A 56-year-old obese man comes to the emergency department complaining of acute-onset shortness of breath. He twisted his ankle 5 days ago and has had limited mobility since. His other medical problems include type 2 diabetes mellitus, hypertension, chronic kidney disease, and right knee osteoarthritis. His medications include insulin, amlodipine, and low-dose aspirin. His blood pressure is 110/60 mm Hg and pulse is 110/min. His hemoglobin level is 11.2 g/dL and platelet count is 230,000/µL. The estimated glomerular filtration rate is 20 mL/min/1.73 m². Ventilation perfusion scan shows a right upper-lobe perfusion defect with good ventilation. Which of the following is the best initial treatment for this patient?

Question

Quizplus · Accepted Answer

This patient has confirmed pulmonary thromboembolism. Untreated pulmonary embolism (PE) has a mortality risk of up to 30% due to recurrent embolism. As a result, immediate anticoagulation is required unless contraindicated. There are many anticoagulant options available. Low-molecular-weight heparin (enoxaparin), fondaparinux (injection factor Xa inhibitor), and rivaroxaban (oral factor Xa inhibitor) cannot be used in patients with severe renal insufficiency (estimated glomerular filtration rate <30 mL/min/1.73 m²) as reduced renal clearance increases anti-Xa activity levels and bleeding risk (Choices A, B, and C). ² Unfractionated heparin is recommended in patients with decreased estimated glomerular filtration rate as it is more convenient to monitor its therapeutic level via activated partial thromboplastin time (aPTT). Once the heparin produces therapeutic anticoagulation (goal PTT >1.5-2 times normal), warfarin is initiated. Warfarin can take up to 5-7 days to reach therapeutic levels. It also inhibits proteins C and S (anti-thrombogenic proteins) and can be thrombogenic without a second anticoagulant (eg, heparin) as a "bridge." After reaching a therapeutic International Normalized Ratio, heparin can be stopped and warfarin can be continued long-term (Choice E). Rivaroxaban is an oral anticoagulant with immediate onset of action (unlike warfarin). Therefore, no bridging with heparin is indicated. Unfortunately, this is not an option for patients with severe renal insufficiency. Educational objective: For anticoagulation, unfractionated heparin is preferred over low-molecular-weight heparin, fondaparinux, and rivaroxaban in patients with severe renal insufficiency (estimated glomerular filtration rate <30 mL/min/1.73 m²) as reduced renal clearance increases anti-Xa activity levels and bleeding risk. ² References: Deep venous thrombosis and pulmonary embolism. part 1. Initial treatment: usually a low-molecular-weight heparin. (http://www.ncbi.nlm.nih.gov/pubmed/23662321)

A 56-Year-Old Obese Man Comes to the Emergency Department Complaining