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Difficulty: Very hardPharmacological Therapies

A practical nurse (PN) is reviewing morning laboratory results for a client receiving a continuous intravenous heparin infusion. The client also began oral warfarin therapy 4848 hours ago. The client's baseline platelet count on admission was 250,000/mm3250,000/\text{mm}^3. The current laboratory results are as follows:

Laboratory TestCurrent ResultReference/Control
International Normalized Ratio (INR)1.41.42.02.0 - 3.03.0 (Target)
Activated partial thromboplastin time (aPTT)6868 seconds3030 seconds (Control)
Platelet count82,000/mm382,000/\text{mm}^3150,000150,000 - 400,000/mm3400,000/\text{mm}^3

The PN is preparing to administer the scheduled morning dose of oral warfarin. Based on these findings, which of the following is the priority action by the PN?

  1. A
    Administer the scheduled warfarin because the client's INR remains below the therapeutic target.
  2. Withhold the scheduled warfarin and immediately notify the registered nurse (RN) of the platelet count.Answer
  3. C
    Administer the warfarin and reinforce teaching about using a soft-bristle toothbrush due to the low platelets.
  4. D
    Document the laboratory results in the electronic health record and continue routine clinical monitoring.

Answer

Withhold the scheduled warfarin and immediately notify the registered nurse (RN) of the platelet count.
The correct action is to withhold the warfarin and notify the RN immediately. The significant drop in platelets (greater than 50%50\% from baseline) indicates a high probability of Heparin-Induced Thrombocytopenia (HIT), a paradoxical, life-threatening clotting disorder caused by heparin exposure. In acute HIT, administering oral warfarin is strictly contraindicated because it rapidly depletes Protein C, drastically increasing the risk of microvascular thrombosis and venous limb gangrene. The practical nurse must prioritize client safety by withholding the medication and escalating this critical laboratory finding so the healthcare team can halt the heparin infusion and initiate a non-heparin anticoagulant.

Step-by-Step Solution

1
Analyze the INR result.
An INR of 1.41.4 is expected after 4848 hours of warfarin therapy, as it typically takes 33 to 55 days to reach the therapeutic range of 2.02.0 to 3.03.0.
Understanding the expected timeline for oral anticoagulants prevents inappropriate dosage adjustments.
2
Analyze the aPTT result.
An aPTT of 6868 seconds is within the normal therapeutic range for a continuous heparin infusion (typically 1.51.5 to 2.52.5 times the control value).
Verifying that the heparin infusion is therapeutic rules out overt toxicity as the primary issue.
3
Analyze the platelet count trend.
The platelet count has dropped from 250,000/mm3250,000/\text{mm}^3 to 82,000/mm382,000/\text{mm}^3, representing a decrease of more than 50%50\%.
A severe drop in platelets during heparin therapy is the hallmark sign of Heparin-Induced Thrombocytopenia (HIT).
4
Determine the safest clinical action based on the LPN scope of practice.
The PN must withhold the warfarin and immediately escalate the critical findings to the RN.
HIT is a life-threatening complication. Warfarin is contraindicated in acute HIT due to the high risk of venous limb gangrene, and the heparin infusion must be halted by the RN.

Key Concept

Heparin-Induced Thrombocytopenia (HIT) and Anticoagulant Safety

Alternative Method

While calculating the exact percentage drop in platelets is helpful, simply recognizing that the platelet count has plummeted from a normal baseline to well below the normal range during heparin therapy is sufficient to flag the finding as a critical adverse reaction requiring immediate escalation.
Estimated Time:2m 0s
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Topics

Pharmacological Therapies

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