Heparin gtt - anti-xa vs. PTT

So I had an interesting case today where I got called from lab with a critical PTT (>200) but the anti-xa, which we use to monitor heparin gtts, was therapeutic. My understanding is anti-xa measures more the levels of heparin in the blood and PTT is a marker of anticoagulation levels of the blood, and some institutions use PTT and some use anti-xa. PTT, or preferably aPTT, makes more sense to me, but some of what I'm reading suggests the results can be misleading. I guess my questions are these:

1) What lab test is used at your facility?

2) Would you feel comfortable continuing a heparin gtt on a pt with a critical PTT? Assume no major signs of bleeding and VSS otherwise.

[mh356, BSN, RN, EMT-B]

We use PTT on all our Heparin gtt patients. Do you use a nomogram-something that tells you how to run the gtt depending on how high or low the PTT is? Our facility says PTT; we don't even check the anti-xa.

[Anna Flaxis, BSN, RN]

1) PTT/aPTT

2) No.

While the anti-xa measures the amount of Heparin in the bloodstream, the aPTT measure's the patient's *response*, which will vary from person to person due to lots of different things such as renal insufficiency, for instance. Since it's the therapeutic response we're after, I would be more comfortable going by the aPTT.

But there is much I don't know, so if there is something I'm missing, feel free to enlighten me.

[#1ME]

We go by the Ptt at my hospital. We having a protocol that we follow. The rate is determined by the Ptt, meaning we wii decrease/increase depending upon the Ptt results. You should check your policy there, and if you still don't feel comfortable, call the doc and ask if he wants to continue

[theVaway]

PTT is what we use to monitor.

[talaxandra]

We only use anti-Xa levels when they're unsure about enoxaparin dosing. For heparin infusions it's APTT all the way.

[ckh23, BSN, RN]

1. PTT

2. No