肺动脉栓塞的诊治制作XGHRH 基本概念肺栓塞是以各种栓子阻塞肺动脉系统为其发病原因的一组疾病或临床综合征的总称，包括肺血栓栓塞症，脂肪栓塞综合征，羊水栓塞，空气栓塞等。肺血栓栓塞症为来自静脉系统或右心的血栓阻塞肺动脉或其分支所致疾病。肺梗死为肺动脉发生栓塞后，其支配区的肺组织因血流受阻或中断而发生坏死。肺栓塞的现状发病率高：仅次于CAD 和HBP 。易漏诊及误诊：警惕性不高，漏诊率高。不经治疗死亡率高：达20%-30% 。明确诊疗者死亡率明显下降：可降至2-8% 。Epidemiology There is no accurate data for pulmonary embolism because we has limit knowledge of it. In the United States, it is responsible for about 2.3 new cases per 10,000 persons and 50,000 deaths every year. 流行病学生存率比较Risk Factors for DVT/Pulmonary Embolism （Essential ）Risk Factors for DVT/Pulmonary Embolism （Second ）深静脉血栓形成肺血栓与深静脉血栓肺栓塞的大体解剖观肺栓塞的显微镜下观肺栓塞的病理生理肺血管阻塞，神经体液因素或肺动脉压力感受器的作用，引起肺血管阻力增加；肺血管阻塞→肺泡死腔↑→气体交换↓→肺泡通气↓→低氧血症→V/Q 单位↓→气体交换面积↓→二氧化碳↑刺激性受体反射性兴奋（过度换气）支气管收缩，气道阻力增加肺水肿、肺出血、肺泡表面活性物质减少，肺顺应性降低。肺栓塞后右心功能不全的病生肺栓塞后肺血流动力学变化前毛细血管高压	 血管床减少		 支气管收缩		 小动脉血管收缩侧支血管的形成	 支气管-肺动脉吻合形成		 肺内动静脉分流血流改变：血流重分布呼吸动力学改变过度通气：肺动脉高压			 顺应性下降				 肺不张气道阻力增加：		 局限性低碳酸血症			 化学介质临床分型大面积PE(massive PE) ：	 休克和低血压；	 动脉收缩压<90mmHg 		 或下降幅度≥40mmHg ，持续15min 以上；除外其他原因所致血压下降。次大面积PE (submassive PE) 亚型	 超声心动图示右心室运动功能减弱	 右心功能不全表现。非大面积PE(non-massive FE) ：	 不符合以上大面积PE 标准的PE 。症状体征D- 二聚体分析肺栓塞胸片检查X-RAY FOR CHEST Atelectasis and parenchymal densities are quite common. The areas of atelectasis are more common in the lower lobe as are the areas of parenchymal density Most of these densities are caused by pulmonary hemorrhage and edema and can be confused with infectious infiltrates or malignant masses Pleural effusions are common and most often unilateral despite the fact that most clots are bilateral. These effusions are usually visible when the patient seeks medical attention. They are almost always small, occupying less than 15% of a hemithorax and rarely increase in size after 3 days. Any increase in size after 3 or 4 days should raise the suspicion of a pulmonary infection or re-embolization. Pleural based opacities with convex medial margins are also known as a Hampton's Hump. This may be an indication of lung infarction. However, that rate of resolution of these densities is the best way to judge if lung tissue has been infarcted. Areas of pulmonary hemorrhage and edema resolve in a few days to one week. The density caused by an area of infarcted lung will decrease slowly over a few weeks to months and may leave a linear scar. A diaphragm may be elevated, reflecting volume loss in the affected lung. The central pulmonary arteries may be prominent either from pulmonary hypertension or the presence of clot in those arteries. Cardiomegally is a non-specific finding but may imply an enlarged right ventricle as seen in the patient who presented with large bilateral pulmonary emboli. A Westermark's sign implies an area of decreased vascularity and perfusion accompanied by an enlarged central pulmonary artery on the affected side. 肺栓塞的心动超声征象直接看到血栓右室扩张右室活动减弱室间隔异常活动三尖瓣反流速度增快肺动脉扩张无吸气性下腔静脉塌陷减弱室间隔异常活动Color-Flow-Doppler-ultrasound 非挤压性充盈缺损心电图表现不完全性或完全性右束支传导阻滞Ⅰ、avL 的S波>1.5mm Ⅲ、avF 有Qs 波，但Ⅱ无Qs 波QRS 轴>900 或不确定肢导联低电压Ⅲ、avF 的T波倒置或V1~V4T 波倒置Ventilation/Perfusion Lung Scan PIOPED ：肺扫描分类与肺动脉造影结果的比较肺扫描怀疑PE 的患者约25 ％可因肺灌注正常而否定诊断，而且不用抗凝治疗可能是安全的怀疑PE 的患者约25 ％具有高度的肺扫描结果，他们可能需要行抗凝治疗其余的患者需要进一步的诊断性检查，而这些检查是更广泛的诊断策略典型肺栓塞It is high sensitivity but low specificity The differential diagnosis for a ventilation perfusion mismatch includes: 		 acute pulmonary embolus 		 previous pulmonary embolus 		 congenital vascular abnormalities 		 vasculitis, 		 bronchogenic carcinoma, 		 radiation therapy,et al. 	