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Bronchiectasis

Definition
  • Bronchiectasis is the permanent dilatation of bronchi due to the destruction of the elastic and muscular components of the bronchial wall
  • It is often caused as a consequence of recurrent and/or severe infections secondary to an underlying disorder
  • The majority of patients will present with a chronic cough and sputum production
Risk Factors
  • Strong
    • cystic fibrosis
    • host immunodeficiency
    • previous infections
    • congenital disorders of the bronchial airways
    • primary ciliary dyskinesia
  • Weak
    • alpha-1 antitrypsin deficiency
    • connective tissue disease
    • inflammatory bowel disease
    • aspiration or inhalation injury
    • focal bronchial obstruction
    • rheumatoid arthritis
Differential diagnosis
  • COPD
    • Rhonchi in combination with diminished breath sounds, characterising COPD, are not found in bronchiectasis.
    • In bronchiectasis, rhonchi may be auscultated, but with additional inspiratory squeaks and crackles.
    • Chest CT may be normal or show emphysema in COPD, as opposed to the characteristic abnormal results found in bronchiectasis
      • Thickened, dilated airways with or without air fluid levels
      • Varicose constrictions along airways
      • Ballooned cysts at the end of a bronchus
      • Tree-in-bud pattern
    • Patients with COPD may also develop bronchiectasis.
  • Asthma
    • Inspiratory squeaks and crackles, often present in bronchiectasis, are not present in asthma.
    • Airflow obstruction is often reversible in asthma.
    • Chest CT may be normal or show mosaicism in asthma, as opposed to the characteristic abnormal results found in bronchiectasis
  • Pneumonia
    • Patients with pneumonia describe symptoms of short duration (7 to 10 days), as opposed to years in bronchiectasis.
    • Auscultation findings (rhonchi, wheezing, crackles) may be similar in bronchiectasis and pneumonia, especially multi-lobar pneumonia.
    • CXR and chest CT results in pneumonia are quite variable and often depend on aetiology.
    • In bronchiectasis, there is characteristic dilatation of bronchi without airway thickening.
  • Chronic sinusitis
    • The inspiratory squeaks and crackles found in bronchiectasis are uncommon in chronic sinusitis.
    • CXR and chest CT are normal in chronic sinusitis
    • Sinus CT shows opacification of the involved facial sinus in chronic sinusitis.
Epidemiology
  • The prevalence worldwide is unknown due to the lack of standardised medical care and poor healthcare access in underdeveloped countries
  • In the US, an estimated 110,000 individuals are affected
  • The disease appears more common in the older population and in women. [5]
  •  In the UK, incidence is estimated at 1.06 to 1.3 per 100,000 population. [6] 
  • In general, it is estimated that the incidence has decreased over the past several decades due to implementation of vaccination programmes and the development of more potent antibiotics.
  • Infection is the most common cause of bronchiectasis in underdeveloped countries. [8]
  • Factors that affect mortality in patients with moderate to severe bronchiectasis include:
    • advanced age
    • St George's Respiratory Questionnaire activity score
    • Pseudomonas aeruginosa infection
    • total lung capacity (TLC)
    • residual volume divided by TLC
Aetiology
  • Post-infectious
    • Prior childhood respiratory infections due to viruses
      • measles, influenza, pertussis
    • Prior infections with Mycobacteria tuberculosis or severe bacterial pneumonia
    • Exaggerated response to inhaled Aspergillus fumigatus
    • Swyer-James or Macleod's syndrome
      • Chronic manifestation of bronchiolitis or pneumonitis in childhood, characterised by unilateral pulmonary hypoplasia and radiographic hyperlucency
  • Immunodeficiency
    • Host immunodeficiency (primarily immunoglobulin deficiency)
    • Selective immunoglobulin deficiency
    • HIV infection.
