A 58-year-old man with a 3-day history of acute onset dyspnea and pleuritic chest pain presents to the emergency department. His D-dimer is elevated at 2.5 µg/mL. Chest X-ray shows a small right pleural effusion but no consolidation or pneumothorax. Arterial blood gas reveals mild hypoxemia (PaO₂ 72 mmHg on room air). Clinical suspicion for pulmonary embolism is high. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient has a high pretest probability of PE based on acute dyspnea, pleuritic chest pain, elevated D-dimer, and hypoxemia. The chest X-ray is relatively clear, making it suitable for CTPA imaging. ## Why CTPA is the Next Step **Key Point:** CT pulmonary angiography (CTPA) is the gold standard imaging modality for diagnosis of PE in hemodynamically stable patients with high clinical suspicion and interpretable chest X-rays. **High-Yield:** CTPA has: - Sensitivity: 83–100% (depending on PE size and technique) - Specificity: >95% - Fast acquisition time (10–15 seconds) - Allows assessment of right heart strain and alternative diagnoses ## Management Algorithm ```mermaid flowchart TD A[High clinical suspicion PE + elevated D-dimer]:::outcome --> B{Hemodynamically stable?}:::decision B -->|Yes| C{CXR interpretable?}:::decision B -->|No| D[Thrombolysis or embolectomy]:::urgent C -->|Yes| E[CTPA immediately]:::action C -->|No| F[Bedside echo or V/Q scan]:::action E --> G{PE confirmed?}:::decision G -->|Yes| H[Anticoagulation]:::action G -->|No| I[Investigate alternative diagnosis]:::action ``` **Clinical Pearl:** Anticoagulation should NOT be delayed awaiting imaging in high-risk patients, but CTPA is performed urgently (not after anticoagulation is started). In this case, the patient is hemodynamically stable, so CTPA is the diagnostic priority. **Tip:** Remember the "rule of 90s" — CTPA should be performed within 90 minutes of presentation in suspected PE to guide definitive therapy. [cite:Harrison 21e Ch 297]