Cystic fibrosis and bronchiectasis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Defective CFTR chloride and bicarbonate transport reduces airway-surface hydration and impairs mucociliary clearance. Thick mucus traps bacteria, producing neutrophilic inflammation and progressive bronchiectasis.

In non-CF bronchiectasis, an initiating infection, aspiration, immune defect or ciliary disorder creates the same infection-inflammation-clearance cycle. Finding the cause changes prevention and family counselling.

A wet cough reflects airway secretions even when a young child cannot expectorate. Parents may describe rattling or swallowing sputum; ask whether cough is present every day between colds.

CT is performed when clinically stable and with child-appropriate dose reduction. Radiological dilatation must be interpreted against age because artery-to-airway ratios differ in children.

Microbiology is longitudinal. A single upper-airway swab may not represent lower-airway infection, but repeated samples and bronchoalveolar lavage when indicated guide treatment.

Airway clearance is collaborative, not one universal technique. Positive expiratory pressure, active-cycle methods, autogenic drainage and oscillating devices are selected for age, independence and disease.

Exacerbations can occur without fever. Change from the child's baseline in cough, sputum, exercise, appetite, weight and spirometry drives early contact with the specialist team.

CF nutrition is treatment because malabsorption and inflammation raise energy needs. Enzyme dose is titrated to food fat, stool, symptoms and growth rather than a fixed age schedule.

Dornase alfa cleaves extracellular DNA in purulent sputum; hypertonic saline draws water into airway surface. They are not interchangeable and response and tolerance are reviewed.

Long-term macrolide or inhaled antibiotic can reduce exacerbations in selected children but promotes resistance and requires hearing, liver, ECG or organism-specific monitoring according to regimen.

Complications extend beyond lung: CF-related diabetes, liver disease, bone disease, sinus disease, infertility and anxiety need scheduled surveillance.

Care is delivered by an accredited multidisciplinary CF or paediatric respiratory team while primary care supports vaccination, acute recognition, repeat prescriptions and shared psychosocial care.

Key points

Cystic fibrosis is an autosomal-recessive CFTR disorder causing dehydrated secretions in lung, pancreas, gut, biliary and reproductive tracts. Bronchiectasis is irreversible bronchial dilatation from repeated infection and inflammation and has many causes.
Think CF with chronic wet cough, recurrent infection, poor weight gain, steatorrhoea, meconium ileus, rectal prolapse, salt-loss episodes, nasal polyps or affected sibling.
Newborn screening uses immunoreactive trypsin with mutation testing, but it is screening rather than diagnosis. Symptomatic children still require a specialist CF pathway.
Reference diagnostic test: sweat chloride using pilocarpine iontophoresis in an accredited service. At least 60 mmol/L supports CF, 30–59 is intermediate and below 30 makes CF less likely; interpret with phenotype and CFTR genotype.
Confirm bronchiectasis with specialist thin-section chest CT showing airway dilatation relative to accompanying artery, failure to taper and peripheral visibility. Do not use chest radiography to exclude it.
Investigate non-CF bronchiectasis for immune deficiency, primary ciliary dyskinesia, aspiration, airway foreign body, post-infectious damage and structural disease; test CF when phenotype or cause remains compatible.
First-line daily care is individually taught airway-clearance physiotherapy plus exercise. Increase frequency during exacerbations and review technique as the child grows.
Obtain sputum or cough-swab culture at routine review and before antibiotics when possible. Treat exacerbations promptly with culture-directed oral or intravenous antibiotics, commonly for about 14 days in bronchiectasis, with specialist adjustment.
New Pseudomonas in CF usually triggers an eradication protocol; chronic infection may require inhaled antibiotic. Regimens are organism-, age- and centre-specific and must use the CF team's current protocol.
CF mucolytic treatment may include dornase alfa first, hypertonic saline or mannitol according to age, response and NICE guidance; bronchodilator is used for demonstrable benefit or before hypertonic therapy.
Pancreatic-insufficient CF requires pancreatic enzyme replacement with every fat- or protein-containing meal and snack, high-energy nutrition, salt advice and fat-soluble vitamins guided by a CF dietitian.
CFTR modulators are disease-modifying and mutation/age specific. The CF centre checks genotype eligibility, interactions, liver tests, eye monitoring where applicable, adherence and pregnancy implications.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Biallelic CFTR variants

Pathogenic variants inherited in an autosomal-recessive pattern reduce CFTR quantity or function across multiple epithelial organs.

