Bronchiectasis: Causes, Diagnosis, Treatment

Bronchiectasis is a chronic condition characterized by irreversible dilation and deformation of the bronchi with impaired mucociliary clearance, chronic inflammation, and respiratory infections. Diagnosis is confirmed by high-resolution computed tomography (CT) imaging based on bronchial dilation relative to the adjacent artery and wall thickening. Classic radiographic findings include signet ring and tram track patterns, as well as varicose and cystic changes. [1]

The clinical picture is characterized by chronic productive cough, frequent exacerbations, decreased exercise tolerance, and frequent sinusitis. The disease is heterogeneous in its causes and course, so the modern approach relies on phenotyping and the search for "treatable features" such as chronic colonization with Pseudomonas aeruginosa, bronchial hyperreactivity, and concomitant immunoglobulin deficiency. [2]

In recent years, updated international guidelines have emerged that standardize diagnosis, risk stratification, and treatment methods. These include the role of long-term antibiotic prophylaxis in patients with frequent exacerbations, inhaled antibiotics for chronic Pseudomonas aeruginosa infection, and the necessity of daily airway clearance techniques. [3]

The high frequency of co-occurrence with chronic obstructive pulmonary disease, bronchial asthma, and reflux requires multidisciplinary management and correction of modifiable risk factors. Individualized treatment and regular monitoring can reduce the frequency of exacerbations and improve quality of life. [4]

Epidemiology

Current estimates indicate that the prevalence of bronchiectasis is higher than previously thought and varies significantly between countries. A recent meta-analysis in adults yielded a pooled rate of approximately 680 cases per 100,000 population, highlighting the significant burden of the disease on healthcare systems. The variability across studies can be as large as tens of times due to differences in diagnostic criteria and availability of computed tomography. [5]

The incidence increases with age and is more common in older women and people with chronic respiratory diseases. The increased detection rate is explained by both improved availability of computed tomography and greater attention to causative factors, such as immunodeficiencies and previous infections. [6]

An increased disease burden is observed in low socioeconomic groups and in patients with underlying chronic conditions. Hospitalizations and exacerbations account for a significant share of costs, making exacerbation prevention and vaccination important public health measures. [7]

Registries and cohorts show that the proportion of chronic Pseudomonas aeruginosa colonization correlates with a higher frequency of exacerbations, decreased lung function, and worse outcomes. This has led to the identification of a "high-risk" phenotype and more aggressive management regimens. [8]

Reasons

Bronchiectasis is a syndrome with multiple causes. Common etiologies include post-infectious changes following bacterial and viral pneumonia, immunodeficiencies, primary ciliary dyskinesia, aspiration, allergic bronchopulmonary mycosis, and bronchial obstruction. Identifying the underlying cause is essential, as addressing it improves the prognosis. [9]

Prolonged or repeated infection damages the bronchial wall and ciliated epithelium, creating a vicious cycle of infection and inflammation. Bacterial persistence in biofilms supports neutrophilic inflammation and mucus production, contributing to progression. Identifying chronic Pseudomonas aeruginosa fundamentally changes the treatment strategy. [10]

Immunodeficiency conditions, including immunoglobulin deficiencies, lead to ineffective elimination of microbes and increase the risk of frequent exacerbations. Screening of immune status is recommended for all patients after diagnosis to determine the need for replacement therapy and infection prevention. [11]

Allergic bronchopulmonary mycosis, most often associated with Aspergillus species, causes bronchial congestion, central bronchiectasis, and high immunoglobulin E levels. These cases require an anti-inflammatory and antifungal approach other than standard regimens.[12]

Risk factors

Key risk factors include previous lung infections, chronic obstructive pulmonary disease, asthma, gastroesophageal reflux, immunodeficiencies, and systemic connective tissue diseases. Occupational and household exposures leading to microaspiration and damage to the ciliated epithelium increase the risk. [13]

Smoking and older age are associated with a more severe course and frequent exacerbations. The addition of chronic colonization with Pseudomonas aeruginosa creates a high-risk phenotype that requires more frequent monitoring and, often, inhaled antibacterial therapy. [14]

Inherited defects of mucociliary clearance, including primary ciliary dyskinesia, lead to early onset of the disease. Early diagnosis and training in daily airway clearance techniques slow progression and reduce the infectious burden. [15]

