Systemic pulmonary embolism

Introduction Body pulmonary embolism refers to obstruction by the embolus of blood flow caused by the body or pulmonary artery. There are peripheral venous thrombosis, pulmonary embolism and bronchial arterial degeneration at the same time, mainly thromboembolism. It can also be caused by air, fat, or septic emboli. Generally, there will be abnormal sleep, abnormal blood sugar, blood sugar and blood pressure. Early identification of risk factors and early prevention are key to preventing pulmonary embolism. Studies have confirmed that if timely diagnosis and treatment can be obtained, the mortality rate of pulmonary embolism can be reduced to less than 8%.

Cause

Infectious emboli of the surrounding veins fall off and cause pulmonary embolism and pulmonary aneurysms. It is generally believed that the occurrence of pulmonary aneurysms is associated with persistent pulmonary hypertension, but pulmonary aneurysms also occur in patients without pulmonary hypertension. It can also be caused by air, fat, or septic emboli.

Embolism caused by thrombus shedding is called thromboembolism and is the most common type of embolism. Because of the source of thromboemboli, the size of the embolus and the location of the embolism, its effect on the body is also different. Tumor cell embolization can occur during the metastasis of tumor cells. Parasitic eggs, bacteria or fungal masses and other foreign bodies such as bullets can enter the blood circulation and cause embolism.

an examination

Related inspection

Electrocardiogram EEG examination

Clinical symptoms include sudden shortness of breath, chest pain, hemoptysis, and even shock and loss of consciousness. Signs of cyanosis, rapid heart rate or arrhythmia, the second heart sounds in the pulmonary valve area. X-ray chest can have wedge-shaped, flaky shadows, which can be accompanied by pleural effusion. Electrocardiogram showed pulmonary P wave and right ventricular strain. X-ray chest radiograph, visible nodular shadows.

1, blood smear: amniotic fluid formed by the femoral vein or jugular vein cannula to remove the vena cava or superior vena cava blood 5 ~ 10ml, after centrifugation or static tube sedimentation, take the upper and lower layers to form a smear staining mirror Check. Amniotic fluid embolism can be diagnosed by finding bristles, squamous epithelial cells or fat cells.

2, coagulation dysfunction check: DIC diagnostic indicators including platelet count 15 × 109 / L, fibrinogen 160g / L, prothrombin time 15 seconds, plasma protamine coagulation test (3P test) positive, Fibrin degradation products (FDP) 80 g / ml and euglobulin dissolution time 120 min.

3, imaging examination:

1X line chest X-ray examination, visible signs of pulmonary embolism.

2 for head CT examination when cerebral infarction occurs.

Differential diagnosis

Differential diagnosis of pulmonary pulmonary embolism:

(a) thromboembolism

Embolism caused by thrombus shedding is called thromboembolism and is the most common type of embolism. Because of the source of thromboemboli, the size of the embolus and the location of the embolism, its effect on the body is also different.

1. Pulmonary embolism: Most of the emboli of pulmonary thromboembolism comes from deep veins of the lower extremities, especially the iliac vein, femoral vein and iliac vein, and occasionally from the pelvic vein or right heart wall thrombus. According to the size and number of emboli, the consequences of embolization are also different. 1 small and medium embolization embolizes the small branch of the pulmonary artery, which is common in the lower lobe of the lung. It generally does not cause serious consequences because the lung has double blood circulation, pulmonary artery and There are abundant anastomotic branches between the bronchial arteries, and the collateral circulation can play a substitute role. These emboli can be dissolved or machined into fibrous cords. If the lungs have severe congestion before embolization, the internal pressure of the microcirculation is increased, and the blood supply to the bronchial artery is blocked, which may cause hemorrhagic infarction of the lung tissue; 2 large thromboembolism, embolization of the trunk or large branch of the pulmonary artery, Long emboli can embolize the left and right pulmonary trunk, called pulmonary embolism, often causing serious consequences. The patient may suddenly have difficulty breathing, cyanosis, shock, or even sudden death.

The mechanism of sudden death is generally considered to be that when the pulmonary artery trunk or large branch is embolized, the internal resistance of the pulmonary artery increases sharply, resulting in acute right heart failure. 2 Studies have shown that pulmonary embolism stimulates the vagus nerve, causing paralysis of the pulmonary artery, coronary artery, bronchial artery and bronchus through nerve reflex, resulting in acute right heart failure and asphyxia; thromboembolic surface of pulmonary embolism sticks platelets, releasing 5-HT And thromboxane A2, can also cause paralysis of the pulmonary blood vessels.

2. Systemic arterial embolization: most of the embolus comes from the left heart (such as heart valve sputum in subacute bacterial endocarditis, left atrial wall thrombus in mitral stenosis, wall thrombus in myocardial infarction); Thrombosis on the surface of atherosclerotic ulcers or aortic aneurysms; very few emboli from the vena cava can enter the left heart through the ventricular septal defect, and cross-embolism occurs. The main parts of arterial embolism are the lower extremities and the brain, and may also affect the intestines, kidneys and spleen. The consequences of embolization depend on the location of the embolization and local collateral circulation as well as tissue tolerance to ischemia. When the embolized artery lacks an effective collateral circulation, it can cause local tissue infarction.

