Reversibility measured by spirometry in chronic obstructive pulmonary disease (COPD) is defined as an increase in forced expiratory volume in first second (FEV1) that is both more than 12% and 200 mL above the pre-bronchodilator value in response to inhaled bronchodilators. FEV1 only may not fully reverberate the changes caused by reduction in air trapping or hyperinflation. To date, the studies that examined the effect of inhaled bronchodilators (BD) on residual volume (RV) and total lung capacity (TLC) are limited. This study was carried out to assess the differences between flow and volume responses after bronchodilator reversibility testing in patients with different COPD GOLD stages (GOLD stage I to stage IV). Spirometry and whole body plethysmography were done before and 15 min after inhalation of 400 μg salbutamol. Majority (53.3%) of cases were volume responders, 18.7% were flow responders, 20% were flow and volume responders, and 8% were non responders. Significant increase in Δ FEV1% was found in 15% of cases while 55% showed a significant increase in Δ FVC (P= < 0.001). Mean difference of Δ FVC (L) post BD was significantly increased with advancing GOLD stage (P= 0.03). A cutoff point > 20% for Δ RV% had 70% sensitivity and 60% specificity and > 12% for Δ TLC% showed 90% sensitivity and 45% specificity for prediction of clinically significant response to BD based on FEV1. A cutoff point > 18% for Δ RV% had 78% sensitivity and 29% specificity and > 14% for Δ TLC% had 50% sensitivity and 70% specificity for prediction of clinically significant response to BD based on FVC. ΔFEV1 underestimates the true effect of bronchodilators with advancing GOLD stage. Measurement of lung volumes in addition to the standard spirometric indices is recommended when determining bronchodilator response in COPD patients.

中文翻译：

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肺容量在慢性阻塞性肺疾病可逆性评估中的诊断性能

通过肺活量测定法在慢性阻塞性肺疾病（COPD）中测得的可逆性定义为：对吸入的支气管扩张剂的响应，第一秒钟强迫呼气量（FEV1）的增加比支气管扩张剂前值高出12％和200 mL以上。FEV1可能无法完全消除由于空气滞留或过度充气而引起的变化。迄今为止，检查吸入性支气管扩张剂（BD）对残留量（RV）和总肺活量（TLC）的影响的研究是有限的。这项研究的目的是评估不同COPD GOLD期（I期至IV期）患者支气管扩张剂可逆性试验后流量与容量反应之间的差异。吸入400μg沙丁胺醇之前和之后15分钟进行肺活量测定和全身体积描记法。多数（53。3％的病例为容积反应者，18.7％为流量反应者，20％为流量和容积反应者，8％为无反应者。在15％的病例中发现ΔFEV1％显着增加，而55％的病例显示ΔFVC显着增加（P = <0.001）。BD后ΔFVC（L）的平均差异随着GOLD阶段的进展而显着增加（P = 0.03）。ΔRV％的阈值> 20％具有70％的敏感性和60％的特异性，而ΔTLC％的阈值> 12％具有90％的敏感性和45％的特异性，可预测基于FEV1对BD的临床显着反应。ΔRV％的临界点> 18％具有78％的敏感性和29％的特异性，而ΔTLC％的临界点> 14％具有50％的敏感性和70％的特异性，以基于FVC预测对BD的临床显着反应。ΔFEV1低估了GOLD进展期支气管扩张剂的真实作用。