Pulmonary embolism (PE, hereafter referred to as pulmonary embolism) is a clinical and pathophysiologic syndrome in which endogenous or exogenous emboli occlude the pulmonary arteries or their branches causing obstruction of the pulmonary circulation. In the United States, the incidence of pulmonary embolism accounts for the third highest incidence of cardiovascular disease, after coronary heart disease and hypertension. Since the first case of pulmonary embolism was reported by Laennec in 1819, it has been misdiagnosed and underdiagnosed. The misdiagnosis rate of pulmonary embolism reported at home and abroad is around 70%, which suggests that the misdiagnosis of pulmonary embolism should be alarmed. Most of the patients with pulmonary embolism firstly come from the grassroots hospitals, and this topic introduces how the grassroots doctors can recognize pulmonary embolism within their capacity and avoid misdiagnosis and omission, so as to make this “covered” disease appear in its original form. Five notes on the causes of misdiagnosis ① The diversity of clinical manifestations and auxiliary examinations of pulmonary embolism, and the lack of specificity in diagnosis are factors that can easily lead to misdiagnosis. Clinicians should pay attention to grasp the common clinical manifestations of pulmonary embolism and auxiliary examination characteristics. ② The first physician should pay attention to the history and examination should be detailed, diagnostic ideas are not too limited. Such as shortness of breath during activity do not only think of heart failure, bronchial asthma, chest pain, palpitations, ECG chest lead T-wave inversion, elevated cardiac enzymes do not only think of coronary artery disease, fever, elevated white blood cells, lung X-ray shadow do not only think of pneumonia. Be aware that these are common clinical features of pulmonary embolism. ③ Pay attention to analyze the significance of abnormal results of auxiliary examinations, such as elevated blood D-dimer, electrocardiogram suggestive of right ventricular hypertrophy, and echocardiographic signs of pulmonary hypertension. Whether these manifestations are somehow related to pulmonary embolism. ④ Narrow diagnostic thinking, poor clinical skills, satisfied with “inertia thinking”, not focusing on differential diagnosis. Therefore, you should pay attention to improving your medical level. ⑤ Also pay attention to consulting with higher-level physicians, cardiologists and respiratory physicians, and have basic interdisciplinary knowledge. Clinical manifestations: the first “barrier” for recognizing pulmonary embolism Because pulmonary embolism lacks specific clinical manifestations, it is easy to be misdiagnosed and underdiagnosed, so it is crucial to master the common clinical manifestations of pulmonary embolism. Clinical research results show that the symptoms of pulmonary embolism are mainly dyspnea, chest pain, cough, palpitations, other symptoms such as hemoptysis, anxiety, fear, sweating, fainting, etc., the signs are mainly manifested as accelerated respiration, the second heart sound of the pulmonary valve, accelerated heart rate, precordial murmur, but also to see the cyanosis, lower limb edema, fever, hepatomegaly, lung woven mat carefully off the ridge, the guessing of this collateralized collateralization banging about the target target Tsushu Σ Lie bow to take the needs of the people who need to be careful. It should be reminded that syncope and hemoptysis are often indicative of massive or submassive pulmonary embolism, and hypotension and shock are indicative of massive pulmonary embolism, so it is advisable to be highly vigilant. Core tips on clinical manifestations of pulmonary embolism in internal medicine, external medicine, gynecology, and pediatrics ○In particular, patients should be carefully asked to identify whether the complaint of “tightness in the chest” is dyspnea or angina, whether syncope is cardiac or pulmonary, or neurogenic, and whether chest pain is pleuritic or angina. ○It should be noted that less than one-third of patients have the classic triad of pulmonary infarction (dyspnea, chest pain, and hemoptysis), and most of them have only one or two symptoms, with unexplained exertional dyspnea being the most common. ○Watch out for signs that reflect increased right ventricular load, such as jugular venous distension, hepatomegaly, and lower extremity edema. When deep vein thrombosis of the lower extremity is accompanied by dilatation and swelling of the superficial veins of the affected extremity, the circumference of the thigh or calf on the affected side is 1 cm larger than that on the opposite side, which is diagnostic. ○Surgery after a few days to a dozen days for the high incidence of pulmonary embolism time window, due to local tissue