Boulet L P, Turcotte H, Hudon C, Carrier G, Maltais F
Université Laval, Sainte-Foy, Canada.
Can Respir J. 1998 Jul-Aug;5(4):270-7. doi: 10.1155/1998/780739.
To compare clinical features, pulmonary function and high-resolution computed chest tomography (HRCT) findings of asthmatic patients with a component of incomplete reversibility of airflow obstruction (AIRAO) with those of patients with smoking-induced chronic obstructive pulmonary disease (COPD).
Thirteen patients with COPD (six males and seven females, mean age 59 years, mean smoking 50.5 pack-years) and 14 patients with AIRAO (six males and eight females, mean age 52 years) despite optimal treatment, with no significant smoking history (mean 1.5 pack-years) and no significant environmental exposure or any other respiratory disease, were studied. Patients had respiratory questionnaires, pulmonary function tests, allergy skin-prick tests and an HRCT to evaluate possible parenchymal or bronchial abnormalities. Eight patients in each group also had exercise tests. All patients were stable at the time of the study.
As expected, atopy was more prevalent in AIRAO (n=13) than in COPD (n=1) patients. Mean forced expiratory volume in 1 s (FEV1) and forced vital capacity (percentage of predicted value) were 39% and 61%, respectively, in COPD patients and 49% and 71%, respectively, in AIRAO patients; FEV1 improved by 18% in COPD patients and and by 22% in AIRAO patients after use of inhaled salbutamol. Mean functional residual capacity was greater in COPD patients than in AIRAO patients (178% versus 144% of the predicted value), while the mean carbon monoxide diffusing capacity of the lungs (DLCO) was lower in COPD patients than in AIRAO patients (62% versus 89% of the predicted value). Exercise tolerance was similar in both groups, as were postexercise changes in arterial oxygen pressure (PaO2). Emphysematous changes were observed in COPD patients and AIRAO patients who had evaluable HRCTs (10 versus two patients, although very mild in asthma), bronchial dilations (zero versus six patients), bronchial wall thickening (two versus eight patients) and an acinar pattern (one versus five patients). Mean thickness of the large airway wall to outer diameter (intermediary bronchus) ratio was 0.176 in COPD and 0.183 in AIRAO (P>0.05).
Asthma may lead to physiological features similar to COPD but may be distinguished by demonstrating a preserved DLCO and a higher ratio of airway to parenchymal abnormalities on HRCT scan.
比较气流受限不完全可逆（AIRAO）型哮喘患者与吸烟所致慢性阻塞性肺疾病（COPD）患者的临床特征、肺功能及高分辨率胸部计算机断层扫描（HRCT）表现。
研究了13例COPD患者（6例男性，7例女性，平均年龄59岁，平均吸烟史50.5包年）和14例AIRAO患者（6例男性，8例女性，平均年龄52岁），这些AIRAO患者尽管接受了最佳治疗，但无显著吸烟史（平均1.5包年），无显著环境暴露或其他任何呼吸系统疾病。患者接受了呼吸问卷、肺功能测试、变应原皮肤点刺试验及HRCT检查，以评估可能存在的肺实质或支气管异常。每组8例患者还进行了运动试验。研究时所有患者病情均稳定。
正如预期，特应性在AIRAO患者（n = 13）中比在COPD患者（n = 1）中更常见。COPD患者的第1秒用力呼气容积（FEV1）和用力肺活量（预测值百分比）平均值分别为39%和61%，AIRAO患者分别为49%和71%；吸入沙丁胺醇后，COPD患者的FEV1改善了18%，AIRAO患者改善了22%。COPD患者的平均功能残气量高于AIRAO患者（分别为预测值的178%和144%），而COPD患者的肺一氧化碳弥散量（DLCO）低于AIRAO患者（分别为预测值的62%和89%）。两组的运动耐力相似，运动后动脉血氧分压（PaO2）的变化也相似。在可进行HRCT评估的COPD患者和AIRAO患者中观察到肺气肿改变（分别为10例和2例，尽管哮喘患者中非常轻微）、支气管扩张（分别为0例和6例）、支气管壁增厚（分别为2例和8例）及腺泡样改变（分别为1例和5例）。COPD患者大气道壁厚度与外径（中间支气管）比值的平均值为0.176，AIRAO患者为0.183（P>0.05）。
哮喘可能导致与COPD相似的生理特征，但可通过HRCT扫描显示DLCO保留及气道与肺实质异常比例更高来加以区分。
