Empyema overview

Empyema Microchapters
Patient Information
Overview
Classification Subdural empyema Pleural empyema
Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Prince Tano Djan, BSc, MBChB [2]

Overview

An empyema is a collection of pus within a pre-existing body cavity. It must be differentiated from an abscess, which is a collection of necrotic and suppurated tissue located in the parenchyma of an organ. Empyema is most commonly used to refer to pus collection in the pleural cavity although several other organs can be affected example brain, gallbladder, joint and urinary bladder. Thoracic empyema arises from an infection within the lung, often associated with parapneumonic effusions. Parapneumonic effusions may be uncomplicated or complicated effusions. Complicated parapneumonic effusion results when bacteria invade the pleural space with a resultant formation of an empyema.

Historical Perspective

Pleural infection was first described by Hippocrates as far back as 460-370 B.C. During this time open chest drainage was the sole treatment modality and was associated with high mortality.

In 1300s, Guy de Chauliac also called Guido or Guigo de Cauliaco, a surgeon of medieval France, commented with surprise on the lack of ancient writings concerning thoracic wounds and the disagreements on the treatment of these wounds. Lanfranc of Paris, William of Bologna, and Roland of Parma advocated that open treatment of penetrating thoracic wounds using tents and drains allow blood and decaying organic materials to escape however, Henri de Mondeville was of different opinion that immediate closure of wounds helps to prevent heat loss and air entry.

During the early 1500s, Giovanni da Vigo, an Italian surgeon and physician of Pope Julius II, was one of the first surgeons to discuss firearm wounds to the chest.

IN 1873, Playfair gave the first description of a water-seal chest drainage system in the treatment of a child with thoracic empyema.

In 1875, Gotthard Bülau a German Internist described the use of closed water-seal chest drainage to treat an empyema, as an alternative to the standard rib resection and open tube drainage. He punctured the pleura membrane with trocar and introduced a rubber catheter into the pleural cavity. The free end of the catheter inserted in a bottle one-third full of solution allowing pus to flow freely from the chest into the bottle.

Closed chest tube drainage was experimentally practised during the influenza epidemic in 1917–19 when open surgical drainage was associated with a high mortality rate. This coincided with world war I and the resultant crisis of streptococcal pneumonia and empyema.

In 1950, Vincenzo Monaldi an Italian Pulmonologist suggested draining the thoracic cavity with a more superior approach at the second or third intercostal space.

The modern three chamber thoracic drainage system was first described by Howe in 1952 but not widely employed at the time.

Closed chest tube drainage became the standard of treatment from late 1950.

Pathophysiology

The process leading to the formation of empyema involves migration of organisms into the pleural cavity. Lung parenchymal infection stimulates local pleural immune activation, neutrophil migration and release of inflammatory cellular components and toxic oxygen species, such as IL-6, IL-8 and tumour necrosis factor (TNF)-α. These mediators promotes endothelial injury resulting in increased pleural membrane permeability and increased osmotic pressure. With persistent inflammation, increased permeability of vascular and mesothelial membranes results in increased plasma leakage into the pleural cavity. Coagulation cascade when activated within the pleural cavity contributes to the development of a “fibrinopurulent” or “complicated” parapneumonic effusion. Fibrin is deposited over the pleural surfaces with fibrinous septae producing loculated effusions.

Causes

Streptococcus pneumoniae was the most common bacteria found in empyemas before the development of antibiotics. More recently, however, anaerobes have become the predominant organism in culture positive empyemas (and therefore careful anaerobic cultures should always be sent when working up parapneumonic effusions). Mixed aerobic and anaerobic infections are also common. In general any bacteria can cause an empyema, however different bacteria are associated with different rates of empyema formation. Some of the common bacteria causes include; bacteroides, fusobacterium, haemophilus influenzae, pneumococcal infections, staphylococcus aureus, streptococcus, and TB.

Epidemiology and Demographics

The incidence and prevalence of empyema has been increasing over the past 15 years. More than 40% of patients have preexisting comorbidities. There have been a 26% increase in age and sex-standardized incidence rate from 8.7 per 100,000 person-years in 1997 to 11.8 per 100,000 person in 2011. This increment is most notably among older people aged ≥ 80 years (87.3% [from 20.4 per 100,000 in 1997 to 38.2 per 100,000 in 2011]) compared with people aged 40 to 64 years (27.8% [from 10.7 per 100,000 in 1997 to 12.6 per 100,000 in 2011]). Men are more commonly affected with empyema than women. The male to female ratio is approximately 1.7- to 3.1-fold higher in men than in women. The rate of patients with empyema requiring hospitalization appear to be increasing in western populations, however updated population-based data are scanty. The few available data on adult empyema have reported increase between 30% and 97% over the past 15 years in the United States and Canada. There is however a decreasing trend in the median days of hospital stay from 22 days 17 days.