(two) fat embolism

It refers to the appearance of fat droplets in the circulating blood flow obstructing small blood vessels, called fat embolism. Embolons are common in long bone fractures, adipose tissue contusions, and fatty liver crush injuries. Fat cell rupture releases lipid droplets, which enter the blood circulation from ruptured venules.

Fat embolism is common in organs such as the lungs and brain. Lipid emboli with vein into the right heart to the lung, a lipid embolus with a diameter of >20m causes embolization of the branches of the pulmonary artery, arterioles or capillaries; lipid emboli with a diameter of <20m can pass through the pulmonary veins of the alveolar wall to the left The branch of the heart circulation can cause embolism of multiple organs throughout the body. The most common is embolism of the cerebral blood vessels, causing cerebral edema and punctiform hemorrhage around the blood vessels. Lipid droplets can be found in the blood vessels under the microscope. Its clinical manifestations may include sudden onset of shortness of breath, dyspnea and tachycardia after injury.

(3) Gas embolism

A large amount of air rapidly enters the blood circulation or the gas originally dissolved in the blood is rapidly released, forming a bubble blocking the cardiovascular, called air embolism.

Air embolism is mostly caused by rupture of venous injury, and the outside air is caused by the venous defect into the bloodstream. Such as head and neck surgery, chest wall and lung injury vein, positive pressure intravenous infusion and artificial pneumothorax or pneumoperitoneal injury to the vein, the air can be inhaled due to the negative pressure in the venous cavity, from the injury into the vein.

The consequences of air entering the blood circulation depend on the speed of entry and the amount of gas. A small amount of gas enters the blood and dissolves into the blood without gas embolism. If a large amount of gas (>100ml) quickly enters the vein, and the blood flows to the right heart, the air and blood are stirred by the heart to form a large number of bubbles, which make the blood become a compressible foam filled the heart chamber, hindering the return of venous blood. And the output to the pulmonary artery, causing serious circulatory disorders. Patients may have difficulty breathing, cyanosis and sudden death. Part of the bubble entering the right heart can enter the pulmonary artery, block the branch of the small pulmonary artery, causing gas embolism of the pulmonary arteriole. Small bubbles can also pass through small branches of the pulmonary artery and capillaries to the left heart, causing embolization of some organs of the systemic circulation.

Decompression sickness, also known as caisson disease and divers disease, is a type of gas embolism. Decompression refers to the rapid entry of the human body from a high-pressure environment into a normal or low-pressure environment, so that gases originally dissolved in blood, tissue fluid and adipose tissue, including oxygen, carbon dioxide and nitrogen, rapidly form bubbles, but oxygen and carbon dioxide can be redissolved. The body fluid is absorbed, and the nitrogen dissolves slowly in the body fluid, causing many microbubbles or merging into large bubbles in the blood and tissues, which in turn causes embolism.

(four) amniotic fluid embolism

Amniotic fluid embolism is a rare and severe complication (1/50,000) in childbirth with a very high mortality rate. During the process of childbirth, when the amniotic membrane is ruptured or prematurely broken, the placenta is peeled off early, and the fetus obstructs the birth canal, due to the strong contraction of the uterus, the intrauterine pressure is increased, and the amniotic fluid can be pressed into the venous sinus of the uterine wall, and enter the pulmonary artery branch through the blood circulation. Amniotic fluid embolism occurs in small arteries and capillaries. A small amount of amniotic fluid can pass through the pulmonary arteries of the lungs to the left heart, causing small blood vessel embolization of the systemic circulatory organs. Under the microscope, amniotic fluid components such as keratinized squamous epithelium, fetal hair, sebum, meconium and mucus were observed in the small arteries and capillaries of the lung. The disease is acute, and patients often have difficulty breathing, cyanosis, shock and death.

Amniotic fluid embolism causes acute mechanical obstruction in addition to pulmonary circulation. In the amniotic fluid, fetal metabolites enter the bloodstream to cause anaphylactic shock and reflex vasospasm. At the same time, amniotic fluid has a coagulation-like enzyme-like effect causing DIC, which leads to death of the patient.

(5) Other embolism

Tumor cell embolization can occur during the metastasis of tumor cells. Parasitic eggs, bacteria or fungal masses and other foreign bodies such as bullets can enter the blood circulation and cause embolism.

Clinical symptoms include sudden shortness of breath, chest pain, hemoptysis, and even shock and loss of consciousness. Signs of cyanosis, rapid heart rate or arrhythmia, the second heart sounds in the pulmonary valve area. X-ray chest can have wedge-shaped, flaky shadows, which can be accompanied by pleural effusion. Electrocardiogram showed pulmonary P wave and right ventricular strain.

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