Lung abscess
- Localised suppuration in the lung with tissue necrosis
- End-stage of suppurative pneumonia with thrombosis of associated artery
Etiology
- Pneumonia due to streptococcus, pneumococcus, haemophilus, staphylococcus
- Bronchial obstruction due to tumours or foreign body
- Chronic upper respiratory tract infection due to sinusitis, tonsillitis, dental infection
- Septicaemia
- Aspiration
Pathophysiology
- As pus accumulates, tension increases inside the abscess cavity causing spread into other areas of the lung or rupture into the bronchus
Clinical features
- Acute onset of fever
- Cough with expectoration
- Haemoptysis with foul smelling sputum
- Pleuritic pain
Investigations
- CXR – localised opacity with smooth margin
- Bronchoscopy and biopsy – to rule out carcinoma
- Sputum for culture
- CT
Differential Diagnosis
- Pulmonary TB
- Carcinoma lung
- Fungal infections – aspergillosis
Treatment
- High dose antibiotics – penicillins, 3rd gen cephalosporins
- Postural drainage
- Bronchoscopy
- Chest tube drainage
- CT guided transthroacic drainage
- Lobectomy
Complications
- Spread into other areas of lung
- Metastatic cerebral abscess – as a result of pyaemic emboli through paravertebral veins
- Hemorrhage – due to erosion of the vessel in the abscess wall
- Pneumothorax
- Bronchopleural fistula
- Empyema
Pulmonary gangrene
- Necrosis with multiple microabscesses which coalesce to form a larger cavity
- Lies on a spectrum – pulmonary abscess → necrotising pneumonia → pulmonary gangrene
Aetiology
- Aspiration, sedatives, anesthesia,
- Most common bacteria – klebsiella, enterobacter, pseudomonas, H.influenza
Pathophysiology
- Extent of necrosis and thrombosis of the large vessels differentiates pulmonary gangrene from pulmonary abscess and necrotising pneumonia
- There is sloughing of a large amount of lung tissue
Clinical Features
- Difficulty swallowing
- Breath odour, shortness of breath, wheezing, chest pain, cough
- Fatigue, excessive sweating, cyanosis
- Fever
Investigations
- Blood and Sputum culture
- CXR
- CT – normal architecture within necrosed segment is lost
- ABG
- Bronchoscopy
Treatment
- Drainage
- Antibiotics
- Resection
- Sepsis and multiple organ dysfunction if left untreated
Bronchiectasis
- An obstructive disease of the lung that causes local irreversible dilation of bronchial tree
Etiology
- Congenital – cystic fibrosis, Kartagener’s syndrome (disorder of cilia motility)
- Acquired – tumours, rheumatoid arthritis, ulcerative colitis/Crohn’s disease, infection (S.pneumoniae, H.influenza, S.aureus, TB)
Pathogenesis
- Destruction of alveolar walls (and elastin) with fibrosis of parenchyma
- Can be due to foreign body obstruction – airway dilates and surrounding scar tissue contracts
- Causes secondary inflammatory changes – leads to further airway obstruction
- Usually lower lobes are affected more – causes pooling of bronchial secretions
- Predisposes to infections in this area – pus accumulates
Clinical features
- Inspiratory crackles
- Chronic cough with copious foul-smelling sputum
- Hemoptysis
- Lung collapse – no breath sounds
- Fever and malaise
Investigations
- Sputum sample – bronchoscopy
- CXR – thickened airway walls, cystic spaces, consolidation, collapse
- CT – dilated airways (more sensitive)
- CF – genotyping and sweat electrolyte testing
- Blood – FBC, U+E, LFTs, ESR
Complications
- Pneumonia
- Pleural effusion
- Pneumothorax
- Hemoptysis
- Cerebral abscess
- Amyloidosis
Treatment
- Antibiotics – cefaclor, ciprofloxacin, flucloxacillin
- Bronchodilators
- Corticosteroids – to slow down disease progression
- Drainage
- Surgery – for focal bronchiectasis (surgery is contraindicated if >1 lobe affected)
- Transplantation