Cystic Fibrosis Flashcards
Define cystic fibrosis.
Autosomal recessive condition characterised by recurrent lung infections, malabsorption + failure to thrive.
What is the aetiology of cystic fibrosis?
Defect in cystic fibrosis transmembrane conducts regulator gene (CFTR; which codes a cAMP-regulated chloride channel)
80% due to delta F508 on Chr7
Summarise the epidemiology of cystic fibrosis.
1/2500 live births.
More common in Caucasians.
When is cystic fibrosis screened for in children?
At birth: heel prick test
If cystic fibrosis screening is positive, what further tests are performed to confirm diagnosis?
Sweat test (abnormally high NaCl)
Genetic tests
If no history of CF screening, what else can diagnosis be based on?
Clinical manifestations supported by sweat or gene results
Describe results of sweat test in CF
Abnormally high sweat chloride
normal value < 40 mEq/l, CF indicated by > 60 mEq/l
List 6 causes of a false positive sweat test
Malnutrition
Adrenal insufficiency
Glycogen storage diseases
Nephrogenic DI
Hypothyroidism, hypoparathyroidism
G6PD
What is the most common reason for false negative sweat tests?
Skin oedema, often due to hypoalbuminaemia/ hypoproteinaemia secondary to pancreatic exocrine insufficiency.
List 3 presenting symptoms of CF
Delayed passage of meconium/ meconium ileus
Malabsorption: Voracious appetite, Steatorrhoea, FTT (poor weight gain/ dropping deciles)
Recurrent chest infections
List 6 features of CF that may present later in childhood/ early adulthood
Short stature
Diabetes mellitus
Delayed puberty
Rectal prolapse (due to bulky stools)
Nasal polyps
Male infertility, Female subfertility
What are the signs of cystic fibrosis?
Signs of malnutrition: Muscle mass decreased
Resp: Wet cough, hyperinflation
Others: Clubbing, bilateral absence of the vas deferens
What is seen on lung function testing in cystic fibrosis?
Obstructive picture with air trapping + hyperinflation (Decreased FEV1, Increased Total lung capacity).
What is the long-term management for the respiratory symptoms of cystic fibrosis?
Specialist PT sessions to mobilise secretions.
Inhaled bronchodilator (salbutamol)
Inhaled mucolytic
How frequent should physiotherapy be done for respiratory symptoms in CF?
Twice a day
What is used for mucolytic therapy in cystic fibrosis?
1st line = rhDNase (Dornase alfa)
2nd line = rhDNase + hypertonic saline
What additional therapy can be added on for respiratory management in CF?
Inhaled Tobramycin for initial/ chronic Pseudomonas infection.
Inhaled corticosteroid (if co-morbid asthma/ ABPA)
Ivacaftor: CFTR potentiator (only useful in G551D gene mutations).
What respiratory intervention is reserved for CF patients who have all alternatives?
Bilateral lung transplant
Name a contraindication to lung transplant in CF
Chronic infection with Burkolderia cepacia
Why should CF patients try to minimise contact with each other?
To prevent cross infection with Burkholderia cepacia + Pseudomonas aeruginosa
What is the long-term management for the GI symptoms of cystic fibrosis?
Specialist dietician: high calorie, inc. high fat intake
Pancreatic insufficiency: Pancreatin (pancreatic enzyme replacement)
+ fat-soluble vitamin supplementation.
+/- PPIs
Liver disease: Urosdeoxycholic acid to prevent gallstone development.
GORD: Famotidine (2nd PPIs)
Ivacaftor in specific CFTR mutations.
What is the long-term management for non-specific symptoms of cystic fibrosis?
Psychological support + counselling for carer + patient.
Specialist nurses.
Specialist pharmacists.
Regular follow-ups + monitoring for complications.
Immunizations esp. for influenza + pneumococcus.
What is the acute management for meconium intestinal obstruction?
Water-soluble contrast enema + osmotic agent (Lactulose)
NG decompression if still obstructed
Surgery if peritonitc
What is the mangement for acute respiratory infection in cystic fibrosis?
Mild: Co-amoxiclav PO
Mod- Severe: IV Tobramycin
Regardless of severity:
Increased chest physiotherapy.
Bronchodilator, mucolytic.
What are the possible complications of cystic fibrosis?
Respiratory: Bronchiectasis, cor pulmonale, pneumothorax, hemoptysis.
GI: Cirrhosis, portal hypertension, distal intestinal obstruction syndrome; viscid mucofaeculent material obstructs the bowel.
Endocrine: DM, decreased fertility. 99% of males are infertile due to obstruction + abnormal development of vas deferens.
Psychological
What is the prognosis of cystic fibrosis?
Most survive into adult life (median survival 40y).
Children with Pseudomonas colonization have a 2–3-fold increased mortality over 8y.
