Lung Abscess

Chapter 17: Lung Abscess

Introduction

  • A lung abscess is a localized collection of pus within the lung, often due to infection.
  • Understanding lung abscess involves recognizing its anatomy, causes, associated organisms, radiographic features, and management.

Anatomic Alterations of the Lungs

  • Various alterations occur in the lungs due to a lung abscess:
    • Alveolar Consolidation: Dense liquid or solid mass replaces the normal air in alveoli.
    • Alveolar-capillary and Bronchial Wall Destruction: Damage to the structural integrity of lung tissue.
    • Tissue Necrosis: Death of lung tissue due to prolonged infection or inflammation.
    • Cavity Formation: Creation of a space within the lung tissue filled with pus and necrotic debris.
    • Fibrosis and Calcification of the Lung Parenchyma: Replacement of lung tissue with fibrous tissue results in reduced elasticity and gas exchange.
    • Bronchopleural Fistulae and Empyema: Formation of abnormal connections between the bronchial tubes and pleural space, leading to pus accumulation.
    • Atelectasis: Collapse of lung segments, affecting ventilation.
    • Excessive Airway Secretions and Empyema: Excess mucus production and infection in pleural space.

Etiology

  • Predisposing Factors for Aspiration:
    • Alcohol Abuse: Increases likelihood of aspiration.
    • Seizure Disorders: Can impair swallowing ability.
    • General Anesthesia: Risk for aspiration during surgery.
    • Head Trauma: Can affect consciousness and swallowing function.
    • Cerebrovascular Accident (Stroke): May lead to dysphagia (difficulty swallowing).
    • Swallowing Disorders: Conditions impairing swallowing can lead to aspiration.

Organisms Known to Cause Lung Abscess

Common Organisms from Aspirations
  • Anaerobic Gram-Positive Cocci:
    • Peptococci
    • Peptostreptococci
  • Anaerobic Gram-Negative Bacilli:
    • Bacteroides fragilis
    • Prevotella melaninogenica
    • Fusobacterium sp
Less Likely to Cause Lung Abscess
  • Klebsiella
  • Staphylococcus
  • Mycobacterium tuberculosis
  • Histoplasma capsulatum
  • Coccidioides immitis
  • Blastomyces
  • Aspergillus fumigatus
Other Organisms Known to Cause Lung Abscess
  • Some Parasites:
    • Paragonimus
    • Echinococcus
    • Entamoeba histolytica
  • On Rare Occasions:
    • Streptococcus pneumonia
    • Pseudomonas aeruginosa
    • Legionella pneumophila

Chest X-Ray Findings

  • Chest radiographs are crucial in diagnosing lung abscesses. Typical findings include:
    • Increased Opacity: Areas of consolidation in the lung appear denser on X-ray.
    • Cavity Formation: Visible hollow spaces in lung tissue.
    • Cavities with Air-Fluid Levels: Suggest presence of pus and air in the cavity.
    • Fibrosis and Calcification: Indicate chronicity and previous lung damage.
    • Pleural Effusion: Fluid accumulation in the pleural space can complicate underlying conditions.

General Management of Lung Abscess

  • Antibiotics: Primary treatment for lung abscesses; aim to target causative organisms effectively.
  • Administer based on culture and sensitivity when possible.
Respiratory Care Treatment Protocols
  • Oxygen Therapy Protocol: Administer supplemental oxygen as needed to maintain adequate oxygen levels.
  • Bronchopulmonary Hygiene Therapy Protocol: Techniques to clear secretions from the airways.
  • Lung Expansion Therapy Protocol: Methods to improve lung expansion and avoid atelectasis.

Figures

  • Figure 16-1 shows a cross-sectional view of a lung abscess with labeled components such as air-fluid cavity, pyogenic membrane, and ruptured bronchus.
  • Figure 16-2 illustrates reactivation tuberculosis with a large cavitary lesion containing an air-fluid level, plus smaller cavitary lesions in other lobes.