Cystic Fibrosis Flashcards
What is cystic fibrosis?
It is a genetic condition that affects the mucus glands of multiple organs within the body
It specifically results in an increased viscosity of secretions
What is the inheritance of cystic fibrosis (CF)?
Autosomal recessive
What is the most common genetic disorder in caucasians?
Cystic fibrosis
Which genetic mutation is associated with cystic fibrosis? Which chromosome is this gene contained on?
A mutation of the transmembrane conductance regulator (CFTR) gene
Chromosome 7
What is the function of the CFTR gene?
It codes for a cAMP-regulated chloride channel, which enables efflux of chloride ions and inhibits influx of sodium ions
What is the most common mutation variant of the CFTR gene?
Delta-F508
Due to the genetic mutation of the CFTR gene, describe the pathophysiology of cystic fibrosis?
There is an increased amount of chloride ions that leave the cell, and an increased amount of sodium ions that are reabsorbed along with water
Subsequently, secretions become dehydrated and thickened
What are the twelve clinical features of cystic fibrosis?
Respiratory Tract Infections
Bronchiectasis
Meconium Ileus
Steatorrhoea
Rectal Prolapse
Pancreatic Insufficiency
Diabetes Mellitus
Failure To Thrive
Delayed Puberty
Infertility
Nasal Polyps
Finger Clubbing
How does cystic fibrosis result in recurrent respiratory tract infections and bronchiectasis?
This is due to thickened airway secretions resulting in reduced mucociliary clearance from the bronchi and increased salt concentration leadings to impaired bacterial defences
This leads to bacterial colonisation and lung inflammation
What is the first clinical feature of cystic fibrosis?
Meconium ileus
What is meconium?
It is the first stool a baby passes, which is usually black
How quickly after birth should meconium be passed?
Within 24 hours
What is meconium ileum?
It is defined as intestinal obstruction in the newborn, due to decreased digestive secretions resulting in the meconium being sticky
What are the three clinical features of meconium ileum?
The absence of meconium passing within 24 hours
Abdominal distension
Vomiting
What is steatorrhoea? How does cystic fibrosis result in steatorrhoea?
It is defined as the production of loose, greasy stools
It is due to thickened secretions blocking the pancreatic ducts resulting in reduced production of the fat digesting enzyme - lipase
What is pancreatic insufficiency?
It is defined as a condition in which the pancreas doesn’t produce enough of enzymes that are used to digest food within the small intestine
What are the two classifications of pancreatic insufficiency?
Endocrine
Exocrine
What is the clinical manifestation of endocrine pancreatic insufficiency?
Diabetes mellitus
What is the clinical manifestation of exocrine pancreatic insufficiency?
Malabsorption of nutrients and fat soluble vitamins
In males, how does cystic fibrosis result in infertility?
It can result in congenital bilateral absence of the vas deferens
This results in a blockage which means that the sperm in the testes are unable to mix with the ejaculate
In females, how does cystic fibrosis result in subfertility?
It is due to the thickened mucus secretions in the cervix and irregular menstruation cycles
How does cystic fibrosis result in nasal polyps?
This is due to thickened secretions leading to recurrent nasal infection
What are the seven investigations used to diagnose cystic fibrosis?
Newborn Blood Spot Test
Sweat Test
Genetic Testing
Sputum Culture
Faecal Elastase
Chest X-Ray (CXR)
CT Scan
What is another term for the newborn blood spot test?
Guthrie test
What is the newborn blood spot test?
It involves pricking the newborns heels to produce a blood sample and enable identification of nine serious health conditions
When is the newborn blood spot test conducted?
Between 5 and 9 days old
What newborn blood spot test result indicates cystic fibrosis?
Increased Immunoreactive Trypsinogen (IRT) Levels
What is conducted following a positive newborn blood spot test for cystic fibrosis?
The baby is referred for clinical assessment and further cystic fibrosis testing – sweat test
What is the gold standard investigation used to diagnose cystic fibrosis?
Sweat test
What is the sweat test?
It involves measuring the chloride concentration in sweat.
How do we conduct the sweat test?
