The pathophysiology of a tension pneumothorax relates to ventilation and cardiac output. The insertion of a large-bore needle or medium-bore catheter into the affected pleural cavity rapidly accomplishes decompression. The McSwain Dart was developed for the prehospital care of tension pneumothorax. The dart is inserted into the secondary costal space, mid-clavicular line, or the fourth intercostal space mid-axillary line. Proper identification of the indications for use of this device is often difficult in the prehospital setting.