair brush to brush your teeth, The movement is gentle, so as not to cause unnecessary trauma; the diet should be light and digestible, so as to avoid food damage to the digestive tract, and many foods rich in cellulose to keep the stool smooth.

3. Post-thrombotic syndrome

It is the most common and most important complication. During the process of thrombosis, the venous valve is damaged or even disappears or adheres to the wall of the vessel, resulting in secondary deep venous insufficiency, ie, post-thrombotic syndrome, after thrombosis. The syndrome occurs several months to several years after the deep venous thrombosis of the lower extremity. It is mainly characterized by chronic edema of the lower extremities, pain, muscle fatigue (venous claudication), varicose veins, hyperpigmentation, subcutaneous tissue fiber changes, and severe local ulcer formation. Influencing the quality of life of patients, it has been reported that patients with deep venous thrombosis of the lower extremities follow the doctor's advice, wear elastic stockings after discharge, and take anticoagulant drugs (such as aspirin 100mg (/day·day)) for 3 months to half a year to avoid long-term standing. Sedentary, raising the affected limb at rest, rarely after the thrombosis syndrome, for patients with post-thrombotic syndrome, if valve closure can be used for valve repair, the operation should be light, avoid Injury of the vein, intraoperative use of pulse electrodes to stimulate the calf muscles to increase contraction and promote reflux, postoperative encourage patients with foot and toe often active, have achieved satisfactory results.

Symptoms of deep venous thrombosis of lower extremities Common symptoms Painful skin temperature reduces gastrocnemius tenderness persistent pain Venous thrombosis venous stone painful femoral varicose veins varicose inferior vena cava thrombosis Lower extremity edema

1. Swelling of the affected limb: This is the most common symptom of venous thrombosis of the lower extremity. The tissue of the affected limb is high in tension, non-depressed edema, reddish skin color, high skin temperature, and blisters on the skin when the swelling is severe. Depending on the location of the thrombus, the swelling site is also different. In patients with iliac-femoral vein thrombosis, the entire affected limb is swollen. In patients with calf venous thrombosis, the swelling is limited to the lower leg; the patient with inferior vena cava thrombosis Both limbs are swollen. If the thrombus starts in the iliac-femoral vein, the thigh will be swollen in the early stage. If it starts from the venous plexus of the calf and gradually extends to the iliac-femoral vein, the calf is swollen first, then the thigh is involved, and the swelling is swollen. Most of them are the heaviest on the 2nd and 3rd day after onset, and then gradually subsided. When the regression occurs, the tissue tension is weakened first, and then the circumference of the affected limb is gradually reduced, but it is difficult to turn to normal unless the early thrombus is completely removed. In the late stage of thrombosis, although some veins have been recanalized, the venous pressure of the affected limb is still high due to the destruction of the venous valve function, which is similar to the primary lower limb valve insufficiency.

2. Pain and tenderness: There are two main reasons for pain: 1 The thrombus causes an inflammatory reaction in the vein, causing persistent pain in the affected limb. 2 The thrombus blocks the vein, the venous return of the lower extremity is blocked, the affected limb is painful, and the erect When the pain is aggravated, the tenderness is mainly limited to the site of the venous thrombosis, such as the femoral vein or the calf. The calf gastrocnemius tenderness is also called Homans sign positive. Because the calf squeezes the risk of thrombus shedding, it is not appropriate to check. Big.

3. Superficial varicose veins: superficial varicose veins are compensatory reactions. When the main venous venous occlusion, the venous blood of the lower extremities passes through the superficial venous return, and the superficial veins are compensatoryly dilated. Therefore, the superficial varicose veins are generally not obvious in the acute phase, and are the lower extremity veins. A manifestation of thrombosis sequelae.

4. Femoral bruising: When the lower extremity DVT extensively involves the intramuscular venous plexus, the iliac vein and its collaterals are all blocked by the thrombus, and the tissue tension is extremely increased, resulting in lower extremity arterial spasm, limb ischemia or even necrosis, clinically manifested as pain. Severe, the skin of the affected limb is bright, accompanied by blisters or blood blisters. The skin color is blue-purple, called Phlegmasia Cerulea Dolens, often accompanied by arterial spasm. The lower extremity arteries beat weakened or disappeared, and the skin temperature decreased. In addition, a high degree of circulatory disorder occurs, and the patient's systemic reaction is strong, accompanied by high fever, wilting, prone to shock performance and wet gangrene of the lower extremities.

