Small-Airway Dynamics under Experimental Conditions

The in vivo response of airways ≤1.0 mm in diameter to increased air volumes, gas mixtures, anesthetics, and various ventilatory states was studied. Bronchodilatation was evident with 100% oxygen and with halothane anesthesia. Unilateral liquid contrast bronchography produced small-airway obstruction without resting dimensional changes. No measurable small-airway diameter changes were seen during hypoxia, hypercapnea, and hypocapnea.