title: Physiologic correlates of airway collapse in chronic airflow obstruction.
abstract: Forty percent of 89 patients with chronic airflow obstruction (CAO) demonstrated maximum expiration flow-volume (MEFV) patterns consistent with sudden collapse or marked narrowing of large central airways. In contrast, 43 percent of the CAO patients demonstrated a curvilinear (C) pattern; the remainder (17 percent) were intermediate. Volume displacement plethysmography indicated that the airway collapse (AC) pattern was influenced by, but was not solely, a gas compression artifact. Airway collapse patients had more obstruction and hyperinflation than C patients and also had decreased diffusing capacity, absence of density dependence, reduced lung recoil, and no effort dependence of airflow. Bronchodilator administration in AC patients typically produced large reduction of residual volume and increase of vital capacity, with a smaller increase of airflow. These data suggest that AC patients have significant, partially reversible peripheral airways obstruction plus emphysema. Possible determinants of AC include reduced central airway support, increased peripheral resistance, loss of lung recoil, and increased pleural pressures during forced expiration. The MEFV contour appears to evolve from normal to curvilinear to the AC pattern as the severity of airflow obstruction worsens.
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents / Q000627:therapeutic use; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008170:Lung Compliance; D008173:Lung Diseases, Obstructive / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity; D011669:Pulmonary Wedge Pressure; D012129:Respiratory Function Tests
chemical_list: D001993:Bronchodilator Agents; D008688:Methacholine Compounds