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Difficulty: MediumInterpreting Imaging Results

Emergency medical services bring a male construction worker to the trauma bay after he fell from a 1515-foot scaffolding. The patient, who is 4242 years old, is immobilized on a backboard with a cervical collar in place. He complains of severe pain in his left chest and significant shortness of breath. Initial vital signs show a blood pressure of 118/76118/76 mmHg, a heart rate of 108108/min, a respiratory rate of 2626/min, and an oxygen saturation of 94%94\% while receiving 44 L/min of supplemental oxygen via nasal cannula. Auscultation reveals slightly diminished breath sounds on the left side, though a full examination is limited by the patient's discomfort. Point-of-care laboratory studies demonstrate a leukocyte count of 14,000/mm314,000/\text{mm}^3 and a hemoglobin level of 13.813.8 g/dL. A portable anteroposterior chest radiograph is obtained with the patient remaining in the supine position. The resulting image reveals an abnormally deep, hyperlucent left costophrenic angle that extends caudally toward the upper abdomen, without a visible pleural line at the lung apex. The mediastinal silhouette is midline. Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in management?

  1. A
    Computed tomography of the chest
  2. B
    Left-sided thoracentesis
  3. Left-sided tube thoracostomyAnswer
  4. D
    Administration of broad-spectrum intravenous antibiotics
  5. E
    Immediate needle thoracostomy of the left second intercostal space

Answer

The most appropriate next step in management is left-sided tube thoracostomy to treat the pneumothorax identified by the deep sulcus sign.
The correct answer is left-sided tube thoracostomy. The patient's supine chest radiograph demonstrates a deep, hyperlucent costophrenic angle, which is the classic presentation of the 'deep sulcus sign'. In an upright patient, intrapleural air accumulates at the lung apex. However, in a supine patient, air collects in the most non-dependent areas of the pleural space, which are anteromedial and basal, resulting in the deep sulcus sign. This finding is diagnostic of a pneumothorax. Given that the patient is symptomatic (tachypneic and requiring oxygen) following blunt chest trauma, the definitive and most appropriate next step in management is the placement of a tube thoracostomy to evacuate the air and re-expand the lung.

Step-by-Step Solution

1
Evaluate the patient's clinical presentation and vital signs.
The patient is a trauma victim presenting with left-sided chest pain, tachypnea, and diminished breath sounds, but remains hemodynamically stable without signs of tension physiology (e.g., normal blood pressure, no mediastinal shift).
Establishing the acuity and hemodynamic stability of the patient dictates the urgency and type of subsequent interventions.
2
Interpret the specific findings on the supine anteroposterior chest radiograph.
The radiograph demonstrates a deep, hyperlucent left costophrenic angle, which is classic for the 'deep sulcus sign'.
In a supine patient, pleural air accumulates in the non-dependent anteromedial and basal spaces rather than the lung apex, producing this specific radiolucent pattern that is diagnostic of a pneumothorax.
3
Determine the most appropriate management based on the imaging diagnosis.
A left-sided tube thoracostomy is required.
A symptomatic, traumatic pneumothorax identified on imaging requires definitive drainage with a chest tube to re-expand the lung and prevent progression to a tension pneumothorax.

Key Concept

Recognition of the deep sulcus sign on a supine chest radiograph as a diagnostic indicator of a pneumothorax, and understanding the indication for tube thoracostomy in a symptomatic trauma patient.
Estimated Time:1m 30s
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Interpreting Imaging Results

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