Antithrombin-III substitution in preterm infants--effect on intracranial hemorrhage and coagulation parameters.

In preterm infants the activity of antithrombin III (AT-III), the main inhibitor of thrombin, is reduced depending on gestational age and complications such as sepsis or respiratory distress syndrome. Babies with low levels of AT-III have been shown to have a higher mortality and an increased incidence of intracranial hemorrhage. In our study we tried to show the effect of early AT-III substitution on coagulation parameters and the incidence of intraventricular hemorrhage (IVH). One hundred three preterm infants at a gestational age of 25-32 weeks (mean 28.9 weeks; birth weight 600-2,170 g, mean 1,285 g) received AT-III concentrate at a single dosage of 50-200 IU/kg on the day of birth and subsequently only in case of a new decrease below an AT-III activity of 50%. We measured AT-III activity, Quick's prothrombin time (PT), partial thromboplastin time (PTT) and platelet count on the day of birth, and after 1 and 5-9 days in 25 patients. AT-III activity before substitution was lower than described for term infants (20-72%, mean 40%). Within the first week of life Quick's PT and PTT reached almost term values. No significant differences of the platelet count were found within the first week of life. The incidence of IVH was lower than in current epidemiologic studies: in only 13% of the study patients. Six percent of the infants had IVH grade I, 3% grade II, 4% grade III and none grade IV. Therefore, in preterm infants AT-III substitution may reduce the incidence and progression of intracranial hemorrhage.