The progress of chronic airway obstruction in relation to measurements of airway resistance and lung elastic recoil.

Sequential measurements of airway resistance, elastic recoil of the lungs, and forced ex­ piratory flow during a three-year period in 34 patients with severe chronic obstructive lung disease were correlated with clinical and physiologic findings. Eight patients with decreased lung recoil (group A) had clinical and physiologic features similar to those previ­ ously described in type A or emphysematous patients, and 8 patients with increased air­ way resistance (group, B) were similar in many respects to type B or bronchial patients. Neither of these groups could be clearly differentiated clinically from a group of 16 pa­ tients with increased airway resistance and decreased lung recoil (group C). Changes in forced expiratory flow were related to changes in airway resistance in patients of group A but not in patients of any other group. Changes in lung recoil could not be related to changes in forced expiratory flow. The rate of decline of forced expiratory flow was greatest in group C, and 6 of the 7 patients who died were in this group. Two patients with marked impairment of expiratory flow but with normal values for airway resistance and lung recoil (group D) showed a continued decline in forced expiratory flow. These findings emphasize the need for repeated measurements of airway resistance and lung recoil to assess prognosis in patients with chronic obstructive lung disease.