Dear Editor,
We read with interest the article “EXTENDED-FAST Plus MDCT in Pneumothorax Diagnosis of Major Trauma: Time to Revisit ATLS Imaging Approach?” by Ianniello et al. [1] and would like to make some comments.
First, the complete chest scan by ultrasound (US) is not frequently possible because of the trauma itself or its complications. Indeed, the authors limited the examination to "the anterior and lateral wall only, not the posterior one" [1]. However, the air content of the lungs and the bone structures of the thoracic cage reduce the pleural surface visualized by US to about 70% [2]. This is true also when US is performed under ideal conditions and all scans (anterior, lateral, and posterior) are made [2]. Hence, pneumothorax located in the remaining 30% of the surface of the lungs that is unexplored by US (i.e., the retroscapular and retrosternal regions, the mediastinal portion of the parietal pleural, and the rib-vertebral recess area) cannot be diagnosed [3]. Additionally, cases of pneumothorax associated with subcutaneous emphysema cannot be diagnosed by US. Indeed, the presence of emphysema in the subcutaneous tissue does not allow the US beam to reach the pleural line, thus preventing the visualization of any image [4].
With reference to cases of pneumothorax associated with subcutaneous emphysema, there is some doubt about the correspondence between US and multidetector computed tomography (MDCT) images reported in Figs. 2 and 3, in which no subcutaneous emphysema is seen at the US scan.
Another important point is that when pneumothorax is suspected, further investigation is always required to determine its extent and depth, US being a two-dimensional technique, and, therefore, not allowing this kind of evaluation [2]. For this purpose, it would be better to perform a chest X-ray. Although it is a two-dimensional technique, the use of the posterior–anterior and lateral–lateral projections allows the estimation of the lungs’ depth and the assessment of pneumothorax even in the presence of subcutaneous emphysema. Additionally, the E-FAST examination does not provide a comprehensive visualization of the mediastinum and the detection of other potential post-trauma complications that could possibly influence patients’ management [4].
Finally, the authors reported different sensitivity, specificity, and accuracy over the years (Fig. 5). This point could be related to differences in the ability to perform US between operators and may represent a major limitation of the study.
Hence, in case of major trauma, why should we lose precious minutes to explore each hemithorax bilaterally by US to highlight only 70% of the superficial pleura? Which patients would benefit from the US examination? Would US be useful when MDCT is not available?
Why performing US if only MDCT will see the pneumothorax, estimate its extension, and may detect all other possible post-trauma complications as well?
As the authors correctly stated, MDCT, better if ultrafast, is the gold standard for the assessment of major traumas, as it allows the detection of all cases of pneumothorax and any other complications. The urgent need for an MDCT scan does not allow any delayed time to perform any other examination (including US) in these conditions.
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Conflict of interest
The authors have nothing to disclose.
Footnotes
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References
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