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RESP - 1 > Cystic Fibrosis > Flashcards

Cystic Fibrosis Flashcards

1
Q

Is cystic fibrosis a genetic condition? If so, is it autosomal dominant or recessive? What is the gene prevalence?

A

Yes, recessive

1:25 gene prevalence - the commonest inherited, life-shortening disorder amongst N. European populations.

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2
Q

Where does the cystic fibrosis gene lie?

A

Long arm of chromosome 7.

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3
Q

What is the cystic fibrosis causing gene?

A

Cystic fibrosis transmembrane conductance regulator (CFTR) which codes for a chlorine channel that allows chlorine from inside the cell to move out of the cell.

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4
Q

What can different mutations of the CFTR disease result in?

A

Different phenotypes of disease. Not all mutations can cause disease, some present with infertility or will present with problems later in life.

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5
Q

What is the most common mutation in N. Europeans?

A

Phe508del (deltaF508).

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6
Q

What does the normal CFTR gene code lead to in healthy patients?

A

CFTR coded for a matures, so chlorine is effectively moved into the ECF.

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7
Q

What are some of the situations that occur leading to this chlorine channel being dysfunctional?

A

Abnormal mRNA produced –> abnormal protein, most of it gets picked up and destroyed, the small amount that makes it to the membrane has very little function.
Or they might just not produce the CFTR at all, or the regulation for the gene is blocked. The channel might make it to the surface but not actually open properly.

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8
Q

What determines the severity of the CF?

A

In severe mutation get little or no CFTR, in milder will have some but maybe don’t work as well as normal.

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9
Q

What can the drug Ivacaftor do?

A

Allows these dysfunctional chlorine channels to open, but only works for about 10% of the population.

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10
Q

What is the function of CFTR?

A

Active transport channel for chloride - regulates liquid volume on epithelial surface (reduced chlorine efflux, increased sodium influx via ENaC). Prevent villa collapse and excessive inflammation.

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11
Q

What is abnormal about ciliary function in CF patients?

A

Fluid is abnormal and the hairs collapse, mucus builds up and sets up an inflammatory cycle leading to little or no movement of the mucus.

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12
Q

What are the clinical presentations of antenatal CF patient?

A

CVS, echogenic bowel

less commonly - perforated meconium ileus

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13
Q

What are the clinical presentations of neonatal CF patient?

A

Screening, mec ileus (10%)

less commonly - gut atresia, obstructive jaundice, vitamin deficiencies

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14
Q

What are the clinical presentations of infant and young children CF patients?

A

Recurrent chest infections, failure to thrive

less commonly - rectal prolapse, pseudo-Batter’s syndrome, anaemia, oedema, hypoproteinaemia.

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15
Q

What are the clinical presentations of older children and adult CF patients?

A

Recurrent chest infections, nasal polyps and sinusitis, male infertility
less commonly - acute pancreatitis, liver disease, pseudo-Bartter’s, atypical mycobacteria

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16
Q

When are neonatals screened for CF?

A

With newborn blogspot on day 5 (Guthrie test).

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17
Q

What is used to test for CF?

A

Initial screen - immune-reactive trypsinogen, if positive mutation analysis performed, if screened positive referred sweat test.

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18
Q

What is the sweat test?

A

Measure chlorine in sweat, in CF patients it is abnormally high.
Normal value <40mEq/l
CF indicated by >60mEq/l

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19
Q

Is screening important to CF prognosis?

A

‘Probably’ reduces infant mortality.
Maybe improves lung function
Better nutrition in those picked up during screening
Brain - vit E deficient at diagnosis had lower cognitive skills index and head circumference.

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20
Q

When was screening introduced in Scotland?

A

2003

21
Q

What are the accepted sweat values in CF and normal health?

A

> and equal to 60 = indicative of CF

> and equal to 20 (39 if 6 months or younger) = CF unlikely

22
Q

What is primary care’s responsibility in management of CF patients?

A

Surveillance and early treatment of infection

23
Q

CF is a multi-organ disease, what does this mean in terms of management of it?

A

Need specialist multi-disciplinary team.

24
Q

What percentage of CF patients suffer from pancreatic insufficiency?

A

85-90%

25
Q

What are the two cardinal features of CF?

A

Pancreatic insufficiency

Recurrent bronchopulmonary infections

26
Q

How is pancreatic insufficiency treated?

