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Yr 4 - Paediatrics > Respiratory: Cystic Fibrosis & Primary Ciliary Dyskinesia > Flashcards

Respiratory: Cystic Fibrosis & Primary Ciliary Dyskinesia Flashcards

1
Q

What is cystic fibrosis (CF)?

A

Cystic fibrosis is an autosomal recessive disease caused by a mutation in the CF transmembrane conductance regulator gene (CFTR) resulting in multisystem dysfunction.

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2
Q

How is CF inherited?

A

Autosomal recessive disease.

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3
Q

What mutation is seen in CF?

A

Genetic mutation of the cystic fibrosis transmembrane conductance regulatory (CFRT) gene on chromosome 7.

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4
Q

What % of Caucasian Europeans are carriers of a CF gene?

A

Approx 4% (1 in 25)

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5
Q

What is the most common variant of the CFTR mutation in CF?

A

Delta-F508 mutation.

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6
Q

Prevalence of CF?

A

1 in 2500 have CF

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7
Q

What chromosome is the cystic fibrosis transmembrane conductance regulatory gene (CFTR) located on?

A

Chromosome 7

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8
Q

What is the normal role of the CFTR gene?

A

Codes for CFTR protein –> a chloride channel.

This channel is found on epithelial surfaces.

Channel pumps Cl- into secretions –> this helps draw water into secretions –> thins secretions.

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9
Q

What are the 3 consequences of the CF mutation?

A

1) Thick pancreatic and biliary secretions that cause blockage of the ducts, resulting in a lack of digestive enzymes such as pancreatic lipase in the digestive tract

2) Low volume thick airway secretions that reduce airway clearance, resulting in bacterial colonisation and susceptibility to airway infections

3) Congenital bilateral absence of the vas deferens in males. Patients generally have healthy sperm, but the sperm have no way of getting from the testes to the ejaculate, resulting in male infertility

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10
Q

Both parents are healthy, one sibling has cystic fibrosis and a second child does not have the disease, what is the likelihood of the second child being a carrier?

A

We know the child doesn’t have the condition, so the answer is two in three.

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11
Q

What does the CFTR gene encode?

A

Encodes the CFTR protein – a chloride channel that is present in numerous epithelial tissues.

Chloride is driven against its concentration gradient using ATP.

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12
Q

Pathophysiology of CF in regard to the respiratory tract?

A

1) In the airway, CFTR (chloride channel) is present on airway epithelial cells and submucosal glands

2) When defective, this results in LESS chloride being pumped into secretions –> water cannot be drawn in (i.e. reduced airway surface liquid) –> thick secretions.

3) The airway surface liquid is an important component of the mucociliary escalator and also has key immunological functions.

4) The effects of reduced airway surface liquid serve to impede mucus clearance.

5) The altered lung environment provides a niche for bacterial growth with the biofilm mode of growth providing ideal conditions to protect bacteria from the host immune system and the actions of antibiotics.

6) The pro-inflammatory cascade contributes to tissue damage.

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13
Q

Pathophysiology of CF in regard to the pancreas?

A

In the pancreas the pancreatic duct is usually occluded in-utero causing permanent damage to the exocrine pancreas rendering patients with CF ‘pancreatic insufficient’.

Over time, endocrine pancreas is affected with 28% of those older than 10 years requiring treatment for CF-related diabetes mellitus.

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14
Q

What causes pancreatic enzyme insufficiency in CF?

A

Thick pancreatic and biliary secretions cause blockage of the ducts, resulting in a lack of digestive enzymes such as pancreatic lipase in the digestive tract.

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15
Q

What leaves CF patients susceptible to airway infections?

A

Low volume thick airway secretions that reduce airway clearance.

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16
Q

What causes infertility in males with CF?

A

Congenital bilateral absence of the vas deferens.

Patients generally have healthy sperm, but the sperm have no way of getting from the testes to the ejaculate, resulting in male infertility.

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17
Q

How can CF cause meconium ileus?

A

In the GI tract, the small intestine secretes viscous mucus which can cause bowel obstruction in-utero which can cause meconium ileus.

