Cystic fibrosis Flashcards
(24 cards)
What type of condition is CF?
Autosomal recessive genetic condition affecting the mucus glands
What is the most common mutation causing CF?
The most common is the delta-F508 mutation.
What does the CFTR gene code for?
This gene codes for cellular channels, particularly a type of chloride channel.
What are the key consequences of the cystic fibrosis mutation?
- thick pancreatic and biliary secretions that cause blockage of the duct ⇒ a lack of digestive enzymes eg. pancreatic lipase in the digestive tact
- low volume thick airway secretions that reduce airway clearance ⇒ bacterial colonisation and susceptibility to airway infections
- congenital bilateral absence of the vas deferens in males (patients have healthy sperm, but the sperm have no way of getting from the testes to the ejaculate ⇒ male infertility)
How is CF screened for at birth?
Newborn bloodspot test.
What is often the first sign of CF?
- meconium ileus
- meconium is the first stool that a baby passes, this is usually black and should be passed within 24 hours of birth
- in 20% of babies, the meconium is thick and sticky, which causes it to get stuck and obstruct the bowel = meconium ileum
Meconium is the first stool that a baby passes, usually black and should be passed within 24 hours of birth.
How does meconium ileus present?
Not passing meconium within the first 24 hours, abdominal distension, vomiting.
If CF isn’t diagnosed shortly after birth, how may it present later in life?
Recurrent LRTIs, failure to thrive, pancreatitis.
What are some symptoms of CF?
- chronic cough
- thick sputum production
- recurrent RTIs
- steatorrhoea (loose, greasy stools), due to lack of fat digesting lipase enzymes
- abdominal pain and bloating
- parents may report that the child tastes salty when they kiss them, due to the concentrated salt in the sweat
- poor weight and height gain (failure to thrive)
What are some signs of CF?
- low weight or height on growth chats
- nasal polyps
- finger clubbing
- crackles and wheeze on auscultation
- abdominal distension
What are some causes of clubbing in children?
- cyanotic heart disease
- cystic fibrosis
- IBD
- hereditary clubbing
- infective endocarditis
- TB
- liver cirrhosis
What are the diagnostic methods for CF?
- newborn blood spot testing (performed shortly after birth)
- sweat test = gold standard for diagnosis
- genetic testing for CFTR gene can be performed during pregnancy by amniocentesis or chorionic villous sampling, or as a blood test after birth
What is the sweat test?
- gold standard for confirming the diagnosis
- use a patch of skin on arm or leg
- pilocarpine applied to skin on the patch
- electrodes are placed either side of the patch and a small current is passed thought the electrodes ⇒ this causes the skin to sweat
- the sweat is absorbed with lab issued gauze or filter paper and sent to the lab for the chloride concentration
Sweat is absorbed with lab issued gauze or filter paper and sent to the lab for chloride concentration.
What is the diagnostic chloride concentration for cystic fibrosis?
More than 60mmol/L.
What are some examples of common colonisers in CF?
Staphylococcus aureus, pseudomonas aeruginosa, haemophilus influenza, klebsiella pneumoniae, escherichia coli, Burkholderia cepacia.
What are patients with CF on long term to prevent S. aureus infection?
Prophylactic flucloxacillin.
Why is pseudomonas difficult to get rid of?
These bacteria can become resistant to multiple antibiotics.
Can children with CF be with other children with CF?
They should avoid each other as there’s a risk of spreading pseudomonas.
How is pseudomonas colonisation treated?
Nebuliser antibiotics like tobramycin and oral ciprofloxacin.
How is CF managed?
- chest physiotherapy → several times a day is essential to clear mucus and reduce the risk of infection and colonisation
- exercise → improves respiratory function and severe, and helps clear sputum
- high calorie diet is required for malabsorption, increased respiratory effort, coughing, infections and physiotherapy
- CREON tabels → digests fats in patients with pancreatic insufficiency (these replace the missing lipase enzymes)
- prophylactic flucloxacillin tablets to reduce the risk of bacterial infections (particularly s.aureus)
- treat chest infections when they occur
- bronchodilators eg. salbutamol inhalers can help treat bronchoconstriction
- nebuliser DNase is an enzyme that can breakdown DNA material in respiratory secretions, making secretions less viscous and easier to clear
- nebuliser hypertonic saline
- vaccinations including pneumococcal, influenza and varicella
What are some other treatment options for CF?
- lung transplantation is an option in end stage respiratory failure
- liver transplant in liver failure
- fertility treatment involving testicular sperm extraction for infertile males
- genetic counselling
What monitoring is done for CF patients?
- usually every 6 months
- regular monitoring of their sputum for colonisation of bacteria like pseudomonas
- the also need monitoring and screening for diabetes, osteoporosis, vitamin D deficiency and liver failure
What is the prognosis for CF patients?
- 90% of patients CF develop pancreatic insufficiency
- 50% of adults with CF develop CF related diabetes and require insulin treatment
- 30% of adults develop liver disease
- most males are infertile due to an absent vas deferens
What are some complications of CF?
Bronchiectasis, cor pulmonale, chronic liver disease, pneumothorax, osteoporosis.
