Extended focused assessment with sonography for trauma (eFAST) does not improve the diagnostic screening performance of the national emergency X-radiography utilization study (NEXUS) chest clinical decision instrument, recent research suggests.
A team led by Dr. Madeline Grade from the University of California, San Francisco found that eFAST cannot replace the NEXUS instrument in emergency settings in its study of nearly 2,000 patients from eight trauma centers. The results were published February 7 in the Annals of Emergency Medicine.
"The eFAST-added clinical decision instrument did not improve sensitivity for all thoracic injuries," Grade and co-authors wrote. "Furthermore, the eFAST-replaced clinical decision instrument did not improve sensitivity or specificity for major injuries, and it, in fact, had lower sensitivity than the original NEXUS chest clinical decision instrument."
The NEXUS chest clinical decision instrument was developed within the past decade to decrease unnecessary thoracic CT use in adult blunt trauma patients. However, it doesn't include the use of eFAST, a bedside ultrasound protocol that detects peritoneal fluid, pericardial fluid, collapsed lung, and blood collected between the chest wall and lung in trauma patients.
Grade and colleagues wanted to find out if eFAST could improve the diagnostic screening performance of the NEXUS instrument, which would position eFAST as a replacement predictor variable for chest radiographs.
The researchers gathered data from 1,957 patients from eight level-one trauma centers. Out of these, 624 had blunt thoracic injuries and 126 had major injuries. The patients had documented CT, chest radiographs, clinical NEXUS criteria, and "adequate" eFAST.
The researchers tested eFAST's performance as both an add-on and replacement to the NEXUS protocol. They found that this led to an unchanged screening performance as an add-on. Also, it had unchanged sensitivity for major injuries and lower sensitivity for any injury.
| eFAST as add-on, replacement for NEXUS chest clinical decision instrument | ||||||
| Major Injury | Any injury | |||||
| NEXUS | eFAST add-on | eFAST replacement | NEXUS | eFAST add-on | eFAST replacement | |
| Sensitivity | 0.98 | 0.98 | 0.93 | 0.97 | 0.97 | 0.93 |
| Specificity | 0.29 | 0.28 | 0.31 | 0.22 | 0.21 | 0.23 |
| Positive predictive value | 0.09 | 0.09 | 0.09 | 0.37 | 0.37 | 0.36 |
| Negative predictive value | 0.99 | 1.00 | 0.98 | 0.94 | 0.94 | 0.88 |
The researchers noted several reasons why these results came to be. One is that collapsed lung was the only injury type queried in the standard eFAST exam of the five most prevalent thoracic injury types in the study. The remaining most prevalent injury types in the study are not routinely examined on eFAST. These included rib, sternal, and vertebral fractures, as well as pulmonary contusions.
"Furthermore, although in some studies, eFAST has demonstrated excellent screening performance for identifying traumatic pneumothorax with higher diagnostic yield than a supine chest radiograph, newer data has failed to show the superiority of eFAST for this indication," the study authors wrote.
They also suggested that since ultrasound is a skill-based imaging modality subject to operator variability, it is possible that this may have resulted in "less-than-ideal" image characteristics.
However, the team called for future studies to use a standardized approach in implementing eFAST implementation, as well as find other possible ways to use eFAST to improve specificity.
"Finally, protocols in which eFAST is modified to examine other chest injuries when other NEXUS clinical decision instrument criteria are present could produce better screening performance and diagnostic utility," the group added.
