Detection of spontaneous pneumothorax with chest ultrasound in the emergency department
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A 38-year-old man was brought by ambulance to the Emergency Department (ED) with left sided chest pain, which occurred while he was competing in a bicycle race. The pain increased with deep inspiration, and did not radiate. The patient denied shortness of breath, abnormal sweating, or palpitations.
The physical examination was unremarkable: the lung sounds were clear and symmetrical, the heart tones were regular without murmurs. The vital signs were: blood pressure 132/80 mmHg, heart rate 80 beats per minute, respiratory rate 16 breaths per minute, oxygen saturation while breathing room air 99%, temperature 36.8°C.
The patient had no family history of coronary artery disease, and did not smoke. He had sustained a spontaneous pneumothorax 20 years earlier. The ECG showed sinus rhythm without acute ST changes, therefore, making myocardial ischemia an unlikely differential diagnosis.
Chest ultrasound, performed at the bedside, showed absence of “lung sliding” at the left apex, absence of B lines and presence of A lines. On M-mode, the typical finding of the “stratosphere sign” confirmed the presence of a left apical pneumothorax.
Chest radiography confirmed the presence of the left pneumothorax. The right lung was normal on chest scan. Chest ultrasound findings of pneumothorax have a high sensitivity in ruling out pneumothorax, and in the supine patient, this tool is more reliable than a chest X-ray study. “Lung point”, not found in this patient, is a dynamic image containing both normal and pneumothorax findings which has a specificity of 100%.
Lung ultrasound: examination technique and findings
Lung sonography largely consists of the analysis of artifacts because only artifacts appear on the screen. However, the ribs can be identified because they produce a posterior shadow. In a longitudinal scan between two ribs and about 0.5 cm deeper, an horizontal hyperechoic line is produced by the pleural interface.
Lung ultrasound has a greater specificity than chest X-ray study in the detection of pneumothorax in the supine patient . The lack of lung sliding, a finding of pneumothorax, shows only multiple A lines, an artifact due to the presence of air, that do not allow one to calculate the size of the pneumothorax. A small as well as a huge pneumothorax has the same ultrasound appearance. Therefore, chest X-ray study is mandatory to quantify the extent of the pneumothorax. Tension pneumothorax has no further ultrasound findings, and therefore is still a clinical diagnosis. The patient had a small apical pneumothorax, and no treatment was deemed necessary. The patient had no other studies.
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