Lec 12 Bronchiectasis Flashcards
What is the definition of bronchiectasis?
permanent abnormal dilation of bronchi
pathologic/radiological diagnosis
What is vicious cycle hypothesis of bronchiectasis?
external insult –> causes resp tract damage –> more prone to infection –> more inflammation –> more damage etc
What are infectious causes of bronchiectasis?
measles/pertussis pneumonia
other bacteria/viruses –> TB, mycobacterium
allergic bronchopulmonary aspergillosis
Who gets allergic bronchopulmonary aspergillosis?
patients with asthma or cystic fibrosis
What are some causes of recurrent airway infection?
- airway obstruction
- impaired mucous clearance
- defect in host defense
What are the 3 patterns of bronchiectasis?
- cylindrical = smooth dilation of bronchus
- varicose = focal narrowings along a dilated bronchus
- cystic = progressive dilation of bronchus which terminates in cysts or saccules
What signs of bronchiectasis?
permanently dilated airways cough purulent sputum recurrent infections hemoptysis
What causes hemoptysis in bronchiectasis?
inflammation causes increased blood supply
- bronchial arteries enlarge and increase in number; new anastamoses form between bronchial + pulm artery circulations
erosion/truama leads to rupture/hemoptysis
What do you see on physical exam with bronchiectasis?
- may have normal lugn exam or wheezing
- clubbing
What do you see on pulm function tests with bronchiectasis?
low FEV1/FVC
high RV and RV/TLC ratio
What is treatment for bronchiectasis?
- antibiotics with exacerbation
- bronchopulmonary drainage
- bronchodilators if co-existing asthma
What is epidemiology of CF?
- autosomal recessive
- mutation in gene for cystic fibrosis transmembrane conductance regulator [CFTR]
- most prevalent in pple of northern/central europe descent
What is function of CFTR?
- ion channel regulates Cl and H2O absorption/secretion
in sweat duct = Na but not fluid absorbing
in airways = fluid absorption
in pancreas/intestine = fluid secretion
What happens in lungs in CF?
- lung epithelium dried out = cilia can’t move as well and stuff gets stuck
- less airway surface liquid volume
normally when high liquid volume: channels open allow Na/Cl absorption and H2O to follow in but close when low volume and net water out
in CF = can’t regulate; channels always open and bring fluid in even when there is already low volume
What happens in CF in pancreas?
- CFTR is needed to secrete HCO3 and water into pancreatic ducts
in CF –> acidic secretions lead to retention of enzymes in pancreas and destruction of pancreatic tissue
What happens in CF in intestine?
intestinal epithelium can’t flush secreted mucin and other macromolecules
have intestinal obstruction
What happens in CT in sweat glands?
- CFTR needed to reabsorb Cl from sweat secretions
in CF –> Cl not reabsorbed have isotonic [rather than hypotonic] sweat
What are the 6 types of CFTR mutations?
type 1 = no functional CFTR protein type 2 = CFTR trafficking defect, never reaches surface type 3 = defective channel regulation type 4 = decreased channel conductance type 5 = reduced synthesis of CFTR type 6 = decreased CFTR stability
What is type 2 CFTR mutation?
normal transcription but abnormal folding –> have trafficking defect and CFTR never makes it to cell surface
What is type 1 CFTR mutation?
transcription abnormal = no protein produced
What is type 3 CFTR mutation?
transcription/translation normal but abnormal regulation
What is type 4 CFTR mutation?
decreased conductance of chloride in channel
What is type 5 CFTR mutation?
have some corent + some incorrect RNA due to splicing defect
so end up with reduced synthesis of CFTR
What is type 6 CFTR mutation?
have decreased CFTR membrane stability
