Resp - cystic fibrosis Flashcards
What peripheral signs are present in CF?
Clubbing of fingers
Short stature
What is the inheritance of CF?
autosomal recessive
Which mutation causes 78% of cystic fibrosis
ΔF508 mutation
How is screening for CF performed?
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
What does the biochemical screening performed on all babies in the UK (Guthrie heel-prick test) test for?
Phenylketonuria Congenital hypothyroidism Haemoglobinopathies Cystic Fibrosis MCAD deficiency
What nutrition may be advised in children with CF?
specialised formula
Which investigation is performed for CF?
CXR and sweat test
How does CF lead to failure to thrive?
Pan-nutrient Malabsorption (pancreatic insufficiency)
Increased requirements
Clinical chest signs of CF?
Expiratory wheeze
Hyperinflation of chest due to airtrapping
Coarse inspiratory crepitations
What is the defect in CF?
CF transmembrane regulator deficiency
cAMP dependent chlorine channel
Gene located on chromosome 7
How does CF affect cells in the lung?
Reduction in airway surface liquid layer and consequent impaired ciliary function and retention of mucopurulent secretions
What is the effect of CF on the GI system?
thick viscid meconium is produced
Meconium ileus in 10-20% of infants
Steatorrhoea
Pancreatic enzyme deficiency and malabsorption due to blockage of ducts
Which organisms often cause chronic chest infections in CF?
Initially Staph aureus
and Haemophilus influenza
Then pseudomonas aeruginoase and burkholderia species
What are the effects of chronic chest infections on the lungs?
Damage to bronchial wall, bronchiectasis and abscess formation
Persistent loose cough, productive of purulent sputum
What is meconium ileus? How is it managed?
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
How is CF diagnosed?
Concentration of NaCl in sweat is markedly elevated
60-125mmol/L
Normal 10-40
What is the purpose of physio in CF?
Clear airways of secretions
At least twice daily
Older patients can perform controlled deep breathing exercises and use physio devices
Physical exercise is beneficial
How is the respiratory aspect of CF managed?
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)
Describe the nutritional management of CF
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
Which medication may be useful to improve flow of bile
Ursodeoxycholic acid
How can the liver be affected in CF?
1/3 hepatomegaly
Abnormal LFTs
Rarely cirrhosis, portal HTN, liver failure
Transplant usually very successful
How is distal intestinal obstruction in meconium ileus managed?
Oral gastrografin
How is fertility affected by CF?
Females can have children if they can tolerate pregnancy
Males have absent vas deferens - infertile
What may be inserted into the chest of a CF patient?
Central venous line eg. portacath for IV antibiotics
There may be a scar on the stomach from meconium ileus operation
