Cystic fibrosis Flashcards
What is the inheritance pattern of CF ?
Autosomal recessive
What is the disease prevalence ?
1/2500
What is the prevalence for carriers ?
1/25
Where is the CFTR gene ?
Long arm of chromosome 7
What is the commonest mutation in CF ?
DF508
What is the cause of death in 90% of CF ?
Respiratory failure
If both parents are carriers for the mutation , what is the chnace that the child will be affected ?
1/4
If both parents are carriers for the mutation , what is the chnace that the child will be a carrier ?
2/4
If both parents are carriers for the mutation , what is the chnace that the child will be unaffected ?
1/4
How does CF occur ?
Due to mutation in the transmembrane conductance regulator protein (CFTR)
What does abnormal transport of chloride and sodium cause ?
Reduced air way surface liquid
Thich sticky mucous
Shearing
Impaired bacterial killing via neutrophils
How many mutations classes of CFTR are there ?
6
What does classes I-III indicate ?
Severe disease
What does classes IV-VI indicate ?
Milder disease
How id CF diagnosed ?
Antenatal screening
Neonatal screening
Sweat test
What are the ways of antenatal screening ?
Pre-implantation genetic diagnosis
Chorionic villus sampling
Amniocentesis
What are the ways of neonatal screening ?
Gurthie test
+ screening- referred for clinical assessment and sweat test
What is the sweat test ?
Measures the concentration of chloride excreted in sweat
What happens to chloride in CF ?
Cl is elevated
When is sweat chloride abnormal ?
> 60mmol/L
What are the possible diagnosis outcomes ?
CF
Not CF
CF- screen positive inconclusive diagnosis (SPID)
Where about in the body can CF affect ?
Lungs GI and liver Psychosocial Nasal Nutrition Reproductive
What are 2 main diseases caused by CF ?
Infection and bronchiectasis
Pancreatic insufficiency
What other organ can CFTR affect ?
Pancreas
What do lack of enzymes from the pancreas cause ?
Malabsorption
Abnormal stools
Failure to thrive
What are the effects of the different classes of CF disease on the pancreas ?
Class I-III = pancreatic insufficiency
Class IV-VI = some pancreatic function
What % of CFTR function do we need to have sufficient pancreatic function and be asymptomatic ?
5%
What is recurrent chest infections linked to ?
Pneumonia
Bronchiectasis
Scarring
Abscesses
What does CFTR abnormality cause ?
Abnormal electrolyte transport across cell memebrane
Dehydration of airway surface layer (water later which allows mucous to slide easily up
airway to be coughed up)
Decreased mucocilary clearance
Mucous sticks to mucosal surface and causes shearing and inflammation
Increased access to bacteria
Decreased bacteria killing
How do pateints get repeated respiratory infections ?
Due to a vicious cycle of events
What is the cycle of events that happen ?
Decreased mucocilary clearance Increased bacterial adherence Decreased endocytosis of bacteria I V Bacterial colonisation I V Inflammation Mucus plugging Airway ulceration Airway damage I V *Bronchiectasis I V (back to the start)
What is progressive bronchiectasis ?
Chronic sputum production
What is progressive airflow obstruction linked to ?
Survival related to FEV1
Increasing breathlessness
Multiple drugs
What is type 1 respiratory failure ?
Decreased PaO2
What is type 2 respiratory failure ?
Decreased PaO2
Increased PaCO2
In CF what does a CT show ?
Tramlines
Signet rings
Mucous plugging
Consolidation (infection)
How is CF managed ?
By a MDT to improve long-term outcome
What is the treatment of pancreatic insufficiency in CF ?
Boosting nutrition
Replace enzymes (CREON)
Diet- high energy + high calorie supplement drinks
Nutritional supplements- fat-soluble vitamin and mineral supplements
What is the treatment of mucus obstruction inflammation in CF ?
Airway clearance via physiotherapy
Mucolytics
Bronchodilators
What is the treatment of chronic infection in CF ?
Antibiotics- oral, IV, nebulised
What is the treatment of increased inflammation in CF ?
Azithromycin
What is the treatment of fibrosis/ scarring/ bronchiectasis in CF ?
Supportive management and management of symptoms
What are a few aspects to be aware of in CF ?
Diabetes
Osteoporosis
Pneumothorax
Haemoptysis
How does diabetes differ in pateints with CF ?
The type of diabetes and its management in CF differs
What happens to pateints with osteoporosis and CF ?
Bone density mineral falls in pateints with CF
What % of people with CF suffer from pneumothorax ?
3-4%
What causes haemoptysis in CF ?
Bronchial wall destruction
What are the risk factors for haemoptysis in CF ?
Severity of CF
High number of exacerbations
Fungal lung infection
Liver disease
What are the social, educational and economic impact on children with CF ?
Barriers to making friends Increased depression/ anxiety Low adherence to time-consuming treatments Siblings Increased costs to the family
What are the social, educational and economic impact on adults with CF ?
Transition from new MDT can be challenging Restrictions on career Transport costs New drugs Pressures Possibility of lung transplant
What are the indications for double lung transplant ?
Rapidly deteriorating lung function FEV1 <30% predicted Life threatening exacerbations Estimated survival <2years Other- recurrent pneumonia, recurrent severe haemoptysis
What % of pateints die on the waiting list ?
30-40%
What are the absolute contraindications to lung transplant ?
Other organ failure Malignancy within 5 year Significant peripheral vascular disease Drug, nicotine, alcohol dependency Active systemic infection Microbiological issues
What is the median age of survival in CF ?
40 years
What is end of life care in CF ?
Oxygen and NIV Exercise Support- physical, mental, social, financial, alternative therapies Advanced care plans DNAR discussions
