A 58-year-old man with ischemic heart disease u goes coronary artery bypass graft surgery under general anesthesia. Two days postoperatively, he experiences increasing respiratory difficulty with decreasing arterial oxygen saturation. On physical examination, his heart rate is regular at 78/min, respirations are 25/min, and blood pressure is 135/85 mm Hg. The hemoglobin concentration has remained unchanged, at 13.7 g/dL, since surgery. After he coughs up a large amount of mucoid sputum, his condition improves. Which of the following types of atelectasis does he most likely have?
A Compression
B Contraction
C Micro
D Relaxation
E Resorption
审题
题目倒是很好懂，但是，没有学过肺不张，不明白肺不张与手术有什么关系，几种肺不张之间有什么区别？
做题
自选答案：无
题目类型：d
标准答案：E
答案解析：Resorption atelectasis is most often the result of a mucous or mucopurulent plug obstructing a bronchus. Air in alveoli distal to the obstruction is resorbed and that portion of lung collapses. This can occur postoperatively, or it may complicate bronchial asthma.
Compression atelectasis results from accumulation of air or fluid in the pleural cavity, which can happen with a pneumothorax, hemothorax, or pleural effusion.
Contraction atelectasis occurs when fibrous scar tissue surrounds the lung.
Microatelectasis can occur postoperatively, in diffuse alveolar damage, and in respiratory distress of the newborn from loss of surfactant.
Relaxation atelectasis is a synonym for compression atelectasis.
知识辐射
atelectasis肺不张：
Resorption ~ :Airway obstruction causes the loss of preexisting air in the peripheral alveoli, leading to alveolar collapse.
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Compression ~:Collapse of small airways and alveoli deep to the pleura that occurs when air or fluid in the pleural cavity is under increased pressure.
三种肺不张-来自高老爷子 Contraction ~:收缩性肺不张？除了罗宾自己的书有，其他资料上没找到这个，答案说是由于肺周纤维斑块形成导致？查uptodate意思接近的有瘢痕性肺不张
Cicatrization (ie, cicatricial atelectasis) results from diminution of lung volume due to severe parenchymal scarring . Common underlying etiologies include granulomatous disease (eg, sarcoidosis), necrotizing pneumonia, and radiation pneumonia.
是由于严重的实质瘢痕导致的肺体积缩小。常见的病因包括肉芽肿性疾病（如结节病）、坏死性肺炎和放射性肺炎。
查《Robin’s basic pathology 9th》有以下定义：
Contraction atelectasis. Contraction (or cicatrization) ate lectasis occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration.
RBP上面的分类图
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microatelectasis：微小肺不张？发生于弥漫性肺泡损伤之后
弥漫性肺泡损伤DAD（Diffuse alverolar damage）是ARDS的一部分，可以分渗出期与机化期，机化后可能导致肺组织纤维化失去正常结构。
反思
在uptodate上肺不张被分为两个大类，阻塞性与非阻塞性，以前学习影像学时也是分为这两大类；
非阻塞性肺不张中最主要的还是压迫性肺不张，瘢痕性肺不张则属于非阻塞型肺不张；
或许这道题的鉴别点在微小肺不张与吸收型肺不张的鉴别上，这俩都可以由手术引起，但是我并没有找到手术引起微小性肺不张的原因，鉴别点在于咳嗽，咯黏液样痰后缓解。
