HEPARIN-THERAPY IN PEDIATRIC-PATIENTS - A PROSPECTIVE COHORT STUDY

Current guidelines for heparin therapy in pediatric patients have been extrapolated from trials in adult patients without rigorous evaluatio n of efficacy and safety. We prospectively monitored consecutive pedia tric patients receiving systemic doses of heparin over 10 mo at one in stitution using a predetermined nomogram to monitor maintenance therap y. Sixty-five consecutive children; 38 males and 27 females, received systemic doses of heparin. Thirty children had deep venous thrombosis and/or pulmonary embolism; 11 had arterial thrombi, most frequently af ter diagnostic angiography, and the remaining 24 received heparin prop hylactically, for congenital heart disease. Twenty-nine (45%) of the 6 5 patients were less than 1 y of age and 22 (34%) were 10 y or older. Congenital heart disease was the predominant diagnosis under 1 y and d eep venous thrombosis in older children. After a bolus dose of 50 U/kg , 39% of children (n = 30) achieved a minimal level activated partial thromboplastin time (APTT). Sixty-eight percent of children achieved a minimal level APTT by 24 h and 81% by 48 h. For all 65 children, APTT values were within the therapeutic range 43% of the time. APTT values outside the therapeutic range were twice as likely to be low as high. The average amount of heparin required to maintain therapeutic APTT v alues for children was 22 U/kg/h: 28 U/kg/h for infants <1 y and 20 U/ kg/h for the rest. Bleeding was rare (2%) and mild. Documented recurre nt thrombotic disease was more common (7%) with associated morbidity. In summary, a commonly used protocol for administration of heparin to children was rigorously evaluated and shown to provide insufficient am ounts of heparin in the first days of treatment. Average requirements of heparin per kilogram per hour were determined and will form the bas es of future studies.