Pulmonary embolism is the most common and dangerous complication of venous disease of the extremities. The vast majority of emboli in pulmonary embolism originate from the deep veins of the lower extremities, and pulmonary embolism complicates about half of all lower extremity deep vein thrombosis. The symptoms of pulmonary embolism are widespread, ranging from transient shortness of breath to acute pulmonary heart disease and even sudden death. Therefore, pulmonary embolism is getting more and more attention.
1.Etiology and pathology.
(1) Etiology: The vast majority of emboli of pulmonary embolism come from peripheral venous system, especially lower limb veins, especially deep vein thrombosis, thrombophlebitis and varicose veins are prone to occur. The main causes of lower limb deep vein thrombosis are blood flow stagnation, blood hypercoagulation and vascular endothelial cell damage. The common causative factors are.
①Long-term bed rest and lower limb inactivity: 7 days of continuous bed rest, blood velocity slows down to the lowest point, and the incidence of deep vein thrombosis is related to the time of bed rest.
②Cardiac and pulmonary diseases: Those with pre-existing cardiac and pulmonary diseases are more likely to have pulmonary embolism.
③Trauma and surgery: the occurrence of pulmonary embolism is related to both local injury and bed rest with little movement.
④Tumor: it can increase the coagulation mechanism and make the incidence of pulmonary embolism increase, especially in pancreatic, lung, urinary tract, colon, stomach and breast cancer.
⑤ Pregnancy and contraceptive pills: Pregnancy and contraceptive pills can increase the incidence of pulmonary embolism.
(6) Other causative factors: such as diabetes, obesity, etc.
(2) Pathology.
①Hemodynamics: The hemodynamic changes of pulmonary embolism are mainly determined by the number of embolized pulmonary vessels and the patient’s cardiopulmonary function status. The mean pulmonary artery pressure (PAPm) can be slightly increased in pulmonary vascular bed blockage > 25%-30%; PAPm can reach 4.0kPa (30mmHg) in pulmonary vascular bed blockage > 30%, and right ventricular pressure increases; PAPm can reach 5.3kPa (40mmHg) in pulmonary vascular bed blockage > 40%-50%, and right ventricular filling pressure increases and cardiac index decreases; pulmonary vascular bed blockage > 50%-70% can appear. Persistent pulmonary hypertension can occur in 50%-70% of cases; sudden death can occur in 85% of cases with pulmonary vascular bed blockage. Chronic recurrent pulmonary thromboembolism can also cause right heart enlargement and failure. Hemodynamic changes are related to body fluids in addition to the mechanical blockage of the embolus.
② Respiratory system: Larger pulmonary emboli can cause bronchospasm, decreased alveolar surface active substance, alveolar atrophy and imbalance of pulmonary ventilation/blood flow ratio. The result is increased airway resistance, reduced lung air content, increased dead space ventilation and intrapulmonary shunts. Patients develop varying degrees of hypoxemia, hypocarbia and alkalemia.
Embolism further causes lung tissue necrosis called pulmonary infarction, mostly seen in patients with pre-existing cardiopulmonary disease.
2.Clinical manifestations and signs
The clinical manifestations of pulmonary embolism are mainly determined by the amount of pulmonary vascular blockage, the speed of occurrence and the basic state of heart and lung. It can be roughly divided into four clinical syndromes.
①Acute pulmonary heart disease: sudden dyspnea, near-death feeling, cyanosis, right heart failure, hypotension, cold extremities, seen in patients with sudden embolization of more than 2 lobes of the lung;
②Pulmonary infarction: sudden dyspnea, chest pain, hemoptysis and pleural grinding sounds or pleural effusion;
③”Unexplained dyspnea”: the embolism area is relatively small and is the only symptom suggesting an increase in dead space;
④Chronic recurrent pulmonary thromboembolism: slow onset, late detection, mainly manifesting as severe pulmonary hypertension and right heart insufficiency, a clinically progressive type with poor prognosis.
In patients with pulmonary embolism, both symptoms and signs are non-specific and insensitive for the diagnosis of acute or chronic pulmonary thromboembolism.
(1) Common symptoms: dyspnea, chest pain, hemoptysis, panic, cough, syncope, etc.
