Focused assessment with sonography for trauma

Focused Assessment with Sonography for Trauma (FAST)

Focused Assessment with Sonography for Trauma (FAST) is a rapid bedside ultrasound examination performed by clinicians to assess patients for internal bleeding, particularly in the setting of trauma. It is a critical component of the initial evaluation of trauma patients, especially those with blunt abdominal trauma, and is used to quickly identify free fluid in the peritoneal, pericardial, and pleural cavities.

History

The FAST examination was developed in the 1990s as a non-invasive, rapid, and repeatable method to assess trauma patients. It has since become a standard part of the Advanced Trauma Life Support (ATLS) protocol. The technique was initially popularized in Europe and Japan before gaining widespread acceptance in North America.

Indications

FAST is indicated in the following scenarios:

• Blunt abdominal trauma: To assess for hemoperitoneum.
• Penetrating trauma: To evaluate for pericardial effusion or hemothorax.
• Hypotension of unknown origin: To quickly identify potential sources of internal bleeding.
• Monitoring: To track changes in fluid status in trauma patients.

Technique

The FAST examination involves scanning four primary areas:

1. Pericardial view (subxiphoid or parasternal): To assess for pericardial effusion. 2. Right upper quadrant (RUQ) view: To evaluate the hepatorenal space (Morison's pouch) for free fluid. 3. Left upper quadrant (LUQ) view: To assess the splenorenal space for free fluid. 4. Pelvic view: To check for free fluid in the rectovesical pouch (in males) or the rectouterine pouch (in females).

The examination is typically performed with the patient in the supine position, using a curvilinear or phased array transducer.

Interpretation

The presence of free fluid in any of the scanned areas is considered a positive FAST examination, suggesting internal bleeding. The absence of free fluid does not rule out injury, and further diagnostic imaging, such as a CT scan, may be necessary.

Limitations

While FAST is a valuable tool, it has limitations:

• Operator dependency: The accuracy of the examination depends on the skill and experience of the operator.
• Limited sensitivity: FAST may not detect small amounts of free fluid or retroperitoneal bleeding.
• Obesity and subcutaneous emphysema: These conditions can limit the quality of the ultrasound images.

Extended FAST (E-FAST)

The Extended FAST (E-FAST) includes additional views to assess for pneumothorax and hemothorax. This extension involves scanning the anterior chest wall to look for the "lung sliding" sign, which is absent in pneumothorax.

Also see

• Ultrasound in trauma
• Advanced Trauma Life Support
• Hemoperitoneum
• Pericardial effusion
• Pneumothorax