A 62-year-old woman is sent to the emergency department from her rehabilitation facility due to sudden-onset dyspnea and nonproductive cough. The symptoms started acutely while the patient was trying to get out of bed. She has no subjective fever, hemoptysis, wheezing, palpitations, leg pain, or lower-extremity edema. The patient underwent right knee replacement 2 weeks ago for severe degenerative joint disease. Her other medical problems include peptic ulcer disease from nonsteroidal anti-inflammatory use, hypertension, and type 2 diabetes mellitus. She drinks alcohol socially and does not use tobacco. Her temperature is 38 C (100.4 F), blood pressure is 130/80 mm Hg, pulse is 110/min, and respirations are 22/min. Pulse oximetry is 91% on room air. BMI is 36 kg/m². The patient is alert and cooperative without cyanosis or jaundice. Lungs are clear to auscultation. The abdomen is soft, nondistended, and nontender. Right knee is without erythema, warmth, or tenderness. ECG shows sinus tachycardia. Chest x-ray is normal. Complete blood count shows a leukocyte count of 6,500/mm³. Which of the following is the best next step in management of this patient?

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11ec25c8_d951_1815_bc81_a993d8433c64_MD0003_00 This patient's dramatic postoperative presentation with sudden-onset dyspnea, nonproductive cough, tachycardia, and mild hypoxia is highly suggestive of acute pulmonary embolism (PE). Early, effective anticoagulation decreases the mortality risk of acute PE and should be considered in patients without absolute contraindications (eg, hemorrhagic stroke, massive gastrointestinal bleed). Peptic ulcer disease is not an absolute contraindication to anticoagulation, although it increases risk of bleeding with anticoagulation. This patient's modified Wells score is 6 (absence of a more likely diagnosis = 3 points, tachycardia = 1.5 points, immobilization due to recent knee surgery = 1.5 points), which correlates to PE being likely (modified Wells score >4). Given that she is clinically stable (normotensive, mild hypoxemia) with no evidence of distress, the diagnosis of PE can be confirmed with CT angiography (CTA). If CTA confirms PE, clinical judgment can dictate whether anticoagulation is initiated or other options are pursued (eg, inferior vena cava filter placement) based on the estimated risk of bleeding from the peptic ulcer. modified Wells score (Choice A) Rapid collection of blood cultures and initiation of antibiotics are appropriate when sepsis is suspected. This patient has a normal leukocyte count, clear lungs, a normal-appearing right knee, and no other evidence of localizing infection. Her tachycardia and low-grade fever can be explained by PE, which is the most likely diagnosis and essential to rule out. (Choice C) D-dimer testing can be helpful in patients presenting with unlikely probability of PE (modified Wells score <4). However, a negative test result cannot be used to reliably exclude PE in patients with a modified Wells score >4. < (Choice D) Compression ultrasonography is the preferred initial test for diagnosis of deep venous thrombosis (DVT). This patient has no clinical manifestations of DVT. In addition, a negative ultrasound result does not rule out PE. (Choice E) Bedside transthoracic echocardiogram (TTE) may show acute PE findings of increased right ventricular size and right ventricular dysfunction. However, these findings are often only seen in massive PE accompanied by syncope, shock, and hemodynamic instability. Therefore, TTE is generally reserved for clinically decompensating patients in whom CTA cannot be obtained. Educational objective: The modified Wells criteria can assess the pretest possibility of acute pulmonary embolism (PE). CT angiography is the test of choice in clinically stable patients in whom PE is likely. Empiric anticoagulation in these patients is often appropriate, but clinical judgment is needed regarding clinical stability and contraindications. References: Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. (http://www.ncbi.nlm.nih.gov/pubmed/16403929)

A 62-Year-Old Woman Is Sent to the Emergency Department from Her