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1、肺动脉栓塞的诊治 制作 XGHRH 敬请指正 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 embo
2、lism 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 Arch Intern Med 154 861 19 94 生存率比较 Arch Intern Med 154 861 19 94 1 0 1 2 3 Risk Factors for DVT Pulmonary Embolism Essential 抗凝血酶缺乏 蛋白C缺乏 先天性
3、异常纤维蛋白原血症 V因子基因突变 血栓调节蛋白 纤溶酶原缺乏 高半胱氨酸血症 异常纤溶酶原血症 抗心肌碱脂抗体 蛋白S缺乏 纤溶酶原激活抑制剂过量 因子缺乏 前凝血酶20210A突变 Risk Factors for DVT Pulmonary Embolism Second 创伤 骨折 外科手术 卒中 制动 高龄 恶性肿瘤 化疗 中心静脉导管 肥胖 慢性静脉机能不全 心力衰竭 吸烟 长途旅行 妊娠 产后期 口服避孕药 克隆病 狼疮 抗凝剂 肾病综合征 假体表面 粘滞性过高 血小板异常 深静脉血栓形成 原因 分类 血流滞缓 小腿肌肉静脉丛血栓形成 髂 股静脉血栓形成 静脉壁损伤 原发性髂 肌
4、静脉血栓形成 继发性髂 股静脉血栓形成 高凝状态股青肿 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 冠状动脉灌注 右心室氧需 右心室壁张力 右心室 排血量 右心室氧供 左心室排血量 肺动脉压力 右心室后负荷 解剖阻塞 神经体液作用 右心室扩张 功能不全 右
5、心室缺血 室间隔移 向左心室 低血压 体循环灌注 左心室前负荷 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 Westermark 征 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1 5mm avF有Qs波 但 无Qs波 QRS轴 900或不确定 肢导联低电压 avF的T波倒置或V1 V4T波倒置 图12000年8月27日 急诊 ECG大致正 常 2000年8
6、月29日 门诊 ECG示 IRBBB S Q T V1V2T波倒置V3V4T波 双向 Ventilation Perfusion Lung Scan PIOPED 肺扫描分类与肺动 脉造影结果的比较 肺扫描肺栓塞肺动脉造 影阴性 总数 有无不肯定 高度可疑1021417124 中度可疑105217933364 低度可疑391991262312 接近正常 正常550274131 总计25148024176931 J Nucl Med 1993 34 1119 肺扫描肺扫描 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
7、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 不典型肺栓塞 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 radiati
8、on therapy et al When a ventilation perfus ion 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 d
9、efects 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 commo
10、n 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 essential
11、ly 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 identi
12、fied 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
13、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
14、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
15、 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 dif
16、ficult 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 正常肺动脉 This selective study was done because of a perfusion defect in the left lower lobe on a ventilation perfusion scan The first angiographic study was inconclusive Therefore a subselective study was done that demonstrated the clot with certainty The most reliable signs of pulmonary embolus are vAn I
