Imperial College Unit of Critical Care, National Heart and Lung Institute, Royal Brompton Hospital, London, UK.
Respirology. 2011 Nov;16(8):1265-72. doi: 10.1111/j.1440-1843.2011.02048.x.
ARDS is characterized by bilateral pulmonary infiltrates and refractory hypoxemia attributed to V/Q mismatch. We used dynamic CT to characterize changes in lung composition, regional perfusion and tissue distribution in patients with ARDS in comparison with healthy subjects.
The Fick principle was applied to serial attenuation measurements constructed from sequential CT images acquired during the passage of a bolus of iodinated contrast medium in healthy subjects (n=3) and patients with ARDS (n=11). Perfusion was calculated by the Mullani-Gould method and mapped throughout both lungs. Gradients of perfusion and tissue density against vertical height were constructed.
In comparison with normal individuals, the tissue component of lungs from patients with ARDS was significantly increased (P<0.05). Blood fraction was unchanged. There was a discernable gradient in tissue density from non dependent to dependent regions in the patients with ARDS that was significantly different from controls. The proportion of perfusion applied to consolidated areas (i.e. shunt) correlated significantly (P<0.05) with the severity of hypoxaemia.
In patients with ARDS there are changes in both lung composition and the distribution of tissue and perfusion that may account in part for the physiological changes that define the syndrome.
ARDS 的特征是双侧肺浸润和由 V/Q 不匹配引起的难治性低氧血症。我们使用动态 CT 来描述 ARDS 患者与健康受试者相比肺成分、区域性灌注和组织分布的变化。
在健康受试者（n=3）和 ARDS 患者（n=11）中，通过在碘造影剂团通过期间获得的连续 CT 图像构建的序贯衰减测量，应用 Fick 原理。通过 Mullani-Gould 方法计算灌注并在整个肺部进行映射。构建灌注和组织密度与垂直高度的梯度。
与正常人相比，ARDS 患者的肺组织成分明显增加（P<0.05）。血液分数不变。在 ARDS 患者中，从非依赖区域到依赖区域的组织密度存在明显的梯度，与对照组明显不同。应用于实变区域（即分流）的灌注比例与低氧血症的严重程度显著相关（P<0.05）。
ARDS 患者的肺组成和组织以及灌注分布均发生变化，这可能部分解释了定义该综合征的生理变化。
