Accuracy of aPTT values drawn from heparinized arterial lines in children.

The practice of withdrawing blood samples for activated partial thromboplastin time (aPTT) analysis from heparinized arterial lines may result in inaccurate aPTT values. The purpose of this study was to compare venous aPTT values to aPTT values withdrawn from heparinized arterial lines in children. The author suggests a method of obtaining accurate aPTT values using a specified discard volume.