Later in life the same pathology can result in distal intestinal obstruction syndrome (DIOS).

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18
Q

How can CF cause neonatal jaundice?

A

CF can cause cholestasis

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19
Q

How can CF present in neonates?

A

1) Meconium ileus

2) Prolonged neonatal jaundice

3) Failure to thrive

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20
Q

When are the majority of cases of CF picked up?

A

Heelprick test at birth.

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21
Q

How does meconium ileus present?

A
  • abdominal distension
  • delayed passaage of meconium
  • bilious vomiting in first days of life
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22
Q

Clinical features of CF?

A

Neonates:
- meconium ileus
- prolonged neonatal jaundice
- failure to thrive

Infancy:
- recurrent LRTIs
- pancreatic insufficiency: steatorrhoea

Childhood:
- rectal prolapse
- nasal polyps (strongly suspect CF in children presenting with nasal polyps)
- sinusitis

Adolescence:
- pancreatic insufficiency: diabetes mellitus
- chronic lung disease e.g. bronchiectasis
- Distal intestinal obstruction syndrome (DIOS)
- gallstones
- liver cirrhosis
- pancreatitis (from blockage of pancreatic ducts)

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23
Q

What causes nasal polyps in CF?

A

Thickened secretions in sinuses can lead to recurrent infection and subsequent nasal polyps due to chronic inflammation.

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24
Q

How does distal intestinal obstruction syndrome (DIOS) present?

A
  • bloating
  • abdo pain
  • vomiting
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25
Q

Symptoms of CF?

A
  • Chronic cough
  • Thick sputum production
  • Recurrent respiratory tract infections
  • Loose, greasy stools (steatorrhoea) due to a lack of fat digesting lipase enzymes
  • Abdominal pain and bloating
  • Parents may report the child tastes particularly salty when they kiss them, due to the concentrated salt in the sweat
  • Poor weight and height gain (failure to thrive)
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26
Q

What signs may be seen in CF?

A

1) Low weight or height on growth charts

2) Nasal polyps

3) Finger clubbing (e.g. bronchiectasis)

4) Crackles and wheezes on auscultation

5) Abdominal distention

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27
Q

How can a diagnosis of CF be made?

A

1) Fitting clinical history

2) Positive chloride sweat test

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28
Q

There are three key methods for establishing a diagnosis of CF that you should remember for your exams.

What are they?

A

1) Newborn blood spot testing –> performed on all children shortly after birth and picks up most cases

2) Sweat test –> gold standard

3) Genetic testing for CFTR gene –> can be performed during pregnancy by amniocentesis or chorionic villous sampling, or as a blood test after birth

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29
Q

What happens in the sweat test for CF?

A

1) Pilocarpine is applied to a patch of skin.

2) Electrodes are placed either side of the patch and a small current is passed between the electrodes.

3) This causes the skin to sweat.

4) The sweat is absorbed with lab issued gauze or filter paper and sent to the lab for testing for the chloride concentration.

5) Increased chloride –> CF

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30
Q

What is the diagnostic chloride concentration for cystic fibrosis?

A

> 60 mmol/l

31
Q

Relevant bedside investigations in CF?

A

1) Urine dip: for glucose in case of diabetes

2) Lung function testing: an obstructive picture is most common but can be restrictive, mixed or normal

32
Q

Relevant lab investigations in CF?

A

1) Bloods:
- FBC and CRP (infection and anaemia)
- U&Es
- fasting glucose
- LFTs (biliary or liver effects)
- vitamin A, C and E levels

2) Sputum culture and sensitivity

3) Sweat testing: high chloride concentration

4) Genetic testing: for CFTR

5) Faecal elastase: for pancreatic insufficiency

33
Q

Relevant imaging investigations in CF?

A

1) CXR:
- bronchiectasis
- hyperinflation

2) High-resolution CT chest:
- bronchial wall thickening
- bronchiectasis (tree-in-bud appearance, signet ring sign)
- mucus plugging (finger in glove)

3) CT angiography: in haemoptysis, if endovascular intervention is being considered

34
Q

What are 6 bacteria that commonly cause respiratory infections in CF?

