Intravascular platelet aggregation and acute respiratory insufficiency

Abstract

Respiratory effects of long-lasting episodes of intravascular platelet aggregation have been studied in cats. Animals in 1 group had the chest opened and were given mechanical ventilation with a constant tidal volume. Animals of another group were breathing spontaneously. Platelet aggregation was induced by intravenous infusion (for 1 hr) of a suspension of collagen fibrils. Such infusions caused acute respiratory distress in both groups. Severe arterial hypoxemia and rapid breathing as well as constriction of airways and lung vessels occurred. Most of these changes were reversed within 2 hr after collagen infusion had ended. Deep lung inflations markedly improved lung function. It is concluded that an acute, but reversible pulmonary insufficiency might be caused by pulmonary microembolization due to intravascular platelet aggregation. The arterial hypoxemia is suggested to be caused by disturbances in the ventilation-perfusion ratio secondary to airway constriction and closure. The present findings also imply that besides platelet aggregation, some additional factors are necessary for irreversible or progressive respiratory insufficiency to develop.