Marquette C H, Copin M C, Wallet F, Neviere R, Saulnier F, Mathieu D, Durocher A, Ramon P, Tonnel A B
Département de Pneumologie, Hôpital A. Calmette, CHU de Lille, France.
Am J Respir Crit Care Med. 1995 Jun;151(6):1878-88. doi: 10.1164/ajrccm.151.6.7767535.
The diagnostic accuracy of protected-specimen brush (PSB), bronchoalveolar lavage (BAL), and endotracheal aspirates (EA) was prospectively evaluated in a series of 28 mechanically ventilated patients (MV patients) who died within 3 d of the bronchoscopic procedure, using postmortem lung examination as the gold standard for establishing the diagnosis of pneumonia. The entire fixed lungs were carefully dissected along the bronchovascular axes and each segment was cut into 5- to 10-mm thick sections, enabling gross examination of the lung parenchyma. Two tissue blocks were taken from each segment, including grossly abnormal areas whenever present. In several cases, two peripheral (subpleural) lung-tissue blocks were also taken from each lobe prior to systematic dissection of the lungs. Quantitative cultures (QC) and direct cytologic and microbiologic examination (DE) was performed on respiratory samples obtained within 72 h before death. Values of 10(3) cfu/ml of Ringer's solution, 10(4) cfu/ml of retrieved fluid, and 10(6) cfu/ml of respiratory secretions were used as cutoff points for quantitative PSB, BAL, and EA cultures, respectively. The main findings in this study were that: (1) Pneumonia was present in 67% of the patients. (2) Histologic lesions of pneumonia were mainly bilateral and predominated in the dependent lung segments. (3) Coexistence of a variety of noninfectious processes was a common finding in patients with pneumonia. (4) In several cases pneumonia was absent from peripheral lung samples while more central areas of the same segment displayed typical foci of pneumonia. (5) The sensitivity of quantitative cultures was 55%, 57%, and 47% for EA, PSB, and BAL, respectively, and the specificity was 85%, 88%, and 100%, respectively. Reducing the diagnostic threshold of EA to 10(5) cfu/ml of respiratory secretions instead of 10(6) cfu/ml resulted in a sensitivity of 63.1% and a specificity of 75% for EA. The sensitivity of direct examination (DE) was 50%, 47%, and 47%, respectively, and the specificity was 75%, 88%, and 87%. (6) The presence of intracellular organisms (ICO) in BAL had a 36.8% sensitivity and 100% specificity in establishing the diagnosis of pneumonia regardless of their percentage. (7) Although 15 patients (53%) were not on antibiotics or were off antibiotics for more than 48 h before testing, no relationship could be established between the patients' antibiotic status and the result of any diagnostic test. By using a recommended methodology for respiratory sampling techniques together with complete postmortem lung examination as a diagnostic "gold standard," this study provides a realistic insight into the diagnostic values of EA, PSB, and BAL in MV patients with suspected pneumonia.
在一系列28例机械通气患者（MV患者）中，前瞻性评估了保护性标本刷检（PSB）、支气管肺泡灌洗（BAL）和气管内吸出物（EA）的诊断准确性，这些患者在支气管镜检查后3天内死亡，以尸检肺检查作为确诊肺炎的金标准。将整个固定的肺沿支气管血管轴仔细解剖，每个肺段切成5至10毫米厚的切片，以便对肺实质进行大体检查。从每个肺段取两块组织块，如有明显异常区域则包括在内。在几例病例中，在对肺进行系统解剖之前，还从每个肺叶取了两块外周（胸膜下）肺组织块。对死亡前72小时内获取的呼吸道样本进行定量培养（QC）以及直接细胞学和微生物学检查（DE）。林格氏液10³ cfu/ml、回收液10⁴ cfu/ml和呼吸道分泌物10⁶ cfu/ml的值分别用作PSB、BAL和EA定量培养的截断点。本研究的主要发现如下：（1）67%的患者存在肺炎。（2）肺炎的组织学病变主要为双侧性，且在下垂肺段占主导。（3）肺炎患者中多种非感染性病变共存是常见现象。（4）在几例病例中，外周肺样本无肺炎，而同一肺段的更中央区域显示典型的肺炎病灶。（5）EA、PSB和BAL定量培养的敏感性分别为55%、57%和47%，特异性分别为85%、88%和100%。将EA的诊断阈值降至呼吸道分泌物10⁵ cfu/ml而非10⁶ cfu/ml时，EA的敏感性为63.1%，特异性为75%。直接检查（DE）的敏感性分别为50%、47%和47%，特异性分别为75%、88%和87%。（6）BAL中细胞内生物体（ICO）的存在在诊断肺炎时敏感性为36.8%，特异性为100%，无论其百分比如何。（7）尽管15例患者（53%）在检测前未使用抗生素或已停用抗生素超过48小时，但患者的抗生素使用情况与任何诊断测试结果之间均未发现关联。通过使用推荐的呼吸道采样技术方法并结合完整的尸检肺检查作为诊断“金标准”，本研究对疑似肺炎的MV患者中EA、PSB和BAL的诊断价值提供了实际见解。