Post-infectious airway damage

Severe pneumonia, tuberculosis, adenovirus or pertussis can initiate persistent impaired clearance and non-CF bronchiectasis. within the child-specific clinical phenotype.

Ciliary, immune or aspiration disease

Primary ciliary dyskinesia, antibody deficiency, recurrent aspiration and obstruction produce repeated infection and bronchial injury. within the child-specific clinical phenotype.

Unexplained bronchiectasis

Some children remain idiopathic after structured assessment, but cause and phenotype should be revisited as features evolve.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Dehydrated airway surface
Abnormal CFTR transport concentrates mucus and slows mucociliary movement, allowing bacteria to persist. during progression of the respiratory disorder.
2
Infection-inflammation cycle
Persistent organisms recruit neutrophils whose enzymes and oxidants injure airway walls and further impair clearance. during progression of the respiratory disorder.
3
Permanent bronchial dilatation
Loss of elastic and muscular support creates enlarged non-tapering airways that retain more secretion. during progression of the respiratory disorder.
4
Extrapulmonary CF disease
Thick pancreatic and biliary secretions cause maldigestion, vitamin deficiency, liver injury and increased energy requirements. during progression of the respiratory disorder.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Respiratory baseline

Define daily wet cough, sputum, exercise, exacerbations, organisms, antibiotics, admissions and lung-function trajectory.

CF multisystem signs

Ask neonatal bowel or jaundice history, stool, appetite, salt loss, sinus disease, growth and family history.

Examination

Plot growth and assess clubbing, crackles, wheeze, hyperinflation, nasal polyps, hepatomegaly and pubertal development.

Cause clues

Identify neonatal distress, chronic otitis, laterality, swallowing symptoms, severe infection and possible foreign-body event.

Exacerbation change

Compare current cough, sputum, breathlessness, fatigue, appetite, weight and spirometry with the child's usual state.

Treatment burden

Assess airway-clearance technique, enzymes, medicines, school time, access, mental health and family priorities.

Red flags requiring action

Chronic daily wet cough is pathological; clubbing, crackles, poor growth or recurrent pneumonia requires respiratory investigation.
Meconium ileus, prolonged neonatal jaundice, salty-tasting skin, rectal prolapse or pancreatic malabsorption suggests cystic fibrosis even after newborn screening.
Haemoptysis, pleuritic pain, sudden breathlessness or unilateral absent air entry suggests major bleeding or pneumothorax.
Increasing cough, sputum, breathlessness, fatigue, reduced appetite, weight loss or lung-function fall signals a pulmonary exacerbation.
Persistent Pseudomonas, MRSA, non-tuberculous mycobacteria or repeated intravenous antibiotics requires specialist infection-control and eradication planning.
A negative newborn CF screen does not exclude disease in a symptomatic child; refer for diagnostic testing.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Reference CF test: sweat chlorideFirst step
Why
Demonstrate CFTR dysfunction after positive screening or compatible symptoms.
Interpretation and limitations
At least 60 mmol/L supports CF, 30–59 requires specialist resolution and below 30 makes CF less likely but does not override a strong genotype or phenotype.
02
CFTR genetic analysis
Why
Confirm disease-causing variants, family implications and modulator eligibility.
Interpretation and limitations
Two pathogenic variants support diagnosis; variants of uncertain significance require specialist functional and phenotypic interpretation.
03
Gold-standard bronchiectasis imaging: thin-section CT
Why
Demonstrate permanent airway dilatation and map distribution.
Interpretation and limitations
Airway-to-artery enlargement, lack of tapering and peripheral visibility support diagnosis on a stable child-optimised scan.
04
Airway microbiology and spirometry
Why
Track infection and lung function and direct exacerbation antibiotics.
Interpretation and limitations
Interpret repeated cultures and FEV1 change against baseline; a young child may need cough swab or specialist lavage.
05
Aetiology and systemic screen
Why
Identify immune, ciliary, aspiration and CF complications.
Interpretation and limitations
Select immunoglobulins and vaccine responses, ciliary testing, swallow studies, faecal elastase, liver, vitamin, glucose and bone assessment by phenotype.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Protracted bacterial bronchitis

Isolated chronic wet cough resolving fully after appropriate antibiotic without CT disease may precede or mimic bronchiectasis.

Asthma

Variable dry symptoms and reversible obstruction differ from persistent wet cough, clubbing and bacterial infection. when timing, examination and trajectory are integrated.

