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Difficulty: MediumPulmonary and Critical Care

A 52-year-old woman is evaluated in the hospital due to sudden-onset right-sided chest pain and shortness of breath. She is currently on postoperative day 3 following an open abdominal hysterectomy for symptomatic uterine fibroids. Her temperature is 38.0°C (100.4°F), blood pressure is 118/76 mm Hg, pulse is 114/min, and respirations are 26/min. Pulse oximetry is 89% on room air. She appears anxious and is in mild respiratory distress. The chest pain worsens with deep inspiration. Lung auscultation reveals clear breath sounds bilaterally without wheezes or crackles. The surgical incision site is clean and intact. The right calf is mildly swollen and tender to palpation compared to the left. Arterial blood gas on room air shows:

pH: 7.52
PaCO2: 28 mm Hg
PaO2: 56 mm Hg
HCO3-: 23 mEq/L

Which of the following is the most appropriate next step in management?

  1. Computed tomography angiography of the chestAnswer
  2. B
    Serum D-dimer measurement
  3. C
    Incentive spirometry and early ambulation
  4. D
    Intravenous piperacillin-tazobactam
  5. E
    Intravenous furosemide

Answer

Computed tomography angiography of the chest
The correct answer is computed tomography angiography of the chest. This patient presents with the classic triad of pleuritic chest pain, dyspnea, and tachycardia, along with clinical signs of a deep vein thrombosis (unilateral calf swelling) following a major abdominal surgery. This presentation yields a high pretest probability for a pulmonary embolism (PE) based on the Wells criteria. According to evidence-based algorithms, hemodynamically stable patients with a high pretest probability of PE should proceed directly to definitive imaging with a computed tomography pulmonary angiography (CTPA). Her arterial blood gas shows an acute respiratory alkalosis (high pH, low PaCO2) and significant hypoxemia, which are hallmark findings in acute PE due to hyperventilation and ventilation-perfusion (V/Q) mismatch.

Step-by-Step Solution

1
Evaluate the clinical presentation and risk factors.
The patient has hypoxia, tachycardia, pleuritic chest pain, and a swollen right calf 3 days after major pelvic surgery.
These findings are classic for deep vein thrombosis (DVT) progressing to a pulmonary embolism (PE).
2
Determine the pretest probability of pulmonary embolism.
Using the Wells criteria, the patient scores highly due to tachycardia (>100/min), recent surgery, clinical signs of DVT, and PE being the most likely diagnosis.
Risk stratification dictates the diagnostic algorithm for suspected PE.
3
Select the appropriate diagnostic pathway based on pretest probability.
A high pretest probability mandates definitive imaging, bypassing screening blood tests.
Computed tomography pulmonary angiography (CTPA) is the standard imaging modality to confirm PE in hemodynamically stable patients with high clinical suspicion.

Key Concept

In patients with a high pretest probability for pulmonary embolism, definitive imaging with CT pulmonary angiography is the appropriate next diagnostic step, bypassing D-dimer testing.
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Topics

Pulmonary and Critical Care

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