Hemopneumothorax is a condition characterized by the presence of both blood (hemo-) and air (-pneumo) in the pleural cavity surrounding the lungs. This condition typically occurs as a result of trauma to the chest, such as a stab wound, gunshot wound, or rib fracture. The presence of both blood and air in the pleural cavity can cause breathing difficulties, chest pain, and potentially lead to respiratory failure if not treated promptly. Treatment usually involves draining the excess blood and air from the pleural cavity and stabilizing the underlying cause of the condition.