Cystic Fibrosis

Question 1

Explain the mutation behind Cystic Fibrosis?

Answer 1

Autosomal Recessive inheritance of mutation in the genes for the Cystic Fibrosis Transmembrane Conductance Regulator Protein on long arm of chromosome 7.

Question 2

What is the effect of mutation on CFTR channels?

Answer 2

The CFTR channels are either absent or defective in which case:

• They no longer transport Cl- from sweat ducts into cells so CF sweat Test
• They no longer inhibit sodium channels on epithelial cells so Na+ travels into cells taking water with it and leaving a dehydrated thick mucous on the surface of epithelial cells.

Question 3

How do respiratory symptoms arise in CF?

Answer 3

Dehydrated Airway Surface Liquid (ASL)

• > Cilia collapse - Thick mucous - inflammation
• > Chronic Infection - Mucous obstruction - Airway Damage (Bronchiectasis)

Question 4

What are the common symptoms/signs of CF?

Answer 4

Cyanosis
Clubbing
Bilateral Coarse Crackles
Cough
Wheeze

Question 5

What are the cardinal signs of CF?

Answer 5

Respiratory:
Recurrent Bronchopulmonary infection -> Bronchiectasis, scarring and abscesses
(Theres also risk of haemoptysis & pneumothorax from airway damage)

Pancreatic Insufficiency:

• Abnormal pale/orange, offensive, oily stools
• Failure to thrive in kids
• ~Pancreatitis
• ~Fat soluble Vitamin Deficiency

Question 6

How does CF affect Fertility?

Answer 6

In most male sufferers there is congenital absecne of blockage of the Vas Deferens causin male infertility

Question 7

How does CF affect the GI tract?

Answer 7

Dysmotility of the GI tract due to:

• Meconium Ileus (neonatal thick/strick meconium blocks ileus)
• Rectal Prolapse/constipation

Gastro-oesophageal reflux

Question 8

In what other ways can CF present?

Answer 8

Arthritis/Osteoporosis
Nasal Polyps & sinusitis
Diabetes
Heat Exhaustion
Vaginal Candidiasis
Hepatopathy

Question 9

What are the most common causative organisms of chronic bronchopulmonary infection in CF?

Answer 9

Haemophilus Influenzae
Staph Aureus
Pseudomonas Aeruginosa (most common)

Question 10

How can CF be spotted prenatally?

Answer 10

With Chorionic Villus Sampling or Amniocentesis

Echogenic Bowel can be seen on Ultrasound

Question 11

Explain Neonatal screening for CF?

Answer 11

Blood prick test on Day 5 (Guthrie Test) - Raised Immuno-reactive Trypsinogen

If +ve confirm with CF sweat test for high chloride & mutation analysis

Question 12

Who manages CF?

Answer 12

A Multi-Disciplinary Team, Primary Care handles surveillance and early infection treatment

Question 13

How is the pancreatic insufficiency handled?

Answer 13

• Record/Chart growth to monitor severity
• Enteric Coated Enzyme replacement tablets
• High Energy Diet
• Fat Soluble Vitamin/Mineral Tablets

Question 14

How do we manage respiratory symptoms pre-chronic infection, often in early years?

Answer 14

• Segregation/Cohorting to prevent cross-infection
• Airway Clearance & Adjuncts
• Mucolytics
• Influenza Vaccine
• Prophylactic Antibiotics

Question 15

What Mucolytics are used for CF?

Answer 15

Alfadornase - expensive - Breaks Down DNA released from neutrophils - Makes sputum easier to clear

Hypertonic Saline - Cheap - Same efficacy

Question 16

What treatments are there for respiratory CF later in life?

Answer 16

Reduce inflammation -> Ibuprofen & Prednisalone
Dilate Airways -> Bronchodilators
Suppres bacterial load -> Azithromycin
Treat infective exacerbations -> Necessary Antibiotics
Ivacaftor -> CFTR channel potentiator (improves breathing and absorption of vitamins

Question 17

What methods are there for airway clearance, and what adjuncts are used?

Answer 17

Percussion & Drainage
Autogenic Drainage (a method of breathing)
Daily Active cycle of breathing

Adjuncts include PEP mask, chest physiotherapy vest etc.