FAST is an integral component of major trauma evaluation. Unfortunately, although lots of people do them, quality control is not very consistent.
Researchers at the University of Pennsylvania studied how the use of a standard checklist and it’s impact on exam quality. Detection of fluid in any of the standard 4 FAST locations was recorded for every exam performed. No attempts were made to grade the amount of fluid seen. The exam was recorded in video format.
Reviewers credentialed in FAST later reviewed the study videos in a blinded fashion using a checklist. They were also not aware of any CT or OR findings. The checklist contained grading for quality (poor, fair, good), result (positive, negative, unclear), and initial interpretation (positive, negative) for each of the 4 areas scanned. The study was also graded for its educational value.
A total of 247 studies were reviewed. All study results were compared with CT (240) or OR (7) results. There 235 true negatives, 6 true positives, 4 false positives and 2 false negatives. Sensitivity was 75%, specificity was 98%, and accuracy was 98%.
Overall, 9% of exams were of good quality, 65% were fair, and 26% were poor. Despite this lack of good quality exams, sensitivity, specificity and accuracy adhered to the usual literature standards. The overall quality in both true and false exams were similar.
Bottom line: This study reveals that we are doing an “okay” job with FAST exams in trauma patients. However, it also shows that there is room for improvement, and that FAST evaluation should be a part of the Performance Improvement program of any trauma centers that use FAST.
Reference: Performance Improvement for FAST Exam. University of Pennsylvania. Presented at the Eastern Association for the Surgery of Trauma meeting, Poster #24, January 2010.
By now, every emergency medicine physician and surgeon knows what FAST is. This valuable technique allows us to quickly (get it?) determine whether a patient has blood in the abdomen or around the heart which might require operative management. Extended FAST (E-FAST) is an extension of the original technique that allows us to detect the presence of pneumothorax or hemothorax more quickly and accurately than with the conventional chest x-ray.
Both hemothorax and pneumothorax can be missed by x-ray. It takes at least 200cc of free fluid in the chest to show on the chest x-ray, assuming an ideal body habitus. As little as 20cc can be detected using the E-FAST. Studies have also shown that 30-50% of pneumothoraces are missed by x-ray. This diagnostic inaccuracy is due to the fact that hemothoraces settle out posteriorly and pneumothoraces anteriorly. Since the vast majority of chest x-rays in major trauma patients are taken with the patient supine to protect their spine, the bulk of the blood or air have layered out and cannot be seen well. A chest x-ray is still needed, however, to determine injury to the mediastinum and lung parenchyma.
E-FAST exam can be performed by using the standard curvilinear probe. It is usually placed longitudinally on the anterior chest to detect pneumothorax, using the space between two ribs as the “window” to the pleura. The depth setting should be adjusted so that only about 4cm is visible on the display. The junction of the visceral and parietal pleura should be visualized at the backside of the ribs. With a very steady hand, the junction between the two sets of pleura should be scrutinized closely.
If the two sets of pleura slide freely over each other, pneumothorax is unlikely. If not, it may be present. Pneumothorax is not a uniform phenomenon, except when it is of large size. It may be necessary to move the probe to a few other rib spaces to ensure that a smaller pneumothorax is not present.
FALSE POSITIVE ALERT! If the patient is not ventilating well, or if they have a right mainstem intubation, the affected lung(s) may not show the sliding sign, leading the examiner to think they have a problem when they may not.
To detect a hemothorax, the probe is directed upward somewhat when doing the right and left upper abdominal views. A dark triangle located above the diaphragm indicates fluid in the chest (blood). The dark crescent on the left in the image below is a large hemothorax.
The bottom line: Extended FAST can be helpful in detecting a significant hemothorax or pneumothorax and can expedite the definitive management of those conditions. If you are already familiar with FAST, a little extra ultrasound training may be very helpful.
The Trauma Professional's Blog provides information on injury-related topics to trauma professionals. It is written by Michael McGonigal MD, the Director of Trauma Services at Regions Hospital in St. Paul, MN. Regions is a Level I Adult Trauma Center, and has partnered with Gillette Children's Specialty Hospital to become the first Level I Pediatric Trauma Center in the Upper Midwest.