Ultrasound has emerged as a sensitive and reliable tool to evaluate patients presenting to the emergency department with acute and sub-acute thoracoabdominal trauma and hypotension.^1-3

Focused bedside ultrasound can accurately detect fluid in the peritoneal and pleural cavities and air in the pleural cavity, and it is more reliable than physical examination.⁴

Furthermore, use of bedside ultrasound in thoracoabdominal trauma expedites time to definitive care, because it can help determine whether an emergent intervention such as chest tube thoracostomy or trauma consultation and surgery are required.⁵

How to Perform the EFAST

• Positioning. Most patients presenting with thoracoabdominal trauma will be positioned supine with the c-spine immobilized. Placing patients in the Trendelenburg position increases the sensitivity of the abdominal FAST examination.⁶
• Probe. A low-frequency probe is utilized for better penetration of tissues in the abdominal cavity. A high-frequency probe is preferred by some operators to evaluate the thoracic cavity because it provides better resolution and detail of the pleura. However, the low-frequency probe can be used to expedite completion of the examination.

Scanning the Anterior Lung

Place the probe in the second or third intercostal space in the mid-clavicular line in a sagittal orientation, and slide the probe caudally for evaluation of a pneumothorax (see image 1).

The upper rib/pleural line/lower rib profile has the appearance of a bat flying out of the screen and is referred to as the bat sign.

At the inferior edge of the thoracic cage, slide the probe laterally at the level of the 6th intercostal space in the anterior axillary line. Normal lung findings include visible sliding at the level of the pleura in B-mode and comet tails (see image 2).

Comet tails are vertical reverberation artifacts arising from the pleural line. Lung sliding and the presence of comet tails are evidence of movement of the visceral on the parietal pleura. In M-mode, this normal lung sliding pattern is casually called the seashore sign⁷ (see image 3). Lung findings suggestive of a pneumothorax include the loss of pleural sliding, as there is loss of contact between the visceral and the parietal pleura.

A distinct pattern on M-mode commonly called the stratosphere sign will be present⁷ (see image 4). Some call this the bar code sign. Lung sliding may be absent in patients who are not spontaneously breathing, even in the absence of pneumothorax. If no lung sliding is present, the heartbeat may be visualized as pulsations of the expanded lung corresponding to the heart rate. This finding, referred to as the lung pulse, is equivalent to lung sliding.⁸ The lung point is the transition between collapsed and normally expanded lung. Although difficult to locate, the lung point is reportedly 100% specific for pneumothorax when present.⁹