hey everyone it's sarah thread sterner sorry and calm and today we're going to talk about the apt t blood tests and as always whenever you get done watching this youtube video you can access the free quiz that will test you on this content so let's get started what is an apt T well this is a blood test used to assess how fast the blood clots and apt T stands for activated partial thromboplastin time and how we collect this test is we stick a patient's vein we remove some blood put it in a special tube and send it to the lab who will run this test now this test is helpful in determining if maybe a patient has a bleeding disorder because it's going to look at specific clotting factors within this coagulation cascade also this test is helpful for monitoring a patient who is on heparin and we talked about this in depth in our pharmacology review over heparin but again to review heparin is an indirect thrombin inhibitor and why did their own Ben do again thrombin helps play a huge role in that claudine process by turning fibrinogen into fibrin so once we get fibrin on board that helps really give our clot form because it's mesh like strands that allow substances to stick to it we get a clot to help treat whatever is going on usually excessive bleeding so heparin what it does is it is going to enhance the activity of a naturally occurring substance in our body called antithrombin 3 and what this is going to do is this going to prevent the activation of thrombin so we won't be able to have fibrinogen turn into fibrin so we're gonna prolong how long it takes for this patient to form a clot so we're gonna prolong this really coagulation cascade and sometimes if they're really wanting to investigate what's going on with this patient do they have a bleeding disorder they're also probably going to order a PT I in our level as well and we talked about that in the previous video so let's talk about this coagulation cascade because it's gonna help us understand what we're actually looking at in our patient when we're ordering an a PTT so this process is started let's say whenever a patient has maybe some type of external injury that's going to deplete their vascular system of blood or they have some inside injury within that vascular system that's causing some type of issue and we need a cloth there to prevent from depleting that vascular system of blood because if we lose all of our blood and our body for dead we don't have anything to profuse our organs and body and we're not going to survive so the coagulation cascade is made up of three pathways we have the intrinsic pathway the extrinsic pathway and the common pathway and these two pathways intrinsic and extrinsic meet together at this common pathway to actually create a clot and certain clotting factors depending on the pathway will be activated in a certain sequence so we get clot formation and if a PTT is going to check the intrinsic pathway now the intrinsic pathway is activated when we have internal damage or injury within that vascular system the extrinsic pathway it's activated when we have external injury that's going to deplete our vascular system of blood loss now whenever we talked about the pt/inr that was what that blood test was checking that extrinsic and those associated clotting factors with intrinsic this is what the PAP TT is checking so the intrinsic pathway deals with clotting factor 12 11 9 and 8 then it's also going to be looking at the common pathway so really how the intrinsic pathway and the common pathway are working together and when we're talking about the common pathway we're talking about factor 1 2 5 and 10 now let's take what we have learned about the AP TT and apply to what we need to know as the nurse and some things we need to know are the normal ranges and how that applies to heparin therapy so the a PTT is measured in seconds and you may be wondering what's the difference between an a PTT versus a PTT well they measure the same thing they're looking at the intrinsic and the common pathways and how they're working together but the a PTT has an activator agent that is used in it that helps speed up the clotting time so that's why we call it an activated partial thromboplastin time hence why this doesn't have an A in front of it so because of that it's going to give us a more of a narrow range and these ranges vary depending on the lab generally it's about 30 to 40 seconds as your normal range but let's say your patients on heparin you want them a little bit higher than that right because we want to prolong a clot forming so with heparin therapy you want to commit this number to memory you want them about one and a half to two and a half times the normal range for them to be therapeutic and for a PTT the range is about 60 to 70 seconds okay so that wraps up this review over the aPTT blood test and don't forget to access the free quiz that will test you on this content