Chest
Volume 133, Issue 1, January 2008, Pages 204-211
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Original Research
CHEST IMAGING
Occult Traumatic Pneumothorax: Diagnostic Accuracy of Lung Ultrasonography in the Emergency Department

https://doi.org/10.1378/chest.07-1595Get rights and content

Background

The role of chest ultrasonography (US) in the diagnosis of pneumothorax (PTX) has been established, but how it compares with lung CT scanning in the diagnosis of radiooccult PTX and in the determination of its topographic extension has not yet been completely evaluated.

Objective

To determine the diagnostic accuracy of chest US in the emergency department (ED) in the diagnosis of occult PTX in trauma patients and to define its ability to determine PTX extension.

Design

An 18-month prospective study.

Patients

A total of 109 conscious, spontaneously breathing patients who had been admitted to the ED for chest trauma or polytrauma.

Methods

All eligible patients underwent a standard anteroposterior supine chest radiograph (Rx) and a spiral CT lung scan within 1 h of ED admission. Lung US was carried out by an operator who was unaware of the other examination results, both for diagnosis and for the quantitative delimitation of the PTX.

Results

Twenty-five traumatic PTXs were detected in the 218 hemithoraxes (109 patients; 2 patients had a bilateral PTX) evaluated by spiral CT scan; of these, only 13 of 25 PTXs (52%) were revealed by chest Rx (sensitivity, 52%; specificity, 100%), while 23 of 25 PTXs (92%) were identified by lung US with one false-positive result (sensitivity, 92%; specificity, 99.4%). In 20 of 25 cases, there was agreement on the extension of the PTX between CT lung scan and lung US with a mean difference of 1.9 cm (range, 0 to 4.5 cm) in the localization of retroparietal air extension; chest Rx was not able to give quantitative results.

Conclusions

Lung US scans carried out in the ED detect occult PTX and its extension with an accuracy that is almost as high as the reference standard (CT scanning).

Section snippets

Goals of This Investigation

The aims of this study were to define the accuracy of lung US in the diagnosis of radiooccult PTX in trauma patients who were admitted to the ED and to define its ability to delineate PTX extension, comparing this technique with chest Rx and CT scanning.

Study Design

This was a multicentric, observational study of consecutive patients who had been admitted to the EDs of Valle del Serchio Hospital, Castelnuovo di Garfagnana, Italy (a small rural hospital with 18,000 ED admissions per year), and of the Policlinico A. Gemelli, Rome, Italy (a large university city hospital with 70,000 ED admissions per year) from June 1, 2005, to November 30, 2006, for chest or major trauma.

Quality Control

Approval from the institutional review boards at both study centers was obtained, and

Results

A total of 116 patients with a diagnosis of chest trauma or multiple trauma was admitted to both EDs during the study period. Among them, seven patients were excluded because of the need of immediate chest decompression (one patient), subcutaneous emphysema (three patients), and the inability to give informed consent (three patients).

The final study population included 109 patients with a mean (± SD) age of 41.4 ± 20.5 years, 62.9% were men (total, 73 subjects). Sixty-five evaluated patients

Discussion

This study demonstrates a high sensitivity and sensibility of lung US as a technique in detecting traumatic PTX. Particularly, lung US has shown a greater ability to detecting PTX in the supine trauma patient when compared to chest Rx. Furthermore, our results indicate the ability of US to define, through the determination of lung points, the extension, and thus the size, of the PTX with an accuracy almost as high as that of a lung CT scan. An evergrowing weight must be given to the necessity

Conclusion

Our study demonstrates the accuracy of lung US in the ED diagnosis of traumatic PTX not shown by traditional chest Rx and in the definition of its extension, whether radiooccult or not. We thus propose the use of lung US as a tool for the diagnosis and semi-quantification of traumatic PTX in the ED.

We believe that echographic evaluation of the thorax should be performed during the primary survey as an extension of the FAST examination in every trauma patient. This could help to identify a

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