Rath Amit K, Sahu Dibakar, De Sajal
Department of Pulmonary Medicine, All India Institute of Medical Sciences, Raipur, India.
Tuberc Respir Dis (Seoul). 2024 Apr;87(2):165-175. doi: 10.4046/trd.2023.0139. Epub 2024 Jan 16.
The prevalence of small airway dysfunction (SAD) in patients with chronic obstructive pulmonary disease (COPD) across different ethnicities is poorly understood. This study aimed to estimate the prevalence of SAD in stable COPD patients.
We conducted a cross-sectional study of 196 consecutive stable COPD patients. We measured pre- and post-bronchodilator (BD) lung function and respiratory impedance. The severity of COPD and lung function abnormalities was graded in accordance with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. SAD was defined as either difference in whole-breath resistance at 5 and 19 Hz > upper limit of normal or respiratory system reactance at 5 Hz < lower limit of normal.
The cohort consisted of 95.9% men, with an average age of 66.3 years. The mean forced expiratory volume 1 second (FEV1) % predicted was 56.4%. The median COPD assessment test (CAT) scores were 14. The prevalence of post-BD SAD across the GOLD grades 1 to 4 was 14.3%, 51.1%, 91%, and 100%, respectively. The post-BD SAD and expiratory flow limitation at tidal breath (EFLT) were present in 62.8% (95% confidence interval [CI], 56.1 to 69.9) and 28.1% (95% CI, 21.9 to 34.2), respectively. COPD patients with SAD had higher CAT scores (15.5 vs. 12.8, p<0.01); poor lung function (FEV1% predicted 46.6% vs. 72.8%, p<0.01); lower diffusion capacity for CO (4.8 mmol/min/kPa vs. 5.6 mmol/min/kPa, p<0.01); hyperinflation (ratio of residual volume to total lung capacity % predicted: 159.7% vs. 129%, p<0.01), and shorter 6-minute walk distance (367.5 m vs. 390 m, p=0.02).
SAD is present across all severities of COPD. The prevalence of SAD increases with disease severity. SAD is associated with poor lung function and higher symptom burden. Severe SAD is indicated by the presence of EFLT.
不同种族慢性阻塞性肺疾病（COPD）患者中小气道功能障碍（SAD）的患病率尚不清楚。本研究旨在评估稳定期COPD患者中SAD的患病率。
我们对196例连续的稳定期COPD患者进行了横断面研究。我们测量了支气管扩张剂（BD）前后的肺功能和呼吸阻抗。根据慢性阻塞性肺疾病全球倡议（GOLD）指南对COPD的严重程度和肺功能异常进行分级。SAD定义为5 Hz和19 Hz时全呼吸阻力差值>正常上限或5 Hz时呼吸系统电抗<正常下限。
该队列中男性占95.9%，平均年龄为66.3岁。预计第1秒用力呼气容积（FEV1）的平均值为56.4%。COPD评估测试（CAT）评分中位数为14分。GOLD 1至4级患者中BD后SAD的患病率分别为14.3%、51.1%、91%和100%。BD后SAD和潮气呼吸时呼气流量受限（EFLT）的发生率分别为62.8%（95%置信区间[CI]，56.1至69.9）和28.1%（95%CI，21.9至34.2）。患有SAD的COPD患者CAT评分更高（15.5对12.8，p<0.01）；肺功能较差（预计FEV1%为46.6%对72.8%，p<0.01）；一氧化碳弥散能力较低（4.8 mmol/min/kPa对5.6 mmol/min/kPa，p<0.01）；肺过度充气（残气量与肺总量百分比预计值：159.7%对129%，p<0.01），6分钟步行距离较短（367.5米对390米，p = 0.02）。
COPD各严重程度均存在SAD。SAD的患病率随疾病严重程度增加。SAD与肺功能差和症状负担较重相关。EFLT提示存在严重SAD。
