interval placement of right-sided chest catheter with subsequent re-expansion of the right lung and significant interval decrease in the previously seen large right pneumothorax which is now small. right lung atelectasis with possible partial collapse of the right middle lobe and there is subsequent elevation of the right hemidiaphragm. there may be a small right pleural effusion. elevation of the right hemidiaphragm can be seen in right lung collapse, however, can also be seen with subpulmonic effusion or intra-abdominal fluid.