Empyema Thoracis

• Young age: Especially infancy, with the peak incidence in the second half of infancy.
• Underlying malnutrition
• A recent or coexisting measles infection

• Early Stage (Dry Pleurisy): In the initial phase, pleural inflammation leads to the accumulation of a minimal quantity of fibrin-rich exudate and a few inflammatory cells, resulting in dry pleurisy.
• Exudative Stage (Pleurisy with Effusion): Subsequently, the condition progresses to the exudative stage, characterized by the accumulation of pleural effusion.
• Fibrinopurulent Stage: In this stage, there is a significant influx of polymorphonuclear cells and bacteria into the pleural cavity. Extensive loculation of the effusion may occur in one or both pleural cavities, accompanied by considerable thickening of the parietal pleura. Thoracocentesis during this stage yields a thick and purulent fluid.
• Organizing Stage: Without prompt therapeutic evacuation of the fibrinopurulent fluid, fibroblast proliferation occurs on both pleural surfaces, leading to the formation of an inelastic membrane (pleural peel). This stage can cause entrapment of the lung parenchyma.
• Complications: In advanced cases, the purulent fluid may extend beyond the pleura, leading to the formation of a bronchopleural fistula and pyopneumothorax. It can also spread into the pericardium, resulting in pyopericardium. Rarely, pus may dissect into the chest wall, leading to conditions like osteomyelitis of the rib or empyema necessitans. Diaphragmatic dissection into the abdominal cavity can result in peritonitis.

• Persistent Symptoms: Symptoms of empyema often include the persistence of fever, cough (usually non-productive), and breathlessness in an infant or an older child with bacterial pneumonia or one with a recent measles infection.
• Duration: At the time of presentation, these symptoms would have typically lasted for days or weeks, but parental concern is usually due to worsening breathlessness.
• Chest Pain (Older Children): In older children, chest pain may be a prominent symptom compared to infants.
• Additional Symptoms in Infants and Toddlers: Infants and toddlers may also present with vomiting, refusal of feeds/anorexia, and occasional abdominal pain as non-respiratory symptoms of childhood empyema.

• Similar to Pleural Effusion: The physical findings of empyema are similar to those of pleural effusion. Additionally, pallor may be evident at presentation, and features of moderate or overt malnutrition, as well as typical post-measles desquamation, may be seen.
• Severity in Older Children: The older child with empyema usually appears more toxic.
• Superficial Infections: Some affected children may have features of superficial infections associated with Staphylococcus aureus, such as impetigo or furunculosis.
• Prominent Respiratory Signs: Grunting is a particularly prominent respiratory sign in empyema, along with tachypnea, chest indrawing, and other features of severe underlying pneumonia.
• Cardiac Signs: Tachycardia and other features of complicating congestive cardiac failure are common in infants and toddlers.
• Tracheal Shift: Tracheal shift and other respiratory findings associated with moderate to massive pleural fluid collection are similar to pleural effusion. However, loculated collections are more common in empyema, and the physical and radiographic findings may not significantly change between the erect and supine positions. Mediastinal shift occurs at a smaller volume of fluid collection in empyema compared to serous, serofibrinous, or transudative varieties.

• Standard Investigations: Investigations for empyema are similar to those for pleural effusion.
• Biochemistry Characteristics: The biochemistry characteristics of empyema are those of an exudative fluid.
• Hematological Findings: Common hematological findings include normochromic normocytic anemia, leucocytosis with a predominance of polymorphonuclear cells, and a high erythrocyte sedimentation rate.

• Intrathoracic Complications and Extension: These include:
  • Bronchopleural fistulae
  • Pneumothorax
  • Interstitial/subcutaneous emphysema
  • Empyema necessitans (empyema that has burrowed through parietal pleura and chest wall to form a subcutaneous abscess that may eventually break through the skin)
  • Lung abscess
  • Purulent pericarditis
• General/Systemic Complications: These include:
  • Severe anemia
  • Septicemia
  • (Extrathoracic) osteomyelitis
  • Septic arthritis
  • Pyogenic meningitis
• Contiguous Extension: This can lead to:
  • Osteomyelitis of the rib
  • Rarely, rupture through the diaphragm culminating in peritonitis

• Treatment of the Inciting Infective Disorder: The primary treatment involves addressing the underlying infective process. For most cases of empyema, this is achieved through systemic antibiotics, preferably guided by sensitivity profiles of the pathogens obtained. Adequate coverage for both Gram-positive and Gram-negative agents, such as Staphylococcus aureus and Klebsiella spp., is required for tropical cases of empyema. The initial choice of antibiotics often includes cloxacillin, a semisynthetic penicillin, or an ampicillin-cloxacillin fixed combination, combined with an aminoglycoside like gentamicin.
• Prompt Surgical Evacuation: Surgical drainage of the purulent fluid from the pleural cavity is crucial. This invasive procedure helps remove infected material and facilitate the recovery process.
• Supportive Measures: These include:
  • Alleviating pain
  • Enhancing effective drainage of loculated pleural pus
• Invasive Cardiothoracic Surgical Interventions: These are occasionally required in severe cases.

Effecting Prompt Drainage of the Pleural Fluid: Chest tube drainage is mandatory to:

1. Prevent significant restriction of pulmonary function
2. Prevent an undue prolongation of the septic process
3. Avoid fibrotic incarceration of the lung in a state of partial collapse

Monitoring of Pleural Drainage: Monitoring involves:

• Post-tube insertion radiograph
• Daily record of the amount and quality of fluid drained
• Monitoring for air-fluid leaks, noticeable by the presence of bubbling through the underwater seal
• Briefly clamping the catheter at the skin to determine the origin of the air leak (inside the pleural cavity or outside the chest)

If the antimicrobial treatment is adequate, removal of the tube should be possible within 10-14 days. However, the presence of bronchopleural fistula and pneumothorax may delay tube removal until bubbling in the underwater drainage segment ceases.

Additional steps may include:

• A pre-extubation clamping for 24 hours
• A post-extubation radiograph

Supportive Measures: Supportive measures include:

• Alleviation of pain
• Bed rest
• Supplemental oxygen for hypoxemic children with restlessness
• Intrapleural instillation of streptokinase or similar agents for 5 days, which may be beneficial in loculated fibropurulent or organizing effusions
• Adequate fluids and calories

Invasive Interventions (Only Occasionally Required): Invasive cardiothoracic interventions include:

• Open-flap drainage
• Pleural decortication using video-assisted thoracoscopic surgery
• Thoracoplasty
• Open thoracotomy

These interventions have proved largely unnecessary in modern times, especially if the initial pleural fluid evacuation is done promptly.