The combination with chronic rhinosinusitis increases the bacterial load and the risk of aspiration. A comprehensive approach involving an otolaryngologist and a physiotherapist improves symptom control and reduces the frequency of exacerbations. [16]

Pathogenesis

The basis is a vicious cycle: impaired mucus clearance leads to bacterial colonization and biofilm formation, which sustains neutrophilic inflammation, damage to the bronchial wall, and further dilation of the lumen. Viscous sputum and decreased mucociliary transport perpetuate the process. [17]

Computed tomography (CT) scans reveal morphological changes in the bronchi. A bronchial diameter to artery ratio greater than one, wall thickening, and the absence of normal peripheral narrowing are considered diagnostically significant. Visual "signet ring" and "tram rail" patterns aid in recognition. [18]

Chronic colonization with Pseudomonas aeruginosa increases inflammation, increases the frequency of exacerbations, and accelerates the decline in lung function. This is reflected in recommendations for the use of inhaled antibiotics and long-term macrolide therapy in patients with frequent exacerbations. [19]

Systemic consequences include weight loss, fatigue, and decreased physical performance. Therefore, rehabilitation and endurance training are important elements of comprehensive management, along with daily airway clearance techniques. [20]

Symptoms

The leading symptom is a chronic cough with sputum production, often purulent, typically daily and lasting for months. Characteristic symptoms include shortness of breath during exertion, wheezing, fatigue, and frequent episodes of "colds," which are actually exacerbations of bronchiectasis. Olfactory impairment and symptoms of rhinosinusitis are common. [21]

Exacerbations are characterized by increased cough, increased sputum volume and purulent content, increased shortness of breath, and systemic symptoms. Frequent exacerbations are associated with worse outcomes, decreased quality of life, and an increased need for antibiotic treatment. [22]

Some patients develop pulmonary hemorrhages of varying intensity, from streaks of blood to hemoptysis. This requires assessment of the source and adjustment of anti-inflammatory and antibacterial therapy, and in the case of recurrent episodes, consultation with an interventional radiologist. [23]

Along with pulmonary symptoms, manifestations of the underlying disease are noted, such as frequent infections due to immunodeficiency or signs of allergic bronchopulmonary mycosis. Recognizing these "clues" facilitates a targeted search for the cause. [24]

Forms and stages

Radiologically, cylindrical, varicose, and cystic bronchiectasis are distinguished. The cylindrical form is more often associated with chronic productive cough and can progress to varicose and cystic forms if infection and inflammation are not adequately controlled. Assessing the extent of the process is important for prognosis. [25]

Based on the clinical course, a stable phase and an exacerbation phase are distinguished. During the stable phase, daily airway clearance techniques, vaccinations, and correction of causative factors play a key role. The exacerbation phase requires antibiotic therapy of sufficient duration and, if risk factors are present, inhalation regimens. [26]

Based on the microbiological phenotype, colonization is differentiated between Pseudomonas aeruginosa, other Gram-negative bacteria, Haemophilus influenzae, and pneumococcus. The colonization phenotype determines the risk of exacerbations and the choice of long-term antibacterial strategies. [27]

Severity can be classified based on exacerbation frequency, sputum volume, the presence of Pseudomonas aeruginosa, and lung function. This stratification helps guide decisions between physiotherapy alone and the need for long-term antibiotic prophylaxis. [28]

Complications and consequences

Frequent complications include recurrent infections, hemoptysis, respiratory failure, decreased quality of life, and hospitalization. In the severe Pseudomonas aeruginosa phenotype, the risk of frequent exacerbations and the need for inhaled antibiotics increases. [29]

Long-term inflammation leads to airway remodeling and decreased lung function. Early diagnosis and daily airway clearance can slow the decline and reduce the need for antibiotics. [30]

Pleural empyema and abscess formation are rare but may occur in severe exacerbations and if treatment is delayed. In such cases, prompt imaging and aggressive antibacterial therapy, sometimes with drainage, are necessary. [31]

Frequent exacerbations and systemic inflammation are associated with fatigue, sarcopenia, and depression. Rehabilitation and activity support are essential elements of comprehensive care. [32]

