Hi George! Our HCO is wanting to change unfractionated heparin (UFH) monitoring to the anti-Xa test from the partial thromboplastin time (PTT). The research supports decreased lenghth of stay, quicker theurapeutic range achievement and improved patient safety monitoring with anti-Xa, as many patients may appear theurapeutic with the PTT but may actually be under or over anticoagulated. Our physicians seem to know nothing about anti-Xa as well as few of our lab co-workers and do not see the need to change. What are your thoughts? Julia Witt.
Hello, Julia, and thank you for your question. There is no question that the chromogenic anti-Xa heparin assay is more reliable than the PTT, in fact, the anti-Xa is the reference method for the ex vivo “Brill-Edwards” curve that we use to establish the PTT therapeutic range. It is also true that despite initial costs, anti-Xa testing produces fewer instances of incorrect dosing and thus few secondary adverse events.
I suggest a demonstration project as was performed at a tertiary care institution in my town. Run parallel PTTs and anti-Xas on all UFH specimens for a few days and graph the results. The scatter that appears on a linear graph should convince everyone that the PTT is unreliable. You may want to show the data to your ICU nursing staff as well as your surgeons and physicians, as they are the ones who have to regularly adjust heparin drip rates on the basis of the PTT. I will be eager to see how others have managed this change.
All good information to have and I appreciate the articles!
All good information to have and I appreciate the articles! The main challenges cited by the committee is physician and nursing education and knowing dosing will be handled appropriately.
I just discovered another article that cited one of our arti
I just discovered another article that cited one of our articles on your issue, Julia. In the Annals of Pharmacotherapy 2011;45:861-8. The article was on APTT vs Anti- Xa heparin assay in monitoring UFH by continuous intravenous infusion. They concluded that monitoring intravenous UFH infusions with the anti-Xa compared to the APTT achieves therapeutic anticoagulation more rapidly, maintains the values within the goal range for a longer time, and requires fewer adjustments in dosage and repeated tests. Good article.
Julia, you might want to read a couple of articles I publish
Julia, you might want to read a couple of articles I published on this issue. We switched immediately back in 2006 in the military. The articles are:
McGlasson DL, Kaczor DA, Krasuski RA, Campbell CL, Kostur MR, Adinaro JT. Effect of Pre-Analytical Variables on the Anti-FXa Chromogenic Assay when Monitoring Heparin Anticoagulation. Clin Lab Sci 2005;18(3):145.
McGlasson DL. Monitoring Unfractionated Heparin and Low Molecular Weight Heparin Anticoagulation with an anti-Xa Chromogenic Assay using a Single Calibration Curve. Clin Lab Sci 2005;18(3):148.