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Point-of-care INR (POC INR) meters can provide a safe and effective method for monitoring oral vitamin K antagonists (VKAs) in children. Stollery Children's Hospital has a large POC INR meter loan program for children requiring oral VKAs. Our protocol requires that POC INR results be compared to the standard laboratory INR for each child on several consecutive tests to ensure accuracy of CoaguChek XS (Roche Diagnostics, Basel Switzerland) meter. It was the objective of the study to determine the accuracy of the CoaguChek XS by comparing whole blood INR results from the CoaguChek XS to plasma INR results from the standard laboratory in children. POC INR meter validations were performed on plasma samples from two time points from 62 children receiving warfarin by drawing a venous blood sample for laboratory prothrombin (PT)-INR measurements and simultaneous INR determinations using the POC-INR meter. Agreement between CoaguChek XS INR and laboratory INR was assessed using Bland-Altman plots. Bland-Altman's 95% limits of agreement were 0.11 (-0.20; 0.42) and 0.13 (-0.22; 0.48) at the two time points, respectively. In conclusion, the CoaguChek XS meter appraisal generates an accurate and precise INR measure in children when compared to laboratory INR test results.

Increasing the starting dose of enoxaparin results in the early achievement of therapeutic anti-factor Xa levels in children receiving enoxaparin which is critical for effective therapy and the reduction of venipunctures. The aim of this study was: i) to determine the enoxaparin dose required to achieve therapeutic anti-factor Xa levels in infants and children, and ii) to establish whether increasing the starting dose of enoxaparin influenced the time required to reach the therapeutic range and the number of venipunctures required for dose-adjustment, and iii) the radiographic outcome of the thrombosis, where applicable. A retrospective chart review of children who received enoxaparin was carried out at the Stollery Children's Hospital, Edmonton, Alberta, Canada. Patients treated with standard-dose enoxaparin (1.5 mg/kg for children < or =3 months of age, 1.0 mg/kg for children > or =3 months of age), were compared with children who received a higher initial starting dose of enoxaparin (1.7 mg/kg for children > or =3 months of age, 1.2 mg/kg for children > or =3 months of age). Infants <3 months required an enoxaparin dose of 1.83 mg/kg, and those who received an increased initial enoxaparin dose resulted in faster attainment of therapeutic anti-factor Xa levels requiring significantly fewer venipunctures. Similarly, infants > or =3-12 months, 1-5 years, and 6-18 years, require enoxaparin 1.48 mg/kg, 1.23 mg/kg and 1.13 mg/kg, respectively, in order to achieve a therapeutic anti-factor Xa level. In conclusion, increasing the starting dose of enoxaparin may result in more rapid attainment of therapeutic range with fewer venipunctures, dose adjustments, and without an increase in adverse events.

Measurement of the partial thromboplastin time performed in combination with that of the anti-factor Xa level can be used to assist health practitioners to identify unfractionated heparin contamination of anti-factor Xa levels drawn from central venous catheters. A careful sampling technique may minimize heparin contamination in central venous catheter blood samples.