5. White swelling: When the deep veins of the lower extremities are acutely embolized, the lower extremity edema reaches the highest level within a few hours, the swelling is concave and high tension, and the obstruction mainly occurs in the femoral vein system. When the infection is combined, the artery is stimulated., visible swelling of the entire limb, pale skin and subcutaneous reticular venous dilation, known as Phlegmasia Alba Dolens.

Examination of deep venous thrombosis of lower extremities

1. Determination of blood D-dimer concentration: It has certain practical value in clinical practice. D-dimer is a degradation product produced by the dissolution of fibrin complex, and the venous thrombosis of the lower extremity is simultaneously fibrinolytic system. Also activated, the concentration of D-dimer in the blood rises, but the concentration of D-dimer after surgery or in critically ill patients also increases, so its positive significance is not large, if the concentration of D-dimer is normal, it is negative. The value is more reliable, and the possibility of acute thrombosis can be basically ruled out, and the accuracy rate is 97% to 99%.

2. Blood routine: Acute bullying often has a total increase in white blood cells and a slight increase in neutrophils.

3. Blood biochemistry: There may be an increase in the undergraduate of lactate dehydrogenation.

4. Blood viscosity, blood coagulability, blood rheology and microcirculation examination.

1. Plottography:

An indirect method of blood circulation physiology, including electrical impedance plethysmography (IPG), strain plethysmography (SGP), venous flowmetry (PRG) and photoplethysmography (PPG), among which electrical impedance volume Tracing is the most widely used, blood flow is a good electrical conductor in the body. The principle of electrical impedance plethysmography is to understand the change of blood volume by measuring the change of electrical impedance. The detection method is to attach a pneumatic cuff on the thigh, on the calf. Attach the electrode strip, first increase the pressure inside the inflatable belt to 6.67 kPa (50 mmHg) for 1 to 2 minutes, so that the veins of the lower extremity are fully expanded, the venous volume is maximized, and then the inflatable band is quickly deflated, and the rate of decrease of the resistance is measured. The method is applicable to patients with acute thrombosis of sputum, femoral and iliac veins, with an accuracy rate of 96%. The advantage is that there is no damage examination method, and the main stem vein obstructive lesion can be detected quite accurately. The disadvantages are: 1 pair of calf venous venous thrombosis The detection rate is low; 2 the rate of detection of asymptomatic lower extremity venous thrombosis is not complete; 3 the rate of detection of old thrombus that has formed recanalization or collateral circulation is low; 4 can not distinguish whether the obstruction is from external compression or intravenous thrombosis.

2. Color Doppler inspection:

Ultrasound examination is currently the most widely used in clinical practice, and has a relatively high detection rate. Its advantages are: 1 no damage; 2 repeated examinations; 3 high accuracy for patients with symptoms or asymptomatic; Distinguishing venous obstruction is from external compression or venous thrombosis; 5 patients with recurrent venous venous plexus and venous thrombosis have a satisfactory detection rate.

(1) Two-dimensional sonogram:

1 The venous lumen is filled with solid echo in the lumen. The echo is more common. The specific performance is related to the different stages of thrombosis. The accuracy of venous thrombosis diagnosis based on solid echo in the lumen is 75%.

A. The newly formed acute thrombus (a few hours to several days) has a low echo, uniform, almost no echo, and the proximal segment of the newly thrombus often does not adhere to the vessel wall. It can be seen on the sonogram that it floats in the lumen of the vessel. Because of the risk of lung infarction caused by the shedding of this thrombus, the movement should be gentle, simple and avoid pressure.

B. Subacute thrombosis (several weeks later) The echo intensity is slightly higher, uneven, attached to the vein wall, and the stenosis is visible, and the curved echoless sinus.

C. The echo of chronic thrombosis (months to years) can be high and medium echo, the thickening of the internal wall of the vein is thickened and integrated with the thrombus. It should be pointed out that the echo of the thrombus in the lumen is related to the time of thrombosis, but the echo intensity The change is gradual and it is not possible to accurately infer the time of thrombosis based on the echo intensity.