  • Genetic
    • Cystic fibrosis
    • Ciliary dyskinesia or immotile cilia syndrome
    • Kartagener's syndrome
      • Autosomal-recessive condition characterised by the triad of bronchiectasis, situs inversus, and chronic sinusitis
    • Young's syndrome
      • A condition, believed to be genetic, characterised by obstructive azoospermia with normal sperm production plus chronic or recurrent sinus and lung infections
    • Alpha-1-antitrypsin deficiency
    • Mounier-Kuhn syndrome
      • Also known as tracheobronchomegaly, characterised by abnormal dilatation of the trachea and main bronchi
    • Williams-Campbell syndrome
      • Also known as tracheomalacia, characterised by absence or weakness of bronchial cartilage, leading to bronchial collapse
    • Yellow nail syndrome
    • Pulmonary sequestration
  • Aspiration or inhalation injury
  • Connective tissue disorders
    • Rheumatoid arthritis
    • Sjogren's syndrome
    • Ehlers-Danlos syndrome
    • Marfan's syndrome
  • Inflammatory bowel diseases
    • Ulcerative colitis
    • Crohn's disease.
  • Focal bronchial obstruction
    • Foreign body
    • Broncholith
    • Stenosis
    • Tumour
    • Adenopathy with extrinsic compression
  • Idiopathic
    • 50% of cases
  • Other
    • Persistent colonisation with Mycobacterium avium-intracellulare
    • Diffuse panbronchiolitis
    • Bronchopulmonary sequestration
Clinical features
  • Presence of risk factors (common)
  • Cough (common)
    • Occurs in 98% of patients and is the most common symptom of bronchiectasis.
    • An acute exacerbation often presents as worsening of cough.
    • May be associated with large amounts of foul-smelling sputum, and less commonly haemoptysis.
    • Cough may be worsened by lying on one side
  • Sputum production (common)
    • Daily sputum production is present in two-thirds of patients.
    • Bloody sputum is present in about 50% of patients and is usually mild (i.e., sputum with flecks of blood).
    • Sputum production will often increase during acute respiratory infections.
    • An acute exacerbation often presents as a change in sputum colour and an increase in sputum volume.
  • Crackles, high-pitched inspiratory squeaks and rhonchi (common)
    • Many patients will have crackles on pulmonary auscultation.
    • Crackles may be associated with high-pitched inspiratory squeaks and rhonchi.
  • Dyspnoea (common)
    • Present in majority of patients, especially with exertion.
    • Often correlates with severity of bronchiectasis on chest CT.
  • Fever (common)
    • More than half of patients with bronchiectasis will have recurrent episodes of fever.
    • An acute exacerbation often presents with fever.
  • Pallor (common)
    • A non-specific sign.
  • Fatigue (common)
    • A non-specific symptom.
    • An acute exacerbation often presents with fatigue.
  • Haemoptysis (common)
    • Present in about 50% of patients and is usually mild (i.e., sputum with flecks of blood).
    • Thought to originate from the bronchial arteries or bronchial-pulmonary anastomoses.
    • May become massive (>250 mL/day), which warrants hospital admission and immediate referral to a pulmonologist and/or a thoracic surgeon.
  • Rhinosinusitis (common)
    • Bronchiectasis due to a primary mucociliary clearance defect, such as primary ciliary dyskinesia or cystic fibrosis, will probably be accompanied by symptoms of rhinosinusitis.
    • May indicate the presence of Kartagener's syndrome, a rare autosomal recessive disorder of impaired ciliary activity that includes situs inversus, bronchiectasis, and chronic sinusitis.
  • Weight loss (common)
    • A non-specific sign.
  • Wheezing (uncommon)
    • Present in one quarter of patients, but more common in bronchiectasis patients who are also smokers.
  • Pleuritic chest pain (uncommon)
    • May be present, especially during periods of fever.
  • Clubbing (uncommon)
    • Clubbing of the digits is rare
Pathophysiology
  • The dilatation and thickening of the bronchi seen in bronchiectasis are due to chronic inflammation elicited by the host response to micro-organisms colonising the airways.
  • This persistent airway inflammation leads to the subsequent development of bronchial wall oedema and increased mucus production.
