bubble_chart Overview

Empyema refers to the invasion of the pleural cavity by pathogenic bacteria, leading to infection and pus accumulation. It can occur at any age, from newborns to the elderly. Empyema is mostly caused by pyogenic bacteria, with the majority of cases secondary to pulmonary infections. In children, Staphylococcus aureus pneumonia is a common cause. Some cases may also result from open chest trauma, thoracic surgery, subphrenic abscess, or sepsis. When pus fills the entire pleural cavity, it is called total empyema; if the pus is confined to a part of the pleural cavity, it is termed localized (encapsulated) empyema.

Based on the duration and pathological response, empyema is classified into acute and chronic types. In reality, there is no clear boundary between the two, and classification based solely on duration is imprecise.

In treatment, classification based on pathological response and clinical manifestations is more clinically practical. For instance, empyema where pus drainage allows lung re-expansion is considered acute empyema, primarily treated with medical and pediatric approaches. Conversely, empyema where pus drainage does not result in lung re-expansion is chronic empyema, requiring surgical intervention.

If empyema results from a ruptured lung abscess or is complicated by a bronchopleural fistula, pneumothorax may coexist, termed pyopneumothorax.

Untreated empyema may lead to pus penetrating the chest wall subcutaneous tissue (known as empyema necessitatis), forming a sinus tract upon rupture, or perforating into the lung to create a bronchopleural fistula. Pus flowing through the bronchopleural fistula can infect the contralateral lung. Empyema may also complicate into mediastinal abscess, osteomyelitis of the ribs or sternum, sepsis, and other conditions.

Most acute empyema cases are secondary to various pneumonias. Chronic empyema largely develops from acute empyema. The main causes of chronic empyema include:

1. Delayed or inappropriate treatment of acute empyema;
2. Empyema complicated by bronchopleural or esophagopleural fistula, allowing continuous entry of contaminants or bacteria into the pus cavity; subphrenic abscess-induced empyema, where incomplete eradication of subphrenic infection or retained foreign bodies in the thorax can lead to chronic empyema due to persistent infection sources;
3. Coexisting specific infections, such as empyema with Mycobacterium tuberculosis infection.

bubble_chart Clinical Manifestations

1. Acute empyema:
   1. High fever, chest pain, shortness of breath, cough, and positional expectoration in cases with bronchopleural fistula;
   2. Restricted respiratory movement on the affected side, fullness of the chest, tracheal deviation to the opposite side, widened intercostal spaces, dull or flat percussion note (tympanic percussion note in the upper part and dullness in the lower part in pyopneumothorax), and diminished or absent breath sounds on auscultation.
2. Chronic empyema:
   1. Recurrent fever (low-grade), loss of appetite, dull chest pain, shortness of breath, cough, and copious purulent sputum in cases with bronchopleural fistula;
   2. Chronic wasting appearance, emaciation, anemia, malnutrition (decreased plasma protein), collapse of the chest wall on the affected side, tracheal deviation toward the affected side, narrowed intercostal spaces, restricted respiratory movement, flat percussion note, diminished or absent breath sounds, scoliosis, and clubbing of fingers (toes).

bubble_chart Diagnosis

1. Acute empyema:
   1. History of pneumonia, chest trauma, or thoracic surgery, with fever, chest pain, cough, shortness of breath, and increased white blood cell and neutrophil counts;
   2. Signs of pleural effusion, with possible mediastinal shift in cases of significant pus accumulation;
   3. Chest X-ray shows pleural effusion, mediastinal shift to the healthy side, and in cases of bronchopleural fistula, lung collapse and fluid level may be observed;
   4. Diagnosis is confirmed by thoracentesis yielding pus, with possible positive bacterial culture. After thoracentesis, 1 mL of methylene blue can be injected to determine the presence of a bronchopleural fistula.
2. Chronic empyema:
   1. History of improper management or inadequate drainage of acute empyema, or unresolved primary cause of empyema, with the abscess cavity remaining unclosed;
   2. Chronic wasting constitution, low-grade fever, thickening of the affected pleura, chest wall depression, or signs of effusion. Clubbing of fingers or toes is often present;
   3. Chest X-ray findings: chest wall depression, pleural thickening, narrowed intercostal spaces, effusion, or air-fluid levels. Iodized oil contrast imaging of the chest wall sinus reveals the abscess cavity. Pleural calcification may sometimes be seen;
   4. Thoracentesis yields pus, and bacterial growth is confirmed by culture. Injection of methylene blue into the thoracic cavity can determine the presence of a bronchopleural fistula.

bubble_chart Treatment Measures

1. Select effective antibiotics to control infection based on bacterial culture and drug sensitivity testing of the pus.
2. Drain the pus completely to promote early lung re-expansion. Perform repeated thoracentesis as early as possible to aspirate thin pus and inject antibiotics or fibrinolytic agents (such as trypsin, streptokinase, or deoxyribonuclease) into the pleural cavity. For cases with poor response to repeated thoracentesis, closed thoracic drainage should be performed promptly. For empyema caused by staphylococcal pneumonia in children, early closed thoracic drainage is often recommended for better outcomes.
3. Systemic supportive treatment includes enhanced nutrition, supplementation of energy and protein, and, if necessary, multiple intermittent blood transfusions.
4. Adjust and improve drainage of the empyema cavity according to the specific situation to facilitate infection control and systemic improvement.
5. Surgical treatment: Eliminate the cause, eradicate the empyema cavity, and restore lung function. For cases with a short disease course and no pulmonary lesions, decortication of the empyema may be performed. For cases with a long disease course, pulmonary lesions, or bronchopleural fistula, pleuropneumonectomy may be performed. If one lung is completely destroyed, total pneumonectomy may be considered. For cases with a long disease course, severe pulmonary fibrosis, or pulmonary lesions unsuitable for re-expansion (such as cavitary pulmonary tuberculosis), as well as failed decortication, if the empyema cavity is around 150 ml, omentoplasty may be used to obliterate the cavity. For larger cavities, intrathoracic thoracoplasty may be performed to eliminate the cavity.

The principles of empyema treatment are to control the disease cause, enhance systemic resistance, ensure unobstructed drainage, and eradicate the empyema cavity. For the primary infection, effective and sufficient antibiotics should be selected based on pus culture and drug sensitivity testing, along with systemic supportive treatment. Acute empyema requires timely pus drainage to relieve systemic toxic symptoms, promote lung re-expansion, eliminate the cavity, and prevent chronic empyema. In the early stage of acute empyema, repeated thoracentesis for pus aspiration and antibiotic injection can cure most patients. If puncture therapy is ineffective, closed thoracic drainage via intercostal or rib resection should be performed as early as possible. For pediatric acute empyema, closed thoracic drainage is often preferred. For chronic empyema, after adjusting drainage and improving systemic conditions, different surgical approaches—such as pleural decortication, pleuropneumonectomy, total pneumonectomy, or intrathoracic thoracoplasty—may be adopted based on pathological changes.

bubble_chart Cure Criteria

1. Cure: Symptoms disappear, postoperative X-ray examination shows the abscess cavity has disappeared. The wound has healed.
2. Improvement: After treatment, clinical symptoms disappear, but a sinus remains in the chest wall or incision with minimal secretion, and the abscess cavity is mostly gone. After several months of observation, if the wound does not heal, further treatment is required.
3. No improvement: Symptoms and signs do not improve, and the abscess cavity persists.