Table 1. Classic radiographic signs of bronchiectasis

Sign	The essence	Where to look
"Signet Ring"	The diameter of the bronchus is larger than the accompanying artery	High-resolution computed tomography
Tram Rails	Parallel thickened walls of a non-narrowing bronchus	Computed tomography and radiography
Absence of normal narrowing of the bronchus to the periphery	Fixed extension sign	High-resolution computed tomography
Varicose and cystic changes	Uneven or cystic deformation	High-resolution computed tomography

A collection of educational and review sources on visualization. [33]

Diagnostics

The gold standard for imaging is high-resolution computed tomography, which confirms morphological criteria and assesses the extent and type of bronchiectasis. It is important to perform the examination during the stable phase to avoid overdiagnosis during acute infections, when the bronchi are temporarily dilated. [34]

Basic etiologic evaluation includes complete blood counts, biochemical blood tests, immunoglobulins and electrophoresis, tests for allergic bronchopulmonary mycosis, and sputum examination for bacteria and mycobacteria. Microbiological stratification is necessary for selecting long-term therapy and preventing exacerbations. [35]

All patients are recommended to undergo regular sputum cultures during the stable phase and during exacerbations to monitor colonization and promptly adjust treatment. If obstruction or difficulty in secretion evacuation is suspected, bronchoscopy with debridement and sample collection is indicated. [36]

Pulmonary function tests help assess the degree of limitation and obstruction. Assessment of exercise tolerance and saturation during walking completes the picture and allows for personalized rehabilitation programs. [37]

Table 2. Minimal etiological and microbiological search

Direction	What to include	For what
Immune status	Immunoglobulins and electrophoresis	Search for deficiencies and indications for replacement therapy
Allergic bronchopulmonary mycosis	Total and specific immunoglobulin E, eosinophils	Identifying a phenotype that requires a different tactic
Microbiology	Sputum cultures in the stable phase and during exacerbation	Selecting a long-term antibacterial strategy
Mycobacteria	Cultures and molecular tests	Exclusion of non-tuberculous mycobacteria
Visualization	High-resolution computed tomography	Confirmation of diagnosis and assessment of prevalence

Summarized from international guidelines. [38]

Differential diagnosis

Bronchiectasis should be distinguished from post-infectious reversible bronchial dilations, which regress after therapy. The absence of clinical stability and signs of persistent deformation on follow-up CT scans indicates the transient nature of the changes. [39]

Cystic fibrosis should be excluded in young patients with early onset, severe infections, and a strong family history. Sweat testing and genetic diagnostics are used for this purpose, followed by management according to specialized protocols. [40]

Allergic bronchopulmonary mycosis masquerades as bronchial asthma with frequent exacerbations and mucus plugs. Central bronchiectasis and high immunoglobulin E levels suggest this diagnosis and a different approach, including antifungal medications and anti-inflammatory therapy. [41]

It is important to distinguish non-tuberculous mycobacterial infections, as they require long-term specific regimens and caution with macrolides to avoid drug resistance. Microbiological verification is mandatory. [42]

Table 3. Differential landmarks

State	Tips	What confirms
Post-infectious reversible changes	Regression in therapy	Control computed tomography without persistent deformations
Cystic fibrosis	Early onset, pancreatic insufficiency	Sweat test and genetics
Allergic bronchopulmonary mycosis	High immunoglobulin E, central bronchiectasis	Serology and Imaging
Non-tuberculous mycobacteria	Slow progression, microscopy	Repeat positive cultures
Aspiration	Reflux, swallowing disorders	Video examinations and risk factor correction

Set of recommendations. [43]

Treatment

Daily airway clearance techniques are the foundation of treatment for all patients. These techniques include active cycle breathing techniques, autogenous drainage techniques, positive expiratory pressure devices, and oscillating devices. Systematic reviews and expert group statements confirm safety and improvement in symptoms and quality of life in stable patients. A physiotherapist will individually select the appropriate technique. [44]

Treatment of exacerbations. A course of antibiotics lasting approximately fourteen days is recommended for bacterial exacerbations, with the choice of drug based on cultures or likely pathogens. In severe cases and the risk of gram-negative pathogens, parenteral regimens with subsequent de-escalation are preferred. Response is assessed after forty-eight to seventy-two hours. [45]

