Bronchiectasis

Notes

Introduction

Bronchiectasis describes the irreversible and abnormal dilatation of the airways.

It normally results from the inflammatory destruction of the elastic and muscular components of the airways. This leads to abnormally dilated airways, persistent sputum production with ineffectual clearance and recurrent chest infections.

Bronchiectasis commonly occurs secondary to cystic fibrosis though this is often considered and covered separately.

Epidemiology

In 2012 it was estimated that 210,000 people in the UK had bronchiectasis.

The figures for prevalence and incidence vary widely by source as the condition often goes unrecognised or undiagnosed.

Data from the British Lung Foundation indicates females are affected more than males. In 2012 they estimated that 379 females and 281 males had bronchiectasis per 100,000. The condition becomes more common with advancing age with around 60% of cases diagnosed over the age of 70.

Pathogenesis and Aetiology

There are a wide range of causes of bronchiectasis though up to 40-50% of cases will be idiopathic in nature.

Generally speaking bronchiectasis results from infective insults combined with defective mucociliary clearance, airway obstruction or impaired host immunity.

Infective pathogens promote an inflammatory response involving the activation of neutrophils and release of inflammatory mediators - this results in damage to elastic and muscular components of the airway resulting in dilated airways. The abnormal dilatation of the airways further predispose patients to infections. This leads to a cycle of infection and worsening bronchiectasis.

Immune deficiency

Immunodeficiencies predispose patients to infection. Recurrent infective insults, combined with a poor host immune response, increase the risk of developing bronchiectasis. Causes may be primary or secondary:

  • Primary:
    • Panhypogammaglobulinaemia
    • IgA deficiency
    • IgG deficiency
  • Secondary:
    • HIV
    • Malignancy

Mechanical obstruction

Airway obstruction can lead to bronchiectasis. Foreign bodies (particularly in children), mucus plugging, stenosis, tumours or lymph nodes can all be responsible.

Mucociliary clearance dysfunction

Ciliated epithelial cells are essential to the normal function of the airways, progressively clearing them of sputum. Dysfunction leads to mucus accumulation and predisposes to recurrent infection. Causes include:

  • Primary ciliary dyskinesia: this disease, inherited in an autosomal recessive pattern, is characterised by immotile cilia often resulting in recurrent infections and bronchiectasis. It is associated with early-onset of symptoms (in childhood/ teenage years), otitis media, rhinosinusitis and male infertility. Kartagener syndrome refers to primary ciliary dyskinesia combined with situs inversus.
  • Young syndrome: is a syndrome characterised by male infertility (obstructive azoospermia), sinusitis and bronchiectasis. It is rare condition and cases appear to be reducing, a causative relationship with mercury exposure has been posited. Its pathogenesis is poorly understood but may feature impaired mucociliary clearance.

Cystic fibrosis causes dehydration and depletion of airway surface liquid - which is key to the normal function of cilia. This is discussed in more detail in our Cystic fibrosis notes.

Congenital airway defects

  • Williams–Campbell syndrome: is a rare disease characterised by defective cartilage in the airways (fourth to sixth division) resulting in bronchiectasis.
  • Mounier-Kuhn syndrome: also termed tracheobronchomegaly, it is a rare disease characterised by dilatation of the trachea itself as well as the bronchi.

Other causes

  • Rheumatic diseases: both rheumatic arthritis and Sjogren’s syndrome have been associated with the development of bronchiectasis.
  • Allergic bronchopulmonary aspergillosis: ABPA, thought to be caused by an exaggerated immune response to Aspergillus, tends to occur in asthmatics and can lead to bronchiectasis.
  • COPD: patients with COPD who smoke are at increased risk of repeated infection and this may lead to bronchiectasis.
  • Inflammatory bowel disease

Clinical features

Patients often present with persistent sputum production associated with a chronic cough.

In adult patients, bronchiectasis should be suspected in those with persistent purulent/mucopurulent sputum production and a persistent cough. Sputum cultures that return P. aeruginosa is also highly suspicious for bronchiectasis. Features may also reflect the underlying aetiology (discussed above).

Of course there is cross-over between the features of bronchiectasis and other pulmonary conditions. Clinicians must consider other differentials including asthma, COPD and malignancies (which themselves may cause bronchiectasis).

Symptoms

  • Persistent sputum production
  • Persistent cough
  • Dyspnoea
  • Haemoptysis
  • Weight loss

Signs

  • Crackles
  • High pitched inspiratory squeaks
  • Wheeze
  • Clubbing (rare)

Acute exacerbations

The clinical course of bronchiectasis may be interrupted by acute infective exacerbations. The abnormal and dilated airways have impaired ability to clear sputum and pathogens from the lungs resulting in increased risk of infection.

Acute infective exacerbations present with a worsening of chronic features (dyspnea, cough and sputum production) as well as those of systemic infection such as fever and malaise.

Diagnosis

CT chest is the the diagnostic modality of choice in patients with suspected bronchiectasis.

