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Flashcards in Cystic Fibrosis Deck (27)
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1
Q

What is CF?

A
  • Multi system disorder with significantly shortened life expectancy
  • Autosomal recessive genetic condition
  • Most common life threatening genetic disorder in Caucasians
2
Q

How is CF diagnosed in Australia?

A
  • Historically: Failure to thrive, unexplained chronic respiratory disease
  • New born screening program: Screen for most common 22 genotypes
3
Q

What are the implications for children diagnosed after newborn screening?

A

Higher mean FEV1 & BMI than those clinically diagnosed

4
Q

What are the genetic causal factors of CF?

A
  • Basic defect on chromosome 7
  • Faulty gene codes for CFTR
  • CFTR protein is a channel protein that controls flow of H2O and Cl- ions into & out of cells
5
Q

What happens when the CFTR protein is malfunctioning?

A

H2O and Cl- ions cannot flow out of the cell due to a blocked channel

6
Q

What is the effect of CFTR dysfunction?

A
  1. Airway surface dehydration
    - Reduced fluid layer at the
    top of the cilia
    - Fluid movement back into cell produces mucus with higher viscosity
    - MCC compromised
  2. Reduced airway surface liquid pH
    - Triggers mucus plugging, chronic inflammation & impaired antibacterial host defence in CF airways
7
Q

What are the mutation classes in CF?

A
I: No synthesis
II: Block in processing
III: Block in regulation
IV: Altered conductance
V: Reduced synthesis
8
Q

What organs are affected in CF?

A
  • Respiratory System
  • Digestive System
  • Reproductive System
  • Sweat Glands
  • Sinuses
9
Q

What occurs in the lungs in CF?

A
  • Lungs close to normal structurally at birth
  • Cilia become damaged, fused & flattened
  • By 12 months abnormal inflammation & infection seen on bronchoscopy
  • Infection stimulates further mucus production
  • Repeated infections - neutrophil bronchiolitis
  • Cycle of infection & inflammation impairs ciliary function & reduces MCC further
  • Bronchiectasis
10
Q

Why do repeated infections (neutrophil bronchiolitis) occur in CF?

A
  • Neutrophils cannot destroy the micro organisms that have chronically infected the small airways
  • They break down and release peptides – neutrophil elastase – destroy lung tissue
11
Q

What is the pathophysiology cycle of CF?

A
  • Abnormal CFTR
  • Abnormal chloride & water transport through the cell
  • Thick & dry mucous & compressed cells
  • Release of proteases & DNA
  • Inflammation
  • Infection & defective immune response
  • Bronchial obstruction
  • Progressive airway damage
12
Q

What are the respiratory features of CF?

A
  • Airway collapse, air trapping, hyperinflation
  • Lung function (FEV1%) drops a small amount further below the average for a child of the same age and sex each year
  • Chronic Hypoxia – pulmonary hypertension
13
Q

How are lung volumes affected in CF?

A
  • FRC increases (gas trapping)
  • Higher closing volume: Point at which airways close during
    expiration (obstruction & reduced elasticity)
  • Chest wall kept more expanded
  • Flattened diaphragm (inefficient, more easily fatigued)
  • Inspiratory muscles work harder (fatigue, shorter & tighter, altered length-tension)
14
Q

How is the GI system affected in CF?

A
  • 90% are pancreatic exocrine & endocrine insufficient
  • Accumulation of mucus in small pancreatic ducts
  • Reduction of enzymes leads to malabsorption of fat from small intestine
  • Pancreatic enzyme replacement therapy can achieve energy losses of <10% of intake
15
Q

What is meconium ileus?

A
  • 25% of patients with CF plugs of mucus also have plugs in the small intestine causing a bowel obstruction (Meconium Ileus)
  • Can be the first indication of CF in the neonatal period
  • Poor prognostic sign
16
Q

What are the characteristics of growth & development in CF?

A
  • Low BMI associated with poor clinical outcome
  • Delayed growth related to balance between absorbed nutrient intake & energy requirement
  • Improvement in growth & weight status associated with decreased hospitalisations & antibiotic courses & increase pulmonary function
17
Q

What are the characteristics of gastroesophageal reflux in CF?

A
  • 35% - 81% people with CF are affected
  • Contributing factors: chronic cough, hyperinflation, chest physio
  • LFTs found to be worse compared to those without significant reflux
  • Upright PEP therapy considered most appropriate
    airways clearance technique for those with GOR
18
Q

How is the liver affected by CF?

A
  • 5% have liver bile canaliculi plugged by mucus
  • Leads to biliary cirrhosis
  • Coagulopathy
  • May require transplant
  • Salivary gland can also be affected
19
Q

How is the reproductive system affected by CF?

A

Males

  • 95-99% infertile
  • Blocked or absent vas deferens

Females

  • Viscous cervical secretions may block sperm entry
  • Success with IVF
20
Q

What are the cornerstones of management for CF?

A
  • Medical & Nursing
  • Physiotherapy
  • Nutrition
  • Psychosocial role expanding all the time
21
Q

What does the medical management of CF involve?

A
  • Early aggressive use of antibiotics for any sign of respiratory illness
  • Nutritional intake (120-150% average requirement)
  • Pulmozyme, hypertonic saline, saline nebs
22
Q

What is the aim of infection control for CF?

A
  • Respiratory pathogens heavily influence morbidity & mortality
  • Aim to prevent transmission
23
Q

What are some of the respiratory pathogens in CF?

A
  • Burkholderia Cepacia: Isolation, associated with rapid decline in late 80s
  • Pseudomonas aeruginosa: Requires IV or neb antibiotics
  • Staph aureus
24
Q

What are the CFTR modulators?

A
  • Ivacaftor/kalydeco

- Orkambi (lumacaftor/ivacaftor)

25
Q

What are the features of ivacaftor/kalydeco?

A
  • CFTR potentiator approved for patients with G551D mutation
  • Improved lung function & weight
  • Sweat chloride normalised
26
Q

What are the features of Orkambi (lumacaftor/ivacaftor)

A
  • Delta F508 mutation
  • Lumacaftor helps move defective CFTR to correct location at the cell surface
  • Ivacaftor increases activity of CFTR
  • Increased flow of salt & fluids, reduces thick mucus buildup
27
Q

When are CF patients considered for lung transplant in Australia?

A
  • When life expectancy is two years or less

- Complex decision making regarding timing of transplant