Paeds: Resp Flashcards
Cystic Fibrosis
what is it
an autosomal recessive genetic condition affecting mucus glands
Cystic Fibrosis
what is it caused by
a genetic mutation of the cystic fibrosis transmembrane conductance regulatory gene
on Ch7
Cystic Fibrosis
what is the most common variant of the cystic fibrosis transmembrane conductance regulatory gene
the delta-F508 mutation: codes for cellular channels, particularly a type of chloride channel
Cystic Fibrosis
what causes a lack of lipase in the digestive tract
thick pancreatic and biliary secretions that cause a blockage of the ducts
Cystic Fibrosis
what causes the susceptibility to airway infections and bacterial colonisation
low volume thick airway secretions that reduce airway clearance
Cystic Fibrosis
what causes male infertility
congenital bilateral absence of the vas deferens
the sperm have no way of getting from the testes to the ejaculate
Cystic Fibrosis
what is the mode of inheritence
autosomal recessive
Cystic Fibrosis
both parents are healthy, one sibling has cystic fibrosis and a second child does not have the disease, what is the likelihood of the second child being a carrier?
2 in 3
Cystic Fibrosis
when is it screened
at birth with the newborn bloodspot test
Cystic Fibrosis
what is often the first sign
meconium ileus (not passing meconium within 24h)
Cystic Fibrosis
sx
- chronic cough
- thick sputum production
- recurrent resp tract infections
- steatorrhoea
- abdo pain and bloating
- salty kisses
- failure to thrive
Cystic Fibrosis
why does steatorrhoea occur
due to the lack of fat digesting lipase enzymes
Cystic Fibrosis
signs
- low weight or height
- nasal polyps
- finger clubbing
- crackle + wheezes on auscultation
- abdo distention
what are causes of clubbing in children
- hereditary clubbing
- cyanotic heart disease
- infective endocarditis
- cystic fibrosis
- TB
- IBD
- liver cirrhosis
Cystic Fibrosis
what are the 3 key methods for establishing a diagnosis
- newborn blood spot testing
- sweat test
- genetic testing for CFTR gene during pregnancy
Cystic Fibrosis
what is the gold standard for diagnosis
sweat test
Cystic Fibrosis
what happens during a sweat test
- pilocarpine applied to skin patch
- electrodes places on either side and current is passed between electrodes
- this causes skin to sweat
- sweat absorbed by filter paper
- sent to lab for Chloride conc
Cystic Fibrosis
what is the diagnostic concentration in the sweat test
> 60mmol/l
Cystic Fibrosis
why does bacteria colonate in these pts easily
they struggle to clear secretions in the airway
perfect environment with moisture and oxygen to colonise
Cystic Fibrosis
what are key microbial colonisers
Staph aureus
pseudomonas
Cystic Fibrosis
how do pts prevent staph aureus infection
take long term prophylactic flucloxacillin
Cystic Fibrosis
why should CF patients stay away from each other
risk of spreading pseudomonas
Cystic Fibrosis
why are pseudomonas difficult
resistant to multiple antibiotics
significant increase in morbidity and mortality
Cystic Fibrosis
trx for Pseudomonas colonisation
long term nebulised abx: tobramycin
PO ciprofloaxin alternatively