In this Chest X-Ray we can identify a left sided pneumothorax - there is absence of lung markings in the periphery and we can also see a shadow which outlines the edge of the lung. A pneumothorax is caused when air enters the potential space between the viceral and parietal pleura and causes the lung to collapse down under the pressure of it's elsatic recoil. In this case it is likely that the pneumothorax has been caused by trauma as we can see air in the soft tissues on the left side (surgical emphysema - clinically feels like bubble wrap). A pneumothorax can be a life threatening condition. The patient presents in respiratory distress with decreased expansion on the affected side. There will be hyperresonance to percussion on that side but absent breath sounds. The emergency treatment is decompression with a large bore cannula in the 2nd intercostal space mid-clavicular line followed by insertion a chest drain in the 5th intercostal space mid-axilllary line
This image shows the cardinal sign of a perforated abdominal viscus. There is air under the diaphragm indicating air within the peritoneal cavity which can occur from a perforated abdominal viscus, following a laparoscopic abdominal procedure (where air is pumped into the peritoneal cavity to improve the views) and after more obscure events such as vigorous waterskiing in a female. When this appearance is seen it should be treated as a surgical emergency until proved otherwise.