DISEASE SEVERITY IS CORRELATED WITH PLASMA CLOTTING AND FIBRINOLYTIC AND KININ-KALLIKREIN ACTIVITY IN NEONATAL RESPIRATORY-DISTRESS SYNDROME

This study was undertaken to determine whether simultaneous activation of clotting, fibrinolysis, and kinin-kallikrein is associated with di sease severity in preterm infants with neonatal respiratory distress s yndrome (RDS), during the first 5 d of life. In the infants with sever e RDS, we found activation of clotting, fibrinolysis, and kinin-kallik rein within 6-12 h of birth, indicated by increased thrombin-antithrom bin III complex formation [22.5 ng/ml versus 1.4 ng/ml (median values) in the mild/moderate RDS infants, p < 0.001], increased tissue-type p lasminogen activator plasma concentrations [5.1 ng/ml versus 2.6 ng/ml (median values) in the mild/moderate RDS infants, p < 0.01], and incr eased plasma kallikrein activity [198% versus 189% of maximal activate d human plasma (median values) in the mild/ moderate infants, p < 0.01 ], respectively. Thrombin generation, tissue-type plasminogen activato r release, and kallikrein activity did not change significantly in the severe RDS group throughout the study. In these infants, kallikrein a ctivity was accompanied by lower values of plasma kallikrein inhibitor y activity. Activation of clotting, fibrinolysis, and kinin-kallikrein was accompanied with a transient decrease of the neutrophil count and a steady decrease of the platelet count in the severe RDS group. The studied parameters of clotting and fibrinolytic and kinin-kallikrein a ctivation were significantly correlated with continuous measures of RD S severity. We, therefore, suggest that this activation process likely contributes to respiratory insufficiency in neonatal RDS.