  • Several inflammatory cells including neutrophils, T lymphocytes, and other immune effector cells are recruited to the airways
    • Subsequently release inflammatory cytokines, proteases, and reactive oxygen mediators implicated in the progressive destruction of the airways
  • This initial insult to the airways by the primary infection leads to increased inflammation
    • Results in bronchial damage
    • Serves as a nidus for subsequent colonisation of the airways
  • As a result, a vicious cycle ensues
    • Predisposes to persistent bacterial colonisation and to a subsequent chronic inflammatory reaction that eventually leads to progressive airway damage and recurrent infections.
  • The factors that predispose individuals with an initial infection to go on to develop bronchiectasis remain unclear.
Investigations
  • CXR
    • May be normal or show obscured hemidiaphragm, thin-walled ring shadows with or without fluid levels, tram lines, tubular or ovoid opacities
  • High-resolution chest CT
    • Thickened, dilated airways with or without air fluid levels; varicose constrictions along airways; cysts and/or tree-in-bud pattern
  • FBC
    • High WBC may show high eosinophil count in bronchopulmonary aspergillosis; neutrophilia suggests superimposed infection or exacerbation
  • Sputum culture and sensitivity
    • Gram-positive bacteria; gram-negative bacteria; non-tuberculous mycobacteria; fungi
  • Serum alpha-1 antitrypsin phenotype and level
    • Presence of S or Z alleles and MM phenotype indicates alpha-1 antitrypsin deficiency
  • Serum immunoglobulins
    • Decreased IgG, IgM, and/or IgA in immunodeficiency states
  • Sweat chloride test
    • >60 mEq/L in cystic fibrosis
  • Rheumatoid factor
    • Positive in rheumatoid arthritis
  • Aspergillus fumigatus skin prick test
    • Immediate cutaneous reactivity to antigen in bronchopulmonary aspergillosis
  • Serum HIV antibody
    • Positive in HIV infection
  • Exhaled nitric oxide
    • Low exhaled nasal nitric oxide level in primary ciliary dyskinesia
  • Pulmonary function tests
    • Reduced FEV1 or FEV1/FVC ratio (<70%)
  • C-reactive protein
    • An elevated C-reactive protein suggests active inflammation and is associated with a faster decline in lung function
  • Bronchial biopsy and electron microscopy of cilia
    • Abnormal ciliary morphology in primary ciliary dyskinesia
  • Cystic fibrosis transmembrane regular protein gene mutation testing (CFTR)
    • Positive in cystic fibrosis
  • Swallow study
    • Aspiration in patients with chronic aspiration
  • Sputum pH monitoring
    • Low pH in patients with chronic aspiration
  • 6-minute walk test
    • Reduced in those with significantly reduced lung function
Management

a) conservative
  • exercise and improved nutrition
  • airway clearance therapy
b) medical
  • bronchodilators
  • hyperosmolar agents
  • long-term oral macrolides
  • inhaled corticosteroids
  • oral antibiotics
c) surgical
  • Complete resection of bronchiectatic areas of the lung may be appropriate in some patients with refractory disease
Prognosis
  • Bronchiectasis is an irreversible condition.
    • The typical disease course consists of periods of symptom control interrupted by periods of exacerbations.
  • Bronchiectasis frequently co-exists with other respiratory disease, making it difficult to determine prognosis for bronchiectasis alone
  • Factors associated with a faster decline in lung function include:
    • More frequent severe exacerbations
    • Increased systemic inflammation (determined by CRP)
  • Quality of life
    • According to the St. George Respiratory Questionnaire, these factors have the greatest impact on the quality of life in patients with bronchiectasis:
      • Dyspnoea
      • Reduced FEV1
      • Daily sputum production
  • Pseudomonas species in sputum
    • Indicates more extensive lung disease and more severe impairment of pulmonary function than in patients without Pseudomonas species colonisation.
    • Some studies have shown that Pseudomonas species colonisation is an independent factor associated with a faster decline in lung function.
      • Evidence is conflicting. [52]
  • Hypoxaemia, hypercapnia, dyspnoea, and radiographic extent of disease have been shown to correlate with mortality.
  • Conversely, a higher BMI, regularly scheduled doctor visits, and vaccinations improve survival.
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