The British Thoracic Society (BTS) guidelines: Bronchiectasis in Adults (2018) advise baseline chest x-ray and thin section CT chest for patients with suspected bronchiectasis:

  • Chest X-ray: this is the routine first-line investigation in patients with suspected bronchiectasis. Can be normal or show non-specific abnormalities. Typical changes include tram-track airways and ring shadows.
  • Thin section CT: the diagnostic modality of choice in patients with suspected bronchiectasis. Dilated airways with an increased bronchoarterial ratio is seen. The signet ring sign is classically described - an appearance caused by the cross-section of a dilated bronchus with its accompanying branch of the pulmonary artery.

Investigations

Investigations aim to identify the underlying cause of bronchiectasis.

A detailed history and examination must be completed for all patients. This should aim to identify features that could indicate an underlying aetiology. The British Thoracic Society (BTS) guidelines: Bronchiectasis in Adults (2018) outlines important investigations to order or consider.

In appropriate patients (e.g. young, indicative history) testing for cystic fibrosis should be completed.

Bloods

  • FBC
  • Renal function
  • Serum immunoglobulins (and serum protein electrophoresis if elevated)

Cultures

  • Sputum cultures: should be performed in all patients for both routine and mycobacterial culture.
  • Blood cultures: in patients presenting with fever or signs of systemic infection.

Aspergillus fumigatus

  • Serum total IgE
  • Sensitisation assessment (specific IgE or skin prick test)

Other

In patients with features of arthritis, vasculitis or connective tissue disease consider rheumatoid factor, anti-cyclic citrullinated peptide, antinuclear antibodies (ANA) and anti-neutrophil cytoplasmic antibodies.

A bronchoscopy should be considered in people with localised disease on imaging to check for a local obstruction - e.g foreign body.

Testing for primary ciliary dyskinesia can be sought if the patient exhibits suggestive features (see aetiology section above).

Management

The goals of treatment are to educate the patient on their condition, treat any underlying cause (where possible) and reduce the number of exacerbations they suffer.

All patient should receive review from both a respiratory clinician and respiratory physiotherapist. Damage to the lung may not be reversed however the progress of disease can be slowed or stopped.

Education and support should be offered and patients given a self management plan. The yearly flu vaccine should be offered in addition to help with smoking cessation, diet and exercise.

Airway clearance

All patients should be taught airway clearance technique by a respiratory physiotherapist. There are a number that may be taught such as active cycle of breathing techniques. Gravity assisted positing can be used as an adjunct to airway clearance techniques.

Mucoactives

Mucoactives are agents that help the clearance of mucus from the airways. They are typically indicated in patients with ongoing exacerbations (e.g. > 3 / year) despite optimal conservative measures.

Isotonic and hypertonic saline may be used and have been shown to improve quality of life. Oral carbocisteine may be trialled and continued if it offers a benefit.

Recombinant human DNase is not recommended in adults with bronchiectasis

Prophylactic antibiotics

Patients with recurrent exacerbations (> 3 per year) despite education, treatment of underlying causes, physiotherapy (+/- mucoactives) should be considered for long term antibiotics. Treatment depends whether or not the patient is colonised by P. aeruginosa:

  • P. aeruginosa colonised: options include inhaled colistin and gentamicin. Oral azithromycin or erythromycin can be considered in those who don’t tolerate inhaled therapy or in addition to inhaled therapy where it is ineffective.
  • Non-P. aeruginosa colonised: azithromycin or erythromycin may be used. Inhaled gentamicin can be considered second line.

Of note macrolide antibiotics should not be used in patients with non-tuberculous mycobacterium where it can breed resistant strains.

Bronchodilators

Bronchodilators can be used in patients with coexisting asthma/COPD or in those with significant breathlessness.

Surgery

Lung resection may be considered in patients with localised disease with uncontrolled symptoms. Lung transplant may be considered, generally in patients aged 65 or younger with an FEV1 < 30% and clinical instability or rapidly deteriorating lung function despite medical intervention. Other indications include complications such as massive haemoptysis and pulmonary hypertension.

Infective exacerbation

Patients require prompt clinical assessment and basic investigations including CXR, blood tests, sputum and blood cultures where indicated.

Depending on the severity of the illness, co-morbidities and psychosocial factors care may be as an inpatient or outpatient. Anyone presenting with features of sepsis should be managed with the sepsis 6 principles in mind and have an early senior review.

Antibiotic therapy may guided by previously obtained cultures and updated once the results of contemporary cultures have been returned. Inpatients should have review by respiratory physiotherapy to ensure optimal airway clearance.

Complications

Bronchiectasis may be complicated by a number of conditions.

  • Infective exacerbation
  • Chronic respiratory failure
  • Haemoptysis (may be massive and life-threatening)
  • Cor pulmonale
  • Pneumothorax
  • Chest pain

Patients with bronchiectasis have been shown to have a higher incidence of ischaemic heart disease, depression and anxiety when compared to the general population.

Prognosis

The prognosis of bronchiectasis is closely linked with the underlying severity of disease.

Patients with mild disease may have a life-expectancy that is equal to the general population. Those with more severe disease tend to have a reduced life expectancy. NICE CKS quote that the age adjusted mortality is twice as high in those with bronchiectasis. Additionally they are more likely to suffer with the complications described in the chapter above.

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