2 The internal diameter of the vein after thrombus formation will not change with the respiratory phase, and the probe pressure is not easy to crush the lumen, which is a reliable basis for the diagnosis of venous thrombosis. In the case of achromatic Doppler, only There is no change in the venous lumen of the probe and the diagnosis of lower extremity venous thrombosis has higher sensitivity and specificity. The specificity reported by Vogel et al. can reach 100%; the specificity reported by domestic scholars is 92.8%, but the position of the iliac vein Deep and with intestinal tube coverage, small calf veins, both of which are difficult to perform probe pressure test.

In the case of acute thrombosis, the diameter of the vein is obviously widened. The subacute thrombus gradually dissolves and contracts due to thrombosis, and the diameter of the tube gradually becomes smaller and close to normal. However, it is also reported that there is no significant difference in the diameter of the tube between the acute phase and the subacute phase. When the thrombus is irregular, the vein wall is irregular in shape, and the inner diameter is smaller than normal. In some patients, due to the disorder of the vein wall structure, the sonogram cannot distinguish the vein and the surrounding tissue.

3 After venous thrombosis of the venous valve, the venous valve is often restricted in activity. The venous valve is thickened during chronic thrombosis, fibrotic deformation, active stiffness, and fixation. The movement of the great saphenous vein is limited, and the fixed display rate is high. The display rate of valvular lesions is not high, which may be related to valve echo and thrombus echo, and also related to the resolution of the instrument.

(2) Color Doppler flow imaging:

1 acute phase: when the venous thrombosis is completely blocked, color Doppler shows the achromatic blood flow signal in the vein; the distal limb is still unable to show the internal blood flow signal, the proximal and distal veins of the thrombus The flow signal is weakened and no collateral circulation is formed.

2 subacute phase: color filling defect in the thrombus formation cavity, part of the recanal color Doppler shows blood flow signal around or in the center of the venous lumen, showing a discontinuous thin bundle; when extruding the distal limb, blood The flow signal is enhanced, and some cases cannot display the internal blood flow signal. Only when the distal limb is squeezed, the fine blood flow is seen, the surrounding superficial vein is dilated, and the blood flow signal is enhanced.

3 Chronic phase: The thrombus is further formed and recanalized. Color Doppler can show a small stream of blood flow in the thrombus, which is most obvious at the peripheral part of the blood vessel; the spontaneous blood flow disappears in the distal vein, and the proximal segment The blood flow velocity is significantly lower than that of the contralateral side. If it is completely recanalized, the venous cavity can basically fill the blood flow signal, and Valsalva can see the reverse blood flow for a long time.

(3) Doppler flow rate curve:

1 acute phase: pulsed Doppler can not measure the blood flow signal; the flow curve of the distal venous vein becomes continuous, loses phase phase, the response is weakened or disappeared when Valsalva moves, and the superficial vein velocity is accelerated.

2 subacute phase: when the thrombus is partially recanalized, the continuous vein velocity curve of the limb can be measured in the vein of the thrombus segment, the direction is centripetal, and the flow velocity is extremely low; the distal limb can accelerate the blood flow velocity, and the distal venous blood flow The signal has no phase change in respiration, and the response to Valsalva action is delayed or weakened.

3 Chronic phase: When the thrombus is completely obstructed, pulse Doppler can not measure the blood flow signal; there are more collateral veins around, and the blood flow direction is different, but the purpose of diverting the distal venous blood back to the heart is to form a recanalization. After that, pulsed Doppler showed continuous blood flow signal in the thrombus segment, and blood reflux was obvious during Valsalva action, indicating that the physiological function of the venous valve was completely lost.

Ultrasound results are completely dependent on the examiner's diagnostic level, requiring the sonographer to be familiar with the anatomy of the vessel, otherwise the accuracy will be greatly affected.

3. Lower extremity venography:

The antegrade lower extremity venography has been used as the gold standard for the diagnosis of venous thrombosis of the lower extremities. The specific method is:

1 The patient lies supine on the X-ray examination platform, with a high head and a low foot, inclined at 30° to 45°.

2 The sputum is tied with a rubber tourniquet so that it can block the superficial venous return.

3 Puncture the superficial vein of the foot with a venous indwelling needle.

4 The patient's limb was in a suspended state and slightly extended outward.

5 Intravenous veins were injected with 30% to 45% of diatrizoate or 50 ml of nonionic iodine contrast agent.

6 Under the TV screen tracking, make a continuous film on the calves, knees and thighs.

7 When the contrast agent is applied to the iliac vein, the inclination of the examination platform is increased to 60°, and the paralyzed patient is held as far as possible (Valsalva method), so that the contrast agent is concentrated in the iliac vein, and then the venous vein is taken.