A

Enteric coated enzyme pellets (to get past stomach acid)
High energy diet (not low fat, tailor enzymes to fat consumption)
Fat-soluble vitamin and mineral supplements
H2 antagonist or proton pump inhibitors

27
Q

What are the signs of pancreatic insufficiency?

A

Abnormal stools that are pale/orange, very offensive, greasy/oily.

Failure to thrive - may thrive quite well on breast milk, may have deficiencies of fat soluble vits. Hence importance of record, charts etc.

28
Q

What kinds of bronchopulmonary infections are CF patients prone to?

A

Pneumonitis, bronchiectasis, scarring, abscesses

29
Q

Why are CF patients more prone to chest infections?

A

Can’t clear out bacteria etc properly.

30
Q

What precautions are taken in the early years to prevent infection in CF patients?

A

Segregating/cohorting to prevent cross-contamiating
Airway clearance and adjuncts
Mucolytics
Prophylatic antibiotics (against staph aureus)
Annual influenza vaccination

31
Q

What is very important in CF patients?

A

Eradication of early infection.

32
Q

What are common respiratory pathogens in CF patients?

A

Staph aureus and H. influenzae in early life and pseudomonas aeruginosa later.

33
Q

What are some less common respiratory pathogens in CF patients?

A

Burkholderia cepacia, stenotrophomonas maltophilia, alcaligenes xylosoxidans, atupical mycobacteria e.g. M abscessus.

34
Q

What organisms most likely give rise to chronic infection in CF patients?

A

Staph aureus
H. influenzae
Pseudomonas aeruginosa.

35
Q

How are these chronic infections managed?

A

By suppressing bacterial load
Treat infective exacerbations
Reducing inflammation using ibruprofen, Azithromycin and prednisolone

36
Q

What is the best way to administer antibiotics in chronic infections?

A

Chronic inhaled antibiotics, remember once patients have these chronic infections their lung function is reduced for the rest of their lives.

37
Q

What is survival like in CF?

A

Treatment has improved so much can be looking at living up to 50 years now.

38
Q

What are other manifestations of CF?

A 
GI dysmotility 
- Meconium ileus
- Gastro-oesphageal reflux
- Distal intestinal obstruction 
- Constipation/rectal prolapse
Co-existent disease
- Crohn's and coeliac 
Hepatopathy 
Upper airway polyps and sinusitis
Diabetes
Bones - osteopenia, arthropathy
Heat exhaustion 
Bilateral absence of vans defers
Vaginal candidiasis, stress incontinence
39
Q

Name three airway clearance techniques.

A

Percussion and drainage
Autogenic drainage
Active cycle of breathing

40
Q

Name three airway clearance adjuncts.

A

Positive expiratory pressure (PEP) mask
Cornet/flutter
High frequency chest wall oscillation

41
Q

Why may sputum be more viscous?

A

DNA released from neutrophils increases viscosity.

42
Q

Name two mucolytics and how they work.

A

DNA-ase (alfadornase) breaks down DNA strands which eases expectoration of purulent secretions, expensive and short to medium term benefit.

Hypertonic saline - similar efficacy to alfadornase, short to medium term benefit but cheap.

43
Q

What are causes of false positive sweat tests?

A 
Malnutrition 
Adrenal insufficiency
Glycogen storage diseases
Nephrogenic DI
Hypothyroidism, hypoparathyroidism
C6PD
Ectodermal dysplasia
44
Q

What is the most common cause of a false negative sweat test?

A

Skin oedema (often due to hypoalbuminaemia/hypoproteinaemia secondary to pancreatic exocrine insufficiency

45
Q

What are the most common presenting features of CF in neonates?

A

Meconium ileus, less commonly prolonged jaundice

46
Q

What are the most common presenting features of CF after the neonatal period?

A

Recurrent chest infections

Malasborption - steatorrhoea, FTT

47
Q

What are other features of CF?

A 
Short stature
DM
Delayed puberity
Rectal prolapse (due to bulky stools)
Nasal polyps
Male infertility, female subfertility
48
Q

What is involved in the management of CF?

A

Regular (2x daily) chest physio + postural drainage
High calorie diet
Minimise contact with other CF patients to avoid cross infection with Burkholderia cepacia + pseudomonas
Vitamins
Pancreatic enzyme supplements

49
Q

What drugs can be used in deltaF508 patients?

A

Lumacaftor - increases no of CFTR proteins transported to cell surface
Ivacaftor - potentiator of CFTR that is already at cell surface (increasing probability that the defective channel will be open + allow chloride ions to pass through)

RESP - 1 (27 decks)

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