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
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.
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
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.
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.