Long-term antibacterial prophylaxis. In patients with frequent exacerbations, long-term macrolide therapy is considered after non-tuberculous mycobacteria have been excluded. Inhaled antibiotics are indicated for chronic colonization with Pseudomonas aeruginosa, as they reduce the frequency of exacerbations and severe exacerbations in selected patients, according to recent reviews. The choice of molecule and regimen is based on tolerability and local practice. [46]

Rehabilitation and vaccination. Endurance and strength training reduce shortness of breath and increase exercise tolerance, while vaccinations against influenza and pneumococcus reduce the risk of infections and subsequent exacerbations. Teaching patients cleansing techniques and self-monitoring of symptoms improves the effectiveness of treatment. [47]

Table 4. Stepwise approach to therapy

Level	What to do	Who is it indicated for?
Base	Daily cleansing techniques, vaccinations, treatment of rhinosinusitis and reflux	To all patients
First escalation	Antibiotics for exacerbation according to cultures for fourteen days	If there are signs of exacerbation
Second escalation	Long-term macrolide prophylaxis for frequent exacerbations	After excluding mycobacteriosis
Third escalation	Inhaled antibiotics for chronic Pseudomonas aeruginosa	High-risk phenotype
Additionally	Rehabilitation, nutritional support, bronchoscopic sanitation as indicated	According to individual indications

Summarized from international recommendations and contemporary reviews.[48]

Table 5. Inhalation antibiotics for chronic Pseudomonas aeruginosa guidelines

Drug platform	Main objectives	Notes on use
Tobramycin inhalation	Reducing the frequency and severity of exacerbations	Selection by phenotype, bronchospasm monitoring
Aztreonam lysine inhalation	Monitoring symptoms and bacterial load	Alternating courses according to local protocol
Other inhalation regimens	Individual selection	Assessment of tolerability and quality of life

Summary of clinical series and efficacy reviews.[49]

Table 6. Monitoring objectives in outpatient care

Direction	What to track	When to rethink tactics
Symptoms	Volume and nature of sputum, shortness of breath, frequency of exacerbations	Increased frequency of exacerbations, new blood streaks
Microbiology	Sputum cultures in the stable phase and during exacerbations	The emergence of Pseudomonas aeruginosa or new pathogens
Lung function	Spirometry, six-minute walk test	Decline in performance or intolerance to stress
Tolerability of treatment	Bronchospasm, hearing impairment with aminoglycosides	Side effects require adjustment
Visualization	Control computed tomography as indicated	Suspected progression or complications

Summarized from practical guidelines and review publications. [50]

Prevention

Primary prevention includes influenza and pneumococcal vaccinations, smoking cessation, treatment of rhinosinusitis and reflux, and patient education on daily airway clearance techniques. Early referral at signs of exacerbation and collection of culture material before initiating antibiotics help quickly determine an effective regimen. [51]

Secondary prevention aims to reduce the frequency of exacerbations and progression: regular visits to a physiotherapist, a personalized rehabilitation program, sputum microbiology monitoring, consideration of long-term macrolide prophylaxis and inhaled antibiotics in selected cases. A multidisciplinary approach involving a pulmonologist, physiotherapist, and otolaryngologist increases the effectiveness of this strategy. [52]

Forecast

The prognosis ranges from a stable course with rare exacerbations to frequent hospitalizations in the high-risk phenotype. Timely diagnosis, daily airway clearance, and targeting of chronic colonization can significantly reduce exacerbations and improve quality of life. [53]

Unfavorable factors include advanced age, frequent exacerbations, colonization with Pseudomonas aeruginosa, and decreased lung function. In such situations, escalation of therapy, rehabilitation, and tight microbiological control are indicated, which can reduce the disease burden and slow the decline in function. [54]

FAQ

• How is the diagnosis confirmed?

High-resolution computed tomography for morphological criteria, including a bronchial-to-associated artery diameter ratio greater than one and typical imaging features.[55]

• How long does a course of antibiotics last during an exacerbation?

Guidelines recommend focusing on a course of approximately fourteen days with adjustments based on clinical and microbiological factors. [56]

• When are inhaled antibiotics needed?

They are considered in chronic colonization with Pseudomonas aeruginosa and frequent exacerbations in selected patients, with an assessment of tolerability and effect. [57]

• Why are daily airway clearance techniques necessary?

They improve sputum evacuation, reduce symptoms and the frequency of exacerbations, improve quality of life and are the basis of therapy for all patients. [58]