Extended-FAST plus MDCT in pneumothorax diagnosis of major trauma: time to revisit ATLS imaging approach?

Pneumothorax (PNX) detection is of the utmost clinical relevance because it may quickly progress to cause hemodynamic instability as a consequence of invasive ventilation. Radiography is characterized by a low sensitivity to detect this disease; in recent years, chest ultrasound (US) has gained increased visibility in the diagnosis of acute respiratory emergencies including PNX. The aim of this retrospective study was to evaluate the clinical impact of extended focused assessment with sonography in trauma (E-FAST) during the past 6 years of experience with this technique in our Level I trauma center.

Between January 2013 and December 2018, we performed a retrospective case-series study including 3320 consecutive patients admitted to the emergency department of our hospital because of major trauma. Extended-US was always performed and reported immediately after FAST during primary survey and before multidetector computed tomography (MDCT) scans. The presence of PNX was determined using the well-known accepted US criteria. US findings were compared with computed tomography (CT) findings, the reference standard for PNX detection.

Of the 6640 lungs observed with E-FAST, there were 1244 PNX cases, while 1328 PNX cases were detected either on the basis of MDCT or on the basis of the presence of air flush during the thoracic decompression in the emergency room. Among the 84 false negatives, 12 patients had subcutaneous emphysema, 38 had a body mass index higher than 27, 6 had a thoracic wall hematoma, and 4 had chest penetrating trauma. There were 10 false positives in the diagnosis of PNX at US examination, with mild extension and not clinically significant. The overall sensitivity of E-FAST for PNX detection was 93.6% (1244/1328), the specificity of E-FAST was 99.8% (5312/5322), the negative predictive value (NPV) was 98.4% (5312/5396), and the positive predictive value (PPV) was 99.2% (1328/1338).

Our results demonstrate that bedside thoracic US is characterized by a very good accuracy in the diagnostic work-up of major trauma patients, even in difficult conditions, allowing rapid diagnosis of PNX.

The novelty of this research lies in the possibility of diagnosing potential life-threatening conditions in a very short time by means of US, thus proposing a revision of the Advanced Trauma Life Support (ATLS) guidelines in order to incorporate it in the work-up of high-energy injured patients.