This is conducted by the application of pilocarpine onto a patch of skin and the placement of electrodes on either side, which produce small electrical currents
This results in the production of sweat, which is then absorbed with gauze and tested for its chloride concentration
What sweat test result indicates cystic fibrosis?
Chloride concentration > 60mmol/l
In what two ways is genetic testing conducted antenatally?
Amniocentesis
Chorionic villus sampling
How do we conduct genetic postnatally?
Blood test
How is a sputum culture used to diagnose cystic fibrosis?
They are used to identify the microbial colonisers within the respiratory tract to enable appropriate management guidance
What are the seven microbial colonisers associated with cystic fibrosis?
Staphylococcus Aureus
Pseudomonas Aeruginosa
Escherichia Coli
Haemophilus Influenza
Klebsiella Pneumonia
Burkhodheria Cepacia
Aspergillus
What are the two most common microbial colonisers associated with cystic fibrosis?
Staphylococcus Aureus
Pseudomonas Aeruginosa
What is important to note about pseudomonas aeruginosa infections?
It is associated with an increased mortality and morbidity
It is a bacteria that can become resistant to multiple antibiotics, and is therefore difficult to provide treatment for
What is a faecal elastase test?
It involves measuring the amount of the human pancreas specific enzyme, elastase, is contained within faeces
How is a faecal elastase test used to diagnose cystic fibrosis?
This enables evaluation about the pancreas’s function and therefore identification of pancreatic insufficiency - which is indicated by a decreased level of faecal elastase
What are the two signs of cystic fibrosis on CXR?
Bronchiectasis Features
Hyperinflation
What are the three signs of cystic fibrosis on CT scan?
Bronchial Wall Thickening
Bronchiectasis Features
Mucus Plugging
In what six ways can we manage the respiratory manifestations of cystic fibrosis?
Annual Vaccinations
Chest Physiotherapy
Antibiotics
Bronchodilators
Mucolytics
Lung Transplant
What three annual vaccinations are administered to cystic fibrosis patients?
Pneumococcal
Influenza
Varicella
How is chest physiotherapy used to treat cystic fibrosis?
It improves respiratory function and enables clearance of mucus
This reduces the recurrence of respiratory tract infections
What prophylactic antibiotic is administered to cystic fibrosis patients? What infection does this reduce the risk of?
Oral flucloxacillin
Staph. aureus
What is the most common antibiotic administered to treat acute respiratory exacerbations of cystic fibrosis?
Azithromycin
What two antibiotics are used to treat pseudomonas aeruginosa infections?
Nebulised tobramycin
Oral ciprofloxacin
How are bronchodilators used to treat cystic fibrosis?
They are used to treat airway obstruction related to bronchoconstriction
Name two mucolytics
Hypertonic saline
Dornase alfa
What is the function of mucolytics?
They are enzymes that break down DNA material in respiratory secretions to make them less viscous and easier to clear
When is lung transplant considered in cystic fibrosis?
In cases of end stage respiratory failure
In what three ways do we treat the gastrointestinal manifestations?
Creon Tablets
Dietician Input
Diabetes Mellitus Management
When do we administer creon tablets to cystic fibrosis patients?
In those that develop pancreatic insufficiency
What is the function of creon tablets?
They contain the pancreatic enzyme lipase, which is used to digest fats within the gastrointestinal tract
Why is dietician input important in cystic fibrosis?
This is due to recurrent infection and malabsorption resulting in weight loss
In what two ways do dieticians promote weight gain in cystic fibrosis?
High calorie, high fat diet
Pancratic enzyme supplementation
How often should cystic fibrosis patients take pancreatic enzyme supplementation?
They should take this with every meal
What two nutritional management options are considered when first line options fail?
Enteral feeding via PEG
NG tube
How is diabetes managed in cystic fibrosis patients?
Insulin
How do we manage male infertility in cystic fibrosis patients?
Testicular sperm extraction
What are the six complications of cystic fibrosis?
Pneumothorax
Haemoptysis
Cor Pulmonale
Diabetes Mellitus
Chronic Liver Disease
Osteoporosis
