肺水肿大致可被划分为流体静力压性(亦称为心源性或压力增高性)和毛细血管通透性增加性(非心源性)两大类别。通透性水肿有可能与流体静力压性水肿同时存在,通透性水肿还可能与弥漫性肺泡损害(DAD)并发,从而可能诱发急性呼吸窘迫综合征(ARDS)。 先前提出的肺水肿分类方法包括:①流体静力压性水肿;②无DAD的通透性增加性水肿;③混合性水肿;④伴DAD的通透性水肿(ARDS)。这种分类在病理学、生理学和影像学表现上均表现出较好的一致性。尽管通过胸片或高分辨率CT(HRCT)来区分肺水肿类型并不完全可靠,但它们之间的表现确实存在一些差异。 一、流体静力压性肺水肿 流体静力压性肺水肿是由于血管内与血管外之间流体静力压和胶体渗透压之间的平衡关系发生改变所引发。多数情形下,血管内压力升高主要归因于肺静脉压增高,导致液体渗入间质并流失。此外,由于低白蛋白血症引发的血管内胶体渗透压降低,亦可能加剧液体向间质的渗漏。 影像学表现:流体静力压性肺水肿的典型表现为小叶间隔增厚与肺内磨玻璃影的同时出现。如小叶间隔增厚或磨玻璃影。此外,还可能观察到铺路石征和实变等征象。 上图:心肌病的流体静力压性肺水肿。HRCT显示小叶间隔增厚和斑片状磨玻璃影,右侧为著。支气管血管周围间质增厚(表现为支气管壁增厚、胸膜下间质增厚(表现为叶间裂增厚)。 ▲上图:肾衰竭合并流体静力压性肺水肿。小叶间隔增厚和斑片状磨玻璃影,支气管血管周围间质增厚和胸膜下间质增厚。 ▲图:患者被确认为患有流体静力压性肺水肿,其特点为小叶间隔增厚。在充血性心力衰竭的背景下,观察到广泛的小叶间隔增厚。此外,患者的支气管血管周围间质也有增厚现象,表现为支气管壁增厚,同时左侧叶间裂亦出现增厚。另外,两侧存在少量的胸腔积液。 [1] Ketai LH and Godwin JD present a novel perspective on pulmonary edema and acute respiratory distress syndrome in the Journal of Thoracic Imaging, 1998;13:147-171. [2] Gluecker T, Capasso P, Schnyder P, and colleagues detail the clinical and radiographic characteristics of pulmonary edema in the journal Radiographics, 1999;19:1507-1531, with a discussion section from 1532-1533. [3] Hommeyer SH, Godwin JD, and Takasugi JE contribute to the field of computed tomography of airspace disease in the Radiology Clinics of North America, 1991;29:1065-1084. [4] Primack SL and Muller NL discuss the use of high-resolution computed tomography in acute diffuse lung disease among immunocompromised patients in the Radiology Clinics of North America, 1994;32:731-744. [5] Todo G and Herman PG present their findings on high-resolution computed tomography of the pig lung in Investigative Radiology, 1986;21:689-696. Webb WR, Stein MG, Finkbeiner WE, and colleagues provide insights into normal and diseased isolated lungs using high-resolution computed tomography in the journal Radiology, 1988;166:81-87. [6] Bessis L, Callard P, Gotheil C, and team present a precise correlation between high-resolution computed tomography findings and histologic results in parenchymal lung disease in the journal Radiographics, 1992;12:45-58. [7] Hedlund LW, Vock P, Effimann EL, and colleagues analyze lung density changes in hydrostatic pulmonary edema using computed tomography in Investigative Radiology, 1984;19:254-262. [8] Scillia P, Kafi SA, Melot C, and team evaluate thin-section computed tomography in dogs with oleic acid-induced lung injury in the journal Radiology, 2001;219:724-731. [9] Forster BB, Müller NL, Mayo JR, and colleagues contribute to the understanding of high-resolution computed tomography in experimental hydrostatic pulmonary edema in the journal Chest, 1992;101:1434-1437. |
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