Grudzinski Kevin M, Fenske Samuel, Peltekian Alec, Markov Nikolay S, Pawlowski Anna, Kang Mengjia, Walter James M, Pickens Chiagozie I, Nadig Nandita R, Agrawal Ankit, Singer Benjamin D, Wunderink Richard G, Gao Catherine A
Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL.
Division of Pulmonary and Critical Care, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL.
medRxiv. 2024 Nov 4:2024.05.04.24306709. doi: 10.1101/2024.05.04.24306709.
Pneumonia is the most common infection in ICU patients and a leading cause for death. Assessment of bronchoalveolar lavage fluid (BALF) cellularity can aid in pneumonia diagnosis. Low percentages (<50%) of BALF neutrophils have a high negative predictive value for bacterial pneumonia in a general medical ICU population. The operating characteristics in patients with immunocompromise and neutropenia are less clear.
To compare BALF % neutrophils operating characteristics in patients with and without immunocompromise or neutropenia.
This was a single center observational cohort study. Patients were categorized into three groups: (1) patients with neutropenia, (2) patients with underlying immunocompromise, and (3) patients with neither. BAL-level analysis reflected neutropenia and immunocompromise state on day of BAL sampling. Operating characteristics of BALF % neutrophils were calculated using varying thresholds of alveolar neutrophilia. Median [Q1,Q3] are reported for nonparametric data and compared using Mann-Whitney U tests.
688 mechanically ventilated patients had 1736 BAL samples. Among bacterial pneumonia episodes, no difference was found in BALF % neutrophils between patients with underlying immunocompromise and patients with neither neutropenia nor immunocompromise on day of sampling: 82.0% [61.0, 91.0] vs 81.0% [66.0, 91.0], p=0.859. However, when neutropenic on day of sampling, the median BALF % neutrophils was 35.0% [8.8, 67.5] (p<0.001 compared with other categories). In patients with neutropenia, a BALF % neutrophil threshold of 7% had a sensitivity of 90% for excluding bacterial pneumonia.
We found that among patients with bacterial pneumonia, BALF % neutrophil was not significantly lower in patients with a broad spectrum of immunocompromised states but was significantly lower when measured during acute neutropenia. We found varying thresholds of BALF % neutrophils across the three groups. Patients with neutropenia who mount even a low percent of alveolar neutrophils should raise concern for bacterial pneumonia.
肺炎是重症监护病房（ICU）患者中最常见的感染，也是主要的死亡原因。评估支气管肺泡灌洗（BAL）液的细胞成分有助于肺炎的诊断。在普通内科ICU患者中，BAL液中性粒细胞比例低（<50%）对细菌性肺炎具有较高的阴性预测价值。免疫功能低下和中性粒细胞减少患者的相关特征尚不清楚。
比较有或无免疫功能低下或中性粒细胞减少患者BAL液中性粒细胞的特征。
这是一项单中心观察性队列研究。患者分为三组：（1）中性粒细胞减少患者，（2）存在基础免疫功能低下患者，（3）两者均无的患者。BAL水平分析反映了BAL采样当天的中性粒细胞减少和免疫功能低下状态。使用不同的肺泡中性粒细胞增多阈值计算BAL液中性粒细胞百分比的特征。非参数数据报告中位数[Q1，Q3]，并使用Mann-Whitney U检验进行比较。
688例机械通气患者有1736份BAL样本。在细菌性肺炎发作中，采样当天存在基础免疫功能低下的患者与既无中性粒细胞减少也无免疫功能低下的患者之间，BAL液中性粒细胞百分比无差异：82.0%[61.0，91.0]对81.0%[66.0，91.0]，p = 0.859。然而，采样当天出现中性粒细胞减少时，BAL液中性粒细胞百分比中位数为35.0%[8.8，67.5]（与其他类别相比，p<0.001）。在中性粒细胞减少患者中，BAL液中性粒细胞阈值为7%时，排除细菌性肺炎的敏感性为90%。
我们发现，在细菌性肺炎患者中，广泛免疫功能低下状态患者的BAL液中性粒细胞百分比并无显著降低，但在急性中性粒细胞减少期间测量时显著降低。我们发现三组患者的BAL液中性粒细胞百分比阈值各不相同。即使肺泡中性粒细胞百分比很低的中性粒细胞减少患者也应警惕细菌性肺炎。
