Deep vein thrombosis (DVT) of the lower extremities is a common disease in vascular surgery. With the increasing incidence of DVT and pulmonary embolism (PE), its hazards are being paid attention to by physicians in various departments, but the prevention, attention and treatment strategies for DVT and PE in China are far less than those in western countries.
I. Increasing incidence rate
United States: DVT incidence rate ranks third after coronary heart disease and hypertension. In the past, people thought that Asian people have low incidence of DVT and PE, but this is not the case statistically.
The percentage of people at risk of DVT receiving preventive treatment in the West is 17%, while in Asian countries it is only 6%.
From February to April 2003, 233 cases of major surgery patients were selected at the First Affiliated Hospital of Peking University, and the detection rate of DVT was 47.64% and 1.29% for proximal DVT by ultrasonography 3 to 10 days after surgery. Major surgery refers to those who operate under general anesthesia for more than 30 min, in which the orthopedic rate is rather low because of the use of low molecular heparin sodium.
17% of maternal deaths in the United States are due to venous thromboembolism (1988)
II. Risk factors of DVT
(a) German pathologist Virchow, in 1856, in the account of “thrombosis and embolism” put forward three major risk factors of venous thrombosis: 1.
1.Slow blood flow: prolonged bed rest, sedentary, limb immobilization
2.Vascular endothelial damage
(1) Direct injury: exposure of the subintima and collagen, including lacerations and contusions (pulling hooks should be noted)
(2) Trauma causing endothelial and functional damage to veins, including
Chemical injury: drugs, such as lower extremity infusion (it is suggested that intraoperative infusion is not easy to puncture the left foot, and the possibility of deep vein thrombosis in the left lower extremity is higher than that in the right lower extremity, while the possibility of pulmonary embolism due to dislodged deep vein thrombosis in the right lower extremity is higher than that in the left)
Infectious injury: pathogens directly adhere to damage the vascular endothelium, and the released toxins and metabolites of the body cause endothelial injury, such as (endometritis can cause uterine vein thrombosis)
3, the hypercoagulable state of blood: smoking, obesity, pregnancy, postpartum, postoperative, trauma, etc. make platelet adhesion increased and fibrinolytic activity decreased; the application of hemostatic drugs; oral contraceptives, hormone replacement therapy (HRT), malignant tumor tissue lysates (for hypercoagulable substances), heart disease, etc.
(II) Clinically, DVT and PE are mainly seen in postpartum, post-pelvic surgery, post-operative orthopedic surgery, post-neurosurgery, trauma, advanced cancer, coma and long-term bedridden patients
III. Perioperative period and DVT
(a) Preoperative: there is often fasting and fasting, enema, insufficient rehydration often leads to patient dehydration, blood volume deficiency and hemoconcentration, which causes the hypercoagulable state of blood. Combined with diabetes mellitus, hypertension
(ii) Intraoperative.
1, anesthesia leads to peripheral vasodilatation, muscle paralysis (pumping hypoperfusion), low venous return and blood stagnation.
2, bed rest, lower limb binding and braking, to slow venous blood flow stasis and cellular metabolic disorders in the lower limbs.
3, intraoperative pull hook compression, device injury resulting in intimal injury to the iliac vessels in the pelvis. Intraoperative accidental injury to the vein, or injury to the venous wall and intima activating the coagulation mechanism.
4, Intraoperative blood pressure fluctuation, hypotension time over the field to slow down the blood flow.
5.Intraoperative tissue injury and inflammation release of cytokines damage endothelial cells.
6.Large and medium-sized surgery especially lymphatic dissection
(C) postoperative.
1. Continue fasting and abstaining from food and drink, resulting in insufficient blood volume.
2, postoperative bed rest (fear of pain, retention of urinary catheter).
3, Application of hemostatic drugs.
4, other: estrogen use, antitumor chemotherapy drugs, “mooning”, high-dose estrogen reflux (it has been reported that postpartum DVT, 75% occurs when high-dose estrogen reflux), oral contraceptives
5, postoperative chemotherapy.
(iv) For obstetrics and gynecology.
Compression of lower limbs by bladder truncation; highly dilated pelvic vessels and slow blood flow during pregnancy; compression of inferior vena cava by enlarged uterus; hypertensive disease during pregnancy and other comorbidities.
IV. Classification of risk factors for venous thrombosis
Low risk.
Minor surgery
No other risk factors
Intermediate risk
Age older than 40 years and major surgery
Age less than 40 years combined with other risk factors and major surgery
High risk
Age greater than 60 years and major surgery
Tumor
History of deep vein thrombosis or pulmonary embolism
Tendency to thrombosis
Very high risk
Age > 60 years combined with tumor or history of venous thrombosis
***** risk factors: obesity, varicose veins, history of DVT or pulmonary embolism, current oral estrogen, tamoxifen, birth control pills