Resp - cystic fibrosis

Question 1

Cystic fibrosis - what gene is faulty and what are the cellular implications of this?

Answer 1

CFTR gene which moves Cl- ions is faulty
this means that Cl is not pumped into the mucus - which makes it very thick because water moves with Cl

On the skin, the Cl cant be reabsorbed so sweat is very salty

[Chromosome 7, del-F508]

Question 2

how is CF inherited? How many people are affected by the gene?

Answer 2

Autosomal recessive

1/25 carrier rate

Question 3

CF - how might is be seen in a newborn

Answer 3

routinely on the heel prick test (high immunoreactive trypsinogen (IRT) - from damaged pancreas)
present with meconium ileus [GI obstruction, vomiting, abdominal distension]

Question 4

once suspected, what is done to confirm a CF diagnosis

Answer 4

sweat test

genetic test

Question 5

how is the pancreas/GI system affected in CF?

Answer 5

thick secretions block the pancreatic ducts
this means lipases, amylases and proteases can’t get into the intestines and fats and proteins arent absorbed -> failure to thrive+steatorrhoea

acute pancreatitis is then caused by the digestive enzymes digesting the pancreas (cysts and fibrosis occur)
chronic pancreatitis can also happen, with insulin dependent diabetes ensuing
rectal prolapse can also feature (thick stools?)

Question 6

how is the respiratory system affected in CF?

Answer 6

impaired mucocilary function from the thick secretions mean that bacteria aren’t all shipped out and cause chronic infections and inflammation
this causes bronchiectasis (bronchial wall damage and dilation)
can eventually cause respiratory failure and death

can get nasal polyps
RECURRENT CHEST INFECTIONS

Question 7

Respiratory symptoms in CF?

Answer 7

persistent wet cough
purulent sputum
chest hyperinflation
coarse inspiratory creps

nasal polys
sinusitis

Question 8

does CF cause infertility?

Answer 8

In men it does - no vas deferens

Question 9

Other symptoms in CF

Answer 9

clubbing
rectal prolapse
diabetes
GI obstruction
cirrhosis/portal hypertension
pneumothorax
short stature

Question 10

what infections do you tend to get in CF?

Answer 10

Pseudomonas aeruginosa is the big one

S aureus and H influenza beforehand

Question 11

Management of CF

Answer 11

Pancreatic enzyme replacement
fat soluble vitamins ADEK
high calorie diet

chest physio
prophylactic antibiotics (flucloxacillin)
PIC line
hypertonic saline nebs

N-acetyl cysteine - liquifies mucus