Lack of correlation between heparin dose and standard clinical monitoring tests in treatment with unfractionated heparin in critically III children

The activated partial thromboplastin time (aPTT) and anti-Xa activity are used for monitoring unfractionated heparin (UFH) therapy in children and may not be optimal. Objective: Determine correlations of aPTT, anti-Xa and UFH dose in children. Single centre prospective cohort study in children receiving UFH. The aPTT and anti-Xa results from routine coagulation monitoring were collected. Thirty-nine children (median age 18 days) were enrolled. There was no relationship between aPTT and UFH dose (r2=0.12) or anti-Xa and UFH dose (r2=0.03) or aPTT and anti-Xa (r2=0.22). aPTT and anti-Xa do not accurately monitor UFH therapy in children.