Joseph Wrenn, a 67-year-old male with a history of hypertension and hyperlipidemia, presented to the emergency department experiencing sudden sharp pain and swelling in his left calf. He reported the pain started two days prior and had progressively worsened, making it difficult to walk. Joseph denied any recent trauma, infection, or prolonged immobilization. He takes lisinopril for hypertension and simvastatin for hyperlipidemia. He is allergic to penicillin and has no prior history of blood clots or bleeding disorders.
Upon examination, Joseph's left calf was tender, swollen, and warm to the touch compared to the right. Homan's sign (increased pain with dorsiflexion of the foot) was positive. A Doppler ultrasound confirmed DVT in the left popliteal vein.
Joseph's initial laboratory tests showed:
- Platelet count: 250,000 uL (within normal range)
- PTT: 28 seconds (within normal range)
Based on the clinical presentation and imaging confirmation, Joseph was diagnosed with DVT and started on a continuous IV heparin drip (UH) to prevent further clot formation and promote clot resolution.
History of Present Illness
Five days after starting heparin, Joseph reported experiencing new-onset chills, low-grade fever, and worsening pain in his calf. A repeat physical examination revealed the presence of scattered petechiae on his legs and abdomen, which were not present previously. A blood test showed a significant drop in his platelet count. Platelet count: 80,000 uL (thrombocytopenia).
Assessment/Screening
During routine assessments, nurses should be vigilant for signs and symptoms suggestive of HIT, particularly in patients receiving heparin therapy. Here are key elements to consider:
Onset: New-onset or worsening signs and symptoms of thrombosis 4-14 days after starting heparin.
Bleeding: Skin bleeding, such as petechiae, purpura, or oozing from wounds or mucous membranes.
Fever: Low-grade fever may occur.
Thrombocytopenia: A significant drop in platelet count (at least 50%) compared to baseline.
Precautions for HIT
History review: Nurses should inquire about any allergies to heparin or other medications and document any previous episodes of HIT.
Baseline platelet count: Measure the platelet count before starting heparin and monitor it regularly during therapy.
Heparin administration technique: Use an aseptic technique and avoid using heparin flushes in arterial lines.
Screening for HIT
4T Score: A scoring system based on clinical features (thrombocytopenia, timing of onset, type of reaction, and other factors) can help assess the pre-test probability of HIT.
HIT antibody test: A specific blood test can confirm the presence of antibodies against heparin-platelet complexes, supporting the diagnosis of HIT.
Plan of Care
Suspecting HIT, the heparin drip was immediately discontinued. A HIT antibody test was ordered, and alternative anticoagulation therapy was considered. Based on the positive HIT test result, the plan of care included:
- Discontinuation of heparin: All forms of heparin were stopped immediately to prevent further platelet destruction.
- Alternative anticoagulation: Fondaparinux, a medication not affected by HIT, was initiated to prevent new clot formation.
- Platelet count monitoring: Joseph's platelet count was monitored closely to track its recovery.
- Supportive care: Medications were administered to manage Joseph's fever and chills.
Follow Up Evaluation
John's platelet count increased within 24 hours of stopping heparin and improved gradually over the next few days. The HIT antibody test confirmed the presence of HIT antibodies, supporting the diagnosis. Fondaparinux was continued for seven days, followed by a switch to warfarin, a vitamin K antagonist, for long-term anticoagulation therapy. John was educated about HIT and the importance of avoiding heparin-based medications in the future. He was discharged home after showing clinical improvement and tolerating the new medication regimen.
