An INR above 4 to 5 or significant bleeding requires holding warfarin and notifying the provider immediately.
Before you read
Test yourself first: 3 questions
Question 1 of 3
A client receiving a continuous heparin infusion has an aPTT of 120 seconds (control 30 seconds). What is the nurse's priority action?
Answer: B. An aPTT of 120 seconds is well above the therapeutic target of 1.5 to 2.5 times the control (45 to 75 seconds here), indicating excessive anticoagulation and high bleeding risk. The priority is to stop or reduce the infusion per protocol and notify the provider. Increasing the rate would worsen the danger.
Question 2 of 3
A client is admitted with a pulmonary embolism and started on a heparin infusion. The nurse understands that the desired aPTT range for therapeutic anticoagulation is approximately:
Answer: B. Therapeutic unfractionated heparin maintains an aPTT of about 1.5 to 2.5 times the control value, commonly cited as roughly 60 to 80 seconds when the control is around 30 seconds. Values near the control indicate subtherapeutic dosing, and values much higher than this range indicate excessive anticoagulation.
Question 3 of 3
A nurse is reviewing new prescriptions for a pregnant client who requires anticoagulation. Which medication is contraindicated because it crosses the placenta and is teratogenic?
Answer: C. Warfarin crosses the placenta and is teratogenic, causing fetal warfarin syndrome, so it is contraindicated in pregnancy. Heparin and the low-molecular-weight heparins enoxaparin and dalteparin do not cross the placenta and are the preferred anticoagulants during pregnancy.
Keep the streak going with more questions like these, each with a full rationale.
What is coagulation studies (pt/inr/aptt)?
PT and INR monitor warfarin, while aPTT monitors heparin. A useful memory aid is PT-warfarin and PTT-heparin, where the longer drug name pairs with the longer test name.
Key points to remember
- INR standardizes the PT and is the primary value used to dose warfarin.
- A therapeutic INR for most anticoagulation goals is 2.0 to 3.0.
- aPTT guides heparin dosing, with a therapeutic target of roughly 1.5 to 2.5 times the control.
- Vitamin K is the antidote for warfarin and reverses an elevated INR.
- Protamine sulfate is the antidote for heparin and reverses an elevated aPTT.
- Low molecular weight heparin generally does not require routine aPTT monitoring.
Nursing priorities
- Assess for bleeding in the gums, urine, stool, IV sites, and for bruising before and during therapy.
- Verify the INR or aPTT is within target before giving the next anticoagulant dose.
- Hold the anticoagulant and notify the provider when values exceed the therapeutic range.
- Keep the appropriate antidote available and know which reverses each drug.
- Implement bleeding precautions such as soft toothbrush and fall prevention.
Labs & values
Patient teaching
- Keep vitamin K intake consistent rather than suddenly changing leafy green vegetable consumption while on warfarin.
- Report any unusual bleeding, dark stools, or pink urine and attend all lab monitoring appointments.
Red flags: report now
- An INR above 4 to 5 or significant bleeding requires holding warfarin and notifying the provider immediately.
- Signs of internal bleeding such as severe headache, abdominal pain, or hypotension are emergencies.
- Never give a routine anticoagulant dose without checking the most recent coagulation value.
References
Clinical references for this topic
