This accumulation of fluid in the pleural cavity is called pleural effusion. Pleural effusions are given specific names depending on the nature of the fluid: hydrothorax for serous fluid, pyothorax for pus, hemothorax for blood, and urinothorax for urine. Signs and symptoms
Signs and symptoms include anxiety, rapid breathing, restlessness, shock, and pale, cool, clammy skin. When the affected area is percussed, a dull feeling may be observed. Neck veins may be flat and breathing sounds reduced. It can also cause a collapsed lung (atelectasis). Massive hemothorax, often defined as over 1.5 liters of blood initially when an intercostal drain is placed, or a bleeding rate greater than .2 liters/hr, can result in shock with two causes: massive bleeding resulting from hypovolemic shock, and venous pressure from the retained blood, impairing blood flow. Causes
Hemothoraces are classified in three broad categories according to the cause and in order of frequency: traumatic, iatrogenic, or nontraumatic. All three categories have the potential to affect major arteries and result in death by blood loss. Traumatic
Hemothorax is most often caused by blunt or penetrating trauma to the chest. In blunt traumatic cases, hemothorax typically occurs when rib fracture damages the intercostal vessels or the intraparenchymal pulmonary vessel, while in penetrating trauma, hemothorax occurs due to injuries directly affecting blood vessels in the thoracic wall, lung parenchyma, or the heart. If large blood vessels such as the aorta are damaged, the blood loss can be massive.
Penetrating trauma is significantly less common, and has a much higher death rate, with up to 90% dying before arriving at the hospital. Gunshot wounds are associated with a higher death rates compared to stab wounds. In cases of penetrating trauma involving the heart, less than 1% survive. Complications
Complications can occur following a hemothorax, and are more likely to occur if the blood has not been adequately drained from the pleural cavity. Blood that remains within the pleural space can become infected, and is known as an empyema. It occurs in 3–4% of traumatic cases, and 27-33% of retained hemothoraces. It is more likely in people who develop shock, had a contaminated pleural space during the injury, persistent bronchopleural fistulae, and lung contusions. The likelihood of it can be reduced by keeping thoracostomy tubes sterile and by keeping the pleural surfaces close together to prevent fluid or blood from accumulating between the surfaces. The retained blood can irritate the pleura, causing scar tissue (adhesions) to form. If extensive, this scar tissue can encase the lung, restricting movement of the chest wall, and is then referred to as a fibrothorax. Less than 1 percent of cases go on to develop a fibrothorax. Cases with hemopneumothorax or infection more often develop fibrothorax. After the chest tube is removed, over 10% of cases develop pleural effusions that are mostly self-limited and leave no lasting complications. In such cases, thoracentesis is performed to eliminate the possibility of an infection being present.