When a ventilation/perfusion scan does not fit into either the normal or high probability category, then we consider the study to be non-diagnostic and further investigation is required. The majority of cases fall into this category which is characterized by scans with subsegmental defects or defects of any size that match abnormalities on the chest x-ray or the perfusion scan. A low probability category has been suggested by a number of authors. However, as we can see from the PIOPED data this is not a particularly reliable category. Disagreement among experienced readers is common when perfusion defects are small and limit the utility of this category. This study was originally read as showing a small subsegmental defect. Without the arrow, this study has subsequently been called normal by a number of experienced readers Conclusion 	Lung scans are sensitive exams that essentially rule out the diagnosis of pulmonary embolus when they are normal. Patients with high probability lungs can often be treated without further workup. Those patients with non-diagnostic studies require further diagnostic investigation. CT of Pulmonary Embolism 	Pulmonary infarcts are more readily identified on CT. Modern CT scanners now have faster acquisition times and are providing a detailed assessment of the lung parenchyma that is not available from the chest radiograph. The typical appearance of a pulmonary infarct on CT includes a pleural based density with convex borders and a linear strand at the apex of the triangle The apex of the triangle is often truncated and not wedge shaped which corresponds to the normal configuration of a secondary lobule in the lung periphery. Low attenuation areas within the infarct represents viable lung. It is important to note, however, that this appearance is not specific for pulmonary infarction. The differential diagnosis for this abnormality includes infarct, hemorrhage, pneumonia, fibrosis, neoplasia and edema 	Since the clinical presentation of pulmonary embolus is usually non-specific, the findings on CT are often the first clinical indication that the patient may be suffering from pulmonary embolus. In addition to visualizing the area of infarction we are often able to see the clot itself. 	CT has been show to be especially useful in the assessment of patients with chronic dyspnea and known pulmonary artery hypertension. These patients are often difficult to diagnose as is exemplified by this patient with known sclerodema and pulmonary artery hypertension whose CT unexpectedly showed a large calcified clot in the right pulmonary artery. 肺动脉造影The most reliable signs of pulmonary embolus are: An Intraluminal filling defect An Abrupt termination of a branch vessel Conclusion Angiography is most accurate in segmental and larger sized arteries. The reproducibility of readings is subsegmental and smaller vessels is poor. Angiography is a safe procedure that is most accurate when imaging emboli that lodge in segmental or larger arteries. The Diagnosis Algorithm Interpretation Criteria High Probability (80-100% likelihood for PE ): 	Greater than or equal to 2 large mismatched segmental perfusion defects or the arithmetic equivalent in moderate or large and moderate defects. Intermediate Probability (20-80% likelihood for PE ): 1. One moderate to 2 large mismatched perfusion defects or the arithmetic equivalent in moderate or large and moderate defects. 2. Single matched ventilation-perfusion defect with a clear chest radiograph . 3. Difficult to categorize as low or high, or not described as low or high. 4. Nonsegmental perfusion defects (e.g., cardiomegaly, enlarged aorta, enlarged hila, elevated diaphragm). 5. Multiple matched V/Q abnormalities, even when relatively extensive, are low probability for PE . The prevalence of PE in patients with extensive matched V/Q defects and no CXR abnormality was