Cystic Fibrosis Flashcards
What is Cystic Fibrosis?
Cystic fibrosis (CF) is a severely life-shortening genetic disease resulting from abnormalities in the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel found in cells lining the lungs, intestines, pancreatic ducts, sweat glands, and reproductive organs.
The most common clinical manifestations are
pancreatic dysfunction, resulting in calorie malabsorption; and lung disease, resulting from a cycle of mucus retention, infection, and inflammation.
membrane mutation
• Mutations in cystic fibrosis transmembrane conductance regulator CFTR result in abnormal salt transport by epithelial cells, resulting in thick, sticky secretions.
what happens to the pancreas?
this leads to blockage of exocrine ducts, early activation of pancreatic enzymes, and eventual autodestruction of the exocrine pancreas. Therefore, most patients require supplemental pancreatic enzymes.
what happens in the intestine?
bulky stools can lead to intestinal blockage.
what happens in the respiratory system?
the absence of CFTR function results in mucus retention, chronic infection, and inflammation that eventuate in the destruction of lung tissue.
• Lung disease is the most common cause of morbidity and mortality.
Newborn screening for CF.
- It is performed by quantifying serum immunoreactive trypsinogen from a dried heel-stick blood spot.
- Newborn screening allows for early diagnosis and treatment, and provides significant clinical benefits, including improved nutrition and cognition.
- It may also decrease lung disease and admissions to hospital.
Diagnosis of CF.
- generally present in infancy or early childhood with failure to thrive.
- will present with prolonged or severe bronchiolitis or recurrent respiratory complaints.
- Undiagnosed adults with CF, who are usually pancreatic sufficient, may present with chronic or recurrent bronchitis, sinusitis, or pancreatitis.
• The appearance of malnutrition
• Nasal polyps.
Investigations
- sweat test
- sweat test
- In this test a small amount of pilocarpine is placed on the skin of the forearm to stimulate sweating.
- To absorb the Pilocarpine into the skin, the area is stimulated by a small current from a battery, for around five minutes. This may produce a tingling sensation, but it does no harm and does not hurt.
- The stimulated sweat is collected in a microcapillary tube so that its chloride content can be measured.
sweat test ranges
- A negative sweat test (defined as a sweat chloride measurement of <30 mmol/L [<30 mEq/L] in all age groups) suggests that CF is unlikely. However, if questions remain, referral to a CF centre is recommended even in the presence of a negative sweat test.
- A positive sweat test (defined as a sweat chloride measurement of ≥60 mmol/L [≥60 mEq/L]) is consistent with CF and requires immediate referral to a CF centre
if sweat test is inconclusive then you use
- an initial ‘screen’ for the most common cystic
fibrosis transmembrane conductance regulator (CFTR) mutations.
• If two common mutations are not found, most laboratories have an option for sequencing more of the CFTR gene or the entire CFTR gene.
• Other ancillary tests include a sinus x-ray, which may show pansinusitis, and a deep throat swab performed after a gag, which may demonstrate respiratory pathogens, although neither of these are specific tests for CF.
Management of CF.
no cure
• Airway clearance should be performed to mobilise secretions from the airway walls into the lumen, where they can be coughed out.manual chest physiotherapy, active cycle of breathing, high-frequency oscillatory vest device (VEST therapy), flutter valve, or positive expiratory pressure mask.
• Non-invasive ventilation (NIV)
Inhaled therapy.
• Short-acting bronchodilators (e.g., salbutamol) are generally given before airway clearance