damage, surgical trauma repair, the need for increased coagulation function, postoperative prolonged bed rest of the lower limb muscle pump function disappeared, the blood flow is slow, can be secondary to thrombosis. Therefore, when there is sudden chest pain, shortness of breath or chest tightness, followed by dyspnea, cyanosis, jugular vein distension, blood pressure and partial pressure of blood oxygen fall sharply, shock, should immediately think of the possibility of massive pulmonary embolism. ○Pregnancy to 2 weeks after delivery is hypercoagulable and prone to pulmonary embolism. Children with chronic heart disease (e.g., congenital heart disease and infective endocarditis) are prone to pulmonary embolism, but there are few signs and symptoms that can be easily overlooked in the early stages, so careful observation and physical examination should be done. The results of our clinical study showed that deep vein thrombosis of the lower extremities (23.4% of patients), trauma and post-surgery (16.2%), prolonged bed rest (14.3%), and various types of organic heart disease (7.6%) were the four major risk factors for pulmonary embolism. Chronic atrial fibrillation (3.8%), pregnancy and childbirth (3.8%), and diabetes mellitus (1.4%) are less likely to develop pulmonary embolism, but they have attracted enough attention in recent years. Therefore, patients with these diseases are at risk of developing pulmonary embolism. Pulmonary embolism involves multiple disciplines and clinical departments, including internal medicine, surgery, gynecology, pediatrics, emergency medicine, oncology, and imaging. Primary care physicians should be a qualified general practitioner with a vertical understanding of multidisciplinary knowledge and proficiency in the clinical manifestations of pulmonary embolism. Auxiliary examination: the second “barrier” for diagnosis of pulmonary embolism Electrocardiogram (ECG) The ECG manifestations of pulmonary embolism are varied and complex, and our investigation results show that its manifestations can reach more than 30 kinds, with sinus tachycardia occurring at the highest incidence of 55.4% to 80%, and the specificity is not high. Its typical performance of SⅠQⅢTⅢ was 25.9%～37.1%, and clinically it presented one or several performances of SⅠ, SⅠQⅢ, QⅢTⅢ, QⅢ, TⅢ, and SⅠQⅢTⅢ, which were mostly accompanied by dynamic changes. However, more common are the often undetected signs of right ventricular strain, such as T-wave inversion in leads V1 to V4, and newly appeared incomplete or complete right bundle branch block, which, together with SⅠQⅢTⅢ and the various combinations of manifestations, are meaningful electrocardiographic indicators suggesting the presence of pulmonary embolism, and should be included as the key electrocardiographic reference indexes for the diagnosis of pulmonary embolism. Although ECG changes are common in pulmonary embolism, ECG alone does not have sufficient sensitivity and specificity for diagnosis or exclusion of the condition, because these ECG changes can be seen in other diseases with right ventricular overload, such as pulmonary heart disease and idiopathic pulmonary hypertension. Therefore, the value of ECG in the diagnosis of pulmonary embolism lies in the close integration of clinical aspects. Chest X-ray Chest X-ray may show regional sparse and thin pulmonary vascular texture, increased pulmonary translucency, decreased pulmonary blood at the site of embolism (Westermark’s sign), and a corresponding increase in the texture of the uninvolved portion of the body (uneven distribution of pulmonary blood). Sparse pulmonary field vascularization, prominent pulmonary artery segments, widening of the right lower pulmonary artery, and elevation of the diaphragm are important suggestive values for diagnosis (Figure 1). The results of the multicenter survey showed that increased lung texture (46.4%) and lung shadows (36.1%) were more common, but were not the characteristic changes of pulmonary embolism. Figure 1: Chest X-ray of a patient with pulmonary embolism: the left arrow suggests widening of the right lower pulmonary artery; the right arrow suggests prominence of the pulmonary artery segment; and it also shows elevation of the right diaphragm X-ray indexes such as regional pulmonary field vascularization, prominence of the pulmonary artery segment, widening of the right lower pulmonary artery, diaphragm elevation, and pulmonary atelectasis should be regarded as more important reference indexes for the diagnosis of pulmonary embolism. Cardiac ultrasound The data show that 66.7% of the patients have pulmonary hypertension by ultrasound. Echocardiography can directly visualize large thrombi in the main trunk of the left and right pulmonary arteries (6.8%), and it can also visualize thrombi in