Lower respiratory tract diseases - CYSTIC FIBROSIS Flashcards
what is cystic fibrosis?
an INHERITED cause of severe bronchiectasis.
what gene passes on cystic fibrosis?
autosomal recessive
what leads to respiratory failure & death in cystic fibrosis?
- viscous circle of mucous stasis
- inflammation
- infection
what does CFTR stand for?
cystic fibrosis transmembrane conductance regulator
what causes cystic fibrosis?
autosomal recessive mutations of the gene encoding the CFRT.
what is CFTR?
a transmembrane chloride channel found in the respiratory epithelium, exocrine gland and sweat ducts.
- by transporting chloride ions across the cell membrane, CFTR controls the movement of sodium and water out of the cell and into the mucous later
- this movement of water is necessary for the production of thin, free flowing mucus.
what happens if the CFTR functions poorly?
- chloride flow across cell membrane is impaired
- mucous is inadequately hydrated and becomes thick and sticky
what are the 5 classes of defects in the CFTR and what effect do each of them have.
1) Class 1
- defective protein synthesis
- no CFTR made
2) Class 2
- defective protein processing
- CFTR os stuck within the cytosol
3) Class 3
- protein is made but there is defective Chanel regulation
4) Class 4
- not much protein is passed through, therefore, defective chloride conductance
5) Class 5
- reduced synthesis because of unstable messenger RNA
how does pancreatic damage & failure arise?
when mucus blocks the pancreatic ducts
clinical features of cystic fibrosis?
- chronic phlegm production and daily cough
- recurrent respiratory infections
- breathlessness
- wheeze
- pneumothorax
- bronchiectasis
- nasal polyps
- haemoptysis
GI;
- pancreatic insufficiency
- gallstones
- cirrhosis
Other;
- male infertility’s
- osteoporosis
- arthritis
- vasculitis
- nasal polyps
- sinusitis
- hypertrophic pulmonary osteoarthropathy
describe 3 crucial differences between cystic fibrosis and bronchiectasis?
Cystic fibrosis;
- starts in early childhood
- usually worse in lung apices
- almost always results in fatal respiratory failure due to severe airway obstruction
what are SIGNS of cystic fibrosis?
- finger clubbing
- low body mass
- extensive CREPITATIONS in both lungs
- obvious signs of airway obstruction with poor respiratory function
what are the clinical features of cystic fibrosis OUTSIDE the respiratory system?
- infertility in males
- abnormal liver function tests
- meconium ileus in neonates
- glucose intolerance and diabetes
- pancreatic insufficiency with malabsorption and deficiency of vitamins A, D & K
- chronic sinusitis
- osteoporosis
when are most cystic fibrosis diagnosis made?
most are made at newborn screening.
- involves measuring immuno-reactive trypsinogen at the time of neonatal heel prick test.
- if the conc is raised, formal testing is performed.
what are diagnostic methods are used?
- common clinical features
- CFTR functional testing; the SWEAT TEST. this measure Cl- ion concnenntrationn, if its high it indicates cystic fibrosis.
- confirm it with genetic testing
name 3 ways in which cystic fibrosis should be managed?
1) regular physiotherapy supported by chest clearance device (e.g. the fuller valve or chest cuirass)
2) frequent antibiotics for bronchial infections
3) regular use of inhaled B-agonists
describe the prophylactic treatment that most patients should receive.
- flucloxacillin against chronic S. aureus colonisation as well as azithromycin
- nebulised DNase and hypertonic saline slow the decline in lung function
respiratory failure is very common in cystic fibrosis. How should it be treated?
- oxygen and non-invasive ventilation
how is pancreatic insufficiency treated?
- pancreatic enzymes and vitamin supplements
- diet and calorie supplements
