Usefulness of the suspended microbubble sign in differentiating empyemic and nonempyemic hydropneumothorax.

Abstract

Objective. The suspended microbubble sign is defined as the image seen on ultrasonography consisting of a pleural effusion strewn with numerous hyperechoic pinpoints and more or less linear shadows that move synchronously with respiration. In this study, we intended to evaluate the clinical usefulness of the suspended microbubble sign in differentiating empyemic and nonempyemic hydropneumothorax. Methods. This series consisted of 8 patients with empyemic hydropneumothorax and 23 patients with nonempyemic hydropneumothorax. The finding of the presence of the suspended microbubble signs on ultrasonography was recorded. To further elucidate the generation of the suspended microbubble sign, the interaction between air and pleural fluid of different types was investigated in vitro. Results. The suspended microbubble sign was shown on ultrasonography in all 8 patients with empyemic hydropneumothorax but was absent in the 23 patients with nonempyemic hydropneumothorax. These findings were supported by the observation that the pus seemed to mix with and trap the air more easily than did the nonpurulent pleural fluid, as shown in vitro. In this selected population, the sensitivity and specificity of the suspended microbubble sign in aiding a diagnosis of empyemic hydropneumothorax were both 100%. Conclusion. The suspended microbubble sign shown on ultrasonography might be of considerable value in differentiating empyemic and nonempyemic hydropneumothorax. Key words: ultrasonography; empyema; hydropneumothorax; pneumothorax. Recently, ultrasonography has proved valuable in detecting PN and has been applied widely to various pleural disorders. [3][4][5][6][7][8][9][10][11] To the best of our knowledge, the role of ultrasonography in HPN has not been well investigated, except for 1 study by Targhetta and colleagues in 1992.2 Their results indicated that the curtain sign, the movement of the airfluid level observed during real-time ultrasonography, and loss of the gliding sign (also called lung or pleural sliding) above the air-fluid level were of considerable value in detecting HPN. Furthermore, a peculiar ultrasonographic finding, an image caused by air microbubbles within the pleural fluid, was reported in 2 of 11 patients with HPN; however, its clinical significance remained unknown. The authors called this ultrasono-

Multimodality imaging characteristics of tension pyopneumothorax secondary to pulmonary carcinoma in a cat

“…Two studies have suggested that patients with signs of intrathoracic air bubbles are more likely to have empyemic fluid requiring repeated drainage and surgical treatment, meaning that the disease process is more advanced. 15,16 These findings have not been reported in the veterinary literature, and further studies are needed to determine the clinical relevance of intrathoracic air bubbles. However, it should be considered that when a pleural effusion with multiple gas opacity foci is identified on plain radiographs, pyopneumothorax should be listed in the differential diagnosis.…”

“…The presence of multiple, small gas opacity foci on radiographs may be considered unusual and suggests the coexistence of high pleural fluid viscosity and air in the thoracic cavity . The clinical significance of air bubbles in the thoracic cavity has not been determined, even in human medicine.…”

“…The clinical significance of air bubbles in the thoracic cavity has not been determined, even in human medicine. Two studies have suggested that patients with signs of intrathoracic air bubbles are more likely to have empyemic fluid requiring repeated drainage and surgical treatment, meaning that the disease process is more advanced . These findings have not been reported in the veterinary literature, and further studies are needed to determine the clinical relevance of intrathoracic air bubbles.…”

“…The presence of multiple, small gas opacity foci on radiographs may be considered unusual and suggests the coexistence of high pleural fluid viscosity and air in the thoracic cavity. 15 The clinical significance of air bubbles in the thoracic cavity has not been determined, even in human medicine. Two studies have suggested that patients with signs of intrathoracic air bubbles are more likely to have empyemic fluid requiring repeated drainage and surgical treatment, meaning that the disease process is more advanced.…”

Lung abscess or empyema? Taking a closer look

“…NMR: This appearance is the suspended microbubble sign which has been described in patients with pyopneumothorax6 and represents air bubbles inside the fluid. It is not specific to empyemas, as it is seen in other purulent collections caused by gas-forming organisms 5 6…”