Hemothorax overview

# Overview
Hemothorax as a clinico-pathological entity can be defined in two ways. Morphologically, it is a pathologic collection of blood within the pleural cavity, between the lung surface and inner chest wall.  Clinically , hemothorax is defined as a pleural fluid with a hematocrit ranging from at least 2550% of peripheral blood. In cases of long standing haemothorax due to haemodilution, hemothorax can appear with lower levels of hematocrit. massive hemothorax is defined as the drainage of more than 1500 cc of blood upon chest tube insertion.

# Historical Perspective
Haemothorax has been detailed in numerous medical writings dating back to ancient times. In 1794, the first  intercostal incision was developed by John Hunter to treat and drainage of the hemothorax. Although Hunter's method was effective in evacuating the hemothorax, an iatrogenic pneumothorax as a result of the procedure was significant. Some recommended closure of chest wounds without drainage. Observing the advantages and dangers of both forms of therapy, Guthrie, in the early 1800s, proposed early evacuation of blood through an existing chest wound. Finally, by the 1870s, early hemothorax evacuation by intercostal incision was considered standard practice.

# Classification
Spontaneous haemothorax (SH) is a subcategory of haemothorax.

# Pathophysiology
Haemothorax is a pathologic collection of blood within the pleural cavity, between the lung surface and inner chest wall. Three mechanisms of bleeding in haemothorax include torn adhesion between the parietal and visceral pleurae, rupture of neovascularized bullae as a complication of subpleural emphysematous blebs, and torn congenital aberrant vessels branching from the cupola and distributed in and around the bulla in the apex of the lung. There are some genetic disorder that are predisposed to haemothorax.

# Causes
Haemothorax  may be caused by trauma or can be spontaneous and iatrogenous. Causes of traumatic haemothorax include blunt force injuries ,penetrating thoracic injuries, and thoracoabdominal injuries. Causes of spontaneous haemothorax include vascular disorders, malignancies, connective tissue disorders, gynecological disorders, hematological disorders, and miscellaneous pathological entities. Haemothorax can also be a complication of various iatrogenically-related procedures. In addition, the cause of haemothorax can remain unknown even after exploratory thoracotomy.

# Differentiating haemothorax from other Diseases
Haemothorax must be differentiated from other diseases that cause dyspnea and respiratory distress.

# Epidemiology and Demographics
The exact incidence of haemothorax is not clear. Chest injuries occur in approximately 60% of all polytrauma cases and haemothorax is most frequently caused by chest trauma. The occurrence of haemothorax related to trauma in the United States is estimated to be 300,000 cases annually.

# Risk Factors
Common risk factor in the development of hemothorax is trauma. Non-traumatic hemothorax is a relatively uncommon entity. Procedure can be another risk for hemothorax.

# Natural History, Complications and Prognosis
Bleeding into the pleural space is exposed to the motion of the diaphragm, lungs, and other intrathoracic structures. The agitation of cardiac and respiratory movement  defibrinates the blood, and a fibrin clot thus formed is deposited on the layers of pleura. After several hours, clot formation is inevitable and it should be evacuated. if left untreated, it may progress to develop some complications.

# Diagnosis

## Symptoms
The most common symptoms of hemothorax include severe chest pain and shortness of breath. Orthopnea can be another symptom of hemothorax.

## Physical Examination
Patients with hemothorax usually appear dullness to percussion, decreased breath sounds, tracheal deviation, and dyspnea that can be life threatening when hemodynamic instability and hypovolemic shock occurs.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of hemothorax include reduced concentrations of hemoglobin in complete blood count (CBC) and pleural fluid with a hematocrit ranging from at least 2550% of peripheral blood.

## Imaging Findings
Radiological examination is the key for accurate identification of the source of bleeding:
- An chest x-ray may be helpful in the diagnosis of hemothorax. On chest x-ray, hemothorax is characterized by signs of occupation by pleural fluid, meniscus of fluid blunting the costophrenic angle or diaphragmatic surface and tracking up the pleural margins of the chest wall.
- Ultrasound may be helpful in the diagnosis of hemothorax. In lung ultrasound, hemothorax is diagnosed as a dependent dark zone free of echo.
- Radiological examination is the key for accurate identification of the source of bleeding. CT of the chest demonstrates pleural effusion. An enhanced chest CT scan can reveal the bleeding site and the severity of the haemothorax. It is not usually indicated in the initial trauma setting to diagnose hemothorax.

# Treatment

## Medical Therapy
The mainstay of medical therapy for hemothorax is, fluid resuscitation and blood transfusion. All patients, regardless of causes, require attention for fluid resuscitation and blood transfusion. Prophylactic use of antibiotics following haemothorax reduces the rate of infectious complications such as pneumonia and empyema during at least 24 hours after the start of chest tube drainage. Antibiotic treatment should be directed to Staphylococcus aureus and Streptococcus species and the use of first generation cephalosporins during the first 24 hours in patients treated with chest tube drainage is recommended. Intrapleural fibrinolytic therapy (IPFT) has been advocated as an alternative to evacuate residual blood clots and breakdown adhesions in low-resource settings where the relatively costly and sophisticated technique of VATS may not be available, feasible or applicable. Several studies report on IPFT with streptokinase, urokinase or tissue plasminogen activator (TPA). Duration of treatment with IPFT can vary between 2 and 9 days for streptokinase and 215 days for urokinase.

## Surgery
The successful management of hemothorax depends on the severity of the blood loss and subsequent hemodynamic stability of the patient. The mainstay of therapy for hemothorax is intercostal chest drain (ICD) and oxygen therapy that significantly reduce the morbidity and mortality. Evacuation of haemothorax by chest tube does not succeed in all cases. The resultant retained intrapleural collections are referred to as residual hemothorax (RH). Blood in the pleural cavity may organize and fibrose, resulting in a loss of lung volume and empyema if untreated. Video assisted thoracic surgery (VATS), minimally invasive surgery has been found to be highly successful for the treatment of these residual collections, especially when used early. |VATS also can be used to treat patients with active blood loss but with stable haemodynamics, not only to stop the bleeding but also to evacuate blood clots and breakdown adhesions to prevent fibrothorax and restrictive physiology. An optimal period between the start of haemothorax and VATS of 4872 hours is repeatedly advocated and longer intervals lead to increased rates of complications, according to some authors. A longer time span increases the chance of intraoperative conversion to thoracotomy, prolongs postoperative drainage time and is associated with a higher incidence of hospital admissions. Thoracotomy with ongoing resuscitation is the procedure of choice for patients with haemodynamic instability due to massive haemothorax or active bleeding. The criteria for thoracotomy, are blood loss by chest tube 1.500 ml in 24 h or 200 ml per hour during several successive hours and the need for repeated blood transfusions to maintain haemodynamic stability. Surgical exploration allows control of the source of bleeding and evacuation of the intrathoracic blood; and also is required for adequate empyema drainage and/or decortication.

## Primary Prevention
There is no established method for prevention of hemothorax. However, early and adequate treatment which prevents of complication (suppuration) is necessary. Some factors which most frequently promote suppuration of the thoracic cavity, developing from traumatic haemothorax. so, attention is called to secure the necessary personal and material conditions to the preventive treatment.

## Secondary Prevention
Secondary prevention strategies following hemothorax include medical therapy and surgical therapy.