INDICATIONS
The FAST (or E-FAST) exam is the extended focused exam with sonography in trauma. It is designed to look for hemorrhage in the peritoneal and pericardial spaces and to look for hemothorax/pneumothorax in either thorax.
- Penetrating Chest or Abdominal Trauma
- Blunt Chest or Abdominal Trauma
FOCUSED QUESTIONS
- Is there free fluid in the peritoneal cavity?
- Is there free fluid in the rectouterine or rectovescicular space?
- Is there free fluid in the pericardial space?
- Is there free fluid in either hemithorax?
- Is there pneumothorax
POSITIONING
You can increase the sensitivity of your exam by positioning your patient so free fluid (in the case of trauma – blood) will pool in dependent areas of either the upper abdomen or pelvis. Placing the patient in Tredelenburg decreased the amount of free fluid needed for a positive exam from 700 to 300 mL.
VIEWS
PERIHEPATIC
For the Perihepatic (Right Upper Quadrant (RUQ) or Morison’s Pouch) view, you can hold a large curvilinear or phased array probe at the anterior axillary line with the probe marker pointed towards their head. This should produce an image similar to this in which we see liver, kidney, the spine behind and the diaphragm curving upwards from the kidney around the liver.
PERISPLENIC
Similar to the RUQ view, the perisplenic (or LUQ) view is obtained by holding the probe like a pencil, reaching over the bed and allowing the back of your hand to find the stretcher. Bring the probe in to the abdominal wall and you should see the view below with spleen, kidney. You want to make a good search for blood around the spleen. It may be difficult to see above the diaphragm from this view. You may try orienting the plane of your probe parallel to the path of your patients ribs to image through the chest wall.
PELVIC
The pelvic views image behind the rectum or uterus looking for blood in the rectovesicular space in men and the vesocouterine and rectouterine (or pouch of douglas) spaces in women.
Here we see a normal transverse view of the bladder with no free fluid surrounding the bladder.
Of course one view is no view, so we always look in two planes when using ultrasound. By rotating the probe 90 degrees towards the patients head we obtain a sagittal view of the pelvis.
In this sagittal view we see uterus on the left superior to the triangular bladder. In this normal patient, there is no visible free fluid.
Of course, to improve sensitivity, we could flip the patient into reverse trendelenburg.
PERICARDIAL
For the pericardial view we have to scan nearly parallel to the chest wall. Hold the probe with a finger on top below the xiphoid process with the probe marker pointed to the patient’s right.. Point the probe toward the patient’s left shoulder and press into the abdomen toward the stretcher.
Sometimes the heart will not come into view – it may be obscured by gas in the duodenum or stomach. Occasionally, you can move the probe to the patient’s right and image through the liver. If this is unsuccessful, try a different cardiac view (parasternal long axis, apiral 4 chamber).
This is the 2D view that you will ideally see from subxiphoid. The RA and RV are most proximal to the probe and the LV and LA are posterior and superior.
PNEUMOTHORAX ASSESSMENT
The trauma algorithm we refer to as the “FAST” exam now refers to the “E-FAST” or extended FAST exam, which includes assessment for pneumothorax. Ultrasound is significantly more sensitive for pneumothorax than x-ray. To perform this exam, scan down the anterior chest wall in the mid-clavicular lines on both sides looking for loss of lung sliding or other signs of pneumothorax.
Here we see rib shadows on either side of this image with obvious pleural sliding noted in the mid-field.
PATHOLOGY
RUQ – Free Fluid at liver tip
LUQ – Free fluid in the splenorenal recess
LUQ – Splenic laceration / rupture
LUQ – stomach Contents can be confused for free fluid.
PLEURA – loss of lung sliding is seen in this patient with pneumothorax. Unfortunately, there can be other causes of loss of lung sliding: mainstem intubation of the opposite side and mucus plugging can produce similar 2D ultrasound images.
PLEURA – Lung Point, shown below, is seen at the juncture between the patient’s pneumothorax and normally apposed viseral and parietal pleura. As comparedw with loss of lung sliding, lung point is 100% specific for pneumothorax.
INTEGRATING THE FAST EXAM INTO TRAUMA CARE
One approach to using the FAST exam clinically is demonstrated below. The greatest utility is in the unstable patient with an obviously positive FAST exam. In general, these patients will need operative intervention. However, CT results are of such high value to the surgeon managing these patients, that all other patients will usually go to CT even if they are destined for the OR. Even most unstable patients, with vasopressor support and accompanied by the team, can be taken quickly through CT.
