A 54-year-old man arrives at the emergency department due to the sudden onset of left-side… — USMLE Step 2 CK

A 54-year-old man arrives at the emergency department due to the sudden onset of left-sided chest pain and shortness of breath that began $2$ hours ago. The chest pain worsens with deep inspiration. Over the past $6$ months, he has experienced worsening fatigue, frequent headaches, and intense generalized pruritus that is particularly severe after taking hot showers. He also describes a burning sensation in his palms and soles. His temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $142/88\text{ mm Hg}$ , pulse is $112\text{/min}$ , and respirations are $24\text{/min}$ . Pulse oximetry shows an oxygen saturation of $90\%$ on room air. Physical examination reveals a plethoric face and engorged retinal veins. The spleen is palpated $4\text{ cm}$ below the left costal margin. The lungs are clear to auscultation bilaterally. The right calf is visibly swollen, erythematous, and tender to palpation.

Laboratory studies reveal:
Hemoglobin: $19.2\text{ g/dL}$
Hematocrit: $59\%$
Leukocyte count: $15,200\text{ /mm}^3$
Platelet count: $620,000\text{ /mm}^3$

Arterial blood gas analysis (room air):
pH: $7.51$
PaCO $_2$ : $29\text{ mm Hg}$
PaO $_2$ : $60\text{ mm Hg}$

Which of the following is the most appropriate initial step in the management of this patient's acute presentation?

Initiation of therapeutic low-molecular-weight heparinCevap
B
Administration of intravenous furosemide and noninvasive positive-pressure ventilation
C
Administration of inhaled albuterol and systemic corticosteroids
D
Administration of intravenous broad-spectrum antibiotics
E
Administration of intravenous sodium bicarbonate

Cevap

Initiation of therapeutic low-molecular-weight heparin

The patient's presentation of acute dyspnea, pleuritic chest pain, hypoxemia, tachycardia, and a swollen, tender calf is highly suspicious for a deep vein thrombosis (DVT) that has embolized to the lungs, causing a pulmonary embolism (PE). This patient also has classic signs of polycythemia vera (PV), a myeloproliferative neoplasm characterized by the clonal proliferation of all three hematopoietic cell lines (resulting in elevated hemoglobin, leukocytes, and platelets). Clinical features of PV include aquagenic pruritus, erythromelalgia (burning pain in the hands and feet), facial plethora, and splenomegaly. Patients with PV have a significantly increased risk of arterial and venous thrombosis due to hyperviscosity and abnormal platelet function. In a hemodynamically stable patient with a high pretest probability of PE (based on the Wells score), the most appropriate initial step in management is the initiation of empiric therapeutic anticoagulation, such as low-molecular-weight heparin (LMWH), while awaiting definitive diagnostic imaging like a CT pulmonary angiography.

Adım Adım Çözüm

Identify the underlying chronic systemic condition from the patient's history and labs.

The combination of elevated hemoglobin, leukocytes, and platelets, along with aquagenic pruritus, erythromelalgia, facial plethora, and splenomegaly, indicates a diagnosis of polycythemia vera.

Recognizing polycythemia vera establishes that the patient is in a severely hypercoagulable state with a high risk for both arterial and venous thromboses.

Diagnose the etiology of the acute presentation.

Sudden onset of pleuritic chest pain, dyspnea, tachycardia, hypoxemia, and a swollen, tender calf in a hypercoagulable patient points definitively to a deep vein thrombosis (DVT) complicated by a pulmonary embolism (PE).

Matching acute respiratory symptoms and asymmetric leg swelling to the most life-threatening complication of the underlying disease.

Determine the most appropriate immediate intervention for this acute condition.

Because the patient is hemodynamically stable but has a high clinical probability of PE (modified Wells criteria), immediate empiric anticoagulation with an agent like low-molecular-weight heparin is indicated.

Prompt anticoagulation prevents further clot propagation and reduces mortality while awaiting definitive diagnostic imaging such as CT pulmonary angiography.

Anahtar Kavram

Patients with polycythemia vera are at an elevated risk for thrombotic events. In a hemodynamically stable patient with a high clinical probability of an acute pulmonary embolism, empiric therapeutic anticoagulation should be initiated immediately, even before obtaining confirmatory imaging.

Tahmini Süre:1m 30s

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Cevap

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