the right heart appendage. Domestic and international guidelines for the diagnosis and treatment of pulmonary embolism emphasize the value of echocardiography in the diagnosis of pulmonary embolism, which is the basis for the classification of sub-massive pulmonary embolism. Cardiac echocardiography is an important means of diagnosing pulmonary embolism in primary hospitals, and it should include intra-pulmonary thrombus, pulmonary hypertension, right ventricular dilatation, and other manifestations of increased right heart load as the main reference indexes of cardiac echocardiography in the diagnosis of pulmonary embolism. Laboratory tests Blood white blood cell count, serum enzymes can be elevated, arterial blood oxygen partial pressure and arterial blood carbon dioxide partial pressure decreased, the results of the two investigations showed that the positive rate of >50%, so it should be focused on reference. The results of the survey also showed that serum ALT, AST, LDH, CPK, GGT, ALP levels were elevated, and CK-MB elevation was rare. If CK-MB is elevated, the possibility of acute myocardial infarction should be considered. D-Dimer Determination Multi-center survey results show that 25.4% of patients have low D-Dimer, and some literature reports that D-Dimer is significantly higher in the massive and sub-massive pulmonary embolism group than in the non-massive group (P<0.05).The sensitivity of D-Dimer for the diagnosis of acute pulmonary embolism reaches more than 95%, but the specificity is less than 50%. Therefore, D-Dimer has an important exclusion value for acute pulmonary embolism, but D-Dimer can not be high in chronic pulmonary embolism. The above results show that patients with chest X-ray lung shadows accompanied by blood leukocyte counts are not necessarily patients with pneumonia, and attention should be paid to exclude the possibility of pulmonary embolism; D-Dimer is not a constant indicator for determining pulmonary embolism, and is limited to the exclusion of acute pulmonary embolism. Therefore, patients with normal D-Dimer should be further screened with other appropriate tests. Multi-row spiral CT angiography (CTPA) Enhanced CT is widely used in China's tertiary hospitals to diagnose pulmonary embolism, with a diagnostic sensitivity and specificity of >90%, but is less commonly used in primary hospitals. Some experts suggest that spiral CT be used as a first-line diagnostic tool, but there are two important factors that limit the space for its rational use: first, the professional skills and experience of the physician who reads the film have an important impact on the judgment of its results; second, most primary hospitals can only perform first-generation CT examinations, and still do not have the conditions for third-generation CT or enhanced CT. The resolution of the first-generation scanner is 5 mm, and 1/3 of pulmonary embolisms are difficult to detect, especially in subsegmental pulmonary arteries.CTPA can show signs such as single or multiple low-density filling defect images in the pulmonary arteries, asymmetry of pulmonary vascular shadows on both sides, and widening of the pulmonary artery segments (Figure 2). Figure 2: CTPA image of a patient with pulmonary embolism, showing filling defect shadow within the main trunk of the pulmonary artery Application of CTPA to diagnose pulmonary embolism is a simple, feasible and accurate method to diagnose pulmonary embolism in primary hospitals, and is recommended. Core tips on the application of auxiliary tests: emphasizing the application of auxiliary tests, performing appropriate auxiliary tests, and correctly interpreting the results of auxiliary tests play an invaluable role in identifying pulmonary embolism for primary care physicians. It is the second “barrier” to diagnose pulmonary embolism. However, the “gold standard” for the diagnosis of pulmonary embolism is still pulmonary arteriography. Diagnosis of pulmonary embolism: clinical assessment of the likelihood of disease The common clinical assessment criteria for pulmonary embolism are the Canadian Wells Score and the Modified Geneva Score. Both scores are easy to understand and the clinical information required is readily available, making them suitable for use in primary care settings. A low score suggests a high likelihood of a clinical incidence of pulmonary embolism of <10%, a medium score suggests a high likelihood of an incidence of about 30%, and a high score suggests a high likelihood of an incidence of >65%. The Dutch study scale used the Clinical Diagnostic Evaluation Rating Scale to stratify patients with clinically suspected pulmonary embolism, which is convenient and accurate, with only 5% of patients in the low-degree suspicious group ultimately diagnosed with pulmonary embolism. See Table 1.