Department of Emergency and Critical Care Medicine, Nippon Medical School, Tokyo, Japan.
Crit Care Med. 2013 Sep;41(9):2144-50. doi: 10.1097/CCM.0b013e31828a4643.
Acute respiratory distress syndrome is characterized by diffuse alveolar damage and increased extravascular lung water levels. However, there is no threshold extravascular lung water level that can indicate diffuse alveolar damage in lungs. We aimed to determine the threshold extravascular lung water level that discriminates between normal lungs and lungs affected with diffuse alveolar damage.
A retrospective analysis of normal lungs and lungs affected with diffuse alveolar damage was performed.
Normal lung cases were taken from published data. Lung cases with diffuse alveolar damage were taken from a nationwide autopsy database. All cases of autopsy followed hospital deaths in Japan from more than 800 hospitals between 2004 and 2009; complete autopsies with histopathologic examinations were performed by board-certified pathologists authorized by the Japanese Society of Pathology.
Normal lungs: 534; lungs with diffuse alveolar damage: 1,688.
We compared the postmortem weights of both lungs between the two groups. These lung weights were converted to extravascular lung water values using a validated equation. Finally, the extravascular lung water value that indicated diffuse alveolar damage was estimated using receiver operating characteristic analysis.
The extravascular lung water values of the lungs showing diffuse alveolar damage were approximately two-fold higher than those of normal lungs (normal group, 7.3±2.8 mL/kg vs diffuse alveolar damage group 13.7±4.5 mL/kg; p<0.001). An extravascular lung water level of 9.8 mL/kg allowed the diagnosis of diffuse alveolar damage to be established with a sensitivity of 81.3% and a specificity of 81.2% (area under the curve, 0.90; 95% CI, 0.88-0.91). An extravascular lung water level of 14.6 mL/kg represented a 99% positive predictive value.
This study may provide the first validated quantitative bedside diagnostic tool for diffuse alveolar damage. Extravascular lung water may allow the detection of diffuse alveolar damage and may support the clinical diagnosis of acute respiratory distress syndrome. The best extravascular lung water cut-off value to discriminate between normal lungs and lungs with diffuse alveolar damage is around 10 mL/kg.
急性呼吸窘迫综合征的特征为弥漫性肺泡损伤和血管外肺水含量增加。然而，目前还没有能够指示肺部弥漫性肺泡损伤的血管外肺水阈值。本研究旨在确定能够区分正常肺和弥漫性肺泡损伤肺的血管外肺水阈值。
对正常肺和弥漫性肺泡损伤肺进行回顾性分析。
正常肺取自已发表的数据，弥漫性肺泡损伤取自全国性尸检数据库。所有尸检病例均来自日本 2004 年至 2009 年 800 多家医院的院内死亡患者，由日本病理学会授权的认证病理学家进行了完整的尸检和组织病理学检查。
正常肺：534 例；弥漫性肺泡损伤肺：1688 例。
比较两组患者的双肺死后重量。使用验证过的公式将这些肺重量转换为血管外肺水值。最后，使用受试者工作特征曲线分析估计提示弥漫性肺泡损伤的血管外肺水值。
显示弥漫性肺泡损伤的肺的血管外肺水值大约是正常肺的两倍（正常组：7.3±2.8ml/kg 比弥漫性肺泡损伤组：13.7±4.5ml/kg；p<0.001）。血管外肺水水平为 9.8ml/kg 时，可以以 81.3%的敏感性和 81.2%的特异性诊断弥漫性肺泡损伤（曲线下面积，0.90；95%置信区间，0.88-0.91）。血管外肺水水平为 14.6ml/kg 时，阳性预测值为 99%。
本研究可能为弥漫性肺泡损伤提供了第一个经验证的床边定量诊断工具。血管外肺水可能有助于发现弥漫性肺泡损伤，并支持急性呼吸窘迫综合征的临床诊断。区分正常肺和弥漫性肺泡损伤肺的最佳血管外肺水截止值约为 10ml/kg。
