早期呼吸道阻塞多发生在内径小于2mm的小气道,一般的肺功能检查方法难于对小气道阻塞性疾患作出早期诊断。对这一问题,国外作了广泛研究,目前已有闭合气量、流速一容量曲线、频率依赖的肺顺应性等测定,可以用来早期发现小气道结构或功能上的异常。国内近年来也开展了闭合气量测定。据报告,这种方法较灵敏而简便。然而不少单位因限于测定装置而不能开展。1975年Morris Early airway occlusion occurs mostly in small airways with an internal diameter of less than 2 mm. General pulmonary function tests are difficult to make early diagnosis of small airway obstructive disease. To this problem, extensive research has been done abroad. At present, closed-air volume, velocity-volume curve, frequency-dependent lung compliance and the like can be used to detect early small airway structures or functional abnormalities. In recent years, China has also carried out a closed gas measurement. It is reported that this method is more sensitive and simple. However, many units can not be operated due to the limitation of the measuring apparatus. 1975 Morris