Urgent! Clarification needed

I am deeply in need for clarification regarding heparin and coumadin therapy and the aPTT, PT and INR. I am completely confused on how aPTT, PT or INR are used to determine if a patient should receive the therapy or not. How do the values of this labs acutally affect administering the medication? I have read, analysed but for some reason, I still don't get it. Please someone help me out.

Thanks
Check out this thread:http://allnurses.com/cardiac-nursing...nr-169759.htmlYou WILL get it!

@HEALTHCARESTUDENT:If the patient is taking Coumadin (sodium warfarin) it is important that you should check the PT or the INR:PT is 10-12 seconds and the therapeutic level should be 1.5-2 x the control value (10-12 seconds)INR is 2 to 3 if i am not mistakenif the patient is taking heparin , it is tha aPTT which you should check:aPTT is 30-45 minutes (control) and to have a therapeutic level it should be within 1.5-2 x the control .hope this will help you.

I think the above poster did a good job, I'll add that anticoagulants can be very dangerous if given too little (can have CVA, MI-what you are trying to avoid) or if you give too much the pt is also at risk for severe uncontrollable bleeding. That is why it is so important to look at the clotting times. They tell you if the drug is just enough, too much, not enough or not effective.Good luck