The following signs suggest deep vein thrombosis:

1 The venous trunk has a fixed contrast filling defect.

2 The contrast agent is cut through the collateral in the normal vein and redeveloped at the proximal end of the thrombus.

3 small venous plexus angiography may not be able to show all, such as repeated multiple angiography, the same vein is not always developed, suggesting that there may be venous thrombosis.

The advantage of venography is the high accuracy of the diagnosis of venous thrombosis in the lower extremities. It can be used to understand the location of the thrombus, the extent of involvement, and the establishment of collaterals. It is used as the gold standard for judging other tests. The disadvantages include:

1 It is a kind of traumatic examination, which is troublesome and time consuming, and brings some pain to the patient.

2 allergic reactions to contrast agents, as well as renal toxicity.

3 The contrast agent itself will damage the vein wall and cause the risk of venous thrombosis. At present, ultrasound is gradually used instead of venography.

4. Magnetic resonance venography (MRV):

Since the blood flowing in the blood vessel and the tissue fixed around the blood vessel are different in the magnetic signal generated by the radio frequency pulse in the magnetic field, the blood vessel image is displayed, and the artery is displayed or the vein is displayed according to the direction of the blood flow, and the vein can also be passed through the vein. Injection of phase enhancer to better display vascular images, MRV has a high accuracy in the diagnosis of proximal main vein (such as vena cava, iliac vein, femoral vein, etc.), compared with lower extremity venous angiography, MRV For the non-invasive examination method, no side effects such as contrast agent allergy and nephrotoxicity, the image is even clearer. The disadvantage is that the inspection cost is expensive, some metal fixtures in the lower limb bones, or patients with cardiac pacemakers cannot perform MRV. an examination.

5.125I fibrinogen intake check:

Human fibrinogen using radionuclide 125I can be taken up by the thrombus being formed, and the content per gram of thrombus is more than 5 times that of the same amount of blood, thus forming radiographic imaging, by scanning the fixed position of the lower limb, Observe whether there is a sudden increase in the amount of radiation to determine the presence or absence of thrombosis. The disadvantage is that it can not diagnose old thrombus, and it is not suitable for venous thrombosis in the pelvic area. (The urine accumulated in the bladder due to the inclusion of nuclide makes the thrombus unable to Identification, in addition to the lower extremities such as inflammation, hematoma, trauma, etc. will also cause the accumulation of nuclide and difficult to identify, the current detection method has gradually been replaced by color Doppler ultrasound or MRV.

Diagnosis and differential diagnosis of deep venous thrombosis of lower extremities

Deep vein thrombosis of the lower extremities needs to be distinguished from the following two diseases.

1. Lower extremity lymphedema: There are two primary and secondary lymphedema in the lower extremity. Primary lymphedema often has lower extremity edema after birth. Secondary lymphedema is mainly caused by surgery, infection, radiation, parasites, etc. Lymphatic tract is caused by obstruction of lymphatic drainage, so there may be a related medical history. Lymphedema is characterized by depressed edema in the early stage, swelling of the back of the foot is obvious, tissue tension is less than swelling of the lower extremity caused by venous thrombosis, and the skin temperature is normal. Lymphedema due to fibrosis of the subcutaneous tissue, rough skin, thickening, tissue hardening and mass, generally do not appear clinical manifestations of sequelae of lower extremity venous thrombosis, such as pigmentation, ulcers and so on.

2. Local hematoma of the lower extremity: After the trauma of the lower extremity, local hematomas are formed, and the lower extremity is also swollen. Because the treatment of hematoma is opposite to the treatment of venous thrombosis, it is necessary to pay attention to the identification. Most of the hematoma has a history of trauma, swelling is limited, and the whole is rarely involved. Lower limbs, accompanied by pain, visible skin spots or yellow skin in the later stage, color Doppler examination helps identify.

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