Study: Ultrasound could replace x-ray for dyspnea in ED

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Chest ultrasound yielded results highly concordant with chest x-rays among emergency department (ED) patients presenting with shortness of breath, suggesting that ultrasound could replace more time-consuming and radiation-inducing radiography in patients with dyspnea, according to a study published in the May issue of CHEST.

Chest x-rays are currently the first line of imaging for patients presenting in the ED for shortness of breath, with the advantages of relatively low doses of radiation and complete views of the chest, explained Maurizio Zanobetti, MD, and co-authors from the department of critical care medicine and surgery at the University of Florence, in Florence, Italy.

On the other hand, Zanobetti and colleagues noted that chest x-rays cannot be performed among pregnant women, often deliver limited accuracy and can be difficult to acquire. Moreover, x-rays can take substantially longer to perform and interpret than real-time ultrasound, Zanobetti and colleagues added.

The authors sought to examine whether quick and radiation-free chest ultrasound proved comparable to x-ray in the evaluation of ED patients with dyspnea.

Zanobetti and colleagues imaged 404 consecutive dyspnea ED patients with both ultrasound and x-ray, evaluating discordances using chest CT, which served as the gold standard. Chest x-ray and ultrasound resulted in identical diagnoses in 286 cases, 141 of which were interpreted as normal.

Among the 118 patients with dissimilar ultrasound x-ray interpretations, chest CT confirmed the ultrasound diagnosis in 63 percent of cases. “Particularly, ultrasonography exhibited greater sensitivity than radiography in patients with free pleural effusion,” Zanobetti and colleagues observed.

Agreement between chest ultrasound and x-ray was particularly strong in the identification of pulmonary emboli (K= 95 percent), pulmonary fibrosis patterns (K= 87 percent) and pneumothorax (K= 85 percent). Agreement also reached at least 70 percent for the diagnosis of free pleural effusion and lung consolidation.

“In a consecutive series of patients presenting to the ED for dyspnea, our prospective study demonstrated that ultrasonography represents a diagnostic modality at least as accurate as standard radiography with the advantages of a shorter time delay necessary to have the final medical report and no ionizing radiation exposure,” the authors stated.

“In fact, the most important result of our study is the high concordance between the two modalities in the majority of patterns we studied.”

Zanobetti and colleagues estimated that if the concordant results between ultrasound and x-ray were accurate, ultrasound delivered accurate diagnoses for 90 percent of all abnormalities.

The authors acknowledged, however, that the accuracy of ultrasound in their study was likely inflated due to the high level of experience of their hospital’s ED reader. They also noted that agreement between chest x-ray and ultrasound did not guarantee an accurate diagnosis.

“Considering the shorter time delay necessary to have a final medical report from an ultrasound scan compared with the standard radiographic examination, without patient exposure to ionizing radiation, chest ultrasonography could replace standard chest radiography as the first routine imaging modality used in patients with dyspnea admitted to the ED,” Zanobetti and colleagues concluded, before indicating the importance of first replicating their results.