Resp - cystic fibrosis

Question 1

What peripheral signs are present in CF?

Answer 1

Clubbing of fingers

Short stature

Question 2

What is the inheritance of CF?

Answer 2

autosomal recessive

Question 3

Which mutation causes 78% of cystic fibrosis

Answer 3

ΔF508 mutation

Question 4

How is screening for CF performed?

Answer 4

Measure the serum immunoreactive trypsin

(raised due to pancreatic duct obstruction)

DNA test is performed to reduce false-positive rate

If raised, common gene mutations is screened for

Question 5

What does the biochemical screening performed on all babies in the UK (Guthrie heel-prick test) test for?

Answer 5

Phenylketonuria
Congenital hypothyroidism
Haemoglobinopathies
Cystic Fibrosis
MCAD deficiency

Question 6

What nutrition may be advised in children with CF?

Answer 6

specialised formula

Question 7

Which investigation is performed for CF?

Answer 7

CXR and sweat test

Question 8

How does CF lead to failure to thrive?

Answer 8

Pan-nutrient Malabsorption (pancreatic insufficiency)

Increased requirements

Question 9

Clinical chest signs of CF?

Answer 9

Expiratory wheeze
Hyperinflation of chest due to airtrapping

Coarse inspiratory crepitations

Question 10

What is the defect in CF?

Answer 10

CF transmembrane regulator deficiency

cAMP dependent chlorine channel

Gene located on chromosome 7

Question 11

How does CF affect cells in the lung?

Answer 11

Reduction in airway surface liquid layer and consequent impaired ciliary function and retention of mucopurulent secretions

Question 12

What is the effect of CF on the GI system?

Answer 12

thick viscid meconium is produced
Meconium ileus in 10-20% of infants

Steatorrhoea

Pancreatic enzyme deficiency and malabsorption due to blockage of ducts

Question 13

Which organisms often cause chronic chest infections in CF?

Answer 13

Initially Staph aureus
and Haemophilus influenza

Then pseudomonas aeruginoase and burkholderia species

Question 14

What are the effects of chronic chest infections on the lungs?

Answer 14

Damage to bronchial wall, bronchiectasis and abscess formation

Persistent loose cough, productive of purulent sputum

Question 15

What is meconium ileus? How is it managed?

Answer 15

Inspissated meconium causes intestinal obstruction with vomiting, abdominal distension and failure to pass meconium in first few days of life

Initial treatment is Gastrografin enemas, but most require surgery

Question 16

How is CF diagnosed?

Answer 16

Concentration of NaCl in sweat is markedly elevated

60-125mmol/L
Normal 10-40

Question 17

What is the purpose of physio in CF?

Answer 17

Clear airways of secretions

At least twice daily

Older patients can perform controlled deep breathing exercises and use physio devices
Physical exercise is beneficial

Question 18

How is the respiratory aspect of CF managed?

Answer 18

Regular spirometry for FEV1 (in older children)

Many specialists recommend continuous flucloxacillin for prophylaxis, with additional rescue oral antibiotics.
Persisting symptoms require 14 day IV therapy

Nebulised DNAse or hypertonic saline may be useful in to decrease viscosity of sputum

Bilateral sequential lung transplantation is the only therapeutic option for end-stage CF lung disease (rarely required in childhood)

Question 19

Describe the nutritional management of CF

Answer 19

Assess dietary status regularly

Oral enteric-coated pancreatic replacement therapy (with all meals)

High-calorie diet is essential

Dietary intake 150% of normal (overnight feeding via gastrostomy is increasingly used)

Most require fat-soluble vit supplements

Question 20

Which medication may be useful to improve flow of bile

Answer 20

Ursodeoxycholic acid

Question 21

How can the liver be affected in CF?

Answer 21

1/3 hepatomegaly
Abnormal LFTs
Rarely cirrhosis, portal HTN, liver failure

Transplant usually very successful

Question 22

How is distal intestinal obstruction in meconium ileus managed?

Answer 22

Oral gastrografin

Question 23

How is fertility affected by CF?

Answer 23

Females can have children if they can tolerate pregnancy

Males have absent vas deferens - infertile

Question 24

What may be inserted into the chest of a CF patient?

Answer 24

Central venous line eg. portacath for IV antibiotics

There may be a scar on the stomach from meconium ileus operation