A

1) Staphylococcus aureus

2) Haemophilus influenza

3) Klebsiella pneumoniae

4) Escherichia coli

5) Burkhodheria cepacia

6) Pseudomonas aeruginosa: this is a particularly troublesome coloniser as is hard to treat and worsens the prognosis of patients with CF.

35
Q

What prophylactic Abx do patients with CF take long term to prevent staph. aureus infections?

A

flucloxacillin

36
Q

Why can colonisation with pseudomonas lead to a significant increase in morbidity and mortality in patients with CF?

A

Once patients become colonised with pseudomonas, it can be very difficult to get rid of. Often, these bacteria can become resistant to multiple antibiotics.

The general advice is now to avoid contact with other children with CF.

37
Q

What can pseudomonas colonisation be treated with in CF?

A

Long term nebulised antibiotics such as tobramycin. Oral ciprofloxacin is also used.

38
Q

What does the management of CF involve?

A

1) Patient & family education

2) Airway clearance & chest symptoms management

3) Nourishment & exercise

4) Managing/preventing airway infections

5) Monitoring the disease

39
Q

What is involved in the management of respiratory manifestations in CF?

A

1) Twice-daily chest physiotherapy: to increase airway secretion clearance to reduce airway obstruction and minimise risk of infection.

2) Prophylactic antibiotics and antibiotics for acute exacerbations.

3) Inhaled bronchodilators

4) Mucolytics (oral or inhaled): hypertonic saline or dornase alfa

40
Q

What is the role of DNase (dornase alpha) in CF?

A

DNase (dornase alpha) is inhaled and reduces viscosity of mucus by digesting DNA which is abundant in the sputum of patients with CF.

41
Q

What is the role of hypertonic saline in CF?

A

Hypertonic saline can aid airway clearance (and can be used at time of physiotherapy to further aid clearance)(limited evidence to support use in under 12 yrs).

42
Q

How is pancreatic insufficiency in CF usually managed?

A

Pancreatic enzymes (Creon)

43
Q

What does management of nourishment & exercise involve in CF?

A

1) Encouraged to undertake physical exercise

2) Pancreatic enzyme supplementation (Creon) with meals which contain fats (should be taken at the start or during the meal)

3) Vitamin A, D and E supplements

4) Monitor growth

5) Children with CF may have poor weight gain:
- Build-up milkshakes can be used to supplement meals (not in place of)
- May be necessary to have supplemental of enteral feeding (e.g. via a gastrostomy)

44
Q

What are the fat soluble vitamins?

A

A, D, E and K

45
Q

Why do patients with CF with pancreatic insufficiency require vitamin A, D and E supplements?

A

Fat-soluble vitamins (A, D, E and K) are poorly absorbed in those who have pancreatic insufficiency.

Pancreatic enzyme replacement is not enough hence children with pancreatic insufficiency will also need to take vitamin A, D and E supplements.

46
Q

How long should all courses of Abx in CF last?

A

2 weeks.

47
Q

What is the mainstay of surgical management of CF?

A

Transplant (lung +/- heart).

48
Q

Respiratory complications of CF?

A

1) Bronchiectasis

2) Recurrent infections

3) Cor pulmonale from pulmonary HTN and right heart strain

4) Haemoptysis (can be large volume and life-threatening)

5) Pneumothorax

6) Nasal polyps

7) Respiratory failure will eventually occur

8) Allergic bronchopulmonary aspergillosis (ABPA)

49
Q

What is allergic bronchopulmonary aspergillosis (ABPA)?

A

An immune response to the prescence of Aspergillus spp. There are specific diagnostic criteria.

ABPA can initially be treated with oral corticosteroids (prednisolone) and itraconzaole can also be tried.

50
Q

What can ABPA initially be treated with?

A

Oral prednisolone

51
Q

What are the GI complications of CF?

A

1) Rectal prolapse (from frequent passage of bulky stools)

2) Distal intestinal obstruction syndrome (DIOS)

3) CF related liver disease:
- Cholestasis
- Gallstones
- Liver cirrhosis

52
Q

What are the endocrine complications of CF?

