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.