Foreign body

Abrupt onset and recurrent focal infection requires bronchoscopy even when CT also shows local bronchiectasis. when timing, examination and trajectory are integrated.

Primary ciliary dyskinesia

Neonatal respiratory distress, year-round rhinitis, otitis and laterality defect directs nasal nitric oxide and specialist testing.

Immune deficiency or aspiration

Unusual infections, poor vaccine responses or feed-related cough requires immunology and swallowing assessment. when timing, examination and trajectory are integrated.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Suspect CFRefer despite screening historyFirst stepMultisystem CF features or an affected sibling is present.

1Refer to a specialist CF centre and obtain accredited sweat testing.
2Use CFTR genetics and functional interpretation when sweat is intermediate or discordant.
3Begin nutrition and infection assessment without waiting for advanced lung disease.

02BronchiectasisConfirm and find the causeDaily wet cough, recurrent pneumonia or clubbing persists.

1Obtain respiratory specialist assessment and stable thin-section CT.
2Perform culture, spirometry and a structured immune, ciliary, aspiration, obstruction and CF work-up.
3Treat the identified cause and establish daily airway clearance.

03ExacerbationCulture and treat promptlyCough, sputum, breathlessness, appetite or lung function worsens from baseline.

1Send airway culture and assess oxygenation, hydration, weight and need for admission.
2Start previous-culture-directed antibiotic through the specialist plan, generally about 14 days for bronchiectasis.
3EscalationIncrease airway clearance and reassess response early, escalating to intravenous treatment when severe or unresponsive.

04Long termIntegrate lung and nutrition careCF or bronchiectasis is established in specialist respiratory care.

1Use individual daily airway clearance, exercise, vaccination and smoke avoidance.
2Provide organism-specific suppression or eradication and CF mucolytic or modulator therapy when eligible.
3Monitor growth, enzymes, vitamins, liver, glucose, bone, hearing and psychosocial health through the MDT.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Progressive respiratory failure

Repeated exacerbations reduce lung function and can lead to oxygen need, ventilation and transplantation assessment. when recognition or effective treatment is delayed.

Haemoptysis and pneumothorax

Abnormal bronchial vessels and fragile hyperinflated lung can cause life-threatening bleeding or air leak. when recognition or effective treatment is delayed.

Chronic resistant infection

Pseudomonas, MRSA and non-tuberculous mycobacteria complicate treatment, infection control and prognosis. when recognition or effective treatment is delayed.

Nutritional and systemic disease

Pancreatic insufficiency, diabetes, liver and bone disease impair growth, puberty and long-term health. when recognition or effective treatment is delayed.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Track symptoms, cultures, spirometry, exacerbations, antibiotic exposure and imaging only when it changes care.
Plot weight, height and BMI and review stool, enzyme timing, vitamins and dietary energy in CF.
Review airway-clearance technique and adherence with the physiotherapist at each meaningful transition.
Monitor drug-specific liver, renal, hearing, ECG, eye and interaction risks through specialist protocols.
Screen CF-related diabetes, liver and bone disease at age-appropriate intervals.
Use separate equipment and current infection-control practice around transmissible CF organisms.
Give families direct exacerbation contact and avoid waiting for fever before seeking advice.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Screening is not diagnosis

A newborn result reduces probability but does not exclude CF in a child who later develops a convincing multisystem phenotype.

Wet cough is a sign

Children swallow sputum, so absence of an expectorated sample does not make a daily rattly cough dry or benign.

CT confirms structure

Chest radiography may be normal or nonspecific and cannot exclude early bronchiectasis.

Enzymes follow food

PERT is adjusted to fat and protein intake and symptoms, not prescribed as one fixed dose for every meal.

Modulators remain genotype specific

Eligibility, dosing and interactions change with age and product, so every prescription belongs to the CF centre.

11Common pitfallsFrequent interpretation and management errors.

01
Do not dismiss chronic wet cough as recurrent viral infection.
02
Do not exclude CF because newborn screening was negative.
03
Do not diagnose bronchiectasis from chest radiography.
04
Do not give repeated empirical antibiotics without airway culture and cause assessment.
05
Do not stop airway clearance when the child feels well.
06
Do not prescribe fixed enzymes without meal and growth review.
07
Do not start long-term macrolide before excluding non-tuberculous mycobacteria when required.
08
Do not manage CFTR modulators outside the specialist interaction and monitoring pathway.