(2) Common signs: general manifestations: hypothermia, increased respiratory rate, cyanosis, sinus tachycardia and jugular venous anger. Cardiovascular system: there may be systolic pulsations between the 2nd and 3rd ribs at the left edge of the sternum, closed vibrations of the pulmonary valve are palpable, the 2nd heart sound of the pulmonary artery is hyperactive, jet sounds or systolic jet murmurs are heard, diastolic regurgitant murmurs may also be present; systolic regurgitant murmurs can be heard in the tricuspid region; right heart 3rd and 4th heart sounds; pericardial grating sounds and hepatomegaly and swelling. Respiratory system: the trachea is deviated to the affected side, the diaphragm is elevated on the affected side, and dry and wet bow-tie can be heard in the diseased lung.
3.Auxiliary examination.
Routine blood tests showed increased white blood cell count; increased sedimentation; elevated serum bilirubin, normal or mildly elevated glutamate transaminase, and elevated lactate dehydrogenase. Arterial blood gas analysis showed hypoxemia, hypocarbia, and increased partial pressure difference of blood oxygen. The electrocardiogram showed abnormal changes that appeared several hours after the onset and disappeared in a few weeks. The common changes included rightward deviation of the QRS electrical axis, T-wave inversion or ST-segment depression in the right anterior chest and II, III, and aVF leads, and the more meaningful electrocardiogram changes were SⅠQⅢTⅢ type, and also transient incomplete or complete right bundle branch block. Chest X-ray shows pulmonary infiltrates or infarcts, uneven distribution of pulmonary blood, partial or partial enhancement of one lung field, reduced lung volume on the affected side, elevation of the diaphragm, widening of the upper mediastinum, protrusion of the pulmonary artery segment, widening of the transverse diameter of the right inferior pulmonary artery, and enlargement of the right atrium. Radionuclide lung scan: This is a safe and simple test. Both pulmonary ventilation and perfusion scans are usually required to improve the diagnostic accuracy. A normal ventilation scan of the deficient lung perfusion scan is highly suggestive of pulmonary embolism. Pulmonary arteriography is the only reliable method for prenatal diagnosis of pulmonary embolism, but it has certain risks.
4.Treatment
Although part of the thrombus of pulmonary embolism, or even the whole body thrombus, can dissolve and disappear by itself, once diagnosed, treatment should be actively carried out. The purpose of treatment of pulmonary embolism is to enable patients to pass the critical period, relieve embolism and prevent recurrence; maintain and restore sufficient circulating blood volume and tissue oxygen supply as much as possible. Specific western medical treatment is as follows.
(1) Treatment of acute pulmonary embolism.
①Emergency measures: Patients should be admitted to the ICU ward, and blood pressure, heart rate, respiration, ECG, central venous pressure and arterial blood gas analysis should be continuously monitored. General treatment: Keep the patient quiet, warm and oxygenated; for sedation, morphine, dulcolax or codeine can be given if necessary. To prevent intrapulmonary infection, antibiotics may be applied.
②To relieve pulmonary vasospasm and coronary artery spasm caused by vagal hypertonia: intravenous atropine 0.5-1.0mg, if not relieved, can be repeated every 1-4 hours, or subcutaneous, intramuscular or intravenous poppy bases 30mg.
③Treatment of acute right heart insufficiency: fast digitalis preparations (e.g., cetiran) may be used with caution if necessary, and salt restriction and diuresis. When the cardiac index is less than 2L/min/m2, give 1-2mg of isoprenaline dissolved in 5% glucose solution 500mL for slow intravenous infusion.
④Anti-shock, maintain the function of body and lung circulation: firstly, replenish fluids, if not effective, intravenous dopamine, alamine or isoproterenol can be given.
⑤Improve respiratory function: if complicated by bronchospasm, apply aminophylline, gastrin, etc.
(2) Thrombolytic therapy: Thrombolytic therapy is a drug that transforms fibrinolytic zymogen into fibrinolytic enzyme, cleaves a single arginine-valine chain to achieve dissolution of fibrin in the lumen of blood vessels, shrinks or eliminates thrombus, and restores blood circulation to embolized vessels. It is generally used for fresh thrombosis or pulmonary thromboembolism within 5 days. The indications are: large pulmonary embolism; pulmonary embolism with shock; circulatory failure caused by sub-large pulmonary embolism of pre-existing cardiopulmonary disease. Contraindicated in those with bleeding or bleeding tendency. Commonly used drugs and their reference doses are: urokinase first loading dose of 4400 U/kg (or 150,000-250,000 U) administered intravenously over 10 minutes, followed by 4400 U/kg/h for 12-24 hours; streptokinase first dose of 250,000 U administered intravenously over 30 minutes, followed by 100,000 U/h for 24-72 hours; also tissue-type fibrin lysozyme activator (t-PA). The main side effect of thrombolytic therapy is bleeding, with an incidence of 5-7%. Fatal bleeding is about 1%.
