Ferrari da Cruz Thaís, Rufino Rogerio, Lopes Agnaldo José, Noronha Arnaldo, Medeiros Anselmo Fernando, Henrique da Costa Cláudia
Pneumology Department, Pedro Ernesto Hospital of State University of Rio de Janeiro, Rio de Janeiro, PR, Brazil.
Int J Chron Obstruct Pulmon Dis. 2020 Sep 24;15:2267-2274. doi: 10.2147/COPD.S262418. eCollection 2020.
Small airways are not evaluated with traditional pulmonary function tests. The aim of this study was to evaluate the small airways in patients with chronic obstructive pulmonary disease (COPD) with a nitrogen washout test and to verify whether there is a difference between patients with COPD due to smoking and those with COPD due to alpha-1 antitrypsin mutation.
Sixteen patients with mutation in the gene and 45 patients with no mutation were included in this cross-sectional study. All pulmonary function tests, including the single breath nitrogen washout test, were performed for all patients and alpha-1 antitrypsin dosage was assessed with immunonephelometry.
A comparison of patients with COPD due to smoking and those with COPD due to smoking and mutation revealed a significant difference in closure volume (%), which was the poorest in the mutation group. In the group with COPD and mutation, there was an inverse correlation between smoking and closure volume (%). We also verified that similar to forced expiratory volume in the first second (FEV1), the phase III slope (%) and ΔN2 750-1250 mL (%) could be used to differentiate the severity of airflow limitation.
Our results suggest that both variables, phase III slope and the ΔN2 750-1250 mL (%), could be related to COPD severity. Therefore, alterations at the distribution of the location of the emphysema could alter the results of closer volume and that the nitrogen washout test is more sensitive when compared to traditional pulmonary function test in evaluating COPD patients.
传统肺功能测试无法评估小气道。本研究旨在通过氮洗脱试验评估慢性阻塞性肺疾病（COPD）患者的小气道，并验证吸烟所致COPD患者与α-1抗胰蛋白酶突变所致COPD患者之间是否存在差异。
本横断面研究纳入了16名基因发生突变的患者和45名未发生突变的患者。对所有患者均进行了包括单次呼吸氮洗脱试验在内的所有肺功能测试，并采用免疫比浊法评估α-1抗胰蛋白酶剂量。
对吸烟所致COPD患者与吸烟且发生突变所致COPD患者进行比较，发现闭合容积（%）存在显著差异，突变组的闭合容积最差。在患有COPD且发生突变的组中，吸烟与闭合容积（%）呈负相关。我们还证实，与第一秒用力呼气容积（FEV1）类似，III期斜率（%）和ΔN2 750 - 1250 mL（%）可用于区分气流受限的严重程度。
我们的结果表明，III期斜率和ΔN2 750 - 1250 mL（%）这两个变量均可能与COPD严重程度相关。因此，肺气肿位置分布的改变可能会改变闭合容积的结果，并且与传统肺功能测试相比，氮洗脱试验在评估COPD患者时更敏感。
