INTRODUCTION: One of the benefits of thoracic ultrasound (US) is the ability to quickly rule out a significant pneumothorax (PTX) in the critically ill patient. Thoracic US has shown to be much more sensitive than chest radiography for detecting PTX. Despite this fact, thoracic US is still not routinely used for this purpose. We are presenting a case that demonstrates the potential utility of thoracic US in a common clinical scenario where the physician needs to decide whether to place a chest tube, obtain further imaging, or observe the patient.
CASE PRESENTATION: A 53 year-old woman was brought to the emergency department (ED) with history of blunt chest trauma from a fall. She complained of left-sided chest pain and was hypotensive on arrival. Physical examination showed tenderness in the left axillary region. An ultrasound exam was performed to evaluate the abdomen and chest. The abdominal US was unremarkable. The anterior thoracic US was significant for no lung sliding bilaterally, suggesting bilateral PTXs. An upright chest radiograph confirmed a left-sided PTX, but there was no sign of a right-sided PTX. She was volume resuscitated and a left-sided chest tube was placed urgently. However, she continued to remain hypotensive. A second and more extensive right thoracic US exam was then performed with the patient in supine position. Imaging at several locations showed no lung sliding superior to the nipple line and anterior to the mid-axillary line. CT scan of the chest was obtained which confirmed the bilateral PTXs. Right-sided chest tube was placed and the hypotension was immediately resolved.
DISCUSSIONS: Thoracic US is an evolving diagnostic modality for a variety of pulmonary pathologies, including PTX. “Lung sliding” is the sonographic term for the normal to-and-fro movement between the visceral pleura on the lung surface and the parietal pleura on the chest wall. Presence of lung sliding always rules out PTX, whereas absence of lung sliding is highly suggestive of PTX. When the lung sliding is absent in an unstable patient chest tube placement should be considered without further imaging. If the patient is stable, “lung point sign” should be sought, which is 100% diagnostic for PTX. Lung point sign is the sonographic term for detecting the leading edge, where the lung is intermittently touching the chest wall. Due to its high sensitivity, it is common to identify small PTXs with thoracic US, which cannot be identified by plain radiography and may simply be observed in non-ventilated patients. Examining one location bilaterally decreases the sensitivity of the exam but a clinically significant PTX should initially be identified by this method. For a more detailed exam, the probe is moved to several thoracic locations. This makes it possible to estimate the size of the PTX as well as to detect the lung point sign by mapping the leading edge of the lung. Finding the lung point sign in the absence of sliding sign is pathognomonic for PTX, whereas the absence of sliding sign by itself can be caused by several other conditions including pleural adhesions, bronchial intubation, pulmonary infiltrate or contusion, ARDS, and atelectasis.
CONCLUSION: This case highlights the fact that thoracic US can be much more sensitive than plain radiography for detecting PTXs. We suggest that in an unstable patient with no lung sliding, it is reasonable to place a chest tube immediately based on the thoracic US findings alone in an appropriate clinical setting. In stable patients with no lung sliding, lung point sign should be sought or a thoracic CT scan obtained if the plain radiography does not confirm a PTX.
DISCLOSURE: Michael Markos, No Financial Disclosure Information; No Product/Research Disclosure Information