(3) Anticoagulation therapy: commonly used drugs and their reference doses are
① Heparin: used for acute pulmonary embolism, the specific methods of administration are
a, continuous intravenous drip method, the loading amount of 2000-3000u/h, followed by 1000-1200u/h, or 25u/kg/h to maintain;
b, intermittent intravenous injection method, 5000u/h, once every 6-8 hours, the dose is reduced by half after 24 hours;
c, intermittent intravenous and subcutaneous injection method, 5000u intravenous injection, while 10000u subcutaneous injection, and then every 8-12 hours subcutaneous injection. The partial thromboplastin time should be maintained at 1.5-2 times the control value during treatment. The drug is usually administered for 7-10 days.
② Oral anticoagulant; started after 48 hours of heparin treatment, commonly used drug is Warfarin, the first dose is about 4mg for adults, after that the dose is adjusted with reference to prothrombin time and activity, prothrombin activity is maintained between 20-30%, clotting time is 1.5-2 times of normal value. The course of treatment is 3-6 months. Bleeding is the main side effect, causing death in about 1% of cases. Therefore, it is contraindicated or used with caution in people with bleeding tendency.
(4) Surgical treatment.
①Pulmonary artery thrombectomy: for large vessel embolism with shock;
②Inferior vena cava block: used to prevent recurrence of pulmonary embolism, which is less frequently used now. Indications for surgery are: contraindication to anticoagulants; recurrence during adequate anticoagulation therapy; infectious thrombophlebitis; recurrent pulmonary embolism; pulmonary vascular blockage cross-sectional area greater than 50%; combined pulmonary hypertension or chronic pulmonary heart disease; patients with pulmonary artery thrombectomy. The operative mortality rate is about 5%, and the disability rate is 10%-15%.
(iii) Filter implantation via cardiac catheter;
④Transcatheter pulmonary artery thrombectomy: for fresh large pulmonary embolism within 2 weeks.
5. Identification and treatment.
Pulmonary embolism is an acute disease of internal injury in traditional Chinese medicine, which mostly starts after a long period of illness, with dysfunction of Qi and blood in the internal organs and surgery or trauma, resulting in internal accumulation of phlegm and dampness, upward rebellion of lung qi, asthma and cough, and due to weakness of lung qi and weakness of blood flow, resulting in stagnation of heart veins, chest tightness, shortness of breath, palpitation, blue lips and cold extremities.
Qi stagnation and blood stasis, chest paralysis and cardiac pain (equivalent to chronic pulmonary embolism): this type belongs to the evidence of Qi stagnation and blood stasis after a long period of illness, and the imbalance of the internal organs, with panic and shortness of breath, chest tightness and chest pain, irritability, sometimes seeing the pulse knotted and dark tongue; treatment is recommended to benefit Qi, activate blood and dispel blood stasis, and promote the lung through Yang.
Spleen deficiency, phlegm-dampness obstruction, and loss of lung circulation and descent: prolonged disease injures the spleen, the spleen loses its health, phlegm-dampness obstructs the lung, and the lung loses its circulation and descent. The treatment is to strengthen the spleen, dry dampness and resolve phlegm, promote the lung to lower the rebellion and stop coughing, and fix asthma.
Qi and Yin deficiency internal heat type: deficiency of Qi and Yin, chest pain, panic and shortness of breath, sweating and weakness, dryness of the five hearts, dry mouth and other internal heat of Yin deficiency, thin pulse or sinking and weakness, red tongue, little fluid, little coating. The treatment should be to benefit qi and nourish yin, clear heat and cool blood, with the following prescriptions: princely ginseng, fried atractylodes, astragalus, northern sage, lily of the valley, raw earth, scutellaria, gardenia, mulberry bark, ground bark, etc.; hemoptysis plus cynthia, ground elm charcoal, hyacinth.
Yang Qi wants to escape, Qi reversal and cold syncope (equivalent to acute pulmonary embolism): pale face, cold extremities, palpitations, sweating, shortness of breath, dullness, little urination, restlessness, blue lips and fingers, shortness of breath, weak pulse, pale tongue with little coating. Treatment is recommended to warm the menstruation and disperse cold, return Yang to save rebellion, tonify Qi and replenish Blood, with the following prescriptions: princely ginseng, ripe slices of Phellodendron, dry ginger, roasted licorice, astragalus and rice husk.