UMEM Educational Pearls

Title: Chest US is more sensitive than Chest X ray for detection of traumatic pneumothorax

Keywords: Ultrasound, Trauma, Pneumothorax (PubMed Search)

Posted: 8/11/2020 by David Gordon, MD
Click here to contact David Gordon, MD

While chest X ray (CXR) is routinely obtained in the setting of traumatic injury, ultrasound (US) is a fast and reliable way to evaluate for life-threatening traumatic injuries requiring emergent intervention, and is supported by the Eastern Association for the Surgery of Trauma (EAST) guidelines. A recent Cochrane Review compared the test characteristics of chest US vs CXR for detection of traumatic pneumothorax when using Chest CT or thoracostomy as the gold standard.

Primary end point: sensitivity and specificity for pneumothorax
US performed by nonradiologists.
9 studies, 1271 patients, 410 of which had a pneumothorax
Summary sensitivity: US 0.91 (95% CI 0.85-0.94), ranging from 0.82-0.98 in the included studies, vs. CXR 0.47 (95% CI 0.31- 0.63) ranging from 0.09 to 0.75
Summary specificity: US 0.99 (95% CI 0.97-1.00, ranging from 0.96-1.00 vs. CXR 1.00 (95% CI 0.97- 1.00), ranging from 0.98 to 1.00

There possible weaknesses of this study, including blinding in the original studies, and several studies may or may not have been at risk for bias as their risk of bias was ‘unclear’. However, the results were consistent across the studies analyzed and remained similar after sensitivity analysis.

Several anatomical as well as patient care issues may confound US findings for pneumothorax such as the presence of bleb, prior thoracic surgery or pathology, as well as main stem intubation.

Bottom line: While the presence of pneumothorax is on either CXR or US is highly likely to represent the a true pneumothorax, ultrasound is a far superior screen for the detection of pneumothorax in the trauma patient.

References

1. Chan KK, Joo DA, McRae AD, et al. Chest ultrasonography versus supine chest radiography for diagnosis of pneumothorax in trauma patients in the emergency department. The Cochrane Database of Systematic Reviews. 2018;2018(5):CD013031.

2. Mowery NT, Gunter OL, Collier BR, et al. Practice Management Guidelines for Management of Hemothorax and Occult Pneumothorax. Journal of Trauma and Acute Care Surgery. 2011;70(2):510-518.