Empyema

What is it

 The pleural space is actually a potential space created by the visceral and parietal pleura. Normally, it contains a little amount of fluid  which facilitates movement of the lung with the diaphragm and chest wall. When there is some plural fluid collected abnormally in this space, we call it thoracic effusion. A thoracic effusion provides a rich culture medium in which white blood cell defenses can be impaired and an empyema may flourish. Empyema is the presence of gross pus in the pleural cavity, it consists of an effusion containing polymorphonuclear leukocytes and fibrin.  

Development

By convention, the formation of an empyema can be divided into three phases: exudative, fibrinopurulent and organizing. During the first or exudative phase, pus accumulates. This is followed by fibrin deposition and loculation of pleural fluid known as the fibrinopurulent phase. The last phase,the organizing phase, is characterized by fibroblast proliferation; at this time there is the potential for lung entrapment by scarring.

Symptom  

Pleural effusions are most common in patients with pneumonia. However, empyema is a rare complication of pneumonia. Most patients with empyema will have persistent symptoms despite antibiotic therapy for pneumonia. Symptoms include fever, cough, dyspnea, and pleuritic chest pain. 

Diagnosis 

A chest radiograph will demonstrate a parapneumonic effusion; a sample of the fluid should be obtained by thoracentesis. The diagnosis of empyema is made when gross inspection of the pleural fluid reveals pus. A positive gram stain by microscopic analysis also clinches the diagnosis.

Pleural fluid cultures are often negative in patients with empyema and may be negative secondary to antibiotic therapy or inability to grow the organism. Ultrasound and CT scan determine if an effusion is free flowing or walled off, loculated, or abscess-like. 

How to treat

As we know, the management of empyema involves three core principles:

• Usage of appropriate antibiotics

• Complete evacuation of suppurative pleural fluid

• Preservation or restoration of lung expansion. 

With needle thoracentesis or large closed-tube thoracostomy, and antibiotics, thin fluid in exudative stage can occasionally be completely evacuated and the disease controlled. When it comes into fibrinopurulent stage, viscosity of the pleural fluid is increasing,        coagulation factors are activated, and fibroblast activity begins coating the pleural membrane with an adhesive meshwork. So the drainage alone maybe not effective while it is often blocked by fibrosis or necrosis tissue. 

We only can clear these fragments and pus completely thoracoscopically with good visualization. Thorascopic pleural evacuation and/or decortication earlier in the clinical course (presumably during the fibrinopurulent stage) can reduce hospital stay due to the infectious process and the morbidity.  

The VATS procedure

After one-lung ventilation established with aid of a double-lumen endotracheal tube, the patient is placed in a lateral decubitus position. Placing the patient over a large axillary role widens the contralateral intercostals spaces and facilitates trocar insertion. Based on preoperative imaging studies, two or three small suitable incisions are made in the lateral chest wall for port placement. 10 mm instruments may be utilized for adult patient. The pleural space is inspected and coagulum removed completely. Interlobar collections should also be sought and removed. Adherent peel is carefully removed from visceral and parietal pleural surfaces.