Empyema is a severe medical condition defined by the accumulation of pus, which is infected fluid, within the pleural space. This space is a narrow cavity located between the two layers of the pleura, the thin membranes that line the lungs and the inside of the chest wall. Pus is a thick fluid composed of white blood cells, dead tissue, and bacteria, signifying a complicated infection. Since the fluid collects outside the lung tissue, it cannot be cleared by coughing and must be actively treated. Empyema is considered a serious complication of an infection elsewhere in the body.
How Empyema Develops
Empyema nearly always begins as a complication of bacterial pneumonia, progressing through distinct stages once the infection breaches the lung tissue. The initial inflammatory response causes fluid to leak into the pleural space, forming a parapneumonic effusion. This early fluid, called an exudate, may initially be sterile and thin. If bacteria successfully invade this fluid, the effusion becomes infected, marking the progression toward empyema.
The immune response releases inflammatory cells, causing the fluid to thicken and become purulent. This is the fibrinopurulent stage, where fibrin strands begin to form pockets, or loculations, within the pleural space. Less frequently, empyema can arise from other sources, such as trauma to the chest wall, recent thoracic surgery, or the rupture of a lung abscess. If left untreated, the fibrin strands can organize into a thick, restrictive peel that encases the lung, severely hindering its ability to expand.
Symptoms and When to Seek Help
The clinical presentation of empyema often follows a worsening of symptoms from an initial lung infection like pneumonia. Patients typically experience a high-grade fever accompanied by shaking chills, which may be persistent and difficult to control. A sharp, stabbing chest pain, known as pleuritic pain, is also characteristic, originating from the inflamed pleural lining. This discomfort is often aggravated by taking a deep breath, coughing, or sneezing.
As the infected fluid accumulates and puts pressure on the lung, patients experience increasing shortness of breath (dyspnea). Other systemic symptoms include excessive sweating, particularly night sweats, a persistent cough, and a general feeling of malaise. Immediate medical evaluation is necessary if a person treated for a chest infection experiences a return of high fever, worsening chest pain, or increasing difficulty breathing. Delaying treatment allows the pus to thicken and organize, making effective resolution much more challenging.
Clinical Treatment Path
Diagnosis
Management begins with a precise diagnosis using imaging and fluid analysis. A chest X-ray confirms fluid presence, but a computed tomography (CT) scan better visualizes the fluid’s extent and determines if loculations have formed. The definitive diagnostic step is thoracentesis, where a needle is inserted to withdraw a fluid sample.
Analyzing this fluid confirms the diagnosis, especially if frank pus is aspirated or if the fluid shows a low pH, low glucose, and high lactate dehydrogenase (LDH) level. The fluid is also cultured to identify the specific bacteria, which guides antibiotic selection. Treatment focuses on two primary goals: controlling the bacterial infection and completely draining the infected fluid.
Drainage and Fibrinolytics
Broad-spectrum intravenous (IV) antibiotics are started immediately, often before culture results return, and are later adjusted to target the specific organism. To achieve drainage, a chest tube (thoracostomy tube) is inserted under image guidance. This tube allows the pus to drain continuously, relieving pressure and allowing the lung to re-expand.
If the pus is too thick or trapped in multiple loculations, simple drainage may be insufficient. In these cases, medical professionals may instill fibrinolytics (clot-busting agents) directly through the chest tube. These agents break down the fibrin strands forming the loculations, allowing the trapped fluid to drain more effectively.
Surgical Intervention
When IV antibiotics and chest tube drainage, even with fibrinolytics, fail to resolve the empyema, surgical intervention becomes necessary. This is typically required when the disease has progressed to the organizing stage, forming a thick, fibrous peel around the lung.
Video-Assisted Thoracoscopic Surgery (VATS) is a minimally invasive option where a surgeon enters the chest cavity through small incisions. During this procedure, the surgeon breaks up loculations, removes the fibrous peel from the lung surface (decortication), and ensures complete drainage of infected material.