早期使用抗病毒藥物治療H1N1流感重症患者可以改善病人的存活率。然而臨床上要區 分H1N1或細菌造成的急性呼吸窘迫症候群是困難的，而且流感快篩檢驗的敏感度不夠高。 一般的醫院無法以即時聚合酶鏈鎖反應偵測流感病毒。我們的研究目的是以支氣管肺泡沖洗 液中的淋巴球比例來早期診斷H1N1流感引起的急性呼吸窘迫症候群。我們回朔性分析2014 年到2016年3 月基隆長庚醫院內科加護病房因為肺炎引起急性呼吸窘迫症候群並且有接受支 氣管肺泡沖洗的病人，有9 位是H1N1流感而18位是細菌引起的。H1N1- 急性呼吸窘迫症候群 的病人的病人有較低的APACHE II 分數，支氣管肺泡沖洗液中的淋巴球比例比起細菌- 急性 呼吸窘迫症候群的病人還要高 (15.6 ± 7.5% vs. 7.6 ± 8.0%, p=0.009)。以支氣管肺泡沖洗液中的 淋巴球比例11%來區分是H1N1流感或是細菌造成的急性呼吸窘迫症候群，ROC曲線下面積 為0.829，敏感度85.5%，特異度77.8%，陽性預測值79.4%，陰性預測值84.3%。這個結果可 以幫助我們對於急性呼吸窘迫症候群的病人早期區分是H1N1流感所致，早期給予抗病毒藥 以改善病人的存活率。

Distinguishing between bacterial and H1N1 infection in patients with acute respiratory distress syndrome (ARDS) is difficult based on clinical symptoms alone; moreover, rapid antigen test for influenza has poor sensitivity. The aim of this work was to determine whether the differential cell count in bronchoalveolar lavage (BAL) fluid could aid in early diagnosis of H1N1-ARDS. We retrospectively identified pneumonia-induced ARDS patients who underwent BAL in intensive care unit (ICU) of the Chang Gung Memorial Hospital, Keelung from January 1, 2014 to March 31, 2016. Patient characteristics, severity of illness scores, white blood count (WBC) and differential count, biochemical test, BAL fluid differential cell count, and semi-quantitative culture of lower respiratory tract sample were evaluated. Nine patients with H1N1-ARDS and 18 with non-H1N1-ARDS were identified. Patients with H1N1-ARDS had lower APACHE II scores. Lymphocyte percentage in BAL fluid was significantly higher in the H1N1-ARDS group (15.6 ± 7.5% vs. 7.6 ± 8.0%, p=0.009). The area under the ROC curve (AUC) was 0.829; with a sensitivity of 85.5%, specificity of 77.8%, positive predictive value of 79.4% and negative predictive value of 84.3% for H1N1-ARDS prediction at a cutoff value of 11%. Lymphocyte percentage in BAL fluid was higher in patients with H1N1-ARDS than in those without. This result has potential applicability for early detection of H1N1 influenza virus infection in patients with ARDS. (J Intern Med Taiwan 2018; 29: 46-53)