Is that a lung edge?
Our results show that almost half of our colleagues would have carried out tube thoracostomy when no pneumothorax was actually present. In a situation where a pneumothorax is a clinical possibility we would recommend either temporarily removing the oxygen mask if clinically stable, or fixing the reservoir bag outwith the field of the CXR by means of adhesive tape to avoid any misinterpretation of this 'mask sign'.
The simulation technique is able to accurately assess performance of surgical residents (on a number of parameters) in a relatively brief time period. Simulation data were highly similar to faculty ratings that were based on at least 2 years of experience with the resident.