Bronchiectasis and Cystic Fibrosis Flashcards
Aetiology of bronchiectasis
- Idiopathic
- CF, Primary ciliary dyskinesia, Kartagener’s syndrome
- Post-infectious (decreasing) - after pertussis and diphtheria
- ABPA
- COPD
- Traction secondary to fibrosis - radiological rather than clinical diagnosis
- Aspiration
- Obstruction
- Immunological defects (primary, secondary) - CVID, HI, hypogammaglobulinaemia
- Congenital defects (Marfan’s, ciliary defects, A1AT defieincy)
- Inflammatory - RA, Coeliac disease, DPB, SLE, IBD
- Young’s syndrome
- Amyloidosis
- CF
Investigations for suspected bronchiectasis
- CT Chest
- Sputum x 3 for AFBs
- IgE, Aspergillus precipitins
- Immunoglobulins
- Functional assessment - 6MWT, exercise, ABG
- Possible - CF genotyping, ECHO, bronchoscopy, immune tests - HIV, nasal brushings, upper GI endoscopy
Colonising bacteria in bronchiectasis
- Psuedomonas
- Non-tuberculous mycobacteria
- Aspergillus
- Stenotrophomonas
- S. aureus
Principles of bronchiectasis management
1. Treat cause
2. Improve airway clearance
* Increases wuality of life, techniques include bubble PEP, oscillating PEP, active cycle of breathing, forced expiration technique
3. Treat airway infection
4. Treat airway obstruction
* Low level evidence for SABA +/- LABA/ICS
5. Treat chronic inflammation
* Macrolides e.g. erythromycin -> estalished evidence
* No evidence for steroids or leukotreine antagonists
6. Chronic disease management
Role of inhaled hypertonic saline in bronchiectasis
- Use with caution - only two small studies comparing isotonic to hypertonic
- Possible reduced exacerbations, improved quality of life, PFTs mildly improved
Treatment of acute infections in bronchiectasis
- Guided by sputum culture
- Oral antibiotics (at least 10 days but no evidence)
- Cirprofloxacin
- Inhaled aminoglycosides - wheeze and cough common
- Physiotherapy, mucolytics
- Sometimes need IV antibiotics - betalactam, add in aminoglycoside if multiresistant PsA
Treatment of chronic infection
* Inhaled antibiotics poorly tolerated - trial nebulised tobramycin in frequent exacerbations (not responding to other therapies)
Notes on macrolide antibiotics
When used on regular basis
* Reduce exacberation rates NNT 6/ year
* Improved quality of life and sputum production
* Mild improvement in lung function
* Increased antimicrobial resistance and ?increased non-tuberculous mycobacterium infections
* General principle is to trial in frequent exacerbations (>= 3/year or >= 2 hospitalisations) especially if chronic PsA
* If macrolide intolerant consider doxycycline
Notes on Non-Tuberculous Mycobacteria
Ensure if is pathogenic (symptoms, lab, CT, +/- bronchoscopy)
Speciate (MAC or rapid grower)
MAC - Ethambutol/Rifampicin/Clarithromycin - 12-15 months therapy
M. abscessus
* Transmissible
* Active infection is a contraindication to transplantation
* cefoxitin/amikacin IV for 1 month then maintainence clarithromycin/doxt/cipro for 12 months
Spectrum of manifestations of cystic fibrosis
Radiological features of bronchiectasis
- Thick walled bronchi
- Non-tapering bronchi
- Bronchi larger than the accompanying vessels (signet ring sign)
- Sputum inspissation - possibly tree in bud change, possible air trapping
Notes on genetics of cystic fibrosis
- Mutation in CFTR gene (Cystic Fibrosis Transmembrane Conductance Regulator) - on chromosome 7
- > 2000 mutations idenditifed
CFTR - ion channel located on the apical membrane - in normality -> chloride goes out into secretions followed by water
Diagnosis
1. Clinical presentation at birth with meconium ileus
2. Heal prick test - immunoreactive trypsinogen - high sensitivity, low specificity
3. Sweat test - chloride > 60 mmol, borderline 40-60
4. Gene testing
Notes on CFTR modulators
Ivacaftor
CFTR potentiator - opens the channel of the protein
Tezacaftor, elaxacaftor
CFTR corrector - moves the protein onto the cell surface
Ivacaftor plus tezacaftor
Used for homozygous DF508 mutations
Elexacaftor/ivacaftor/tezacaftor (TRIKAFTA)
For heterozygous DF508 mutations
Benefits
Improve lung function, reduced exacberations,
Role of macrolides in cystic fibrosis
- Reduce exacberations and improve lung function
Indications for adult lung transplantation
Criteria for referral
- FEV1 < 35% predicted (rapid rate of decline)
- Increased frequency of IV antibiotic courses
- pO2 < 60mmHg
- pCO2 > 50mmHg
- Clinical organism resistance
- Impaired quality of life
Notes on treating chronic infection in cystic fibrosis
- S. aureus common in paediatric population
- Psuedomonas very common by time patients reach adulthood - shared strains identified in unrelated patients and centres
Other common pathogens:
- Burkholderia cepacia complex - has been associated with outbreaks
- MRSA
- Achromobacter
- Stenotrophomonas
- Fungal species
