Stănescu Dan, Veriter Claude
Pulmonary Laboratory and Division, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Respiration. 2004 Jul-Aug;71(4):348-52. doi: 10.1159/000079638.
A decreased forced expiratory volume in 1 s/vital capacity (FEV(1)/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV(1)/VC and total lung capacity (TLC) and reflects obstruction of small airways.
To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls.
We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 +/- 7.8 years) and 36 age-matched subjects with normal lung function (42.8 +/- 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DL(CO)).
SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV(1)/VC ratio and TLC were comparable in the two groups. However, FEV(1), VC, DL(CO), and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure.
Our results suggest that a normal FEV(1)/VC ratio does not exclude airway obstruction. A decrease of FEV(1), provided TLC is normal, reflects small airway obstruction.
1秒用力呼气容积/肺活量（FEV(1)/VC）比值降低是气道阻塞定义的标志。我们最近提出一种肺功能模式，我们称之为小气道综合征（SAOS），其FEV(1)/VC和肺总量（TLC）正常，但反映小气道阻塞。
为证实我们的假设，我们测量并比较了SAOS受试者和匹配对照组的肺功能测试，包括最大呼气流量率（MEFR），这是气道阻塞的敏感指标。
我们选择了12名具有SAOS模式但无慢性肺部或心脏疾病的受试者（平均年龄：40.7±7.8岁）和36名年龄匹配的肺功能正常的受试者（42.8±6.3岁）。我们测量了静态和动态肺容积、MEFR和肺弥散能力（DL(CO)）。
SAOS受试者吸烟量更大（p<0.05），体重指数低于对照组受试者（p<0.01）。两组的FEV(1)/VC比值和TLC相当。然而，SAOS组的FEV(1)、VC、DL(CO)和MEFR较低，残气量（RV）和RV/TLC比值较高（p<0.05）。此外，SAOS组的MEFR曲线向左移位，斜率无变化，提示气道过早关闭。
我们的结果表明，FEV(1)/VC比值正常并不排除气道阻塞。在TLC正常的情况下，FEV(1)降低反映小气道阻塞。
