We thank Drs Peris and Barbani for their interest in our CHEST article (March 2012)1 on ultrasonography for the diagnosis of pneumothorax. Our search strategy for the meta-analysis did not include any restrictions by etiology. Only the articles that met the predefined inclusion criteria were included, none of which was performed on ventilated patients. The presence or absence of lung sliding and/or comet tails allows the ultrasonographer to recognize the presence of air in the pleural space (pneumothorax), regardless of its etiology. It is our opinion that there is no physiologic or sonographic reason to believe that ultrasonography would perform differently when the etiology is different. It is, however, the case that preexisting or concurrent conditions like the presence of ARDS can lead to false-positive ultrasonography studies.2 As this was not the objective of our study, we have not discussed this, but as Drs Peris and Barbani point out, it warrants further exploration.