A

1) CF related diabetes

2) Delayed puberty –> can result in reduced bone mineral density which predisposes children to fractures later in adolescence and adulthood.

53
Q

What is primary ciliary dyskinesia (PCD)?

A

It is an autosomal recessive condition affecting the cilia of various cells in the body.

PCD causes dysfunction of the motile cilia around the body.

54
Q

What is PCD also known as?

A

Kartagener’s syndrome

55
Q

How is Kartagener’s syndrome inherited?

A

Autosomal recessive

56
Q

What does Kartagener’s syndrome have a strong association with?

A

Consanguinity (meaning the parents are related to each-other).

Consanguinity increases the risk of a child having two copies of the same recessive genetic mutation.

57
Q

what organs does Kartagener’s syndrome affect?

A

1) Lungs –> dysfunction of the motile cilia in the respiratory tract leads to a buildup of mucus in the lungs. This leads to a similar respiratory presentation to cystic fibrosis, with frequent and chronic chest infections, poor growth and bronchiectasis.

2) Affects the cilia in the fallopian tubes of women and the tails (flagella) of the sperm in men –> reduced or absent fertility.

58
Q

What is Kartagner’s triad?

A

Kartagner’s triad describes the three key features of PCD. Not all patients will have all three features.

1) Paranasal sinusitis

2) Bronchiectasis

3) Situs inversus

59
Q

What is situs inversus?

A

A condition where all the internal (visceral) organs are mirrored inside the body. Therefore the heart is on the right, the stomach is on the right and the liver is on the left.

Dextrocardia is when only the heart is reversed.

60
Q

What % of patients with situs inversus will have PCD?

A

25%

61
Q

What % of patients with primary ciliary dyskinesia have situs inversus?

A

50%

62
Q

Features of Kartagener’s syndrome?

A

1) dextrocardia or complete situs inversus

2) bronchiectasis

3) recurrent sinusitis

4) subfertility (secondary to diminished sperm motility and defective ciliary action in the fallopian tubes)

63
Q

How do patients with Kartagener’s syndrome typically present?

A

Patients typically present with recurrent respiratory tract infections

64
Q

Investigations in Kartagener’s syndrome?

A

1) Careful FH and history of consanguinity in the parents

2) Investigations for situs inversus e.g. CXR

3) Semen analysis: male infertility

4) Take a sample of the ciliated epithelium of the upper airway and examine the action of the cilia.

65
Q

What is the key investigation for establishing the diagnosis of PCD?

A

Take a sample of the ciliated epithelium of the upper airway and examine the action of the cilia –> sample can be obtained through nasal brushing or bronchoscopy.

66
Q

2 options for obtaining sample of the ciliated epithelium of the upper airway in PCD?

A

1) nasal brushing

2) bronchoscopy

67
Q

Management of Kartagener’s syndrome?

A

Management is similar to cystic fibrosis and bronchiectasis with daily physiotherapy, a high calorie diet and antibiotics.

68
Q

How can CF present in neonates?

A

Meconium ileus –> surgical emergency.

1st stool of neonates (the meconium) is so thick and sticky that it gets stuck in intestines.

69
Q

What is the most prominent effect of CF in early childhood?

A

Pancreatic insufficiency

70
Q

Cause of pancreatic insufficiency in CF?

A

Thick secretions block pancreatic duct –> digestive enzymes can’t make it to small intestine.

71
Q

Effects of pancreatic insufficiency in CF?

A

1) Lack of digestive enzymes means that fats and proteins are poorly absorbed –> poor weight gain & failure to thrive.

2) Steatorrhoea (fatty stools).

3) Eventually results in pancreatic damage (as backed up pancreatic enzymes degrade the cells that line the ducts).

4) Acute or chronic pancreatitis (development of cysts & fibrosis)

5) Can result in insulin dependent diabetes

72
Q

What are 2 problematic bacteria in lung problems in CF?

A

1) Staph. aureus (gram +ve)

2) Pseudomonas aeruginosa (gram -ve)

73
Q
A

Yr 4 - Paediatrics (78 decks)

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