Implication of Acute Lung Injury in the Pathogenesis of Hemostatic Disorders

Abstract

Objective: to estimate the implication of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in the pathogenesis of hemostatic disorders, by studying the arteriovenous difference between hemostatic parameters. Subjects and methods. Venous and arterial hemostases were studied in 95 patients treated in an intensive care unit. Three groups were identified, which included: 1) 50 patients with an uncomplicated postoperative period and without any organ incompetence; 2) 21 patients with primary lung injury; and 3) 24 patients with secondary lung injury. Groups 2 and 3 patients were divided according to the degree of acute lung injury. Results. The arterial blood of patients with the uncomplicated postoperative period shows a lower coagulability than venous blood; there is no arteriovenous difference between fibrinolytic activity and platelet levels. The coagulation activity of arterial blood increases in primary lung injury; the higher fibrinolytic activity of arterial blood is a compensatory mechanism in moderate lung injury. Later on, in evolving ARDS, the hemostasiological balance between the pulmonary and systemic circulations impairs; disseminated intravascular coagulation (DIC) develops in both arterial and venous beds. Venous blood coagulability increases in secondary lung injury. By regulating the hemostatic system, the lungs produce a lower coagulation activity of and a higher fibrinolytic activity of arterial blood in ALI. With the development of ARDS, this function triples and DIC spreads to the arterial bed. Conclusion. The lung maintains the hemostasiological balance between the pulmonary and systemic circulations, by holding activated platelets and by enhancing the fibrinolytic activity of the blood flowing from it. The inducer of DIC is the suppressed fibrinolysis of the lesser circulation in patients with primary lung injury and hyperco-agulation in the greater circulation in patients with secondary lung injury. Key words: acute lung injury, arteriovenous hemostasis difference, disseminated intravascular coagulation.