NR 567 Week 7 ICU Anticoagulation Case Analysis Example

Anticoagulation Case Analysis: A New Femoral Vein Thrombosis Beside a Dialysis Catheter, a Platelet Count of 118 and a Tracheostomy in Three Days, Answered With an Unfractionated Heparin Infusion

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College of Nursing, Chamberlain University

NR 567: Advanced Pharmacology for the Adult Gerontology Acute Care Nurse Practitioner

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Month Day, Year

Anticoagulation Case Analysis: A New Femoral Vein Thrombosis Beside a Dialysis Catheter, a Platelet Count of 118 and a Tracheostomy in Three Days, Answered With an Unfractionated Heparin Infusion

Both Risks, on One Page

Day 6 finds the same 66-year-old, still 92 kg, off norepinephrine, on vasopressin at a reduced rate and still on continuous hemodiafiltration through a right femoral catheter. The right leg has become swollen, and compression ultrasound shows an occlusive thrombus in the right common femoral vein around the catheter. The patient had been receiving subcutaneous heparin 5,000 units every 8 hours as prophylaxis since admission.

The clotting case: a proximal deep vein thrombosis, the hemofilter circuit clotting twice in 24 hours, and a patient who will be immobile for days. Untreated proximal thrombosis risks pulmonary embolism.

The bleeding case: the platelet count fell from 210,000 on admission to 118,000 on day 3 during septic shock and has stayed there; hemoglobin has drifted from 9.4 to 7.6 g/dL with oozing at the femoral site, requiring one unit of red cells; and a tracheostomy is planned for day 9.

Both risks are real. The analysis does not resolve the tension by ignoring one of them.

Is This Heparin-Induced Thrombocytopenia?

A falling platelet count with a new thrombosis in a patient on heparin must raise the question. The 4Ts score estimates the probability: the platelet fall is 44% (1 point); it began on day 2 to 3 of a first heparin exposure, too early for the typical pattern (0 points); there is a new thrombosis (2 points); and sepsis is a definite alternative cause of thrombocytopenia (0 points). The total of 3 indicates low probability. Guidance advises against testing or stopping heparin when the 4Ts score is low (Cuker et al., 2018). The platelet count is still checked daily, and the score is recalculated if the count falls further or the pattern changes.

Reversibility as the Purchase

Agent: unfractionated heparin by continuous intravenous infusion, without a bolus.

The choice is bought for reversibility. Unfractionated heparin has a short half-life of about 60 to 90 minutes, so stopping the infusion removes most of its effect within a few hours; protamine reverses it almost completely; and it is cleared largely independently of the kidneys. That matters for a patient on dialysis who will go to a procedure in three days and who may bleed. Guidance supports parenteral anticoagulation for acute proximal deep vein thrombosis (Stevens et al., 2021).

Rejected: enoxaparin. Enoxaparin depends on the kidneys for removal, builds up when they fail, has a longer tail and is only partly reversed by protamine. For a patient on continuous dialysis with a procedure coming, those properties invert the logic of the choice.

Rejected: direct oral anticoagulants. They depend on kidney clearance to varying degrees, are not studied in patients on continuous dialysis in the intensive care unit, and their reversal agents are expensive and not always available.

Rejected: no anticoagulation with a filter or monitoring alone. A proximal thrombosis in an immobile patient carries a substantial risk of embolism.

Why Not Delay Treatment Until After the Tracheostomy

One option discussed on rounds was to hold anticoagulation entirely until after the tracheostomy on day 9, three days away, and rely on the prophylactic dose. That would reduce bleeding risk at the procedure but leave an occlusive proximal thrombosis untreated for three days in an immobile patient, with the hemofilter circuit already clotting. Because unfractionated heparin can be stopped hours before the procedure and restarted afterward, there is no need to accept three days without treatment in order to protect a single procedure. The reversible agent removes that trade-off, which is the purchase the analysis is making.

The Order

Heparin infusion at 15 units/kg/h (1,400 units/h), no bolus because of the oozing and the low hemoglobin, adjusted by the hospital's anti-Xa nomogram. The target anti-Xa level is 0.3 to 0.5 units/mL, the lower part of the usual therapeutic range, chosen deliberately because of the bleeding risk. The same infusion also helps keep the dialysis circuit open.

The Assay and Its Interval

Anti-Xa is measured 6 hours after starting and 6 hours after every rate change until two consecutive results are in range, then daily. The anti-Xa assay is chosen over the activated partial thromboplastin time because septic patients often have raised factor VIII and fibrinogen, which can make the activated partial thromboplastin time unreliable. Platelet count and hemoglobin are checked daily, and fibrinogen every 48 hours.

Holds and Restarts

For the tracheostomy on day 9, the infusion is stopped 4 to 6 hours before the procedure, which allows the effect to fall to near baseline, and the procedural team confirms an anti-Xa below 0.1 before starting. After the procedure, the infusion restarts without a bolus 12 hours later if there is no bleeding at the stoma, at the previous rate. For any line change or catheter removal, the infusion is held for 2 hours before and resumed 2 hours after.

The Plan for a Bleed

If major bleeding occurs, such as hemoglobin dropping by two points or more, bleeding from the stoma or airway, or a new hematoma: stop the infusion immediately; give protamine 1 mg per 100 units of heparin infused in the previous 2 to 3 hours, which at 1,400 units/h is about 35 to 40 mg, given slowly over 10 minutes and not exceeding 50 mg (Garcia et al., 2012); send hemoglobin, platelets, anti-Xa and fibrinogen; transfuse red cells to keep hemoglobin above 7 g/dL; and treat the source. Protamine can cause hypotension and anaphylaxis, so it is given slowly with monitoring. After a major bleed, the decision to restart anticoagulation, or to place an inferior vena cava filter, is made by the attending physician once the bleeding is controlled.

Duration

Treatment of a provoked proximal thrombosis usually continues for three months. Once the patient is off dialysis and eating, the plan is to transition to an oral agent chosen for the recovered kidney function at that time.

The choice of oral agent will also depend on whether the femoral catheter has been removed and on the patient's ability to take tablets after the tracheostomy. Those decisions are recorded as open questions for the step-down team rather than settled now.

Both open questions return to rounds every week until they are settled.

References

Cuker, A., Arepally, G. M., Chong, B. H., Cines, D. B., Greinacher, A., Gruel, Y., Linkins, L. A., Rodner, S. B., Selleng, S., Warkentin, T. E., Wex, A., Mustafa, R. A., Morgan, R. L., & Santesso, N. (2018). American Society of Hematology 2018 guidelines for management of venous thromboembolism: Heparin-induced thrombocytopenia. Blood Advances, 2(22), 3360-3392. https://doi.org/10.1182/bloodadvances.2018024489

Garcia, D. A., Baglin, T. P., Weitz, J. I., & Samama, M. M. (2012). Parenteral anticoagulants: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2 Suppl), e24S-e43S. https://doi.org/10.1378/chest.11-2291

Stevens, S. M., Woller, S. C., Baumann Kreuziger, L., Bounameaux, H., Doerschug, K., Geersing, G.-J., Huisman, M. V., Kearon, C., King, C. S., Knighton, A. J., Lake, E., Murin, S., Vintch, J. R. E., Wells, P. S., & Moores, L. K. (2021). Antithrombotic therapy for VTE disease: Second update of the CHEST guideline and expert panel report. Chest, 160(6), e545-e608. https://doi.org/10.1016/j.chest.2021.07.055