Respiratory Flashcards
Describe cystic fibrosis in lay terms
An inherited condition that causes sticky mucus to build up in the lungs and digestive system. Causes lung infections and problems with digesting food
Inheritance of cystic fibrosis
autosomal recessive
Gene implicated cystic fibrosis
CFTR
Describe key pathogenesis of cystic fibrosis
High sodium sweat: primary secretion of sweat duct is normal but CFTR does not absorb chloride ions, which remain in the lumen and prevent sodium absorption (therefore sweat testing used in diagnosis)
Pancreatic insufficiency: relative dehydration of pancreatic secretions, causing their stagnation in the pancreatic ducts.
Biliary disease: defective ion transfer across the bile duct causes reduced movement of water in the lumen so that bile becomes concentrated, causing plugging and local damage.
Gastrointestinal disease: low-volume secretions of increased viscosity, changes in fluid movement across both the small and large intestine and dehydrated biliary and pancreatic secretions cause intraluminal water deficiency.
Respiratory disease: dehydration of the airway surfaces reduces mucociliary clearance
What does CFTR gene do
Codes a cAMP-regulated chloride channel
Which chromosome most commonly affected in cystic fibrosis
Delta F508 on long arm of chromosome 7
Carrier rate cystic fibrosis
1 in 25
Why should those with CF minimise contact with each other (what bug(s))
Brukholderia cepacia complex and psudeomonas aeruginosa
Whats first line in those with pseudomonas aeruginosa who have failed eradication with antibiotics?
Nebulised colistimethate sodium
Contraindication to lung transplant in cystic fibrosis
Chronic infection with brukholderia cepacia
Drug used for those homozygous for delta F508 mutation (CF) - explain mechanism
Lumacaftor/Ivacaftor (Orkambi)
Lumacaftor increases the number of CFTR proteins that are transported to the cell surface
Ivacaftor is a potentiator of CFTR that is already at the cell surface, increasing the probability that the defective channel will be open and allow chloride ions to pass through the channel pore
Management COPD acute exacerbation
Pred 30mg
Ipratropium bromide 500mcg 5mg NEB
Salbutamol 5mg NEB
Ipratropium MOA
Blocks muscarinic acetylcholine receptors - relaxes bronchial smooth muscle. Tiotropium long acting
Theophylline MOA
Non-specific inhibitor of phosphodiesterase resulting in an increase in cAMP
Montelukast MOA
Block leukotriene receptors
(apparently useful in aspirin induced asthma) –> antiinflammatory and bronchodilatory properties
Features of eosinophilic granulomatosis (small - medium vessel vasculitis)
Asthma
Blood eosinophilia (e.g. > 10%)
pANCA positive in 60%
Mononeuritis multiplex
Sinusitis
Vasculitis
Dyspnoea
Precipitant of eosinophilic granulomatosis
LTRA
Features of granulomatosis with polyangitis
Renal failure
Epistaxis/haemoptysis
cANCA
Saddle shaped nose deformity
Sinusitis (+nasal crusting)
Vasculitis
Dyspnoea
also: vasculitic rash, eye involvement (e.g. proptosis), cranial nerve lesions,
rapidly progressive glomerulonephritis (‘pauci-immune’, 80% of patients)
Is granulomatosis with polyangitis largely cANCA +ve or pANCA +ve?
cANCA
Renal biopsy granulomatosis with polyangitis
Epithelial crescents in bowman’s capsule
Management granulomatosis polyangitis
Steroids
Cyclophosphamide
Plasma exchange
Median survival 8-9 years
What is idiopathic pulmonary fibrosis?
Lung fibrosis when no underlying cause can be identified
Transfer factor IPF
Reduced
Gold standard investigation IPF
CT - honeycombing