Small Airway Constriction and Closure after Induced Intravascular Platelet Aggregation

Abstract

The function of the peripheral airways after intravascular platelet aggregation induced by i.v. infusions of collagen in open chest anesthetized cats, ventilated with constant tidal volume, was studied. Lung compliance was examined under static conditions (stat CL) and under dynamic conditions (dyn CL) at ventilation frequencies of 5, 24 and 50/min. In the control situation dyn CL 24 was approximately 90% of stat CL. Collagen infusions resulted in a pronounced frequency-dependence of lung compliance. When dyn CL 24 had decreased by approximately 40%, a reduction in stat CL was also detected. When dyn CL 24 decreased even more, a concurrent reduction stat CL was evident. The initial event after induced intravascular platelet aggregation is apparently small airway constriction. With more pronounced changes, airway closure and reduction in lung volume occurs. These functional changes in peripheral airways may result in the impaired gas exchange known to occur after intravascular platelet aggregation.